Serial card 85-2026-1 manual

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Mike Ladwig

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Aug 1, 2022, 1:38:53 PM8/1/22
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I got the Hakko desoldering gun and replaced all the tin motherboard headers with gold plated ones: that seems to have fixed the DG-32D memory card issue I wrote about back in mid-July.

But...of course I now I'm working another issue. I'm reasonably sure I've tracked that down to a couple of bad capacitors on the front panel board.

In a case of while I'm at it, I decided to replace all the electrolytics, mylar, and tantalums I haven't already replaced. When I got to the serial card, I couldn't read some of the values on the existing parts. Turning to the manual for those values, I realized that the available scanned manual is for the 595-2032 of the card and I have the 85-2026 version. Most of the capacitors I want to replace on my card don't track in value to what is specified in the 2032 schematic or manual. 

Does anyone have the 85-2026 manual scanned? I've looked for it, only finding the 2032 version.

Thanks,
mike.

glenn.f...@gmail.com

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Aug 1, 2022, 2:17:36 PM8/1/22
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Mike: I presume this is for the H-8-5 serial/cassette board?  What  is the part number on the board itself?  There apparently were quite a few versions.  I have a 85-2109-1 but there are also at least 85-2110-2 and 85-2110-3 (my 2110-2 board is on loan to Norberto and my 2110-3 is currently a bare board).

 

All of my manuals and scans have document number 595-2032, however the 595-2032 manual calls out part # 85-2026-1 for the circuit board so I may be able to get what you need from the parts list in this manual!?  (I also have 595-2032-01 manual and that references circuit board part #85-2110-2 !!)

 

Let me know what board and what capacitor part numbers you’re trying to identify..

 

  • Glenn

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Mike Ladwig

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Aug 1, 2022, 3:20:00 PM8/1/22
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On the front, the board is labeled '85-2026-1' with '031677' in small type below it. Nothing else other than "Serial I/O" at the top. On the back, it is labeled '85-2026'.

Only one of the four capacitors I'm interested in has a component number: C107 (which *might* read 230+/-5% 500V). The other three suspect caps have '047' silkscreened on the board even though those values don't track with the 595-2032 schematic.

norberto.collado koyado.com

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Aug 1, 2022, 3:50:12 PM8/1/22
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Can we get a picture?
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Mike Ladwig <mdla...@gmail.com>
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Subject: Re: [sebhc] Serial card 85-2026-1 manual
 

Mike Ladwig

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Aug 1, 2022, 4:04:29 PM8/1/22
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IMG_4219.jpeg

rand...@hotmail.com

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Aug 1, 2022, 4:13:11 PM8/1/22
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It is a digital circuit. The values to care about are voltage and looks. In digital circuits capacitors are almost exclusively filter caps. You want high farads on the front-end and .01 to .1 to filter individual Ic's I use .1uf.

Unless it is a timer circuit look for parts that look original over value.

Sounds wrong but it's right. 


Randy

glenn.f...@gmail.com

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Aug 1, 2022, 4:58:18 PM8/1/22
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My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar”  based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent.

 

C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options.  For 300 BAUD C107 should be a 1000 pF (.001) polystyrene.  For 1200 BAUD it should be 230 pF mica.  The board has accommodations for either one since they have different dimensions…  based on the picture you sent your board has the 230 pF mica cap (since Heath tapes were recorded at 1200 BAUD this is how the board is recommended to be assembled in the manual, however I guess some other Kansas City tapes were at 300 ?? so I guess they allowed for this option…)

norberto.collado koyado.com

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Aug 1, 2022, 5:16:31 PM8/1/22
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I just put together my new H8-5 board, so I have all the parts in stock for a second board. I only bought parts for the board that uses .001uf and .1uf for the 74123 IC's. The second H8-5 from Glenn has different parts for same circuit.

What is the issue with your H8-5 board?


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Subject: RE: [sebhc] Serial card 85-2026-1 manual
 

Joseph Travis

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Aug 1, 2022, 10:06:57 PM8/1/22
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Mike -

What you have is the H8-5 Serial I/O board which also is the cassette tape interface.  First things first, don't waste your time or money replacing capacitors.  If it ain't broke, don't fix it.  If you google H8-5 manual (or schematic), you should find a PDF you can download.

If you would like to "update" the board to use a USB interface (see attached photo), this would allow you to download H8T (tape image) files from your PC to your H8 at speeds up to 9600 baud - 8 times faster than tape!

I used the (SparkFun USB Serial) FTDI board attached and wired directly to the 8251 USART.  The instructions are as follows:
NOTE: Make sure the solder pad on the bottom of the FTDI board is set for 5V (NOT 3.3V)!

1. Use clear RTV silicone to attach the FTDI board to the 8251 (IC 123)
2. Bend out the following pins on the 8251: 3, 19, 23, 25
3. Connect a wire between TxC (9) and RxC (25) on the 8251
4. Insert a 6 pin header into the FTDI board
5. Make the following connections between the FTDI board header and 8251:
FTDI <---> 8251
GND <---> GND (4)
CTS <---> RTS (23)
Vcc <---> N/C
TXO <---> RxD (3)
RXI <---> TxD (19)
DTR <---> N/C

You can set the SER RX / SER TX jumpers on the H8-5 board for 9600 baud (leave the TAPE TX set to 1200).  In operation, use the slide switch on the H8-5 set to PORT INTCHG when up/downloading tape image files with a PC then switch it to NORM to use it as the terminal interface.  This setup will require a terminal program on your PC, RealTerm is preferred.

Good luck with your system!

Regards,
Joe Travis n6ypc 





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20220214_200449.jpg

norberto.collado koyado.com

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Aug 1, 2022, 10:18:28 PM8/1/22
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We have two or more variations of the H8-5 board. Do we have the schematics for all these variations? Or just the one in Les web page?

glenn.f...@gmail.com

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Aug 2, 2022, 8:22:21 AM8/2/22
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I have pieces of the puzzle but may not have enough to paint the full picture.

 

I have two schematics labelled 595-2032 and 595-2032-01.  I also have the accompanying manuals with the same numbers.  The ‘01’ version is what’s on Les’ site https://sebhc.github.io/sebhc/documentation/hardware/H8/H8-5_AO_Ib_Sc.zip

 

The 2032 manual parts list shows the board as part  number 85-2026-1.  The 2032-01 shows part number 85-2110-2.

 

There are subtle differences in the parts lists.  For example, the board Mike is working on appears to be the earlier design which uses .047 caps at C101, C105 and C108.  The later design uses a .1uF mylar cap at C105 and C108. 

 

I don’t have any documentation that references the 85-2109 board in the parts list but I note that it has the 03-16-77 date silkscreened on it and the “2109” appears to be painted over a previous number (probably 2026? Since 2026 also has the 3/16/77 date).  Perhaps they just renumbered the board and 2109 and 2026 are essentially the same ??  then 2109 would be the “first generation” and 2110 the “second generation” of the board?

 

If its important it would be possible to do a detailed comparison of the parts lists and/or schematics to determine the differences…

image001.png

norberto.collado koyado.com

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Aug 2, 2022, 6:31:41 PM8/2/22
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Glenn,

I compared both boards, the “2109", the "2110" boards, and it is the two capacitors that changed. My new H8-Z5-4 board is based on the "2110" schematics. 

Thanks,
Norberto
Sent: Tuesday, August 2, 2022 5:22 AM

Mike Ladwig

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Aug 2, 2022, 8:27:58 PM8/2/22
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Thanks for looking into the board differences. Did you check the board circuit only, or also the silk screening text? As I read the 2032 assembly documentation, I think I noticed a few spots where the instructions didn't line up exactly with the board (although I didn't go back to check).

My board also has three instances of a plain number corresponding to 3-16-77

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norberto.collado koyado.com

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Aug 2, 2022, 9:36:25 PM8/2/22
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There are some additional differences. I see additional jumpers on the older board. Also on side 2 there are some blue cables on the older board.

 

Attached is a picture, so that you can compare and check.

 

Norberto

New_Old_H8-5-boards.jpg

Mike Ladwig

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Aug 2, 2022, 9:55:53 PM8/2/22
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>>> My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar”  based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent. C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options.  For 300 BAUD C107 should be a 1000 pF (.001) polystyrene.  For 1200 BAUD it should be 230 pF mica.

Perfect, thank you.

>>> other Kansas City tapes were at 300

The true Kansas City Standard was 300 baud only; the CUTS variant used by the H8 allowed 1200 baud. I don't recall the different implementations being very compatible, and I never did get the Interface Age floppy ROM to load.

norberto.collado koyado.com

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Aug 3, 2022, 1:03:08 PM8/3/22
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I ordered my caps from Tayda Electronics (https://www.taydaelectronics.com/). 

They have a lot of parts at very low prices.



Eventually we could replace it with newer cheaper parts.

Thanks,
Norberto
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Sent: Tuesday, August 2, 2022 6:55 PM

Glenn Roberts

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Aug 3, 2022, 1:26:21 PM8/3/22
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I think they ship from Thailand? But I've mostly had pretty quick response...

Definitely cheap. Good way to stock up on passive components...

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/SN6PR01MB3855AC95BBB33FA48612C3C2F79C9%40SN6PR01MB3855.prod.exchangelabs.com.

norberto.collado koyado.com

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Aug 3, 2022, 2:57:39 PM8/3/22
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Glenn,

There is a Heathkit H-8 Serial I/0 Card 85-2110-3 Brand New in ebay..

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Glenn Roberts

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Aug 3, 2022, 4:22:57 PM8/3/22
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Yes. been there a while due to hi price.  But I hadn’t noticed that it was a 2110-3 (with a 1979 date on the board) so Heath when through a lot of engineering changes to this product!

 

For fun I looked through the catalogs on Mark’s site and the H-8-5 was still available for sale in early 1983 (catalog #860).  By then it was marked down to $69… the H8 kit was listed but in the price field said “NO LONGER AVAILBLE”.

norberto.collado koyado.com

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Aug 3, 2022, 5:04:07 PM8/3/22
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The H8-5 circuit is fast when compared with the H89-5 card. So, I was impressed with the performance at such baud rate. The H8-5 it is a very well design board and I'm happy that I was able to clone it. I wonder what are the differences between -2 and -3. 

As you have a bare -3 board, can you take a picture to scan the parts for possible improvements for the new H8-Z5-4 board?

Future improvements for the new H8-Z5-4 card:
  1. Enable the use of 74HC4046 VCO. Currently uses CD4046 VCO.
  2. Replace 230pf capacitor (hard to find) with 220pf + 10pf caps and tested it out.
Sent: Wednesday, August 3, 2022 1:22 PM
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Subject: RE: [sebhc] Serial card 85-2026-1 manual
 

glenn.f...@gmail.com

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Aug 3, 2022, 6:24:18 PM8/3/22
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Here’s my pic of the 2110-3 board

 

https://photos.app.goo.gl/wQxjMyjckBNf3dAHA

 

this one had been somewhat cannibalized by the previous owner so at some point I de-soldered the parts to have a clean board.

 

Let me know if you spot any differences with the previous designs..

 

  • Glenn

norberto.collado koyado.com

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Aug 3, 2022, 7:06:41 PM8/3/22
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Thanks!

I wonder what are the "J" "J" jumpers!!! I did not see on the schematics or did I miss them???


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of glenn.f...@gmail.com <glenn.f...@gmail.com>
Sent: Wednesday, August 3, 2022 3:24 PM

rw...@robhome.com

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Aug 3, 2022, 7:18:23 PM8/3/22
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I have an assembled 2110-3 board and I have two jumpers in those 5 holes. Here are front and back pics.

[cid:image0...@01D8A765.5CA321C0]

[cid:image0...@01D8A765.5CA321C0]


From: se...@googlegroups.com<mailto:se...@googlegroups.com> se...@googlegroups.com<mailto:se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 3, 2022 6:07 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual

Thanks!

I wonder what are the "J" "J" jumpers!!! I did not see on the schematics or did I miss them???

[cid:image0...@01D8A764.FBA3E4E0]
________________________________
From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of glenn.f...@gmail.com<mailto:glenn.f...@gmail.com> <glenn.f...@gmail.com<mailto:glenn.f...@gmail.com>>
Sent: Wednesday, August 3, 2022 3:24 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: RE: [sebhc] Serial card 85-2026-1 manual


Here’s my pic of the 2110-3 board



https://photos.app.goo.gl/wQxjMyjckBNf3dAHA



this one had been somewhat cannibalized by the previous owner so at some point I de-soldered the parts to have a clean board.



Let me know if you spot any differences with the previous designs..



* Glenn





From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 03, 2022 5:04 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



The H8-5 circuit is fast when compared with the H89-5 card. So, I was impressed with the performance at such baud rate. The H8-5 it is a very well design board and I'm happy that I was able to clone it. I wonder what are the differences between -2 and -3.



As you have a bare -3 board, can you take a picture to scan the parts for possible improvements for the new H8-Z5-4 board?



Future improvements for the new H8-Z5-4 card:

1. Enable the use of 74HC4046 VCO. Currently uses CD4046 VCO.
2. Replace 230pf capacitor (hard to find) with 220pf + 10pf caps and tested it out.

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Glenn Roberts <glenn.f...@gmail.com<mailto:glenn.f...@gmail.com>>
Sent: Wednesday, August 3, 2022 1:22 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: RE: [sebhc] Serial card 85-2026-1 manual



Yes. been there a while due to hi price. But I hadn’t noticed that it was a 2110-3 (with a 1979 date on the board) so Heath when through a lot of engineering changes to this product!



For fun I looked through the catalogs on Mark’s site and the H-8-5 was still available for sale in early 1983 (catalog #860<https://heathkit.garlanger.com/catalogs/1983/Heathkit_Catalog_860.pdf>). By then it was marked down to $69… the H8 kit was listed but in the price field said “NO LONGER AVAILBLE”.







From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 03, 2022 2:58 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



Glenn,



There is a Heathkit H-8 Serial I/0 Card 85-2110-3 Brand New in ebay..



https://www.ebay.com/itm/284816690637?hash=item425065cdcd:g:17UAAOSwZb5igetD

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Glenn Roberts <glenn.f...@gmail.com<mailto:glenn.f...@gmail.com>>
Sent: Wednesday, August 3, 2022 10:26 AM
To: <se...@googlegroups.com<mailto:se...@googlegroups.com>> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



I think they ship from Thailand? But I've mostly had pretty quick response...



Definitely cheap. Good way to stock up on passive components...



On Wed, Aug 3, 2022, 1:03 PM norberto.collado koyado.com<http://koyado.com> <norberto...@koyado.com<mailto:norberto...@koyado.com>> wrote:

I ordered my caps from Tayda Electronics (https://www.taydaelectronics.com/).



They have a lot of parts at very low prices.



0.047 uf = https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/47nf-0-047uf-100v-5-mylar-film-capacitors.html

[https://www.taydaelectronics.com/media/catalog/product/cache/fe145b132621b0983b6b561aaca98059/M/Y/MYLAR-1_100.jpg]<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/47nf-0-047uf-100v-5-mylar-film-capacitors.html>

47nF 0.047uF 100V 5% Mylar Film Capacitors<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/47nf-0-047uf-100v-5-mylar-film-capacitors.html>

Lead Free - Get It Fast - Same Day Shipping

www.taydaelectronics.com<http://www.taydaelectronics.com>





0.1uf = https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/0-1uf-100v-5-jfa-mylar-film-capacitors.html

[https://www.taydaelectronics.com/media/catalog/product/cache/fe145b132621b0983b6b561aaca98059/M/Y/MYLAR.jpg_10.jpg]<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/0-1uf-100v-5-jfa-mylar-film-capacitors.html>

0.1uF 100V 5% JFA Mylar Film Capacitors<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/0-1uf-100v-5-jfa-mylar-film-capacitors.html>

JB Capacitors - Get It Fast - Same Day Shipping

www.taydaelectronics.com<http://www.taydaelectronics.com>

For 230pf: (they are expensive and they also have the 1% cap still more expensive).



https://www.tedss.com/2020091053



Eventually we could replace it with newer cheaper parts.



Thanks,

Norberto

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Mike Ladwig <mdla...@gmail.com<mailto:mdla...@gmail.com>>
Sent: Tuesday, August 2, 2022 6:55 PM
To: SEBHC <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



>>> My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar” based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent. C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options. For 300 BAUD C107 should be a 1000 pF (.001) polystyrene. For 1200 BAUD it should be 230 pF mica.



Perfect, thank you.



>>> other Kansas City tapes were at 300



The true Kansas City Standard was 300 baud only; the CUTS variant used by the H8 allowed 1200 baud. I don't recall the different implementations being very compatible, and I never did get the Interface Age floppy ROM to load.

On Monday, August 1, 2022 at 1:58:18 PM UTC-7 Glenn wrote:

My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar” based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent.



C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options. For 300 BAUD C107 should be a 1000 pF (.001) polystyrene. For 1200 BAUD it should be 230 pF mica. The board has accommodations for either one since they have different dimensions… based on the picture you sent your board has the 230 pF mica cap (since Heath tapes were recorded at 1200 BAUD this is how the board is recommended to be assembled in the manual, however I guess some other Kansas City tapes were at 300 ?? so I guess they allowed for this option…)



* Glenn





From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of Mike Ladwig
Sent: Monday, August 01, 2022 3:20 PM
To: SEBHC <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



On the front, the board is labeled '85-2026-1' with '031677' in small type below it. Nothing else other than "Serial I/O" at the top. On the back, it is labeled '85-2026'.



Only one of the four capacitors I'm interested in has a component number: C107 (which *might* read 230+/-5% 500V). The other three suspect caps have '047' silkscreened on the board even though those values don't track with the 595-2032 schematic.

On Monday, August 1, 2022 at 11:17:36 AM UTC-7 Glenn wrote:

Mike: I presume this is for the H-8-5 serial/cassette board? What is the part number on the board itself? There apparently were quite a few versions. I have a 85-2109-1 but there are also at least 85-2110-2 and 85-2110-3 (my 2110-2 board is on loan to Norberto and my 2110-3 is currently a bare board).



All of my manuals and scans have document number 595-2032, however the 595-2032 manual calls out part # 85-2026-1 for the circuit board so I may be able to get what you need from the parts list in this manual!? (I also have 595-2032-01 manual and that references circuit board part #85-2110-2 !!)



Let me know what board and what capacitor part numbers you’re trying to identify..



* Glenn





From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of Mike Ladwig
Sent: Monday, August 01, 2022 1:39 PM
To: SEBHC <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: [sebhc] Serial card 85-2026-1 manual



I got the Hakko desoldering gun and replaced all the tin motherboard headers with gold plated ones: that seems to have fixed the DG-32D memory card issue I wrote about back in mid-July.



But...of course I now I'm working another issue. I'm reasonably sure I've tracked that down to a couple of bad capacitors on the front panel board.



In a case of while I'm at it, I decided to replace all the electrolytics, mylar, and tantalums I haven't already replaced. When I got to the serial card, I couldn't read some of the values on the existing parts. Turning to the manual for those values, I realized that the available scanned manual is for the 595-2032 of the card and I have the 85-2026 version. Most of the capacitors I want to replace on my card don't track in value to what is specified in the 2032 schematic or manual.



Does anyone have the 85-2026 manual scanned? I've looked for it, only finding the 2032 version.



Thanks,

mike.

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norberto.collado koyado.com

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Aug 3, 2022, 7:36:10 PM8/3/22
to sebhc Google Group
Thank you!

It is to control pins 1-2 and 9 on IC115. So, it is wired properly on the new H8-Z5-4 board. 



At this time, I cannot see any differences on this -3 version. It looks the same as -2 version. My focus was on the caps for the 74123 and VCO IC's.
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of rw...@robhome.com <rw...@robhome.com>
Sent: Wednesday, August 3, 2022 4:17 PM

To: sebhc Google Group <se...@googlegroups.com>
Subject: RE: [sebhc] Serial card 85-2026-1 manual
 

I have an assembled 2110-3 board and I have two jumpers in those 5 holes.  Here are front and back pics.

 

 

 

 

From: se...@googlegroups.com se...@googlegroups.com On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 3, 2022 6:07 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual

 

Thanks!

 

I wonder what are the "J" "J" jumpers!!! I did not see on the schematics or did I miss them???

 

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of glenn.f...@gmail.com <glenn.f...@gmail.com>
Sent: Wednesday, August 3, 2022 3:24 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: RE: [sebhc] Serial card 85-2026-1 manual

 

Here’s my pic of the 2110-3 board

 

https://photos.app.goo.gl/wQxjMyjckBNf3dAHA

 

this one had been somewhat cannibalized by the previous owner so at some point I de-soldered the parts to have a clean board.

 

Let me know if you spot any differences with the previous designs..

 

  • Glenn

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 03, 2022 5:04 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Serial card 85-2026-1 manual

 

The H8-5 circuit is fast when compared with the H89-5 card. So, I was impressed with the performance at such baud rate. The H8-5 it is a very well design board and I'm happy that I was able to clone it. I wonder what are the differences between -2 and -3. 

 

As you have a bare -3 board, can you take a picture to scan the parts for possible improvements for the new H8-Z5-4 board?

 

Future improvements for the new H8-Z5-4 card:

  1. Enable the use of 74HC4046 VCO. Currently uses CD4046 VCO.
  1. Replace 230pf capacitor (hard to find) with 220pf + 10pf caps and tested it out.

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Wednesday, August 3, 2022 1:22 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: RE: [sebhc] Serial card 85-2026-1 manual

 

Yes. been there a while due to hi price.  But I hadn’t noticed that it was a 2110-3 (with a 1979 date on the board) so Heath when through a lot of engineering changes to this product!

 

For fun I looked through the catalogs on Mark’s site and the H-8-5 was still available for sale in early 1983 (catalog #860).  By then it was marked down to $69… the H8 kit was listed but in the price field said “NO LONGER AVAILBLE”.

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 03, 2022 2:58 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Serial card 85-2026-1 manual

 

Glenn,

 

There is a Heathkit H-8 Serial I/0 Card 85-2110-3 Brand New in ebay..

 

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Wednesday, August 3, 2022 10:26 AM
To: <se...@googlegroups.com> <se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual

 

I think they ship from Thailand? But I've mostly had pretty quick response...

 

Definitely cheap. Good way to stock up on passive components...

 

On Wed, Aug 3, 2022, 1:03 PM norberto.collado koyado.com <norberto...@koyado.com> wrote:

I ordered my caps from Tayda Electronics (https://www.taydaelectronics.com/). 

 

They have a lot of parts at very low prices.

 

Lead Free - Get It Fast - Same Day Shipping

 

 

JB Capacitors - Get It Fast - Same Day Shipping

For 230pf: (they are expensive and they also have the 1% cap still more expensive).

 

 

Eventually we could replace it with newer cheaper parts.

 

Thanks,

Norberto

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Mike Ladwig <mdla...@gmail.com>
Sent: Tuesday, August 2, 2022 6:55 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual

 

>>> My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar”  based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent. C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options.  For 300 BAUD C107 should be a 1000 pF (.001) polystyrene.  For 1200 BAUD it should be 230 pF mica.

 

Perfect, thank you.

 

>>> other Kansas City tapes were at 300

 

The true Kansas City Standard was 300 baud only; the CUTS variant used by the H8 allowed 1200 baud. I don't recall the different implementations being very compatible, and I never did get the Interface Age floppy ROM to load.

On Monday, August 1, 2022 at 1:58:18 PM UTC-7 Glenn wrote:

My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar”  based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent.

 

C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options.  For 300 BAUD C107 should be a 1000 pF (.001) polystyrene.  For 1200 BAUD it should be 230 pF mica.  The board has accommodations for either one since they have different dimensions…  based on the picture you sent your board has the 230 pF mica cap (since Heath tapes were recorded at 1200 BAUD this is how the board is recommended to be assembled in the manual, however I guess some other Kansas City tapes were at 300 ?? so I guess they allowed for this option…)

 

  • Glenn

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mike Ladwig
Sent: Monday, August 01, 2022 3:20 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual

 

On the front, the board is labeled '85-2026-1' with '031677' in small type below it. Nothing else other than "Serial I/O" at the top. On the back, it is labeled '85-2026'.

 

Only one of the four capacitors I'm interested in has a component number: C107 (which *might* read 230+/-5% 500V). The other three suspect caps have '047' silkscreened on the board even though those values don't track with the 595-2032 schematic.

On Monday, August 1, 2022 at 11:17:36 AM UTC-7 Glenn wrote:

Mike: I presume this is for the H-8-5 serial/cassette board?  What  is the part number on the board itself?  There apparently were quite a few versions.  I have a 85-2109-1 but there are also at least 85-2110-2 and 85-2110-3 (my 2110-2 board is on loan to Norberto and my 2110-3 is currently a bare board).

 

All of my manuals and scans have document number 595-2032, however the 595-2032 manual calls out part # 85-2026-1 for the circuit board so I may be able to get what you need from the parts list in this manual!?  (I also have 595-2032-01 manual and that references circuit board part #85-2110-2 !!)

 

Let me know what board and what capacitor part numbers you’re trying to identify..

 

  • Glenn

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mike Ladwig
Sent: Monday, August 01, 2022 1:39 PM
To: SEBHC <se...@googlegroups.com>
Subject: [sebhc] Serial card 85-2026-1 manual

 

I got the Hakko desoldering gun and replaced all the tin motherboard headers with gold plated ones: that seems to have fixed the DG-32D memory card issue I wrote about back in mid-July.

 

But...of course I now I'm working another issue. I'm reasonably sure I've tracked that down to a couple of bad capacitors on the front panel board.

 

In a case of while I'm at it, I decided to replace all the electrolytics, mylar, and tantalums I haven't already replaced. When I got to the serial card, I couldn't read some of the values on the existing parts. Turning to the manual for those values, I realized that the available scanned manual is for the 595-2032 of the card and I have the 85-2026 version. Most of the capacitors I want to replace on my card don't track in value to what is specified in the 2032 schematic or manual. 

 

Does anyone have the 85-2026 manual scanned? I've looked for it, only finding the 2032 version.

 

Thanks,

mike.

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rw...@robhome.com

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Aug 3, 2022, 8:02:55 PM8/3/22
to sebhc Google Group
I’m going through my assembly manual. I bought this manual with the board as part of a whole computer I purchased. The manual has the inserts inserted, so I’m looking for the differences.

On an inserted page (16) the addition was to add L101, the 100 uH coil. The original manual (before the inserts) didn’t list L101, the insert added the coil.

I was looking to see if the installation manual showed the two jumps and “why” they are soldered in where they are. I couldn’t find any mention of them. I wonder if this board came from the factory with those two jumpers already there…

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 3, 2022 6:36 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual

Thank you!

It is to control pins 1-2 and 9 on IC115. So, it is wired properly on the new H8-Z5-4 board.

[cid:image0...@01D8A76B.0A57DFE0]

At this time, I cannot see any differences on this -3 version. It looks the same as -2 version. My focus was on the caps for the 74123 and VCO IC's.
________________________________
From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of rw...@robhome.com<mailto:rw...@robhome.com> <rw...@robhome.com<mailto:rw...@robhome.com>>
Sent: Wednesday, August 3, 2022 4:17 PM
To: sebhc Google Group <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: RE: [sebhc] Serial card 85-2026-1 manual


I have an assembled 2110-3 board and I have two jumpers in those 5 holes. Here are front and back pics.



[cid:image0...@01D8A76B.0A57DFE0]



[cid:image0...@01D8A76B.0A57DFE0]





From: se...@googlegroups.com<mailto:se...@googlegroups.com> se...@googlegroups.com<mailto:se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 3, 2022 6:07 PM
To: sebhc Google Group <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



Thanks!



I wonder what are the "J" "J" jumpers!!! I did not see on the schematics or did I miss them???



[cid:image0...@01D8A76B.0A57DFE0]

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of glenn.f...@gmail.com<mailto:glenn.f...@gmail.com> <glenn.f...@gmail.com<mailto:glenn.f...@gmail.com>>
Sent: Wednesday, August 3, 2022 3:24 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: RE: [sebhc] Serial card 85-2026-1 manual



Here’s my pic of the 2110-3 board



https://photos.app.goo.gl/wQxjMyjckBNf3dAHA



this one had been somewhat cannibalized by the previous owner so at some point I de-soldered the parts to have a clean board.



Let me know if you spot any differences with the previous designs..



* Glenn





From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 03, 2022 5:04 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



The H8-5 circuit is fast when compared with the H89-5 card. So, I was impressed with the performance at such baud rate. The H8-5 it is a very well design board and I'm happy that I was able to clone it. I wonder what are the differences between -2 and -3.



As you have a bare -3 board, can you take a picture to scan the parts for possible improvements for the new H8-Z5-4 board?



Future improvements for the new H8-Z5-4 card:

1. Enable the use of 74HC4046 VCO. Currently uses CD4046 VCO.
2. Replace 230pf capacitor (hard to find) with 220pf + 10pf caps and tested it out.

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Glenn Roberts <glenn.f...@gmail.com<mailto:glenn.f...@gmail.com>>
Sent: Wednesday, August 3, 2022 1:22 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: RE: [sebhc] Serial card 85-2026-1 manual



Yes. been there a while due to hi price. But I hadn’t noticed that it was a 2110-3 (with a 1979 date on the board) so Heath when through a lot of engineering changes to this product!



For fun I looked through the catalogs on Mark’s site and the H-8-5 was still available for sale in early 1983 (catalog #860<https://heathkit.garlanger.com/catalogs/1983/Heathkit_Catalog_860.pdf>). By then it was marked down to $69… the H8 kit was listed but in the price field said “NO LONGER AVAILBLE”.







From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, August 03, 2022 2:58 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



Glenn,



There is a Heathkit H-8 Serial I/0 Card 85-2110-3 Brand New in ebay..



https://www.ebay.com/itm/284816690637?hash=item425065cdcd:g:17UAAOSwZb5igetD

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Glenn Roberts <glenn.f...@gmail.com<mailto:glenn.f...@gmail.com>>
Sent: Wednesday, August 3, 2022 10:26 AM
To: <se...@googlegroups.com<mailto:se...@googlegroups.com>> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



I think they ship from Thailand? But I've mostly had pretty quick response...



Definitely cheap. Good way to stock up on passive components...



On Wed, Aug 3, 2022, 1:03 PM norberto.collado koyado.com<http://koyado.com> <norberto...@koyado.com<mailto:norberto...@koyado.com>> wrote:

I ordered my caps from Tayda Electronics (https://www.taydaelectronics.com/).



They have a lot of parts at very low prices.



0.047 uf = https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/47nf-0-047uf-100v-5-mylar-film-capacitors.html

[https://www.taydaelectronics.com/media/catalog/product/cache/fe145b132621b0983b6b561aaca98059/M/Y/MYLAR-1_100.jpg]<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/47nf-0-047uf-100v-5-mylar-film-capacitors.html>

47nF 0.047uF 100V 5% Mylar Film Capacitors<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/47nf-0-047uf-100v-5-mylar-film-capacitors.html>

Lead Free - Get It Fast - Same Day Shipping

www.taydaelectronics.com<http://www.taydaelectronics.com>





0.1uf = https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/0-1uf-100v-5-jfa-mylar-film-capacitors.html

[https://www.taydaelectronics.com/media/catalog/product/cache/fe145b132621b0983b6b561aaca98059/M/Y/MYLAR.jpg_10.jpg]<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/0-1uf-100v-5-jfa-mylar-film-capacitors.html>

0.1uF 100V 5% JFA Mylar Film Capacitors<https://www.taydaelectronics.com/capacitors/polyester-mylar-film-capacitors/0-1uf-100v-5-jfa-mylar-film-capacitors.html>

JB Capacitors - Get It Fast - Same Day Shipping

www.taydaelectronics.com<http://www.taydaelectronics.com>

For 230pf: (they are expensive and they also have the 1% cap still more expensive).



https://www.tedss.com/2020091053



Eventually we could replace it with newer cheaper parts.



Thanks,

Norberto

________________________________

From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Mike Ladwig <mdla...@gmail.com<mailto:mdla...@gmail.com>>
Sent: Tuesday, August 2, 2022 6:55 PM
To: SEBHC <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



>>> My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar” based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent. C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options. For 300 BAUD C107 should be a 1000 pF (.001) polystyrene. For 1200 BAUD it should be 230 pF mica.



Perfect, thank you.



>>> other Kansas City tapes were at 300



The true Kansas City Standard was 300 baud only; the CUTS variant used by the H8 allowed 1200 baud. I don't recall the different implementations being very compatible, and I never did get the Interface Age floppy ROM to load.

On Monday, August 1, 2022 at 1:58:18 PM UTC-7 Glenn wrote:

My manual (the same one that lists the board part # as 85-2026-1) lists C101, C105 and C108 as “.047 uF Mylar” based on the assembly manual I believe these are the three green capacitors in the left quadrant of the board as seen in the picture you sent.



C107 can have two values depending on the desired speed for the tape interface: 300 BAUD and 1200 BAUD were the two supported options. For 300 BAUD C107 should be a 1000 pF (.001) polystyrene. For 1200 BAUD it should be 230 pF mica. The board has accommodations for either one since they have different dimensions… based on the picture you sent your board has the 230 pF mica cap (since Heath tapes were recorded at 1200 BAUD this is how the board is recommended to be assembled in the manual, however I guess some other Kansas City tapes were at 300 ?? so I guess they allowed for this option…)



* Glenn





From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of Mike Ladwig
Sent: Monday, August 01, 2022 3:20 PM
To: SEBHC <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] Serial card 85-2026-1 manual



On the front, the board is labeled '85-2026-1' with '031677' in small type below it. Nothing else other than "Serial I/O" at the top. On the back, it is labeled '85-2026'.



Only one of the four capacitors I'm interested in has a component number: C107 (which *might* read 230+/-5% 500V). The other three suspect caps have '047' silkscreened on the board even though those values don't track with the 595-2032 schematic.

On Monday, August 1, 2022 at 11:17:36 AM UTC-7 Glenn wrote:

Mike: I presume this is for the H-8-5 serial/cassette board? What is the part number on the board itself? There apparently were quite a few versions. I have a 85-2109-1 but there are also at least 85-2110-2 and 85-2110-3 (my 2110-2 board is on loan to Norberto and my 2110-3 is currently a bare board).



All of my manuals and scans have document number 595-2032, however the 595-2032 manual calls out part # 85-2026-1 for the circuit board so I may be able to get what you need from the parts list in this manual!? (I also have 595-2032-01 manual and that references circuit board part #85-2110-2 !!)



Let me know what board and what capacitor part numbers you’re trying to identify..



* Glenn





From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> On Behalf Of Mike Ladwig
Sent: Monday, August 01, 2022 1:39 PM
To: SEBHC <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: [sebhc] Serial card 85-2026-1 manual



I got the Hakko desoldering gun and replaced all the tin motherboard headers with gold plated ones: that seems to have fixed the DG-32D memory card issue I wrote about back in mid-July.



But...of course I now I'm working another issue. I'm reasonably sure I've tracked that down to a couple of bad capacitors on the front panel board.



In a case of while I'm at it, I decided to replace all the electrolytics, mylar, and tantalums I haven't already replaced. When I got to the serial card, I couldn't read some of the values on the existing parts. Turning to the manual for those values, I realized that the available scanned manual is for the 595-2032 of the card and I have the 85-2026 version. Most of the capacitors I want to replace on my card don't track in value to what is specified in the 2032 schematic or manual.



Does anyone have the 85-2026 manual scanned? I've looked for it, only finding the 2032 version.



Thanks,

mike.

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image007.png

Glenn Roberts

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Aug 4, 2022, 5:26:15 AM8/4/22
to se...@googlegroups.com
In my copy of the H-8-5 assembly manual inserting the two jumpers is the very first instruction. I don’t think they’re configuration jumpers but I see no reference to their purpose in the manual…

Sent from my iPad

> On Aug 3, 2022, at 8:02 PM, rw...@robhome.com wrote:
>
> I’m going through my assembly manual. I bought this manual with the board as part of a whole computer I purchased. The manual has the inserts inserted, so I’m looking for the differences.
> To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.
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winmail.dat

glenn.f...@gmail.com

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Aug 26, 2022, 7:21:32 AM8/26/22
to se...@googlegroups.com

I decided to try and replicate Joe Travis’ clever use of the Sparkfun USB/serial breakout board for loading H8T files.  I chose to build a little daughterboard (which we could fabricate as a small PCB if there was sufficient interest):

 

https://photos.app.goo.gl/LZVkY7e1LvuwzgE9A

 

I *was* able to replicate Joe’s results.  I can load Extended BH Basic version 6 in just 13 seconds (at 9600 BAUD).  This is with an 8080 CPU at 2.048 Mhz.  For reasons I don’t understand when I use a Z80 board (Rev 2.6 board at 2.048 Mhz) I have to insert a 2ms delay after each byte.  Without that the loads do not succeed (presumably dropped bytes).  This of course means that downloads are slower with the Z80! (28 seconds for EXBASIC6).  I installed my old speed board in the system so that I can adjust CPU speed via the front panel keypad. With the Z80 at 4Mhz I get essentially the same result as the 8080 – EXBASIC6 loads in 13 seconds (no character waits needed).  I have been unable to load anything at higher speeds (8 and 10 Mhz).  I haven’t had time to explore why that is. Also I see front panel display issues at 10 Mhz, which is odd as this is the new front panel.  Perhaps I have a jumper set wrong…

 

Norberto has suggested using the H8-5 as a storage backup system.  Given the rates I’m seeing (937 Bytes/sec.) it would seem possible to load or unload an entire H17 disk in under 2 minutes. It would take longer than that to restore a disk (you’d presumably read a track at a time from the H8-5 and write it, repeating that process 40 times, similar to the H89LDR program).

 

I don’t think I’ve seen the new H8-5 board show up on Todd’s list yet (?), but when it becomes available I plan to build one out and experiment some more…

image001.png

norberto.collado koyado.com

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Aug 26, 2022, 1:04:40 PM8/26/22
to se...@googlegroups.com
Glenn,

Nice job on prototyping such board.

I will re-test once I get home with the Z80 at 4/8/10MHz to see if any issues with the new board.

The new H8-Z5-4 board does not use the Z80 CPU clock as the original H8-5 does. The new H8-Z5-4 board has it's own oscillator. I do not expect any issues, hopefully.

Norberto



Sent: Friday, August 26, 2022 4:21 AM

Joseph Travis

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Aug 26, 2022, 2:16:21 PM8/26/22
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I had a look at the schematics for the H8-5 and the 8080 CPU board.  As Norberto alluded to, the 02 (phase 2) clock coming from the CPU board is likely too fast for the 8251s on the H8-5 board when running in excess of 4 MHz.  So anyone running a CPU faster than 4 MHz while using a H8-5 will probably need to "downshift" when running tape based  programs.

Joe


norberto.collado koyado.com

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Aug 26, 2022, 2:32:08 PM8/26/22
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The OSC circuit for the new H8-Z5-4 is this one and it follows the specs for the 8251's,




From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Joseph Travis <jtravi...@gmail.com>
Sent: Friday, August 26, 2022 11:16 AM
To: se...@googlegroups.com <se...@googlegroups.com>

norberto.collado koyado.com

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Aug 27, 2022, 2:38:15 PM8/27/22
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I tested the new H8-Z5-4 board at 2/4/8/10 MHz with the new front panel without any issues.

 

Because the clock is fixed, having the CPU clock at 2/4/8/10 MHz and baud rate at 9600bps, it takes 28 seconds to download EXTBASIC6 into the H8 memory.

 

At 1200bps and at CPU clock at 2/4/8/10 MHz, it took 1 minute and 44 seconds to download same file.

 

Also had to insert the 2ms delay to avoid failures during the download. This is expected as the CPU is interrupted every 2ms as well.

 

Thanks,

 

Norberto

Joseph Travis

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Aug 27, 2022, 3:44:01 PM8/27/22
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It only takes 12 seconds to download EXBASIC6 at 9600 baud on my 2 MHz H8 using an 8080 CPU board and the original H8-5.

Joe


norberto.collado koyado.com

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Aug 27, 2022, 6:06:09 PM8/27/22
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The Z80 has more overhead when compared to the 8080A, such as wait states automatically inserted + the Dynamic RAM refresh cycles. The 8080A will give you best performance at 2MHZ.

 

To get 12 seconds or less on the new H8-Z5-4 board, I will need to drive the 8251A clock to 4 or 6 MHz. I do not see the need to do so, as we want a very stable design per specs.

 

I tested uploading from the cassette tape to the H8 memory at 10MHz and it worked fine on the new H8-Z5-4 board. It doesn’t get better than this.

 

Norberto

norberto.collado koyado.com

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Aug 28, 2022, 9:14:06 PM8/28/22
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Norberto has suggested using the H8-5 as a storage backup system.  

Glenn,

If the user has an H8-5, 8080A CPU, H17, and a blank hard sector floppy, how to best enable such system into booting HDOS or TEST17 by using the H8-5 controller!

Thanks,
Norberto
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Saturday, August 27, 2022 3:06 PM

Glenn Roberts

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Aug 28, 2022, 9:56:24 PM8/28/22
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Yes, that’s the question. Let me ponder it…

Sent from my iPad

On Aug 28, 2022, at 9:14 PM, norberto.collado koyado.com <norberto...@koyado.com> wrote:



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