Initial H8 Backplane test!

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norberto...@koyado.com

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Jul 10, 2021, 1:22:21 AMJul 10
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I decided to power up the new H8 backplane to test voltages on the H8 bus. On power-on the power supply turns on and then it shutdown. It seems that I do not have minimum load on the ATX PSU to keep it on. The only voltage I get is the Standby voltage along with it’s LED. I do have the “blue” jumper installed to keep it “on” all the time.

 

Do anyone knows the minimum A load to keep it running? Not sure if minimum load is on the +5 or +3.3 voltage rails. I hope I do not have a bad PDU as it was expensive to buy.

 

Thanks,

Norberto

 



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IMG_9320.jpg

Steven Feinsmith

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Jul 10, 2021, 1:32:29 AMJul 10
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norberto...@koyado.com

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Jul 10, 2021, 1:47:28 AMJul 10
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Thanks for the link, very detailed information. Let me also check the PSU specs as well.

 

Norberto

image001.jpg

Pat OConnor

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Jul 10, 2021, 3:09:32 AMJul 10
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Many years ago I used an ATX supply on my bench. As I recall, witch is questionable the way my memory is, you needed a 50 ma load on the 5 or 12 line. I hope this helps. 
Pat


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On Jul 10, 2021, at 1:47 AM, norberto...@koyado.com wrote:



Thanks for the link, very detailed information. Let me also check the PSU specs as well.

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Steven Feinsmith
Sent: Friday, July 9, 2021 10:32 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Initial H8 Backplane test!

 


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto...@koyado.com <norberto...@koyado.com>
Sent: Saturday, July 10, 2021 1:22:15 AM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: [sebhc] Initial H8 Backplane test!

 

I decided to power up the new H8 backplane to test voltages on the H8 bus. On power-on the power supply turns on and then it shutdown. It seems that I do not have minimum load on the ATX PSU to keep it on. The only voltage I get is the Standby voltage along with it’s LED. I do have the “blue” jumper installed to keep it “on” all the time.

 

Do anyone knows the minimum A load to keep it running? Not sure if minimum load is on the +5 or +3.3 voltage rails. I hope I do not have a bad PDU as it was expensive to buy.

 

Thanks,

Norberto

 

<image001.jpg>



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norberto...@koyado.com

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Jul 10, 2021, 3:23:40 AMJul 10
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Thanks! The original Heathkit backplane as a 150 ohm 2W resistor to discharged the big blue capacitor. Let me buy a 100 ohm 2W instead to get the 50ma range.

 

Norberto

Terry Gulczynski

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Jul 10, 2021, 10:09:30 AMJul 10
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You can do the resistor thing if you want, but for a quick test to check
the power supply, simply connect a spinny-disk IDE drive - it's more
than enough load to meet any minimum the power supply might require.

(We all have a few IDE drives on a shelf somewhere, right?)


Terry



On 7/10/2021 3:23 AM, norberto...@koyado.com wrote:
> Thanks! The original Heathkit backplane as a 150 ohm 2W resistor to
> discharged the big blue capacitor. Let me buy a 100 ohm 2W instead to
> get the 50ma range.
>
> Norberto
>
> *From:* se...@googlegroups.com <se...@googlegroups.com> *On Behalf Of
> *Pat OConnor
> *Sent:* Friday, July 9, 2021 11:45 PM
> *To:* se...@googlegroups.com
> *Subject:* Re: [sebhc] Initial H8 Backplane test!
>
> Many years ago I used an ATX supply on my bench. As I recall, witch is
> questionable the way my memory is, you needed a 50 ma load on the 5 or
> 12 line. I hope this helps.
>
> Pat
>
> Sent from my iPhone
>
>
>
> On Jul 10, 2021, at 1:47 AM, norberto...@koyado.com
> <mailto:norberto...@koyado.com> wrote:
>
> 
>
> Thanks for the link, very detailed information. Let me also check
> the PSU specs as well.
>
> Norberto
>
> *From:* se...@googlegroups.com <mailto:se...@googlegroups.com>
> <se...@googlegroups.com <mailto:se...@googlegroups.com>> *On Behalf
> Of *Steven Feinsmith
> *Sent:* Friday, July 9, 2021 10:32 PM
> *To:* se...@googlegroups.com <mailto:se...@googlegroups.com>
> *Subject:* Re: [sebhc] Initial H8 Backplane test!
>
> https://www.intel.com/content/dam/www/public/us/en/documents/guides/power-supply-design-guide-june.pdf
> <https://www.intel.com/content/dam/www/public/us/en/documents/guides/power-supply-design-guide-june.pdf>
>
> Get Outlook <https://aka.ms/sdimjr> for iOS
>
> ------------------------------------------------------------------------
>
> *From:*se...@googlegroups.com <mailto:se...@googlegroups.com>
> <se...@googlegroups.com <mailto:se...@googlegroups.com>> on behalf
> of norberto...@koyado.com <mailto:norberto...@koyado.com>
> <norberto...@koyado.com <mailto:norberto...@koyado.com>>
> *Sent:* Saturday, July 10, 2021 1:22:15 AM
> *To:* se...@googlegroups.com <mailto:se...@googlegroups.com>
> <se...@googlegroups.com <mailto:se...@googlegroups.com>>
> *Subject:* [sebhc] Initial H8 Backplane test!
>
> I decided to power up the new H8 backplane to test voltages on the
> H8 bus. On power-on the power supply turns on and then it shutdown.
> It seems that I do not have minimum load on the ATX PSU to keep it
> on. The only voltage I get is the Standby voltage along with it’s
> LED. I do have the “blue” jumper installed to keep it “on” all the time.
>
> Do anyone knows the minimum A load to keep it running? Not sure if
> minimum load is on the +5 or +3.3 voltage rails. I hope I do not
> have a bad PDU as it was expensive to buy.
>
> Thanks,
>
> Norberto ☹
>
> <image001.jpg>
>
>
>
> Sent from my iPhone
>
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Glenn Roberts

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Jul 10, 2021, 10:24:23 AMJul 10
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Those two boards should draw enough power to load the switching supply.

How are you activating the "on" signal for the power supply?

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Terry Gulczynski

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Jul 10, 2021, 10:32:04 AMJul 10
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Agreed, but he's trying to test the backplane for proper voltages BEFORE
he plugs in a PCB.



On 7/10/2021 10:24 AM, Glenn Roberts wrote:
> Those two boards should draw enough power to load the switching supply.
>
> How are you activating the "on" signal for the power supply?
>
> On Sat, Jul 10, 2021, 10:09 AM Terry Gulczynski <terr...@cfl.rr.com
> <mailto:terr...@cfl.rr.com>> wrote:
>
> You can do the resistor thing if you want, but for a quick test to
> check
> the power supply, simply connect a spinny-disk IDE drive - it's more
> than enough load to meet any minimum the power supply might require.
>
> (We all have a few IDE drives on a shelf somewhere, right?)
>
>
> Terry
>
>
>
> On 7/10/2021 3:23 AM, norberto...@koyado.com
> <mailto:norberto...@koyado.com> wrote:
> > Thanks! The original Heathkit backplane as a 150 ohm 2W resistor to
> > discharged the big blue capacitor. Let me buy a 100 ohm 2W
> instead to
> > get the 50ma range.
> >
> > Norberto
> >
> > *Pat OConnor
> > *Sent:* Friday, July 9, 2021 11:45 PM
> > *To:* se...@googlegroups.com <mailto:se...@googlegroups.com>
> > *Subject:* Re: [sebhc] Initial H8 Backplane test!
> >
> > Many years ago I used an ATX supply on my bench. As I recall,
> witch is
> > questionable the way my memory is, you needed a 50 ma load on the
> 5 or
> > 12 line. I hope this helps.
> >
> > Pat
> >
> > Sent from my iPhone
> >
> >
> >
> >     On Jul 10, 2021, at 1:47 AM, norberto...@koyado.com
> <mailto:norberto...@koyado.com>
> >     <mailto:norberto...@koyado.com
> <mailto:norberto...@koyado.com>> wrote:
> >
> >     
> >
> >     Thanks for the link, very detailed information. Let me also check
> >     the PSU specs as well.
> >
> >     Norberto
> >
> >     *From:* se...@googlegroups.com
> <mailto:se...@googlegroups.com> <mailto:se...@googlegroups.com
> <mailto:se...@googlegroups.com <mailto:se...@googlegroups.com>>> *On
> Behalf
> >     Of *Steven Feinsmith
> >     *Sent:* Friday, July 9, 2021 10:32 PM
> >     *To:* se...@googlegroups.com <mailto:se...@googlegroups.com>
> <mailto:se...@googlegroups.com <mailto:se...@googlegroups.com>>
> >     Get Outlook <https://aka.ms/sdimjr <https://aka.ms/sdimjr>>
> for iOS
> >
> >
>  ------------------------------------------------------------------------
> >
> >     *From:*se...@googlegroups.com <mailto:se...@googlegroups.com>
> <mailto:se...@googlegroups.com <mailto:se...@googlegroups.com>>
> >     <se...@googlegroups.com <mailto:se...@googlegroups.com>
> <mailto:se...@googlegroups.com <mailto:se...@googlegroups.com>>> on
> behalf
> >     of norberto...@koyado.com
> <mailto:norberto...@koyado.com>
> <mailto:norberto...@koyado.com
> <mailto:norberto...@koyado.com
> <mailto:norberto...@koyado.com>>>
> >     *Sent:* Saturday, July 10, 2021 1:22:15 AM
> >     *To:* se...@googlegroups.com <mailto:se...@googlegroups.com>
> <mailto:se...@googlegroups.com <mailto:se...@googlegroups.com>>
> >     <se...@googlegroups.com <mailto:se...@googlegroups.com>
> <mailto:se...@googlegroups.com <mailto:se...@googlegroups.com>>>
> >     *Subject:* [sebhc] Initial H8 Backplane test!
> >
> >     I decided to power up the new H8 backplane to test voltages
> on the
> >     H8 bus. On power-on the power supply turns on and then it
> shutdown.
> >     It seems that I do not have minimum load on the ATX PSU to
> keep it
> >     on. The only voltage I get is the Standby voltage along with it’s
> >     LED. I do have the “blue” jumper installed to keep it “on”
> all the time.
> >
> >     Do anyone knows the minimum A load to keep it running? Not
> sure if
> >     minimum load is on the +5 or +3.3 voltage rails. I hope I do not
> >     have a bad PDU as it was expensive to buy.
> >
> >     Thanks,
> >
> >     Norberto ☹
> >
> >     <image001.jpg>
> >
> >
> >
> >     Sent from my iPhone
> >
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norberto...@koyado.com

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Jul 10, 2021, 3:27:41 PMJul 10
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Got it working now and feel much better now that is not broken. 😊

 

All voltages checked out (+5V, +3.3V, +5V Standby, +12V, and -12V). Today I will test the 555 timer circuitry that controls the PSU momentary pushbutton latch.

 

Two minor issues.

 

  1. I forgot to solder the PTC that controls the +5V power rails, so no voltage was going to the backplane. Temporary added a cable jumper to see it working.
  2. After reviewing the PSU specs on why I thought it was shutting down, the specs mentions that the fan is off until it is necessary to turn it on to keep power supply completely silent. On power-on, the fan starts to spin-up and then it turns off. I thought the PSU was turning off due to minimum load requirements, but that was not the case. I do not think the H8 loading will ever be able to turn on the fan as it will never reach the 30%  load threshold.

 

I added two 3mm LEDS to the backplane as shown on the picture. One on the front next to the Front Panel to indicate +5V is on. A second one on the back of the system indicating +5V “Standby” voltage is on. This voltage is used by the 555 timer and it could be used to keep power on RAM or RTC circuitry or other new ideas. This voltage along with the +3.3V are available at the top of the backplane to power new circuits. This allows endless ideas going forward.

 

 

New backplane up and running!

image001.jpg
image002.jpg

Glenn Roberts

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Jul 10, 2021, 5:54:51 PMJul 10
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Great! Looking good

Sent from my iPad

On Jul 10, 2021, at 3:27 PM, norberto...@koyado.com wrote:



<image001.jpg>

 

New backplane up and running!

<image002.jpg>



Sent from my iPhone

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norberto...@koyado.com

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Jul 10, 2021, 6:41:31 PMJul 10
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Updates:

  • PSON Switch Jumper working great.
  • PSU momentary pushbutton latch circuitry working great. I did about 30 cycles and no failures detected. Very solid and stable. Even additional AC cycles to verify that the PSU does not turn on by itself when AC is applied. I love this circuit better than using PSON header.

 

I will add next front panel to check bus operation.

 

Partially assembled board pictures attached.

 

 

image005.jpg
image006.jpg

norberto...@koyado.com

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Jul 10, 2021, 7:28:24 PMJul 10
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H8 Front Panel fully operational with new backplane.

 

Next steps:

  1. Complete the Backplane assembly
  2. Update my H8 to use this backplane and PC Power Supply.
    1. Do test with DUAL CPU’s.

 

 

Thanks,

Norberto

image001.jpg
image002.jpg
image005.jpg

Glenn Roberts

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Jul 10, 2021, 7:31:51 PMJul 10
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Wow. Beautiful!

Sent from my iPad

On Jul 10, 2021, at 7:28 PM, norberto...@koyado.com wrote:



H8 Front Panel fully operational with new backplane.

 

Next steps:

  1. Complete the Backplane assembly
  2. Update my H8 to use this backplane and PC Power Supply.
    1. Do test with DUAL CPU’s.

 

<image005.jpg>

 

Thanks,

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto...@koyado.com
Sent: Saturday, July 10, 2021 3:41 PM
To: se...@googlegroups.com
Subject: RE: [sebhc] Initial H8 Backplane test!

 

Updates:

  • PSON Switch Jumper working great.
  • PSU momentary pushbutton latch circuitry working great. I did about 30 cycles and no failures detected. Very solid and stable. Even additional AC cycles to verify that the PSU does not turn on by itself when AC is applied. I love this circuit better than using PSON header.

 

I will add next front panel to check bus operation.

 

Partially assembled board pictures attached.

 

<image001.jpg>

 

<image002.jpg>

Steven Feinsmith

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Jul 10, 2021, 8:45:06 PMJul 10
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Hi Norberto,

It looks great, and kudos for your effort to ensure that everything works properly. Due to my visual problem, I could not figure out the middle of the backplane with yellow plastic. Can you tell me what it is? How much current does it draw from the PSU? Because I have an old Dell PSU from Dell Optiplex 390 that should be capable of powering the future H8 system.

Steven



norberto...@koyado.com

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Jul 10, 2021, 10:28:42 PMJul 10
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On current draw, I will need to load the whole backplane and measure it. As it has 9 main slots (not using the auxiliary slots) based on a 1Amp per slot, so it should be around 9 amps. If using my boards, I think perhaps about 5 amps. To be accurate I will need to load the backplane and measured. For now we can speculate about 10Amps or less.

 

The Dell PSU from Dell Optiplex 390 will work just fine as the power supply is a 265W PSU.

 

The  yellow plastic header is to break the backplane into two independent backplanes. The goal is to run two Z80 systems at the same time on same chassis. You add jumpers on this header to create a single backplane or take out the jumpers and have two independent small backplanes. The first CPU will use the H8 Front Panel as always and the second CPU will run without the Front Panel as the H89 does.

 

One CPU could run HDOS while the second CPU could run CP/M.  The first CPU will have 4 main slots for I/O devices. The second CPU will have 2 main slots. The last slot on the second CPU is labeled “Expansion Card”, so it can be expanded into another H8 backplane if needed.

 

Hope this helps,

Norberto

image001.jpg
image002.jpg

norberto.collado koyado.com

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Jul 11, 2021, 1:51:39 AMJul 11
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H8 Power Supply is rated at +8VDC @ 10 amps. 




From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto...@koyado.com <norberto...@koyado.com>
Sent: Saturday, July 10, 2021 7:28 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: RE: [sebhc] Initial H8 Backplane test!
 

pjoc...@gmail.com

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Jul 11, 2021, 7:45:05 PMJul 11
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The resistor is insurance that you never need to worry about what is or is not plugged into the bus.

 

 

Sent from Mail for Windows 10

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To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/1216ece8-7017-8df8-bd6c-914d1254c904%40cfl.rr.com.

 

norberto.collado koyado.com

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Jul 12, 2021, 1:47:14 PMJul 12
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Steven,

You got me thinking over the weekend on the backplane current handling capabilities. So, I decided to buy 10-pcs of 5 OHM, 5W resistors to load the backplane to 10AMP. This allows me to verify that the backplane traces can handle such current as the power traces are different than what HeathKit did.

Also, I will short out pins 48, 49 to pins 0, 1 on the backplane to verify that the backplane traces do not act as a fuse. 

Thanks,
Norberto


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Saturday, July 10, 2021 10:51 PM
To: se...@googlegroups.com <se...@googlegroups.com>

Steven Feinsmith

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Jul 12, 2021, 5:22:04 PMJul 12
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I am glad that you decided to make further tests to ensure the backplane will function correctly with maximum current on traces without risk of burning out. I also suggest you if you happen to have an infrared camera to see the backplane in false color. The infrared camera is blind to any visible light but can see heat. I tend to use FLIR camera attachment with my iPhone to troubleshoot the components even, heat build-up on traces. It is a straightforward method to catch the problem.

Steven

pjoc...@gmail.com

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Jul 12, 2021, 5:32:13 PMJul 12
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Here is a link that shows current vrs trace width Also copper weight plays in. . Forgive me if this has been discussed before as I didn’t read all the threads. Short circuit current can be calculated if you know the output impedance of the power supply. Hope this helps.

 

Pat

 

https://www.mclpcb.com/blog/pcb-trace-width-vs-current-table/

 

Sent from Mail for Windows 10

 

From: Steven Feinsmith
Sent: Monday, July 12, 2021 5:22 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Initial H8 Backplane test!

 

I am glad that you decided to make further tests to ensure the backplane will function correctly with maximum current on traces without risk of burning out. I also suggest you if you happen to have an infrared camera to see the backplane in false color. The infrared camera is blind to any visible light but can see heat. I tend to use FLIR camera attachment with my iPhone to troubleshoot the components even, heat build-up on traces. It is a straightforward method to catch the problem.

 

Steven

 

On Mon, Jul 12, 2021 at 1:47 PM norberto.collado koyado.com <norberto...@koyado.com> wrote:

Steven,

 

You got me thinking over the weekend on the backplane current handling capabilities. So, I decided to buy 10-pcs of 5 OHM, 5W resistors to load the backplane to 10AMP. This allows me to verify that the backplane traces can handle such current as the power traces are different than what HeathKit did.

 

Also, I will short out pins 48, 49 to pins 0, 1 on the backplane to verify that the backplane traces do not act as a fuse. 

 

Thanks,

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Saturday, July 10, 2021 10:51 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] Initial H8 Backplane test!

 

H8 Power Supply is rated at +8VDC @ 10 amps. 

 

 

norberto.collado koyado.com

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Jul 12, 2021, 5:59:39 PMJul 12
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Those cameras are expensive. I think my best option will be to feel the heat from the trace with my fingers unless there is a better process. I know here at work I can take a picture and the thermal engineer will process the picture and send me back the thermal picture.

Norberto


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Steven Feinsmith <steven.f...@gmail.com>
Sent: Monday, July 12, 2021 2:21 PM

Dave McGuire

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Jul 12, 2021, 6:49:28 PMJul 12
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I have a programmable DC load and a thermal imager in my lab; let me
know if I can assist.

-Dave

On 7/12/21 5:59 PM, norberto.collado koyado.com wrote:
> Those cameras are expensive. I think my best option will be to feel the
> heat from the trace with my fingers unless there is a better process. I
> know here at work I can take a picture and the thermal engineer will
> process the picture and send me back the thermal picture.
>
> Norberto
>
> ------------------------------------------------------------------------
> *From:* se...@googlegroups.com <se...@googlegroups.com> on behalf of
> Steven Feinsmith <steven.f...@gmail.com>
> *Sent:* Monday, July 12, 2021 2:21 PM
> *To:* se...@googlegroups.com <se...@googlegroups.com>
> *Subject:* Re: [sebhc] Initial H8 Backplane test!
>  
> I am glad that you decided to make further tests to ensure the backplane
> will function correctly with maximum current on traces without risk of
> burning out. I also suggest you if you happen to have an infrared camera
> to see the backplane in false color. The infrared camera is blind to any
> visible light but can see heat. I tend to use FLIR camera attachment
> with my iPhone to troubleshoot the components even, heat build-up on
> traces. It is a straightforward method to catch the problem.
>
> Steven
>
> On Mon, Jul 12, 2021 at 1:47 PM norberto.collado koyado.com
> <http://koyado.com> <norberto...@koyado.com
> <mailto:norberto...@koyado.com>> wrote:
>
> Steven,
>
> You got me thinking over the weekend on the backplane current
> handling capabilities. So, I decided to buy 10-pcs of 5 OHM, 5W
> resistors to load the backplane to 10AMP. This allows me to verify
> that the backplane traces can handle such current as the power
> traces are different than what HeathKit did.
>
> Also, I will short out pins 48, 49 to pins 0, 1 on the backplane to
> verify that the backplane traces do not act as a fuse. 
>
> Thanks,
> Norberto
>
> ------------------------------------------------------------------------
> <se...@googlegroups.com <mailto:se...@googlegroups.com>> on behalf
> of norberto.collado koyado.com <http://koyado.com>
> <norberto...@koyado.com <mailto:norberto...@koyado.com>>
> *Sent:* Saturday, July 10, 2021 10:51 PM
> *Subject:* Re: [sebhc] Initial H8 Backplane test!
>  
> H8 Power Supply is rated at +8VDC @ 10 amps. 
>
>
>
> ------------------------------------------------------------------------
> <se...@googlegroups.com <mailto:se...@googlegroups.com>> on behalf
> of norberto...@koyado.com <mailto:norberto...@koyado.com>
> <norberto...@koyado.com <mailto:norberto...@koyado.com>>
> *Sent:* Saturday, July 10, 2021 7:28 PM
> *Subject:* RE: [sebhc] Initial H8 Backplane test!
>  
>
> On current draw, I will need to load the whole backplane and measure
> it. As it has 9 main slots (not using the auxiliary slots) based on
> a 1Amp per slot, so it should be around 9 amps. If using my boards,
> I think perhaps about 5 amps. To be accurate I will need to load the
> backplane and measured. For now we can speculate about 10Amps or less.
>
>  
>
> The Dell PSU from Dell Optiplex 390 will work just fine as the power
> supply is a 265W PSU.
>
>  
>
> The yellow plastic header is to break the backplane into two
> independent backplanes. The goal is to run two Z80 systems at the
> same time on same chassis. You add jumpers on this header to create
> a single backplane or take out the jumpers and have two independent
> small backplanes. The first CPU will use the H8 Front Panel as
> always and the second CPU will run without the Front Panel as the
> H89 does.
>
>  
>
> One CPU could run HDOS while the second CPU could run CP/M.  The
> first CPU will have 4 main slots for I/O devices. The second CPU
> will have 2 main slots. The last slot on the second CPU is labeled
> “Expansion Card”, so it can be expanded into another H8 backplane if
> needed.
>
>  
>
> Hope this helps,
>
> Norberto
>
>  
>
> Of *Steven Feinsmith
> *Sent:* Saturday, July 10, 2021 5:45 PM
> *Subject:* Re: [sebhc] Initial H8 Backplane test!
>
>  
>
> Hi Norberto,
>
>  
>
> It looks great, and kudos for your effort to ensure that everything
> works properly. Due to my visual problem, I could not figure out the
> middle of the backplane with yellow plastic. Can you tell me what it
> is? How much current does it draw from the PSU? Because I have an
> old Dell PSU from Dell Optiplex 390 that should be capable of
> powering the future H8 system.
>
>  
>
> Steven
>
>
>  
>
>  
>
> On Sat, Jul 10, 2021 at 6:41 PM <norberto...@koyado.com
> <mailto:norberto...@koyado.com>> wrote:
>
> Updates:
>
> * PSON Switch Jumper working great.
> * PSU momentary pushbutton latch circuitry working great. I
> did about 30 cycles and no failures detected. Very solid and
> stable. Even additional AC cycles to verify that the PSU
> does not turn on by itself when AC is applied. I love this
> circuit better than using PSON header.
>
>  
>
> I will add next front panel to check bus operation.
>
>  
>
> Partially assembled board pictures attached.
>
>  
>
>  
>
>  
>
> Behalf Of *Glenn Roberts
> *Sent:* Saturday, July 10, 2021 2:55 PM
> *Subject:* Re: [sebhc] Initial H8 Backplane test!
>
>  
>
> Great! Looking good
>
> Sent from my iPad
>
>  
>
> On Jul 10, 2021, at 3:27 PM, norberto...@koyado.com
> <mailto:norberto...@koyado.com> wrote:
>
> 
>
> Got it working now and feel much better now that is not
> broken. 😊
>
>  
>
> All voltages checked out (+5V, +3.3V, +5V Standby, +12V, and
> -12V). Today I will test the 555 timer circuitry that
> controls the PSU momentary pushbutton latch.
>
>  
>
> Two minor issues.
>
>  
>
> 1. I forgot to solder the PTC that controls the +5V power
> rails, so no voltage was going to the backplane.
> Temporary added a cable jumper to see it working.
> 2. After reviewing the PSU specs on why I thought it was
> <mailto:sebhc+un...@googlegroups.com>.
> <https://groups.google.com/d/msgid/sebhc/003b01d775c1%24a55ecb70%24f01c6250%24%40koyado.com?utm_medium=email&utm_source=footer>.
>
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--
Dave McGuire, AK4HZ
New Kensington, PA

Steven Feinsmith

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Jul 12, 2021, 7:26:11 PMJul 12
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Yeah, an IR image camera is expensive but faster to catch before the problem. The old-fashioned with-finger feeling method will work but not get your finger burned. I love my FLIR iPhone-based IR camera as it works very well. I will get the backplane and front panel from Todd in the coming future. I will use my IR images for you through email. The other way, there is a cheap infrared thermometer available from Home Depot, Lowes, or Amazon. It should have a dual laser, and you aim at the trace area, and it will tell you how many degrees in temperature. It will work like the IR image camera but with no images. You won't believe me as I use it to trace down the vacuum tubes or other components. By the way, thanks for designing two backplane patterns in only one backplane. It was an excellent idea.

Steven

norberto.collado koyado.com

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Jul 12, 2021, 8:51:15 PMJul 12
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I do have the infrared thermometer because of COVID. I can use that one. Good feedback.

The dual backplane idea came to me after realizing that we all have at least two Z80 CPU's boards due to the many pcb updates. Why not use them at the same time on the same H8 chassis. You can have the old 8080A board attached to the H8 front panel and have the Z80 V4.0 on the second bus. Or better, have two Z80 v4 CPU boards at the same time on same H8 chassis for better performance.

The requirements are: The oldest Z80/8080A CPU boards have to be attached to the front panel and the latest Z80 v4 on the second bus. For example:

Backplane primary bus:
  1. Front Panel - slot A1
  2. 8080A CPU - slot A2
  3. 64K memory - slot A3
  4. H17 controller - slot A4
  5. H8 Serial board - slot A5
  6. Spare - slot A6
Backplane secondary bus:
  1. Z80 V4.0 - slot A7
  2. 512KB RAM - slot A8
  3. H17/H37/H67 controller - slot A9
  4. Expansion card - slot A10. 
On the B1 -> B6 mini slots, I need to find a 25-pin connector that can be solder between side 1 and side 2 to center the board to the connector. I have been working with Terry S. to find best solution. 
 
Thanks,
Norberto


Sent: Monday, July 12, 2021 4:25 PM

norberto...@koyado.com

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Jul 13, 2021, 3:08:50 AMJul 13
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Once I get the parts that I need, I can send you a bare board with the PTC fuses attached and you can do the test. You can keep the backplane for helping out.

I will install both power connectors so that you can attach a power source such as +5V that can provide more than 10 amps.

Thanks,
Norberto
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norberto...@koyado.com

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Jul 17, 2021, 1:12:54 AMJul 17
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Steven,

 

I loaded the backplane with 5W/5 OHMs for a total of 10 amps or 50 watts @5Vcc. I left the backplane with this load for an 1hr. The +5Vcc traces were cold to the touch. The ground plane was warn due to heat coming from the 5W resistors. The 5 amps PTC fuses did get hot, but did not trigger. The backplane worked fine under these extreme load conditions. As the ATX PSU can drive 30Amp on the +5Vcc traces, I’m limiting it to 10 amps with the PTC fuse to protect the backplane. Also the +12v can drive 46 amps, it is limited to 1 amp as well as the -12V. As I have two 5 amps paths to the +5V load, I forgot to add a trace to combined them, so I had to solder a piece of wire as shown on the picture below. I fixed that for the production board. I feel happy that flowing 10amps thru the board for an hr. did not damaged any copper traces.

 

During the testing I also noticed that I need to add two 2-pin header to provide +12V/GND and +5V/GND to drive a +12V or +5V fan for the system if needed.

 

PTC Fuse specs:

Holding Current:5A
Tripping Current:8.5A

Operating Voltage: 16V

 

TEMP MEASUREMENTS: Using the home touchless thermometer.

PTC FUSE: 102.6F

+5V TRACE AT P9 – 93 F

+5V TRACE AT FRONT PANEL CONNECTOR: 96.9F

GROUND TRACE: 104.8F

Voltage across all resistors was 5Vcc, so no significant voltage drop observed.

 

Here is the setup:

 

 

Thanks,

Norberto

image001.png
image002.jpg
image003.jpg
image006.jpg

norberto...@koyado.com

unread,
Jul 17, 2021, 2:23:25 AMJul 17
to se...@googlegroups.com

Fully assembled and tested H8 backplane. I will defer installation into the H8 chassis until  7/24 as I’m very busy until them.

 

image006.jpg
image007.png
image008.jpg
image009.jpg
image001.jpg
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