H8 Tear down to check the new backplane.

248 views
Skip to first unread message

Norberto Collado

unread,
Jul 31, 2021, 6:33:10 PMJul 31
to se...@googlegroups.com

Here are some pictures on the H8 chassis tear down process and to check the hole alignment to install the BP screws.

 

There is rust inside the chassis. What chemical I can use to remove the rust before re-painting the inside of the chassis for better protection?

 

Tear down:

A picture containing indoor, rack

Description automatically generated

 

New H8 backplane smaller than the old one??? Will it fit?

 

A picture containing text

Description automatically generated

 

New H8 Backplane installed: No shorts from +8V to ground after installing screws.

 

A picture containing indoor

Description automatically generated

 

Only one hole off, but still can install the screw. I just found out that the new H8 Backplane is longer than the original. Will fix for production.

 

A picture containing text, green

Description automatically generated

 

Norberto

Norberto Collado

unread,
Jul 31, 2021, 8:25:48 PMJul 31
to se...@googlegroups.com

The ATX Mini Power Supply fits nicely and the fan covers the transformer hole. No need for a fan guard. This is the final solution and will re-attached the cover for the 110V AC to keep the inside of the H8 safe. I will keep using the original H8 ON/Off switch to control AC ON/OFF to the Power supply. Will replace the fuse with a momentary switch to control DC ON/OFF. I still need to figure out where to install another switch to be able to reset second CPU in dual configuration or perhaps use the SSI board to reset the second CPU board. Any feedback appreciated.

 

Now we have more space on the back of the H8 chassis for future expansion and the H8 chassis is not that heavy as before due to the weight of the transformer.

 

A picture containing text, electronics, circuit

Description automatically generated

 

Norberto

 

Glenn Roberts

unread,
Jul 31, 2021, 9:06:21 PMJul 31
to se...@googlegroups.com
This pretty much mirrors my experience building Rusty.  It’s been my rock solid go to system all these years.  Lightweight and cool running. 

As for removing rust I recommend steel wool and good old elbow grease. I think I painted mine with satin black rustoleum

Sent from my iPad

On Jul 31, 2021, at 8:25 PM, Norberto Collado <norberto...@koyado.com> wrote:



The ATX Mini Power Supply fits nicely and the fan covers the transformer hole. No need for a fan guard. This is the final solution and will re-attached the cover for the 110V AC to keep the inside of the H8 safe. I will keep using the original H8 ON/Off switch to control AC ON/OFF to the Power supply. Will replace the fuse with a momentary switch to control DC ON/OFF. I still need to figure out where to install another switch to be able to reset second CPU in dual configuration or perhaps use the SSI board to reset the second CPU board. Any feedback appreciated.

 

Now we have more space on the back of the H8 chassis for future expansion and the H8 chassis is not that heavy as before due to the weight of the transformer.

 

<image001.jpg>

 

Norberto

 

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/DB593FAF-BB51-486B-AF0B-93683BB8CE71%40koyado.com.

Steven Feinsmith

unread,
Jul 31, 2021, 10:46:34 PMJul 31
to se...@googlegroups.com
NO WAY! never use steel wool!!!! Regardless of any kind of abrasive materials on PCB. During the old days, there was NO solder masking. I heard some people try to polish gold fingers from the PCB. It will ruin easily because of very thin gold plating. In the past, four vintage boards had ruined gold plates on fingers. I had to use chemicals to remove the damaged gold. After several steps then, use electroplating to restore gold on fingers. It was a successful procedure. The traces on the vintage PCB were copper. That is what it needs to be careful to clean with the chemical without destroying it. When the technology was used, the solder mask solved many PCB problems and made it have a long life. During my old days, Many television printed circuit boards had no solder mask. The early computers did not have it. They had problems with the printed circuit, developed oxidation, and ruined it.
Once you get oxidation or/and corrosive on the board. It was DONE! The only way to clone and make a modern type of PCB.

Steven

Mark Garlanger

unread,
Aug 1, 2021, 12:17:44 AMAug 1
to se...@googlegroups.com
Steven, 

The steel wool is not for the boards, it was for the chassis. 

Mark

glenn.f...@gmail.com

unread,
Aug 1, 2021, 9:47:55 AMAug 1
to se...@googlegroups.com

Correct. Thanks for clarifying Mark.  I was responding to two emails at once (the other email Norberto sent asked how to remove rust from the metal chassis)…

 

  • Glenn

Norberto Collado

unread,
Aug 1, 2021, 3:46:23 PMAug 1
to se...@googlegroups.com

Thanks and my way to the HW store to get the parts!

 

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Saturday, July 31, 2021 at 6:06 PM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

This pretty much mirrors my experience building Rusty.  It’s been my rock solid go to system all these years.  Lightweight and cool running. 

Les Bird

unread,
Aug 1, 2021, 9:39:29 PMAug 1
to se...@googlegroups.com
Glad to see my PC power supply feature for the motherboard is coming in handy and extending the life of the H8. New design looks good Norberto. And yes, amazing how much lighter the H8 is without the transformer.

Les


On Saturday, July 31, 2021, 08:25:51 PM EDT, Norberto Collado <norberto...@koyado.com> wrote:


The ATX Mini Power Supply fits nicely and the fan covers the transformer hole. No need for a fan guard. This is the final solution and will re-attached the cover for the 110V AC to keep the inside of the H8 safe. I will keep using the original H8 ON/Off switch to control AC ON/OFF to the Power supply. Will replace the fuse with a momentary switch to control DC ON/OFF. I still need to figure out where to install another switch to be able to reset second CPU in dual configuration or perhaps use the SSI board to reset the second CPU board. Any feedback appreciated.

 

Now we have more space on the back of the H8 chassis for future expansion and the H8 chassis is not that heavy as before due to the weight of the transformer.

 

 

Norberto

 

Norberto Collado

unread,
Aug 2, 2021, 12:10:24 AMAug 2
to se...@googlegroups.com

Les,

 

Agreed and thank you for creating the “H8-H200” project, which has been the inspiration for the upgrades. That was a lot of work for you to do in such short time.

 

As the H8 chassis is all dis-assembled and my son is out of school, he decided to start building the H8 chassis using his CAD tools. In just a few hrs.’ he already completed the side panels. Tomorrow he will do the chassis and then he will add the provided feedback.

 

Here is what we did today:

 

H8 Chassis with internal rust. I do not know why Heath did not paint the inside of the chassis to avoid such rust.

 

Tools to remove rust:

A picture containing ground, outdoor

Description automatically generated

 

H8 Chassis – Rust removed:

 

H8 Chassis Painted: I just painted the internal chassis. Did not paint the exterior.

A picture containing text

Description automatically generated

 

New H8-Chassis in CAD: WIP

 

A picture containing worktable, accessory

Description automatically generated

 

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of Les Bird <les...@bellsouth.net>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Sunday, August 1, 2021 at 6:39 PM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

Glad to see my PC power supply feature for the motherboard is coming in handy and extending the life of the H8. New design looks good Norberto. And yes, amazing how much lighter the H8 is without the transformer.

 

Les

 

 

.

Computer Case Side Pictures.eml

Steven Feinsmith

unread,
Aug 2, 2021, 12:22:17 AMAug 2
to se...@googlegroups.com
It looks good to me as the first step to duplicate the original H8 chassis. I like to call them "Heathkit H-8, Second Generation".

Take care,
Steven

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

Norberto Collado

unread,
Aug 2, 2021, 3:02:03 AMAug 2
to se...@googlegroups.com

During the rust cleaning process the fastener that holds the screw for the front panel top cover came out. I’m guessing it was soldered by Heath supplier, but it came out. I think this was a defect by their supplier. What tool I need to fix this issue to be able to attached the front panel cover underneath screw? Is the same one used on the Heath card mount heatsink bracket, I think.

 

Issue:

 

A picture containing metalware

Description automatically generated

 

Glenn Roberts

unread,
Aug 2, 2021, 5:28:45 AMAug 2
to se...@googlegroups.com
Nice job. Great to see your son’s cad/cam capture of the side panels (a chip off the old block). Any thoughts on where we could get some prototypes manufactured? The most interesting could be clear acrylic. Might have to tweak the design a bit for different materials (e.g. strengthen around screw holes).

I would like to make wooden side panels. Can you share the blueprints with exact dimensions labeled (especially screw holes)? That’s what I’ve been lacking.

The new design with PC power runs so cool I don’t think you need a vented top anymore (power supply fan and holes in the metal cabinet provide sufficient ventilation). This opens up  the possibility for a clear Plexiglas top if we can figure out how to fabricate one.

If Les’ design was the H8-2000 then perhaps this evolved version is the H8-2020!

Sent from my iPad

On Aug 2, 2021, at 12:10 AM, Norberto Collado <norberto...@koyado.com> wrote:



Les,

 

Agreed and thank you for creating the “H8-H200” project, which has been the inspiration for the upgrades. That was a lot of work for you to do in such short time.

 

As the H8 chassis is all dis-assembled and my son is out of school, he decided to start building the H8 chassis using his CAD tools. In just a few hrs.’ he already completed the side panels. Tomorrow he will do the chassis and then he will add the provided feedback.

 

Here is what we did today:

 

H8 Chassis with internal rust. I do not know why Heath did not paint the inside of the chassis to avoid such rust.

<image001.jpg>

 

Tools to remove rust:

<image002.jpg>

 

H8 Chassis – Rust removed:

<image003.jpg>

 

H8 Chassis Painted: I just painted the internal chassis. Did not paint the exterior.

<image004.jpg>

 

New H8-Chassis in CAD: WIP

 

<image005.jpg>

 

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of Les Bird <les...@bellsouth.net>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Sunday, August 1, 2021 at 6:39 PM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

Glad to see my PC power supply feature for the motherboard is coming in handy and extending the life of the H8. New design looks good Norberto. And yes, amazing how much lighter the H8 is without the transformer.

 

Les

 

 

.

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/834BB4B5-16E1-4355-A979-83C61F0D8461%40koyado.com.
<mime-attachment>

Glenn Roberts

unread,
Aug 2, 2021, 6:19:01 AMAug 2
to se...@googlegroups.com
The part is called a self-clinching nut


It was pressed into the hole at the time of manufacture. The hole may now be too distorted to accept a new nut but you could give it a try. You might be able to press it into place with a ViseGrip tool. Perhaps reinforce it with epoxy. I’m dubious about using solder but if you did you’d certainly need a high wattage iron. All of the screws are #6 32 threads per inch.

Sent from my iPad

On Aug 2, 2021, at 3:02 AM, Norberto Collado <norberto...@koyado.com> wrote:



During the rust cleaning process the fastener that holds the screw for the front panel top cover came out. I’m guessing it was soldered by Heath supplier, but it came out. I think this was a defect by their supplier. What tool I need to fix this issue to be able to attached the front panel cover underneath screw? Is the same one used on the Heath card mount heatsink bracket, I think.

 

Issue:

 

<image001.jpg>

 

<image002.jpg>

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

Glenn Roberts

unread,
Aug 2, 2021, 7:56:29 AMAug 2
to <sebhc@googlegroups.com>
P.s. this might be best turned over to a competent machine shop. I think they could easily fix it. Perhaps braze on a new nut if the press fit doesn’t work…

Sent from my iPad

On Aug 2, 2021, at 6:19 AM, Glenn Roberts <glenn.f...@gmail.com> wrote:

The part is called a self-clinching nut

norberto.collado koyado.com

unread,
Aug 2, 2021, 2:01:13 PMAug 2
to <sebhc@googlegroups.com>
Thanks for the feedback and now I know what I'm looking for. I see the #6-32 self-clinch part in Amazon, but not the tool.  


Let me see if a ViseGrip tool can do the job.

Norberto


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Monday, August 2, 2021 4:56 AM

To: <se...@googlegroups.com> <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

Steven Feinsmith

unread,
Aug 2, 2021, 2:58:43 PMAug 2
to se...@googlegroups.com
Hi Norberto,

You do not need a tool for this one. When you insert the self-clinch nut, you need a washer and screw, and it will "clinch" into the metal sheet. If you prefer to use tools for clinching purposes. Here is:

https://www.dontwasteyourmoney.com/best-rivet-nut-tool/

I hope this works for you...

Steven

norberto.collado koyado.com

unread,
Aug 2, 2021, 3:09:56 PMAug 2
to se...@googlegroups.com
Thank you and a much simpler solution. There is a HW store next to me, and I will check it out this evening and hopefully they have the #6-32 self-clinch part.

Norberto


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Steven Feinsmith <steven.f...@gmail.com>
Sent: Monday, August 2, 2021 11:58 AM

norberto.collado koyado.com

unread,
Aug 3, 2021, 1:56:14 PMAug 3
to se...@googlegroups.com
I cannot buy locally, so I order from Amazon a bag. They should be in by tomorrow to start the assembly process again.

Chassis is painted only in the inside with flat black to eliminated/contained as must rust as possible.



Norberto


Glenn Roberts

unread,
Aug 3, 2021, 2:36:02 PMAug 3
to <sebhc@googlegroups.com>
You may have to reduce the diameter of the hole slightly to give the new nut sufficient purchase to hold. Perhaps tamp it a bit using a hammer and with something solid underneath to flatten out the sheet metal a bit around the hole.

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

norberto.collado koyado.com

unread,
Aug 3, 2021, 2:39:57 PMAug 3
to <sebhc@googlegroups.com>
Good idea!


Sent: Tuesday, August 3, 2021 11:35 AM

To: <se...@googlegroups.com> <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

Norberto Collado

unread,
Aug 5, 2021, 1:27:04 AMAug 5
to <sebhc@googlegroups.com>

I received today the #6-32 self-clinch part and did try all possible methods to clinch the part into the metal. No matter how hard even hammering the part in, it does not want to go in. It requires a lot of force to clinch such part into the metal. I need a very powerful tool to do this as the case of the H8 is not aluminum and it is hard steel. Perhaps  a HALF TON Power Press will do as this one.

 

A picture containing appliance

Description automatically generated

 

I will clean up the hole with the steel tool and use Gorilla glue or epoxy to keep the part secure into the chassis. I think this should do it. Then repaint again.

 

Thanks for all the feedback.

 

Norberto

 

 

From: "norberto.collado koyado.com" <norberto...@koyado.com>
Date: Tuesday, August 3, 2021 at 11:39 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

Good idea!

 


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Tuesday, August 3, 2021 11:35 AM
To: <se...@googlegroups.com> <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

You may have to reduce the diameter of the hole slightly to give the new nut sufficient purchase to hold. Perhaps tamp it a bit using a hammer and with something solid underneath to flatten out the sheet metal a bit around the hole.

.

Glenn Roberts

unread,
Aug 5, 2021, 5:34:43 AMAug 5
to se...@googlegroups.com
Wow. Well you tried. Yes I’m sure a press of some sort was used at the factory. Again, the best way to effect this repair is to find a machine shop…

Sent from my iPad

On Aug 5, 2021, at 1:27 AM, Norberto Collado <norberto...@koyado.com> wrote:



I received today the #6-32 self-clinch part and did try all possible methods to clinch the part into the metal. No matter how hard even hammering the part in, it does not want to go in. It requires a lot of force to clinch such part into the metal. I need a very powerful tool to do this as the case of the H8 is not aluminum and it is hard steel. Perhaps  a HALF TON Power Press will do as this one.

 

<image001.jpg>

 

I will clean up the hole with the steel tool and use Gorilla glue or epoxy to keep the part secure into the chassis. I think this should do it. Then repaint again.

 

Thanks for all the feedback.

 

Norberto

 

 

From: "norberto.collado koyado.com" <norberto...@koyado.com>
Date: Tuesday, August 3, 2021 at 11:39 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

Good idea!

 


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Tuesday, August 3, 2021 11:35 AM
To: <se...@googlegroups.com> <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

You may have to reduce the diameter of the hole slightly to give the new nut sufficient purchase to hold. Perhaps tamp it a bit using a hammer and with something solid underneath to flatten out the sheet metal a bit around the hole.

.

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

Paul Birkel

unread,
Aug 5, 2021, 6:22:22 AMAug 5
to se...@googlegroups.com

FWIW, if a filleted epoxy of the current threaded part into place doesn’t hold then you might consider getting a J-style clip-on nut and trimming off the back-end of the J – leaving two tabs that ought to give you better adhesion and control.  Something like this:

 

image002.png

geneb

unread,
Aug 5, 2021, 9:25:01 AMAug 5
to se...@googlegroups.com
On Thu, 5 Aug 2021, Glenn Roberts wrote:

>> On Aug 5, 2021, at 1:27 AM, Norberto Collado <norberto...@koyado.com> wrote:
>>
>> I received today the #6-32 self-clinch part and did try all possible
>> methods to clinch the part into the metal. No matter how hard even
>> hammering the part in, it does not want to go in. It requires a lot of
>> force to clinch such part into the metal. I need a very powerful tool
>> to do this as the case of the H8 is not aluminum and it is hard steel.
>> Perhaps a HALF TON Power Press will do as this one.

A little benchtop arbor press from harbor freight should do the job.

g.

--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby. Geeks collect hobbies.

ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://scarlet.deltasoft.com - Get it _today_!

John Evans

unread,
Aug 5, 2021, 9:29:13 AMAug 5
to se...@googlegroups.com
Another option is to find a soft aluminum rivnut that would fit the hole
or a slightly enlarged hole.  They work like pop-rivets to install.

https://www.rivetnutusa.com/rivnut-rivet-nut/

John - Colorado Springs

norberto.collado koyado.com

unread,
Aug 5, 2021, 1:07:33 PMAug 5
to se...@googlegroups.com
OK, I will give the rivnut a try.

Thanks,
Norberto


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of John Evans <john.ev...@gmail.com>
Sent: Thursday, August 5, 2021 6:29 AM

To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] H8 Tear down to check the new backplane.
--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

norberto.collado koyado.com

unread,
Aug 5, 2021, 1:08:53 PMAug 5
to se...@googlegroups.com
Thanks Paul and Glenn for your feedback. Let me try first the rivenut approach.

Norberto

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Paul Birkel <pbi...@gmail.com>
Sent: Thursday, August 5, 2021 3:22 AM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: RE: [sebhc] H8 Tear down to check the new backplane.
 

Steven Feinsmith

unread,
Aug 5, 2021, 2:28:22 PMAug 5
to se...@googlegroups.com
Hi Noberto,

You try different methods to fix the problem. My solution is to weld the metal then grind it smooth on both sides. Then drill to make a new hole exact as it was before. Tap to create a thread for a screw into it. I read an article about it a long time ago as I am not a machinist.

Steven

norberto.collado koyado.com

unread,
Aug 5, 2021, 6:06:35 PMAug 5
to se...@googlegroups.com
I agree! Worse case, I will bring the chassis to the machine shop. I should get the rivenut this weekend and hope for the best.

Norberto


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Steven Feinsmith <steven.f...@gmail.com>
Sent: Thursday, August 5, 2021 11:28 AM

Steven Feinsmith

unread,
Aug 5, 2021, 6:37:16 PMAug 5
to se...@googlegroups.com

G. Beat

unread,
Aug 5, 2021, 9:42:01 PMAug 5
to SEBHC
I thought that Heathkit is ed PEM Fasteners (Penn Engineering), in these instances.

Norberto Collado

unread,
Aug 6, 2021, 2:56:44 AMAug 6
to se...@googlegroups.com

My son gave me a preview of the original H8 chassis in CAD today. He shall be done tomorrow. Then he will work on the front panel cover and finally the H8 LED’s cover. He will assembled all the parts in CAD to make sure all holes do align properly. Once he is done, we will make a copy to build out the new H8 chassis using all new components and add the feedback received. At least we will have the original H8 design in CAD.

 

Attached is a picture rear sided view.

 

Thanks,

Norberto

 

 

H8-Chassis-CAD.png

Norberto Collado

unread,
Aug 6, 2021, 2:59:26 AMAug 6
to se...@googlegroups.com

H8 Chassis Video attached for fun!

 

Thanks,

Norberto

H8-chassis-video.mp4

norberto.collado koyado.com

unread,
Aug 6, 2021, 8:38:52 PMAug 6
to se...@googlegroups.com
H8 chassis CAD completed. Now what it remains is the top cover and LED protector to have the full system in CAD.

Attached are the pictures for the H8 chassis.

Thanks,
Norberto
H8-Chassis_view1.png
H8-Chassis_view2.png
H8-Chassis_view3.png

Steven Feinsmith

unread,
Aug 6, 2021, 9:47:37 PMAug 6
to se...@googlegroups.com
That is great your son did a good job!

My question is if we are seeking reproduction of the H8 chassis. Do we need to have an open hole for the transformer? We are no longer using the transformer and large capacitors (linear power supply). We use a switching power supply from Meanwell or PC PSU. We can adjust to a minimum voltage level to run in-board voltage regulators or choose a PC PSU and bypass the voltage regulators. Do we need airflow holes on the bottom and top cover? Should we allow open holes on sides for cooling fans with filters to bring forceful airflow to keep components cool as possible?

In case, we use a linear power supply. It is possible to have a company reproduce the transformer (custom-build). My major concern is electrolytic capacitors nowadays because the ripple current was higher during the old days.

Open to the discussion?

Thank you very much,
Steven

--
You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

Glenn Roberts

unread,
Aug 6, 2021, 10:35:35 PMAug 6
to se...@googlegroups.com
This is a baseline capture of the as-built H8 chassis. It is the logical starting point for any modern manufacturing. As Steven points out before any actual manufacture of new sheet metal it would make sense to do some updates.

Sent from my iPad

On Aug 6, 2021, at 9:47 PM, Steven Feinsmith <steven.f...@gmail.com> wrote:



Norberto Collado

unread,
Aug 6, 2021, 11:46:48 PMAug 6
to se...@googlegroups.com

I see two steps here:

 

  1. Reproduction of the original H8 chassis to preserved for history. If someone wants to duplicate the original chassis it can be done.
  2. Use the CAD files in step #1 to build the new H8 chassis. There is another email thread in which a lot of feedback was provided on what we need on this new chassis. In this re-design we add the ATX PSU/Mean Well PSU, RS232 holes, etc. I can expand later when we get to step 2.
    1. Per feedback from Glenn, the ATX PSU has its own fan and that is enough to cool the chassis. If I see space left in the back to put a small fan, I will do so. The new backplane support the +12V/+5V fans using same 4-pin header as in the PC.

 

 

Thanks,

Norberto

norberto.collado koyado.com

unread,
Aug 7, 2021, 12:05:20 AMAug 7
to se...@googlegroups.com
Slowly building out the original H8 Chassis. New pictures attached and holes do align nicely.

During my search for the clinch tools, I saw the press inserts that are used on the H8 side panels and ordered a bag.


Thanks,
Norberto
H8-Chassis-view4.png
H8-Chassis-view5.png
H8-Chassis-view6.png

Norberto Collado

unread,
Aug 8, 2021, 12:29:17 AMAug 8
to se...@googlegroups.com

The rivenut #6-32 worked out fine. Easy to install with the right tools. Not as beautiful as using a clinch nut. To use the clinch nut again, the hole needs to be welded, smoothed, and redrilled as mentioned by Steven. For now the rivenut will do just fine. Tomorrow I will do final inside re-painting to start the build out of the H8 system with the new ATX power supply and new backplane.

 

A note of caution: I only encourage changing the H8 backplane if using the old tin plated pins on the backplane from Heath as it is not reliable. Also if you have a pretty bad H8 system in which the backplane pins were damaged or broken backplane. If your H8 system is using the gold plated pins backplane or using a Trionyx backplane, I do not see the need to change it unless you want to use the dual CPU configuration and protection against shorts. If the H8 original Power supply is working fine, there is no need to change it to a ATX PSU.  This is to preserved the value of the H8 system if you decided to sell it in the near future. I saved all the parts so that I can put it back as the original H8 but using the new backplane. Changing to a ATX PSU is a lot of work and all vintage boards will need to be reconfigured to use 5V inputs. That is a lot of work. Hopefully soon we will have a new chassis that will solve all these upgrade issues.

 

Why I’m doing all these changes to my H8 system? Two reasons: 1. To validate the new H8 backplane with the ATX PSU in a two CPU configuration. 2. To be able to re-create the original H8 chassis in CAD, so that we can develop a new chassis that can support ATX PSU/Mean Well Power Supply along with new chassis enhancements. For this work, I need to strip down the H8 system into bare bones. Also, an opportunity to remove all the rust inside the chassis to protect the metal.

 

 

Tools used:

 

Diagram

Description automatically generated

 

A picture containing text

Description automatically generated

glenn.f...@gmail.com

unread,
Aug 8, 2021, 7:40:38 AMAug 8
to se...@googlegroups.com

The RivNut’s a great solution.  Thanks to John Evans for mentioning this!

 

I have an H8 chassis that had previously been used as an expansion box on an old H8.  There was a home-brew ribbon cable arrangement to string two busses together and (unfortunately) slots cut into the side panels to pass the ribbon cable through.  The chassis had a linear power supply but not all the original Heath parts.  And no front panel…  the backplane used the old tinned connectors…

 

So this is an ideal chassis to build out my “H8-2020” with the Rev 4 CPU and new front panel and backplane boards.  Initially I am patching the side panels (will post pictures separately) but I intend eventually to fabricate some nice looking wooden ones (thanks Norberto for posting a source for the brass screw fittings for the side panels!

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Norberto Collado
Sent: Sunday, August 08, 2021 12:29 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] H8 Tear down to check the new backplane.

 

The rivenut #6-32 worked out fine. Easy to install with the right tools. Not as beautiful as using a clinch nut. To use the clinch nut again, the hole needs to be welded, smoothed, and redrilled as mentioned by Steven. For now the rivenut will do just fine. Tomorrow I will do final inside re-painting to start the build out of the H8 system with the new ATX power supply and new backplane.

--

You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

image001.jpg
image002.jpg
image003.jpg

Norberto Collado

unread,
Aug 8, 2021, 2:38:16 PMAug 8
to se...@googlegroups.com

Glenn,

 

Once we are done with the CAD model, I will send you the information on the side panels. I will check if we can do a 3D print to test it out. Making wooden ones will be great and paint them the same color as the PDP-8 replica. At work I used to have a PDP-8 and the enclosure was all shiny wood and it was very beautiful.

 

A picture containing text, indoor, wooden, wood

Description automatically generated

 

Also, on my H8, I intend to expand outside the H8 into another H8 backplane, but using 2x DB25 cables into the second chassis.

 

On the brass screw fittings for the side panels, I will send you some as I will get 50-pcs. 😊

https://www.amazon.com/240-006-BR-Flush-Press-Insert-Brass/dp/B06XGK7XQR/ref=sr_1_2?dchild=1&keywords=flush+insert+brass+240-006-br&qid=1628446839&sr=8-2

 

For the RivNut, I bought everything in Amazon. Also in Amazon I bought the following parts to replace the old ones and they fit nicely into the H8 chassis. I think we can buy all the parts in Amazon for the H8 chassis…

 

 

https://www.amazon.com/dp/B0839KVBKB?psc=1&ref=ppx_yo2_dt_b_product_details

 

A picture containing electronics, camera, adapter

Description automatically generated

 

 

 

https://www.amazon.com/dp/B071ZM852H?psc=1&ref=ppx_yo2_dt_b_product_details

 

A picture containing text

Description automatically generated

 

 


Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Sunday, August 8, 2021 at 4:40 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>

Subject: RE: [sebhc] H8 Tear down to check the new backplane.

Glenn Roberts

unread,
Aug 9, 2021, 11:03:27 AMAug 9
to se...@googlegroups.com

I will probably use a blank from Woodcraft:

 

https://www.woodcraft.com/categories/wood?thickness%5B%5D=3%2F4%22&width%5B%5D=6%22

 

thoughts suggestions welcome; also on stain and finish…  possibly walnut or cherry…  wondering of there was a particular wood or finish that was popular back in the 70s (e.g. for home stereos, etc.)?

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Norberto Collado

--

You received this message because you are subscribed to the Google Groups "SEBHC" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sebhc+un...@googlegroups.com.

image001.jpg
image002.jpg
image003.jpg
image004.jpg

norberto.collado koyado.com

unread,
Aug 11, 2021, 12:33:34 AMAug 11
to se...@googlegroups.com
Almost done with the H8 original chassis in CAD. Top cover and cross bar are what is left. Attached is latest chassis picture. So far, all holes align properly.

Les, Glenn,

I'm trying to figure out on how to attach the ATX power supply to the chassis to put it back. Any ideas on how you did it?

Thanks,
Norberto




From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Monday, August 9, 2021 8:03 AM
Old_H8_Chassis.png

Les Bird

unread,
Aug 11, 2021, 12:47:21 PMAug 11
to SEBHC
Norby,

Mine is not mounted in but instead it just fits snuggly at the back of the chassis wedged between the back panel and the raised mounts for the transformer. See photo:

IMG_6414.JPG

norberto.collado koyado.com

unread,
Aug 11, 2021, 1:28:01 PMAug 11
to SEBHC
Thanks for the feedback!

Norby


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Les Bird <les...@bellsouth.net>
Sent: Wednesday, August 11, 2021 9:47 AM
To: SEBHC <se...@googlegroups.com>

Steven Feinsmith

unread,
Aug 11, 2021, 1:36:22 PMAug 11
to se...@googlegroups.com
The chassis showed covers for a high-voltage circuit on the left side and capacitors on the right side. They will no longer when we use ATX (PSU). I planned to use Dell's PS-5161-1D1 that provide 160 watts as follows:

+3.3v @ 9A MAX
+5V @ 11A MAX
+12V @ 9A MAX
-12V @ 0.5A MAX
+5VFP @ 2A MAX
+5V and +3.3V load sharing will not be greater than 85W Max. continuous load DC output power shall not exceed 160W.

I believe this device is enough to power the H8 system. The only problem with this unit is that it needs to mount on the left side because of the exhaust vent and AC power socket. The internal fan should be enough to pull airflow from the rest of the chassis. If you seek ATX devices (box style) on many PCs may not have enough room to fit the chassis unless to increase the rear end area.

Here are two pictures to give you an idea:

IMG_3719.jpg

IMG_3720.jpg

This power supply is a compact style used on Dell computers, and it is not expensive. I got it from eBay a long time ago.

Thank you,
Steven

glenn.f...@gmail.com

unread,
Aug 11, 2021, 2:25:35 PMAug 11
to se...@googlegroups.com

I used an Athena Power model AP-MTFX30 in Rusty (which conforms to the “TFX” form factor specification):

 

AP-MTFX30 | athenapower.com

 

https://photos.app.goo.gl/h1949iRCWefnuS7z6

 

it makes for a clean looking install because the fan grille lines up very nicely in the space where the transformer had been:

 

https://photos.app.goo.gl/LegyK8miY4oZLhP86

 

(however I did have to drill new holes).

 

the only problem is that the screws that hold the power supply to the case are those stubby coarse-threaded screws used in PC fans, and they’re screwed into plastic.  If I ever shipped the unit I’d want to remove the power supply as I don’t trust those screws to hold it.

 

as you can see I never got around to adding a cord restraint for the power cord.  I connected the switch to the appropriate power-on connections on the power supply (sorry can’t recall which lines those are but happy to report back more if needed).

 

On my “H8-2000” boards there were originally jumpers across input and output on all of the 5V regulators, but I’ve slowly added Pololu regulators to most of my boards so I can swap at will between PC-style and H8 analog powered chassis.

image005.png
image006.jpg
image007.jpg
image008.jpg
image009.jpg

norberto.collado koyado.com

unread,
Aug 11, 2021, 3:19:28 PMAug 11
to se...@googlegroups.com
Thanks for the feedback!  I will work on this as I need my system up and running again with a secured PC power supply.

Norby


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of glenn.f...@gmail.com <glenn.f...@gmail.com>
Sent: Wednesday, August 11, 2021 11:25 AM

G. Beat

unread,
Aug 11, 2021, 10:02:38 PMAug 11
to SEBHC

Desktop Platform Form Factors Power Supply
Intel Corporation 

G. Beat

unread,
Aug 11, 2021, 10:10:15 PMAug 11
to SEBHC
The other option is to Specify a Popular SMPS, like MeanWell.

Using either an Enclosed or Open Frame model. Preference to enclosed models (safety in open computer case).

greg
elmhurst, il
On Wednesday, August 11, 2021 at 2:19:28 PM UTC-5 Norby wrote: