Introduction and Reason for Contact
Hello, My name is Randy Kaplan and I am joining this list to obtain some information and help. I am a long time computing professional (50 years or so), have built my own hardware, and have been a software developer for many years. I also have many years of teaching computer science at the University level - not entirely relevant, just for background. In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer. I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also. Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session. Please let me know with any information you might think is helpful. Thanks in advance for your assistance. Regards, Randy Kaplan
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years. If you're near Pittsburgh, we can probably collaborate. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
Thank you so much for getting back to me so soon. Alas, I live near Philadelphia, Reading, PA to be specific. Not quite in your back yard. I am really not sure how to begin. I could plug it in you know but I am sure that is not the way to proceed. Are you aware of anyone closer to me? I have worked on projects throughout my lifetime across the web so that might be a possibility although I am sure some of the questions I might ask would be truly from a beginner for a project like this one. Don’t really know. Decided to look into it. Ashame it sits in a closet. Randy On Jan 20, 2025, 4:18 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years.
If you're near Pittsburgh, we can probably collaborate.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
Yeah Philly is a bit of a haul from here. You could easily visit (people have visited LSSM from a dozen *countries*) but for collaborative work that probably isn't practical. I'm afraid then that my involvement would be limited to providing some occasional guidance. First, though, no, definitely don't just plug it in. You'll need to disassemble the power supply, test and reform the big electrolytic capacitors out-of-circuit first, and only after that, voltage soak/test the supply without boards. The 8/e uses linear regulators which are ok to run without a load. There's enough current there to be dangerous, so take your time on that. I typically take several days to bring up a new-to-me 8/e power supply, and I've worked on them before. Carefully inspect the power input cable first. It is clamped onto the back panel of the power supply, and sometimes that causes jacket wear on the cable. If any rear panel fuses blow, do not panic. They are old enough to succumb to fuse fatigue. Replace (appropriately!) and try again. Next, blow the backplane out with dry canned air. Not typical "air compressor air", as that contains oil. Then, pick up a tub of DeOxit gold wipes and give the card edge connectors a scrub. You'll probably need to replace several front panel bulbs. Chicago Miniature Lamp (or VCC) 2309 are the right ones, as are Oshino OL-2. JKL/VCC 7371s will work in a pinch. Flush the front panel board slide switches with CRC QD, then squirt in a small amount of DeOxit D5 while working the switches back and forth. Wipe off any excess. When the time comes to power it all up, there's a toggle-in acceptance test in the manuals. (I assume you've found the manuals) -Dave On 1/20/25 16:24, therenguy via vcf-midatlantic wrote:
Thank you so much for getting back to me so soon. Alas, I live near Philadelphia, Reading, PA to be specific. Not quite in your back yard. I am really not sure how to begin. I could plug it in you know but I am sure that is not the way to proceed. Are you aware of anyone closer to me? I have worked on projects throughout my lifetime across the web so that might be a possibility although I am sure some of the questions I might ask would be truly from a beginner for a project like this one. Don’t really know. Decided to look into it. Ashame it sits in a closet.
Randy
On Jan 20, 2025, 4:18 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years.
If you're near Pittsburgh, we can probably collaborate.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
Would the following directions be acceptable to follow for reforming the capacitors? https://www.qsl.net/g3oou/reform.html Randy On Jan 20, 2025, 4:39 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
Yeah Philly is a bit of a haul from here. You could easily visit (people have visited LSSM from a dozen *countries*) but for collaborative work that probably isn't practical.
I'm afraid then that my involvement would be limited to providing some occasional guidance. First, though, no, definitely don't just plug it in. You'll need to disassemble the power supply, test and reform the big electrolytic capacitors out-of-circuit first, and only after that, voltage soak/test the supply without boards. The 8/e uses linear regulators which are ok to run without a load. There's enough current there to be dangerous, so take your time on that. I typically take several days to bring up a new-to-me 8/e power supply, and I've worked on them before.
Carefully inspect the power input cable first. It is clamped onto the back panel of the power supply, and sometimes that causes jacket wear on the cable.
If any rear panel fuses blow, do not panic. They are old enough to succumb to fuse fatigue. Replace (appropriately!) and try again.
Next, blow the backplane out with dry canned air. Not typical "air compressor air", as that contains oil. Then, pick up a tub of DeOxit gold wipes and give the card edge connectors a scrub.
You'll probably need to replace several front panel bulbs. Chicago Miniature Lamp (or VCC) 2309 are the right ones, as are Oshino OL-2. JKL/VCC 7371s will work in a pinch.
Flush the front panel board slide switches with CRC QD, then squirt in a small amount of DeOxit D5 while working the switches back and forth. Wipe off any excess.
When the time comes to power it all up, there's a toggle-in acceptance test in the manuals. (I assume you've found the manuals)
-Dave
On 1/20/25 16:24, therenguy via vcf-midatlantic wrote:
Thank you so much for getting back to me so soon. Alas, I live near Philadelphia, Reading, PA to be specific. Not quite in your back yard. I am really not sure how to begin. I could plug it in you know but I am sure that is not the way to proceed. Are you aware of anyone closer to me? I have worked on projects throughout my lifetime across the web so that might be a possibility although I am sure some of the questions I might ask would be truly from a beginner for a project like this one. Don’t really know. Decided to look into it. Ashame it sits in a closet.
Randy
On Jan 20, 2025, 4:18 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years.
If you're near Pittsburgh, we can probably collaborate.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
I will give it a read later tonight if no one else chimes in before then. -Dave On 1/20/25 16:44, therenguy via vcf-midatlantic wrote:
Would the following directions be acceptable to follow for reforming the capacitors?
https://www.qsl.net/g3oou/reform.html
Randy On Jan 20, 2025, 4:39 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
Yeah Philly is a bit of a haul from here. You could easily visit (people have visited LSSM from a dozen *countries*) but for collaborative work that probably isn't practical.
I'm afraid then that my involvement would be limited to providing some occasional guidance. First, though, no, definitely don't just plug it in. You'll need to disassemble the power supply, test and reform the big electrolytic capacitors out-of-circuit first, and only after that, voltage soak/test the supply without boards. The 8/e uses linear regulators which are ok to run without a load. There's enough current there to be dangerous, so take your time on that. I typically take several days to bring up a new-to-me 8/e power supply, and I've worked on them before.
Carefully inspect the power input cable first. It is clamped onto the back panel of the power supply, and sometimes that causes jacket wear on the cable.
If any rear panel fuses blow, do not panic. They are old enough to succumb to fuse fatigue. Replace (appropriately!) and try again.
Next, blow the backplane out with dry canned air. Not typical "air compressor air", as that contains oil. Then, pick up a tub of DeOxit gold wipes and give the card edge connectors a scrub.
You'll probably need to replace several front panel bulbs. Chicago Miniature Lamp (or VCC) 2309 are the right ones, as are Oshino OL-2. JKL/VCC 7371s will work in a pinch.
Flush the front panel board slide switches with CRC QD, then squirt in a small amount of DeOxit D5 while working the switches back and forth. Wipe off any excess.
When the time comes to power it all up, there's a toggle-in acceptance test in the manuals. (I assume you've found the manuals)
-Dave
On 1/20/25 16:24, therenguy via vcf-midatlantic wrote:
Thank you so much for getting back to me so soon. Alas, I live near Philadelphia, Reading, PA to be specific. Not quite in your back yard. I am really not sure how to begin. I could plug it in you know but I am sure that is not the way to proceed. Are you aware of anyone closer to me? I have worked on projects throughout my lifetime across the web so that might be a possibility although I am sure some of the questions I might ask would be truly from a beginner for a project like this one. Don’t really know. Decided to look into it. Ashame it sits in a closet.
Randy
On Jan 20, 2025, 4:18 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years.
If you're near Pittsburgh, we can probably collaborate.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
It seemed reasonable. Was targeting tube equipment but did discuss lower voltage caps also. On Mon, Jan 20, 2025 at 04:56:32PM -0500, Dave McGuire via vcf-midatlantic wrote:
I will give it a read later tonight if no one else chimes in before then.
-Dave
On 1/20/25 16:44, therenguy via vcf-midatlantic wrote:
Would the following directions be acceptable to follow for reforming the capacitors?
https://www.qsl.net/g3oou/reform.html
Randy On Jan 20, 2025, 4:39 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
Yeah Philly is a bit of a haul from here. You could easily visit (people have visited LSSM from a dozen *countries*) but for collaborative work that probably isn't practical.
I'm afraid then that my involvement would be limited to providing some occasional guidance. First, though, no, definitely don't just plug it in. You'll need to disassemble the power supply, test and reform the big electrolytic capacitors out-of-circuit first, and only after that, voltage soak/test the supply without boards. The 8/e uses linear regulators which are ok to run without a load. There's enough current there to be dangerous, so take your time on that. I typically take several days to bring up a new-to-me 8/e power supply, and I've worked on them before.
Carefully inspect the power input cable first. It is clamped onto the back panel of the power supply, and sometimes that causes jacket wear on the cable.
If any rear panel fuses blow, do not panic. They are old enough to succumb to fuse fatigue. Replace (appropriately!) and try again.
Next, blow the backplane out with dry canned air. Not typical "air compressor air", as that contains oil. Then, pick up a tub of DeOxit gold wipes and give the card edge connectors a scrub.
You'll probably need to replace several front panel bulbs. Chicago Miniature Lamp (or VCC) 2309 are the right ones, as are Oshino OL-2. JKL/VCC 7371s will work in a pinch.
Flush the front panel board slide switches with CRC QD, then squirt in a small amount of DeOxit D5 while working the switches back and forth. Wipe off any excess.
When the time comes to power it all up, there's a toggle-in acceptance test in the manuals. (I assume you've found the manuals)
-Dave
On 1/20/25 16:24, therenguy via vcf-midatlantic wrote:
Thank you so much for getting back to me so soon. Alas, I live near Philadelphia, Reading, PA to be specific. Not quite in your back yard. I am really not sure how to begin. I could plug it in you know but I am sure that is not the way to proceed. Are you aware of anyone closer to me? I have worked on projects throughout my lifetime across the web so that might be a possibility although I am sure some of the questions I might ask would be truly from a beginner for a project like this one. Don’t really know. Decided to look into it. Ashame it sits in a closet.
Randy
On Jan 20, 2025, 4:18 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years.
If you're near Pittsburgh, we can probably collaborate.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
-- Dave McGuire, AK4HZ New Kensington, PA
While the other respondants are experts whose advice I strongly recommend, you might be interested in this: https://www.cs.drexel.edu/~bls96/museum/pdp8 It's a chronicle of my restorating of my 8/M. Note that as pointed out, your power supply is quite different from mine. However, this might give you some sense of what kind of things you might run into. BLS On Mon, Jan 20, 2025 at 04:24:07PM -0500, therenguy via vcf-midatlantic wrote:
Thank you so much for getting back to me so soon. Alas, I live near Philadelphia, Reading, PA to be specific. Not quite in your back yard. I am really not sure how to begin. I could plug it in you know but I am sure that is not the way to proceed. Are you aware of anyone closer to me? I have worked on projects throughout my lifetime across the web so that might be a possibility although I am sure some of the questions I might ask would be truly from a beginner for a project like this one. Don?t really know. Decided to look into it. Ashame it sits in a closet.
Randy
On Jan 20, 2025, 4:18 PM -0500, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org>, wrote:
On 1/20/25 16:14, therenguy via vcf-midatlantic wrote:
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Where in PA are you? LSSM has a few 8/es, and I personally have a few more, most of which I have restored. I've been working with, on, and inside of 8/es for about 40 years.
If you're near Pittsburgh, we can probably collaborate.
-Dave
-- Dave McGuire, AK4HZ New Kensington, PA
I'm one of the PDP-8 people around. What hardware skills do you have? Do you have any test equipment for working on hardware? The PDP-8/E has linear power supply but somewhat tightly packaged. The 8/E likely has deteriorating foam you need to clean out. Ideally replace but not that critical. The general approach I would take is to first check out the power supply. I like to reform the big capacitors and inspect all for leakage. This era DEC stuff the capacitors normally are still ok. Here is some info on checking out power supplies https://www.retrotechnology.com/restore/8f_fixitmay13.html After checking what you can power up the supply without anything connected and see if output voltages are reasonable. If you have a way to apply load test under load. Then pull all the cards and inspect and clean out the backplane and check for and damage or foreign objects. Start with processor cards and first field of memory and power up machine. Verify if voltages good. Then use front panel to see if you can read and write memory. If you can put in simple test programs https://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=188 You need to verify the cards are properly installed with correct top connector blocks before powering up. If those work put the rest of the memory in and run diagnostic series. Will need serial interface in computer to talk to external computer to send diagnostics. If machine isn't working either you need to pay $$ for boards to swap or do component level troubleshooting to replace bad IC's. People will help you with this at workshops but expect they aren't doing all the work. For getting support there are more DEC folks on the forum than the mailing list. https://forum.vcfed.org/index.php?forums/dec/ Anywhere you ask for opinions you will find people have different approaches. Schematics and manuals are online. On Mon, Jan 20, 2025 at 04:14:08PM -0500, therenguy via vcf-midatlantic wrote:
Hello,
My name is Randy Kaplan and I am joining this list to obtain some information and help.
I am a long time computing professional (50 years or so), have built my own hardware, and have been a software developer for many years. I also have many years of teaching computer science at the University level - not entirely relevant, just for background.
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Please let me know with any information you might think is helpful.
Thanks in advance for your assistance.
Regards,
Randy Kaplan
I think I stepped through all the responses and no one mentioned coming to a workshop in Wall Township. The club, MARCH, holds them roughly monthly. There you can have a number of our seasoned restores take a look with you, and there is a decent chance of crossing paths with David Gesswein. https://vcfed.org/repair-workshops/ Douglas Crawford VCF Mid-Atlantic Museum Mgr InfoAge Science & History Museums 2201 Marconi Road Wall, NJ 07719 On 1/20/2025 4:14 PM, therenguy via vcf-midatlantic wrote:
Hello,
My name is Randy Kaplan and I am joining this list to obtain some information and help.
I am a long time computing professional (50 years or so), have built my own hardware, and have been a software developer for many years. I also have many years of teaching computer science at the University level - not entirely relevant, just for background.
In any event I am the owner of an intact PDP-8/e that was operating once upon a time when I received it. A kind person gave it to me because they had too much hardware and needed a loving home for it. That is how I came to own it. At one point in my career many years ago I was invited to DEC to write code for a similar computer.
I am looking for someone to help me restore it to operating condition. It has not been used for many years and has been sitting and moved between many closets. I have its power supply also.
Can someone help kick off this adventure with me? I would be very interested in having a conversation with anyone who can make suggestions on how to proceed, who to contact, and if perhaps someone is interested, would like to help with such a project. I understand there are sessions help by VCF in this region, I live in PA, and I would certainly be willing to attend such a session.
Please let me know with any information you might think is helpful.
Thanks in advance for your assistance.
Regards,
Randy Kaplan
participants (5)
-
Brian L. Stuart -
Dave McGuire -
David Gesswein -
Douglas Crawford -
therenguy