Repairing Retro / Vintage Computers / Equipment

[Chris Savage]

This thread was inspired by granz's For Sale thread (I didn't want to pollute your thread / post). If you have an old computer (retro computer) or piece of equipment, especially one that hasn't been powered up in many years, I would make the following recommendation.

Having worked in the industrial control world for many years, especially for more than one company that deals with obsolete industrial control systems, I can tell you that there's one primary failure point in most older electronics. The clue to what I am about to say is in the contents of most retro computer refurb kits.

These kits most often contain brand new capacitors. Specifically electrolytic capacitors and sometimes tantalum. Electrolytic capacitors in particular can dry out over the years and fail, sometimes popping or exploding. This often results in the electrolyte blowing out inside the device.

If I were buying a Commodore 64 on eBay (or a Coco or Atari) in unknown condition, the first thing I would do when I received it would be to replace the electrolytic capacitors in it, especially the power supply. In the case of the Commodore 64 / VIC-20 I would literally build a new power supply.

These capacitors are the primary failure point in ALL old electronics. Once the capacitors dry out, they no longer filter signals like they normally do. In power supplies this can result in no voltage output, noisy voltage output or the caps to pop. Even if you do pop your caps, it may be in many case that simply replacing the caps could bring the device back to life.

I bring all this up because a lot of old electronic devices end up in the landfill or e-waste centers do to bad caps. I used to have a buddy that worked for a recycling center and he pulled many things out and refurbed them himself. It's not always caps. Sometimes a diode in the supply will fail or something similar, but these things are easy to detect with a simple multimeter with a diode checker and can be checked in circuit. In some cases power resistors (especially wire-wound) had failed causing an open circuit.

Depending on your skills, you may be able to get many retro devices up and running fairly easy and either acquire stuff you always wished for that is hard to find in working order, or make money on the side (or both). I wish I had access to some of the local auctions some of my peers post on social media. People like John_AZ (who used to be on my old forums) constantly pick up pallets of e-waste that have a lot of great salvageable parts, but sometimes pick up really good deals on old computer hardware and I admit, I am jealous.

[granz]

Some good advice, Chris. I spent many years repairing computers (starting with a multi-million dollar mainframe (the air conditioning alone cost the U.S. Air Force a million dollars a year - in 1980 dollars.  ) After I got out of the AF, in several jobs I had, I was the only one who knew how to repair the things (teaching, and programming, jobs,) so I got to do that stuff in addition to my main job. Your advice is right on the spot, and should help people get stuff repaired that might otherwise be dumped.

Yeah, that terminal going out was my fault. And the worst part is that it was because I was being lazy, and impatient. There have been many times that I powered up an old piece of equipment, and it worked perfectly, many times. The fact is, that I have the equipment (meters, scopes, even a brand new, still in-the-box variac,) and just made a bad bet. That will probably cost me some, but not as much as someone might think - true hobbyists will still buy stuff to repair it, and collectors often don't care if the thing works, or not.

Yes, the terminal could probably be fixed, and the caps are the first things to replace, but (like I said) I was just being lazy. So, because I don't have time, or energy, to work on it, my laziness can give someone a good deal.

[Chris Savage]

Yeah, that terminal going out was my fault. And the worst part is that it was because I was being lazy, and impatient.

There's no judgement here. I've made share of mistakes. However, your experience reminded that back in the late 80s / early 90s, my repair experience was generally defective ICs (RAM, EPROM, LOGIC, etc.), power surges, heat damage (Commodore P/S BAD design), physical damage or wear & tear (floppy drives / hard drives).

These days working with the same exact hardware is usually caps, though I still see wear & tear. I don't fix many things anymore because there are other options. There is so little replacement hardware these days to repair floppy drives, especially for Commodore computers. However, now there are other options such as the now very common SD2IEC Commodore 64 Floppy Drive Emulator and the newer Pi1541 Disk Drive.

Anyway, as you mentioned, it is suggested that those acquiring vintage hardware consider changing the caps before powering up old equipment. If you're using Commodore hardware or any hardware that had an older "brick" P/S, I would consider a upgraded replacement P/S.

[granz]

...If you're using Commodore hardware or any hardware that had an older "brick" P/S, I would consider a upgraded replacement P/S.

Yeah, I have some old Commodore stuff; maybe I should look into that. Do you know where I could get a new replacement P/S for them? Or, maybe I should just get rid of them, trade them in for an SX-64. 

[Chris Savage]

Yeah, I have some old Commodore stuff; maybe I should look into that. Do you know where I could get a new replacement P/S for them? Or, maybe I should just get rid of them, trade them in for an SX-64. 

Ironically, I never had much interest in an SX-64. Seemed more like a novelty. My favorite was the C=128D, of which my first was heavily modified. The front had all kinds of switches and LEDs related to various modifications I made.

A switch and bi-color LED for Jiffy-DOS. A 3-position switch for the floppy drive for Read / Write override. A CPU access LED. Stereo SID chip. Oh, the good old days...

...as for your question. I was one of those people who used to build the repairable, upgraded C=64 power supplies. Ironically, I got ALL the parts, including the enclosure, from Radio Shack. Now that there's no Radio Shack I would have to source the parts again. I used a vented enclosure, two of their transformers (one was a 9V), a solder-ring board and a handful of discrete components. Of course there was a fuse, power switch and bi-color LED. Red for when mains power was connected and then it would turn green when you turned on the power to the C=64. Radio Shack even used to carry the C=64 power connector at one time.

I suppose I could look into sourcing the parts and perhaps do a tutorial / project and possibly sell a kit on Savage///Circuits.

[granz]

Yeah, I have some old Commodore stuff; maybe I should look into that. Do you know where I could get a new replacement P/S for them? Or, maybe I should just get rid of them, trade them in for an SX-64. 

Ironically, I never had much interest in an SX-64. Seemed more like a novelty. My favorite was the C=128D, of which my first was heavily modified. The front had all kinds of switches and LEDs related to various modifications I made.

A switch and bi-color LED for Jiffy-DOS. A 3-position switch for the floppy drive for Read / Write override. A CPU access LED. Stereo SID chip. Oh, the good old days...

I do have a '128, but am not sure of the model. You could probably convince me to part ways with it, if you want; certainly easier, and cheaper, than someone else.

...as for your question. I was one of those people who used to build the repairable, upgraded C=64 power supplies. Ironically, I got ALL the parts, including the enclosure, from Radio Shack. Now that there's no Radio Shack I would have to source the parts again. I used a vented enclosure, two of their transformers (one was a 9V), a solder-ring board and a handful of discrete components. Of course there was a fuse, power switch and bi-color LED. Red for when mains power was connected and then it would turn green when you turned on the power to the C=64. Radio Shack even used to carry the C=64 power connector at one time.

It was truly sad to see the Shack go, but really they went under when they decided that they should turn all of their brick-and-mortar stores into very expensive phone vending machines.

I suppose I could look into sourcing the parts and perhaps do a tutorial / project and possibly sell a kit on Savage///Circuits.

No, don't do that just for my sake. Like I said, I will probably just get rid of my stuff to make more room for the stuff on which I want to concentrate. On the other hand, if you see any need for that, by all means carry on. 

[Chris Savage]

I do have a '128, but am not sure of the model. You could probably convince me to part ways with it, if you want; certainly easier, and cheaper, than someone else.

The C=128 was a standard bread-bin case, whereas the C=128D had an integrated floppy drive in a metal enclosure with an external keyboard. You can see the advantages to having that PC enclosure to hold all the extra bits and pieces.

It was truly sad to see the Shack go, but really they went under when they decided that they should turn all of their brick-and-mortar stores into very expensive phone vending machines.

That and the fact that they changed their sources for everything they sold under their brands. For example, early Radio Shack stereo / audio equipment was manufactured by Harman Kardon and I think Marantz (mixers)? I don't remember who made their speakers back in the day, but eventually everything was made by Pioneer and I am just not a fan.

They also discontinued so many products that people like us use all the time.

No, don't do that just for my sake. Like I said, I will probably just get rid of my stuff to make more room for the stuff on which I want to concentrate. On the other hand, if you see any need for that, by all means carry on. 

If I did it, it would be to offer a kit for sale for those collectors who can't build their own, though I would certainly still have an article showing how to build your own. I'm not in it to make money (it's a hobby), but I still have website expenses to pay.

[granz]

I do have a '128, but am not sure of the model. You could probably convince me to part ways with it, if you want; certainly easier, and cheaper, than someone else.

The C=128 was a standard bread-bin case, whereas the C=128D had an integrated floppy drive in a metal enclosure with an external keyboard. You can see the advantages to having that PC enclosure to hold all the extra bits and pieces.

OK, I have the first one that you mention, not the one with the integrated drive. If you are interested in it, let me know.

[Chris Savage]

OK, I have the first one that you mention, not the one with the integrated drive. If you are interested in it, let me know.

Interested. 

[granz]

Interested. 

PM sent.

[granz]

Actually, I was talking to my wife about this, and I realized that of the dozens, or maybe hundreds, of old/antique devices that I have powered up, this is the first one to blow like that. I have had other devices which, when powered up for the first time in a while, have just not worked, but none have blown up.

So, I would say that my record is pretty good. Although, I think that I will get my Variac out, and use that the next time that I test something like that. 

[Chris Savage]

Actually, I was talking to my wife about this, and I realized that of the dozens, or maybe hundreds, of old/antique devices that I have powered up, this is the first one to blow like that. I have had other devices which, when powered up for the first time in a while, have just not worked, but none have blown up. So, I would say that my record is pretty good. Although, I think that I will get my Variac out, and use that the next time that I test something like that. 

To be clear, a device "blowing up" is the exception. Most of the vintage electronics I repair simple don't power up. Of course, many power supplies are designed not to power up in the event of a failure to prevent damage to other components. Think about even some of the more modern LDO regulators that require output caps to regulate properly. Of course, I am typically working on industrial equipment, so...

[granz]

To be clear, a device "blowing up" is the exception. Most of the vintage electronics I repair simple don't power up. Of course, many power supplies are designed not to power up in the event of a failure to prevent damage to other components. Think about even some of the more modern LDO regulators that require output caps to regulate properly. Of course, I am typically working on industrial equipment, so...

That is true, although the equipment blowing up is pretty memorable.  So, it makes sense that equipment blowing up would be more likely to be reported.

[Chris Savage]

That is true, although the equipment blowing up is pretty memorable.  So, it makes sense that equipment blowing up would be more likely to be reported.

Well, far be it for me to rain on your thunder. LOL 

[granz]

That is true, although the equipment blowing up is pretty memorable.  So, it makes sense that equipment blowing up would be more likely to be reported.

Well, far be it for me to rain on your thunder. LOL 

LOL, and yeah it did sound like thunder - although not quite as loud.