Jump to content
IGNORED

On the bench for refurb/overhaul


mojoatomic
 Share

Recommended Posts

I introduced myself i the appropriate forum about a week ago and mentioned that I had started to refurb and overhaul 2600's after a looooong hiatus... some of the guys requested details/pics and I figured this was a better forum for that. As to not step on any toes, this is not a sales post - just a "How I do it" type thing. I do it now for fun more than anything else :-)

 

I'm a network admin for a fairly large company now, but when I started in the early 80's it was as a lowly board tech. I had 3 scopes, logic analyzers, logic injectors and all manner of test equipment on my bench, and I was good. I'm proud of those days - it may seem silly now to younger folks who have never seen that type of environment, but back then it was a big deal to be a respected and capable bench/board tech. Sometimes manufacturers would implement your repair fixes and apply them to the assembly line if they were good enough, and you trained field techs in the ways of repairs.

 

For those that weren't around or don't know :-), nothing electronic was thrown away back then, if it had value, it was fixed and put back into service. That happened at several levels of service... the lowest level was repair - basically just make it work. Think mom and pop repair shops. Farther up the food chain near the top was refurbishment and overhaul - at this level, you tried to make everything you touched as close to "factory" as possible, including applying service bulletins and anything else that needed to be done. That's where guys like me came in. I worked on Unisys, IBM, Daisytech dumb terminals (among others), various brands of CRT's, Bang & Olufsen, Macintosh (not the computer), Apple ( the early ones - think IIe and +), Atari's - basically anything worth working on that we could get a manufacturer to set us up with depot style repair work for, complete with proper parts, manuals, supply chain, etc. There was no monkey repair or shotgunning of parts - you either knew what you were doing, or you didn't. There's no where to hide when the final test if flipping the power switch :-)

 

Anyway... this hit the bench last night -

 

Before you ask - there's a bottle of Everclear on the bench - I'm not an alcoholic and I don't drink it :-) it's one of the finest solvents available for electronic work; miles and miles beyond that oily drug store isopropal. No residue, and cleans like mad.

 

7801A055-0E85-45BA-8F3E-DA4A451909FE_zps

 

 

A hack has been into this for sure... but no matter, I think we can straighten it out. See the heat sink compound?? Waaaaaay to much. You just need a film of it, that's all. Too much attracts dust, and that's builds up heat and ultimately causes failures. Also, this power switch and it's parts (minus the leaf spring contactors) was rolling around inside... will need a new one, because I don't have any leaf spring contactors lying around.

CBE396F2-C1B9-443A-A954-4D591D83B6C3_zps

 

See the hole blown in the 7508 voltage regulator? That'll cause an issue. Need to check for shorted caps or a bridged ground..

736BDA1D-77ED-4E65-A170-22992D543C7C_zps

 

You only need two things to clean the leaf spring contactors and make them look and function like brand new... a solvent, and a soft brass brush. Why a brass brush? Well, the solvent (Everclear in this case) softens the gummy shellacked buildup on the contactors and leafs, and the brass brush removes the residue without harming either, because the brass is softer than the leaf springs and contactors, yet harder than the buildup. They shine up like new, and you cause no wear cleaning them.

E9C14F0A-4EC7-41D5-A05B-AC52C7DD50FF_zps

 

Just like new - notice that there are no scratches? You won't get this outcome if you use sand paper. These contactors are ready for another 30 years.

273FD318-CD2C-47F9-B026-2FFC536E2E1F_zps

 

Hit these with the alcohol and then the brass brush and they shine up like new money as well...

C47AB7F1-C06D-492E-849D-02085921ED80_zps

 

 

On that note... I'm going to tell you something that a lot of folks don't believe, don't want to hear, or just don't understand. Every electrolytic can on these boards is bad. Period. Electrolytic caps have a useful lifespan of around 10 years... beyond that, the electrolytic degrades and the ESR of the cap goes through the roof. The in circuit ESR reading of the big 2200uF cap was deplorable. Same for the 4.7uF caps - they're even domed now. Bottom line - when they pop, they will take something with them. Just because they "work" doesn't mean that they are working correctly or within design specs. I pull these out and replace them with new, fresh caps, and return the old parts with the unit - I return all pulled parts, actually.

 

A watch that doesn't keep time has no value as a timepiece - it may have historical or other significance lying in it's broken state... but it has no value as a timepiece. That really is the essence of my restorations - to have something as close to factory spec as possible, but still working.

 

That's it for the moment - I've tested some parts, they need replacement and I'm out :-( time for a parts order. I'll go over the rest of the refurb when they get here, including the anatomy of the difficulty selector switches. Basically, 8 caps need to be replaced along with the 7508, and then we'll see what else.

Edited by mojoatomic
  • Like 11
Link to comment
Share on other sites

Proper specs.. Proper cleaning solutions, proper troubleshooting and no shotgunning random parts.. All faulty electronic equipment should be given this sort of TLC!

 

That was a pleasure to read kind sir.

Thank you for that :-)

 

I hope that other's can learn from ramblings like mine and we can keep these consoles running long past my time.

Link to comment
Share on other sites

Terrific post and, for the record.....you had me at "Everclear".

 

Ha!, yeah... That has raised quite a few eyebrows over the years...

 

Used to buy electronics grade alcohol by the gallon back then, but I just don't use that much now. Doesn't take much when you have the right stuff... That bottle on the bench is going on 3 years worth of contact repairs now, and also removing flux residue.

 

There was was a phase in the late 80's through mid 90's when all manner of chemicals were sold to pro shops for electronic related cleaning... Some were great, others just snake oil. Trouble is, none are produced anymore in their original format because they contained fluorocarbons - and you can't sell them any more. Some companies tried to reformulated some of them... None are worth jack now.

 

Anyway, anything electronic can be put in water and washed, so long as you flush it with distilled water afterwards and heat it to dry. Used to run click key IBM keyboard boards in a dishwasher. Switches and all... It was the best way. Same thing with TTL logic boards for terminal servers before repairs, just washed and scrubbed them with a brush. Grain alcohol displaces water and leaves absolutely no residue., and washes away flux like it was never there.

 

Except for DeOxit... I love that stuff and have used it for 30 years now.

 

I'll complete the post when I get some parts in, shouldn't be too long.

  • Like 2
Link to comment
Share on other sites

Only if your local hardware store sells liquor :-) - girl at the liquor store sees me in a suit and tie and says "Huh... you don't look like the type to drink Everclear"

 

Your normal bar wouldn't have it, unless your normal bar is under a bridge near a bypass, but your local frat house would.

  • Like 1
Link to comment
Share on other sites

I introduced myself i the appropriate forum about a week ago and mentioned that I had started to refurb and overhaul 2600's after a looooong hiatus... some of the guys requested details/pics and I figured this was a better forum for that. As to not step on any toes, this is not a sales post - just a "How I do it" type thing. I do it now for fun more than anything else :-)

 

I'm a network admin for a fairly large company now, but when I started in the early 80's it was as a lowly board tech. I had 3 scopes, logic analyzers, logic injectors and all manner of test equipment on my bench, and I was good. I'm proud of those days - it may seem silly now to younger folks who have never seen that type of environment, but back then it was a big deal to be a respected and capable bench/board tech. Sometimes manufacturers would implement your repair fixes and apply them to the assembly line if they were good enough, and you trained field techs in the ways of repairs.

 

For those that weren't around or don't know :-), nothing electronic was thrown away back then, if it had value, it was fixed and put back into service. That happened at several levels of service... the lowest level was repair - basically just make it work. Think mom and pop repair shops. Farther up the food chain near the top was refurbishment and overhaul - at this level, you tried to make everything you touched as close to "factory" as possible, including applying service bulletins and anything else that needed to be done. That's where guys like me came in. I worked on Unisys, IBM, Daisytech dumb terminals (among others), various brands of CRT's, Bang & Olufsen, Macintosh (not the computer), Apple ( the early ones - think IIe and +), Atari's - basically anything worth working on that we could get a manufacturer to set us up with depot style repair work for, complete with proper parts, manuals, supply chain, etc. There was no monkey repair or shotgunning of parts - you either knew what you were doing, or you didn't. There's no where to hide when the final test if flipping the power switch :-)

 

Anyway... this hit the bench last night -

 

Before you ask - there's a bottle of Everclear on the bench - I'm not an alcoholic and I don't drink it :-) it's one of the finest solvents available for electronic work; miles and miles beyond that oily drug store isopropal. No residue, and cleans like mad.

 

7801A055-0E85-45BA-8F3E-DA4A451909FE_zps

 

 

A hack has been into this for sure... but no matter, I think we can straighten it out. See the heat sink compound?? Waaaaaay to much. You just need a film of it, that's all. Too much attracts dust, and that's builds up heat and ultimately causes failures. Also, this power switch and it's parts (minus the leaf spring contactors) was rolling around inside... will need a new one, because I don't have any leaf spring contactors lying around.

CBE396F2-C1B9-443A-A954-4D591D83B6C3_zps

 

See the hole blown in the 7508 voltage regulator? That'll cause an issue. Need to check for shorted caps or a bridged ground..

736BDA1D-77ED-4E65-A170-22992D543C7C_zps

 

You only need two things to clean the leaf spring contactors and make them look and function like brand new... a solvent, and a soft brass brush. Why a brass brush? Well, the solvent (Everclear in this case) softens the gummy shellacked buildup on the contactors and leafs, and the brass brush removes the residue without harming either, because the brass is softer than the leaf springs and contactors, yet harder than the buildup. They shine up like new, and you cause no wear cleaning them.

E9C14F0A-4EC7-41D5-A05B-AC52C7DD50FF_zps

 

Just like new - notice that there are no scratches? You won't get this outcome if you use sand paper. These contactors are ready for another 30 years.

273FD318-CD2C-47F9-B026-2FFC536E2E1F_zps

 

Hit these with the alcohol and then the brass brush and they shine up like new money as well...

C47AB7F1-C06D-492E-849D-02085921ED80_zps

 

 

On that note... I'm going to tell you something that a lot of folks don't believe, don't want to hear, or just don't understand. Every electrolytic can on these boards is bad. Period. Electrolytic caps have a useful lifespan of around 10 years... beyond that, the electrolytic degrades and the ESR of the cap goes through the roof. The in circuit ESR reading of the big 2200uF cap was deplorable. Same for the 4.7uF caps - they're even domed now. Bottom line - when they pop, they will take something with them. Just because they "work" doesn't mean that they are working correctly or within design specs. I pull these out and replace them with new, fresh caps, and return the old parts with the unit - I return all pulled parts, actually.

 

A watch that doesn't keep time has no value as a timepiece - it may have historical or other significance lying in it's broken state... but it has no value as a timepiece. That really is the essence of my restorations - to have something as close to factory spec as possible, but still working.

 

That's it for the moment - I've tested some parts, they need replacement and I'm out :-( time for a parts order. I'll go over the rest of the refurb when they get here, including the anatomy of the difficulty selector switches. Basically, 8 caps need to be replaced along with the 7508, and then we'll see what else.

@OP You really know your stuff. I nearly had a degree in Electrical Engineering Technology, but you seem to have practical knowledge they don't teach in school! ;-)

 

As for the Everclear, why not pick up some SLX denatured alcohol at a hardware store? A half gallon of the SLX Denat stuff costs about the same as that tiny flask. It's also completely anhydrous unlike Everclear (95% grain alcohol) or 91% isopropyl rubbing alcohol. Just don't drink it or you'll go blind! :skull:

 

I tried some Everclear once and I can honestly say it's probably better suited for use as a solvent or motor fuel than for human consumption... :woozy:

Link to comment
Share on other sites

@OP You really know your stuff. I nearly had a degree in Electrical Engineering Technology, but you seem to have practical knowledge they don't teach in school! ;-)

 

As for Everclear, why not pick up some SLX denatured alcohol at a hardware store? It's also completely anhydrous unlike everclear (95% grain alcohol) or 91% rubbing isopropyl alcohol. Just don't drink it or you'll go blind! :skull:

 

I tried some Everclear once and I can honestly say it's probably better suited for use as a solvent or motor fuel than for uuman consumption... :woozy:

 

I thought of denatured alcohol too and looked it up. It sounds like it's basically the same as Everclear, ethanol alcohol except with other additives for various reasons such as color and nasty taste. I wonder with the additives if it would not be as good because it's less pure more likely to leave residue?

Edited by briwayjones
Link to comment
Share on other sites

 

I thought of denatured alcohol too and looked it up. It sounds like it's basically the same as Everclear, ethanol alcohol except with other additives for various reasons such as color and nasty taste. I wonder with the additives if it would not be as good because it's less pure more likely to leave residue?

SLX has 5% methanol and a few other additives. Has a mildly sweet odor too. It's completely clear though and leaves no residue.

 

I worked in a research lab as a teen and we used ethanol and methanol to sterilize lab equipment. I used to could differentiate methanol, ethanol, propanol, butanol apart by their odors. Methanol smells sweeter than ethanol but can be fatal or cause blindness if ingested. Propanol has a deeper aroma (hard to describe, but not a harsh chem odor like rubbing isopropanol) and butanol smells gassy. Not unlike the smells of propane and butane.

Link to comment
Share on other sites

 

I'm going to tell you something that a lot of folks don't believe, don't want to hear, or just don't understand. Every electrolytic can on these boards is bad. Period. Electrolytic caps have a useful lifespan of around 10 years...

Amen. I tell folks this also, but I normally say, 20 years for the smaller/lower voltage caps.

Trouble is, too many think they understand electronics enough to not take good advice.

Link to comment
Share on other sites

Cool write-up. I look forward to more.

 

How does acetone work for cleaning? And would be be willing to list the size/type, and number of each type of caps, and whatever else part wise needed for reconditioning a 2600?

I'd be happy to list everything used :-)

 

Say no to acetone

Link to comment
Share on other sites

@OP You really know your stuff. I nearly had a degree in Electrical Engineering Technology, but you seem to have practical knowledge they don't teach in school! ;-)

 

As for the Everclear, why not pick up some SLX denatured alcohol at a hardware store? A half gallon of the SLX Denat stuff costs about the same as that tiny flask. It's also completely anhydrous unlike Everclear (95% grain alcohol) or 91% isopropyl rubbing alcohol. Just don't drink it or you'll go blind! :skull:

 

I tried some Everclear once and I can honestly say it's probably better suited for use as a solvent or motor fuel than for human consumption... :woozy:

 

Thanks KS, us pesky old guys and our practical knowledge :-) Truthfully though, very, very little that I learned gaining an EE translated to the way things really work. It really just gives you a reference point to begin teaching yourself. There was a phrase used... "Kick and bleed" - as in, "Nah, don't help him with that, he needs to kick and bleed, then he will understand it" - and this was the essence of training back then. Basically, there's no way to pour it all into your head, so we'll get you started but you have to have the horsepower between your ears to put the pieces together. It wasn't out of meanness, it was considered a kindness. No need to prolong the agony of a guy who wasn't going to be able to make the transition.

 

I could show guys how to use a o-scope, I mean really, really use it... but there was no real way to make them understand what they were seeing or tell them all the ways that the data could be interpreted. The guys who couldn't quite put it all together became the ones that followed the cook book recipes of repair. You know the flow charts in the Atari Field Service Manual? That's who they're for. Anytime you see flow charts like that from any manufacturer of that era, that's who they're for. If you have an 0-scope with an octopus, variable power supply, multimeter, a good iron & schematics - flow charts just slow you down.

Edited by mojoatomic
  • Like 2
Link to comment
Share on other sites

Sometimes I'll use an old telephone pickup coil to listen to the radiation coming from a circuit or motor. It can tell you a lot if something is stuck in a loop, or hasn't started. It can tell you if an HDD is having a hard time spooling up, or seeking too much for a track or sector. It can tell you the overall health of the servo system at full extension or when running the butterfly test. All the beeps, blips, scratches, bumps, and flavour of tones, it all means something. I also have an AM radio that has a plug for a remote antenna - and together with a scope and the pickup coil its the ultimate stethoscope for electronics.

 

Troubleshooting and testing involves all your senses, not just what is shown on your DMM. Smell the burned parts, feel the hot burning parts, see the burn marks, listen to the crackle of sparks, taste the silicon seasoning, feel the pressure building up in a cap about to go bang!

 

In the future I'd like to see augmented reality glasses that show the electricity flowing through traces. Color-coded for temperature, current, frequency, voltage.. That way you don't have to build a mental picture of the circuit under test. Just see where the electrons are flowing.

Link to comment
Share on other sites

Thanks KS, us pesky old guys and our practical knowledge :-) Truthfully though, very, very little that I learned gaining an EE translated to the way things really work. It really just gives you a reference point to begin teaching yourself.

 

The degrees are more like learning the language and context. When talking about Atari and I say 9V, it's commonly accepted to mean VCS power adapter as the source. Voltage rectifier power-transistor looking thing on the left side. 120V generally means AC power in the U.S. True RMS while talking about stereos is taken as maximum sustained real power. Degrees are merely specifying the dimension of the canvas that you work on.

Link to comment
Share on other sites

That hole in the voltage regulator isn't "blown", it's meant to be there and a screw is missing that holds it to the pcb.

 

You are joking, right? Look right above the "A" - see that charred hole? - it's cracked through to the rear of the IC.

Yes look closer, there is clearly evidence of charring. And not the giant hole in the heat sink which is supposed to be there to secure the chip and dissipate heat to external radiator. :roll:

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...