Ribbon Connectors and Vintage Digital Gear

[Anderton]

This now makes two things I've fixed in the last week (microwave oven and CompuEffectron 1700) whose only problem was that ribbon connectors had lost contact. Removing them (which isn't always easy), cleaning the contacts on their plastic ribbons (which are pretty damn fragile!), and getting them back into their seats (which runs the risk of ruining them forever if the ribbon gets bent), restored normal operation. Just thought you oughta know, in case you were going to trash that "vintage digital" piece of gear because it wasn't working.

[Mike Rivers]

This now makes two things I've fixed in the last week (microwave oven and CompuEffectron 1700) whose only problem was that ribbon connectors had lost contact.

 

Edgeboard and pin-in-socket connectors are prone to developing enough crud to make poor contact after some time. Many a Mackie hard disk recorder (and consoles, too) has been fixed by going through it, cleaning, and exercising the ribbon cable connectors. And while decent IC sockets are too expensive for most audio gear, firmware EPROMs are often socketed, and often just giving the chip a push to re-seat it in its socket will fix a problem. Connectors and power supplies (and their connectors) are the most common and most easily fixed points of failure.

 

Since I know there are a few folks around here who remember the famous Mackie Ribbon Cable Debacle of the late 1990s, I'll mention it first. It was because of ribbon cable faults that "No Mackie consoles!!!!!!" got into a lot of band and venue equipment riders of the period. This was a built-in problem, though, not one of aging. The purchasing department, shopping for the best deal, bought ribbon sockets from one manufacturer and the pin assemblies from another manufacturer. While each was within the specification tolerance, pushing the socket (the cable end) on to the chassis mounted pins scratched a bit of the gold plating off the pin and left an unprotected surface which oxidized long before the expected useful life of the connector. Mackie replaced a whole lot of ribbon cables under warranty (which they extended - the warranty, not the cable) for certain products manufactured during the period when they were using those just-barely-mismatched connectors.

 

As Richard Hess (an expert in analog tape playback as well as flashlights) said: "If you've ever used a flashlight, you know how annoying poor contacts can be." or something like that.

 

[The Real MC]

Besides the mating contacts, the solder joints for the header can crack, often not visible to the naked eye. I've reflowed plenty of them. Voicecard motherboards in old Oberheim polysynths also need to be reflowed.

[Markyboard]

Just ordered a couple of 60 pin ribbon cables along with other parts for a friend's Prophet 5 rev 2 sitting on my bench. I would normally make them myself if needed for one of my pieces but in this case it was cheaper to just buy them prefabbed.

 

OT: Convection microwave a couple of times (different issues) and this week had to replace the rusting cold water inlet/dip tube on a water heater I installed last year. Used the wrong mating connector and well brass, copper and water don't mix so well. But yesterday was 4 hours of frustrating head scratching over an intermittent blinking light problem we've had for a few weeks. All the lights throughout the house, different circuits but everything else was fine including computers and music gear. Turned out to be bad florescent bulb(s) or the ballast in the basement. Even after they were turned off somehow it would continue to perturb the other non florescent lights for a while. Wtf?

 

Oh well, tis winter - season of indoor repairs/maintenance.

[Notes_Norton]

<...snip...>

As Richard Hess (an expert in analog tape playback as well as flashlights) said: "If you've ever used a flashlight, you know how annoying poor contacts can be." or something like that.

Of course, a flashlight is an appliance for storing dead batteries.

[Mike Rivers]

Of course, a flashlight is an appliance for storing dead batteries.

 

And since you brought that up - Dig through all your little nooks, crannies, and sock drawer and to everything you've forgotten about or haven't used in years. Pedals, recorders, flashlights, cable tester, multimeter . . whatever. Open the battery compartment and if there are batteries in there, remove them. Hopefully you can.

 

One of the problems with alkaline batteries and some low-current (or little used) devices is that the batteries operate for so long that you forget about them, and then they leak. If you catch a leaky cell early enough, you can clean up the corrosion with a cotton swab and water, but if they're pretty far gone, chances are pretty good that the electrolyte has begun to attack the metal parts of the battery holder, or worse, has gotten into the works and is eating away at circuit board traces. It may be difficult to salvage.

 

Small electrolytic capacitors can also leak, and they're mounted directly on the circuit board so they start eating the traces pretty quickly. I had that happen in the passive crossover network of one of my KEF monitor speakers - it ate through a circuit board track which caused the tweeter to be intermittent for a while, then quit completely. After I found the problem, I checked the other speaker and, sure enough, the same capacitor in that one had become leaky, too. Another thing I had here that took me a couple of years to find, was my non-working MIDI guitar. After replacing all of the electrolytics when discovering that most of them had started to leak, and that didn't solve the problem, I eventually found an etched-through circuit board trace. That took me about two years of intermittent (me, not the problem) troubleshooting.

 

 

[KuruPrionz]

Stuff about leaking batteries.

 

I buy and sell stuff I find at thrift stores, pawn shops, craigslist etc.

 

Battery compartments are the first place I check on all musical or photography gear.

Any signs of corrosion and the item becomes SEP "Somebody Else's Problem."

[The Real MC]

Not just SEP. Battery leakage can be so bad that a device is beyond salvaging. I've found batteries literally soaking in their leakage and they could not be removed.

[Mike Rivers]

Battery leakage can be so bad that a device is beyond salvaging. I've found batteries literally soaking in their leakage and they could not be removed.

 

I have a 3xD cell Mag Lite in the glove compartment of my car. It makes a better hammer than the newfangled plastic LED flashlights. My car's pretty reliable so I don't need a flashlight very often, and, yup, I forgot about it for a few years. I wanted to save the flashlight if possible. The batteries were corroded solidly in place, and, wanting to try to save the flashlight, drilled a 3/4" hole down through the batteries and was then able to pick them out in pieces. The black anodizing on the inside surface was pretty messed up, but after a good cleaning, it lived again. Now I remember to check the batteries every few months.