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A common socket problem
Date: 18/6/02
Jane turned up with her Roland D-50 keyboard in its really lovely clamshell case, and all her lead kit.
She was suffering intermittant output and had traced it to the synth or lead, so she had brought both. Jane is one of those people who can actually apply a bit of deductive reasoning to some simple tests and come in already guessing the true nature of the fault.
Looking at the synth output socket it's one of the modern PCB mounting type that has no retaining nut where it pokes through the case.
Specifically the socket, the plug, and anyone tripping over the lead, are supported only by the soldered electrical connections.
From the bench notes...
Disassemble and clean.
Most synths cases these days are a stressed plastic shell with the bottom (generally) held on with a large number of screws, often marked with an arrow.
Be careful of different-looking, sometimes larger, screws under the keyboard proper as these generally hold the metal frame of the keyboard to the case.
If you do have to remove the keyboard for contact cleaning (unlikely but possible) it is better to leave it until after you get the cover off and have a look.
Disassembled these cases become quite flimsy and need to be handled and reassembled with some care.
Demount socket assembly.
At least in this synth the sockets are on their own little board; often the whole main board has to come out.
Exactly as predicted “...I think there's something wrong with that socket...”, all the sockets had fatigue dry joints (fractures) on the mounting/connections.
There is no real solution to this problem in the long term because it is designed-in.
It is a basic rule of soldering that the solder is only for electrical continuity and should not be relied on for physical strength.
The almost universal adoption of cost-cutting printed circuit board mounting components such as these sockets violates that rule because any stress on the lead that is plugged in (just its weight, never mind someone tripping over it) is only supported by these solder joints with no other mechanical support.
Made good.
These sockets are hand-soldered in place after the board has been wave soldered, as can be seen from the blobby joints with excessive solder.
Despite this the joints tend to form a conical fractures with repeated stress and the socket may actually feel loose.
Sometimes the PCB lands are ripped right off, breaking the trace, but generally it's easy to remake the joints however it won't stop it happening again.
Check battery - 3.10 volts, okay.
Note: as with all computers and synths, this memory 'keep alive' battery must be replaced when its voltage falls below 3.00 volts or catastrophic damage due to leakage may result. (the DX-7 actually has a function to display battery voltage)
It should be checked at least annually.
Tested synth in fabulous stereo! - now very okay.
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<<<OzValveAmps
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