I often come across corroded or dirty contacts so the amp stops functioning. If the spriginess of the metal has failed then replace obviously, but what about the more usual case where it is only corrosion/airborn contaminaion, not really necessitating pulling the amp apart to replace them. Any ideas how to deal with.
1/ solvent clean the contact/s
2/ abraid the contacts with file
3/ coat the contacts with something
3/ add compressible material , glued in place, over the spring section to add closure force
4/ if the sockets are never used for effects etc , bridge tightly across the contact with fine copper wire, soldered in place, "shorting" the switch - if plugged into at some future point then the wire will break
5/ any other ideas to reduce the possibility of re-occurance
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
I'm not going to desolder any of the present problematic ones but I would say they are the same as Cliff UK, No 3 type. I've seen the airborn grime problem on gold-flashed contacts though, adding extra closure force would not a bad thing, I would have thought for this grime/corrosion problem and more reliable active, in use, in/out contacts via the plugs. On that line, including on the design/manufacturing side, I was thinking.
1/ socket with no plug in so switch closed
2/ cover the switch area with a piece of plumbers PTFE tape. (if new sockets, then wrapping the PTFE right around each of the contact areas would keep most of the grime out, it should stretch easy enough to allow entry of plugs, and soldering temperatures will not affect the PTFE)
3/ a section of cut down neoprene cordage, diameter the size of the slot or slightly bigger, pushed into the "slot" in the plastic housing above.
4/ Push down the rubber with a small PTFE covered rod of some sort while filling the top with hot-melt glue, extract the rod when cold Unfortunately grime can still enter through the plug hole but if much reduced air flow out of the back of the socket then perhaps less grime going into the plug hole
5/ Another idea "flap valves" on the external holes of the sockets
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
By all means NO. Don't file, sand or otherwise remove metal from switch contacts. That will make matters worse. If I can get in the right spot, I'll "polish" them with a dollar bill (open the contacts, put the bill between the contacts, close the contacts and work the bill around or pull it out a few times.)
Caig D5 usually does the trick.
Nah. If it's worn out, replace it.
You're better off just using a short patch cord from Out to In.
OK, school-time: what you need is a GC Electronics 9337 "Plastone" contact burnishing tool. This particular one is exactly the right size for cleaning Cliff's (and Re-An and other Cliff's-clone) jacks. The tool is flexible, and can be bent into any necessary shape to reach the jacks' switch contacts. You insert a plug into the jack to open the contacts, stick the burnisher between them, and remove the plug, allowing the contacts to close on the burnisher. You then saw the burnisher back and forth a few times to remove the crud. THIS WILL NOT DAMAGE THE CONTACT SURFACES, regardless of what you might see posted here by anyone else. Finsh the job off with a shot of Caig D-5 or D-100 between the contacts.
This GC tool is from the heyday of the telco era, and was designed to service the phone system when it was largely electro-mechanical. There is a larger size - the GC 9338 - which is ideal for cleaning Switchcraft 12A and other American-style open-frame jacks found on older Fender amps. Best thing about these tools is that they cost less than two bucks each, and last virtually forever. Here's a dopesheet:
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If you can't find them locally, I sell 'em - and so do a lot of other distributors. They're an essential part of any PRO amp tech's kit.
Lord Valve Expert
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I specialize in top quality HAND SELECTED NOS and current-production vacuum tubes for guitar and bass amps. Good prices, fast service. Authorized dealer for QSC amps, Sovtek/Electro-Harmonix, Behringer, Hammond-Suzuki, Leslie, Rolls, Weber VST, etc.
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Put a U-jumper. Normalled contacts have no place in a high-vibration environment anyway... unless they are doing non-critical (input shorting) work. __ Steve .
The trouble is calling them contacts is mutton dressed as lamb. The static part of the "contact" is just the cut end of metal strip that is touched by the moving part of the switch, likely to score any burnishing tool.
Clean the ones that respond and replace the ones that don't. The worst part about this is that you will have to test clean to know if it works. This is not nearly so big a deal as you make of it.
Burnishing works. I can't see why you object to the concept.
The Cliff type jacks are not usually problems and really don't require this overcomplication you're bringing to the subject. Annual execise by the user and the occasional professional cleaning keep them in shape. You can complain about the aesthetics, but they work fine and have for decades.
I'm sure that I'm probably opening myself up to a bunch of abuse here, but I have to say that in over 35 years of repairing group amps, the number of occasions that I've found the effects send and return socket switches causing a problem of intermittent output, has been so small that I would consider it negligible as a problem, and certainly not one that would warrant doing things like wrapping the sockets up in plumber's tape or shorting across them with breakable wires.
I would absolutely refute that replacement is the *only* way to deal with any such bad contacts, and that any sockets treated with a contact burnishing tool and then with a protective contact oil, will bounce any quicker than if a replacement socket had been fitted.
There is absolutely no reason at all that if an oxide layer is chemically or physically removed from a contact surface, without removing any material from the actual contact material, or if airborne contamination is removed from a non-reactive precious metal plated contact surface, that those contacts are not restored to the exact same condition that they were when they left the factory. You could buy a *new* socket that had sat in a bin in a supplier's warehouse for two years, and had plenty of time for the contacts to start oxidising, so fitting that may not in fact be any better than correctly cleaning the already-fitted socket.
Over the last few months, Mr Cook has voiced some very odd concerns on here, and seems to have had more than his fair share of - how shall we say - unusual ? - problems. If my working day was filled with such concerns all the time, I would never make any money, and would be considering it time to give up, I feel ...
Going by the rusty cabinet screws on a lot of the kit I see they must be stored in sheds or garages. Anyway this example I "abraided" with a cut segment of nylon cable tie and "Brasso" metal polish, cleaned off by a strip of card dampened with meths. Drilled a hole through the board either side of the switch and tied some silicone rubber cordage around the switch passing through a piece of plastic barrel that seated neatly in the top of the flexing metal strip.
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
Yeah, you may have been servicing it, but you don't have the valuable experience of making your own solder and flux to an ancient family recipe, drawing your own wire or rebuilding amps using parts from a 1920 Indian Chief.
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