| Author | Message | ||
     Barry Marie |
I'm currently trying to troubleshoot dead reverb in my RD-100. It was initially ok, but wouldn't switch off (I mostly have it on all the time). Then, it seemed to come good (footswitch suddenly worked), but now it won't switch on. I tried installing another SPST switch, however the replacement has three terminals (and in my haste, I may have installed it incorrectly). What I'd like to confirm is which RCA plugs (underneath chassis) are correct for Reverb and Distortion - from the footswitch I have a red & black male RCA plugs - but I'd like to be 100% sure that I have them plugged in correctly. Can someone help here? Thanks Barry M | ||
| Langley |
WAS THE OLD SW REALLY AT ISSUE? Using a VOM or some sort of continuity tester, Check the old switch to see if it is/was at fault to begin with. USE THE NEW OR OLD SW? If the old switch is good you may wish to spray a cleaner such as 'deoxit" or 'cramolin red" down the switch shaft, to clean it. Let it dry overnight. Follow up with a short burst of Radio Shack Tuner/Control cleaner. It's got a lubricant. You don't want too much of that. Let it dry. Test it. If it doesn't work you'll have to determine the polarity, via continuity, of the contacts on your new switch, assuming it's the correct one. The schematic shows a SPDT which includes/isolates an LED. Wire and install. MAINTAINENCE ON THE VULERNABLE STUFF. Using the VOM/Continuity tester, test for the On/Off functioning of the Footswitch assembly at the RCA plugs. Wiggle the wires to check for intermittents. If the test fails,you may have to rewire the switch. Use this test also to validate the wires that go from the chassis to the reverb tank. CLEAN CONTACTS ARE HAPPY CONTACTS Spray a little contact cleaner on a papertowel and clean all of the RCA plugs, m/f. Soak a round toothpick in contact cleaner and gently make tiny little circles into the center of the fem RCA (The RCA jack may require dinner and a movie first...). Check the seated plugs for tightness, slightly crimping the plug's "-" shield, as necessary, to tighten. RCA PLUGS CHASSIS FOOTSW LOCATIONS: if either reverb/sw works the reverb, and/or the distortion/sw works the distortion then it's Miller time... If the labeled function is inverted, then reverse the plugs. (my 210-65 chassis has a "red dot" indicating the location of the Red RCA plug. Does yours?) You may wish to 'tag' the plug/jack locations. IF YOU CAN'T FIND THE CULPRIT... You may have to repeat some or all of this diagnosis proceedure, slowly, a couple of times. At some point time you may need to validate the Reverb Tank - a whole story onto itself. If that proves out good, then there may be issue within the chassis. At this point the amp needs a Tech. Get some new tubes and make the most of the visit... | ||
| Barry Marie |
Thanks Langley .. I'd already resolved the problem before I read your post, however I was able to confirm that the switches (both old and new) were both ok, via continuity test. In the end, I had two separate problems - one being a fault in the actual footswitch cable (reverb only) - found again via continuity test. A wire had also become loose in the reverb tank - needed resoldering. An important thing to consider with any diagnosis is that it's possible to have more than one problem .. Many Thanks .. Barry M | ||
| Steve Kennedy |
AMEN! I have lost count of the number of electronic repairs I have done where it was a combination of problems that were responsible for the final symptoms! Human nature is a funny thing... people can ignore or filter out problems or find work arounds until they pile up deep enough to be a bigger combined problem! |