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Conference napalm::guitar

Title:	GUITARnotes - Where Every Note has Emotion
Notice:	Discussion of the finer stringed instruments
Moderator:	KDX200::COOPER

Created:	Thu Aug 14 1986
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	3280
Total number of notes:	61432

2427.0. "Troubleshooting Fender 'The Twin'" by PHAROS::SAKELARIS () Thu Jan 09 1992 15:53

    I searched for something on troubleshooting but didn't see any specific
    posting. Greg, if you can think of a better place to put this, by all
    means....
    
    I seem to be having a problem with the channel switching of my
    amp (Fender "the Twin"). The footswitch  doesn't switch channels, my
    overdrive channel is on all the time. The footswitch does have an 
    LED to indicate when the overdrive channel is on, and it toggles every
    time as it should. 
    
    The clean channel works fine. I can determine this because the twin has 
    a pair of inputs that select both channels when plugged into, and when
    I plug into 'em I get both channels. 
    
    Any ideas, bros of tone?
    
    "sakman"

T.R	Title	User	Personal Name	Date	Lines
2427.1	STEP 1	MANTHN::EDD	Daze of the weak...	`Thu Jan 09 1992 15:58`	4
	Borrow a known good footswitch and find out which end of the wire the problem lives on for starters... Edd
2427.2		BTOVT::BEST_G	Baby, assess my gingiva	`Thu Jan 09 1992 16:15`	10
	Edd, If the footswitch is bad, please explain how the LED can still toggle via the footswitch.... (I'm assuming that the LED does toggle via the footswitch, as opposed to a manual switch on the front of the amp or something.) guy
2427.3		MANTHN::EDD	Daze of the weak...	`Thu Jan 09 1992 16:23`	9
	Without a schematic or knowledge of the footswitch circuitry I couldn't say for sure, but after years of troubleshooting all kinds of things (from cars to synths to computers) I've learned to never trust the indicator light to tell you something is OK. (But always give it the benefit of the doubt if it says NFG!) Besides, it's a 10 second effort to pop another switch in, no? Edd
2427.4		KDX200::COOPER	Step UP to the RACK !	`Thu Jan 09 1992 17:58`	8
	FWIW - A stereo cable in a mono application or a mon cable in a stereo application will drive footswitch circuits CRAZY. Try using a mono cable to bypass a DSP128+ sometime. All the DSP did was cycle thru all the presets and blocked the signal path. Try a cable too. What the heck ! jc
2427.5		GOES11::G_HOUSE	I think I'm gonna hurl! -G. Bush	`Thu Jan 09 1992 18:40`	7
	re: .4 Yeah, I can echo that. Remember that night that Tom got that godawful noise from the GK when he had the stereo footswitch cable stuck in his effects loop for his stomp box's? WHOOOOOOSH! Greg
2427.6	try manual	GIDDAY::KNIGHTP	do it in dubly	`Thu Jan 09 1992 21:02`	6
	Sakman, can you manually select ch 2 from the amp itself ( I think I can do this on mine by pulling on the volume pot for one of the channels) that tells you if it is the amp or the switch. If the sound changes that is. P.K.
2427.7		COPCLU::SANDGREN	Lhep! I'm trpdd ina P11D*P	`Fri Jan 10 1992 05:38`	6
	Yeah, Sakman, try disconnect the footswitch and pull the master volume switch - should do exactly the same for ya... Poul
2427.8	if not the footswitch	RANGER::WEBER		`Fri Jan 10 1992 08:34`	6
	This happened once to my Showman, after I had zonked it with static. It was a failed CMOS switch on the logic board. The chip was easy enough to replace, but it took me awhile to find a replacement (It was a TL 064, I think). Danny W.
2427.9		PHAROS::SAKELARIS		`Fri Jan 10 1992 09:47`	21
	regarding the footswitch substitution, I don't think its just your common everyday footswitch. It does have voltage and there is some circuitry inside. If I had a footswitch from another twin I'd try it. My gut tells me this might a logic problem as happened to Danny Weber. Dan, you are talking about a new Showman aren't you? They're the same as "The Twin" except sans speakers. ************************************************ OOOOPS! I might be dumb ass here. I never realized the volume control was a channel select. I just read the manual and saw that pulling it out DE-SELECTS the footswitch. Crissakes, I've lost too many braincells. I'll bet thats exactly what happened since I was foolin with the reverb level which is the next knob over. Now that I think about it, I'd bet $$ to doughnuts that's what it is - I'm such a dipshit. I'll letcha know in my next. Thanx for the help fellow tone bros ( and sisters - Hi Sandy!) "sakman"
2427.10		RAVEN1::BLAIR	Bush: Japan should import Buuuuicks!	`Fri Jan 10 1992 09:51`	4
	If you are worried that another footswitch may not work the same way, you could try shorting the end of the footswitch cable manually to bypass the footswitch.
2427.11		PANACH::sandy	Err on a G String	`Fri Jan 10 1992 12:06`	5
	Hi sakman! Hope your amp is ok, not to mention those brain cells :^} Sandy
2427.12		PELKEY::PELKEY	Snert ! Fetch me my dagger.	`Fri Jan 10 1992 14:57`	2
	hey Sakman, save us the roach o.k.
2427.13	coincidence? I think not	RANGER::WEBER		`Thu Feb 06 1992 06:35`	19
	The day after Sakman started this, my Mk IV footswitch got stupid: when I selected R1, it chose either R2 or Lead, at random. R2 and Lead switches worked normally. I called Mesa--the guy there (not the one I usually deal with) assured me that it couldn't be the footswitch and send a pair of IC's. It took over a week to get them and one of them turned out to be the wrong chip anyway. When that didn't fix it, they sent a new footswitch, which cured the problem. They were very apologetic over the delay, the wrong parts and the fact that they didn't believe me when I told them what was broken. The good part was at least the amp was useable while I was waiting for them to get their act together. Somehow, I think this is all Sakman's fault for bringing the subject up in the first place, so watch it next time :-) Danny W.