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Marshall f/sw wiring help...
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 4/23/2000 4:39 PM |
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Ian Anderson |
Marshall f/sw wiring help... I have a Marshall JTM60 combo, but the f/sw I got with it was a channel/chorus f/sw. The picture below shows the current wiring arrangement. The channel switching works like this, but since the amp hasn't got chorus on it I want to use the chorus switch to turn the reverb on/off (which it doesn't do at present). I'm sure this is a very simple operation, but I'm not sure of how this would be achieved myself. Thankyou in advance for your help... Ian |
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| 4/23/2000 5:17 PM |
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| Wailin |
Gday! I am almost positive that the JTM series of amps doesn't have footswitchable reverb. The footswitch that comes with these amps is a one button. The footswitch you have is from a VS265 Combo. Or..I could be totally confused:-> If you don't get confirmation from someone else, I will double check tomorrow at work. Wailin |
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| 4/23/2000 7:16 PM |
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| dale |
Re: i'm sure it'll work if you bypass the resistors and diodes. it's likely the resistors that are the problem, but as you said the diodes may be backwards and therefore also causing it. what i'd do is take both the resistors and diodes out, then put led's in place of them, and if that doesn't work just reverse the led leads and i'm sure that'll work. drill holes to put the led's in as indicator lights, if there are no holes allready. i'm assuming that when you said diodes you meant DIODES and not led's. of course if you don't care about having indicator lights don't put anything in it. dale |
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| 4/24/2000 7:07 AM |
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| Ian Anderson |
Sorry! - night shift! I *did* mean LED's *not* diodes (duh!). The f/sw is connected as it comes when bought new so the LED's will be installed correctly for the intended purpose (chorus on/off switch), but not for reverb on/off switching. I'm sure that taking the LED out would enable the switching, but I'm selling the amp this week and want to have the f/sw working correctly for the guy who is buying it. Cheers... Ian |
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| 4/24/2000 7:52 AM |
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| dale |
i still think the resistors are most suspect. why not just try bypassing them. you could do it in a second with a wire with alligator clips, or just quickly solder a wire to bypass it. dale |
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| 4/24/2000 1:44 PM |
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| Ray Ivers |
Re: Marshall f/sw wiring help... Ian, Maybe you've sold the thing already, and it doesn't matter, but... I just downloaded the JTM60 schematic from the Marshall amp schematic page (schematics.cjb.net) and I have to agree with Wailin - there's no footswitchable reverb function in this amp. There is an MS201 switching op-amp that's used to toggle the two reverb controls - one for each channel, evidently - when the channels are switched, but it appears the jack's 'ring' connection is unused and shorted to ground. The Marshall literature I have here mentions the P801 footswitch for this amp, "single footswitch w/lead". The new owner can always order a new switch from Korg (part number PED801, price 35.00 - their number is (516) 333-9100). Marshall says the proper footswitch is the P801, same price, without the LED; but it seems clear to me from the print that if an LED were present it would work - you make the call. Ray Ivers |
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| 4/24/2000 4:54 PM |
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| Ian Anderson |
Thanks one and all! I haven't tried messing with the f/sw yet as I wanted to consider everyone's advice here first. If the reverb can't be f/sw'd, so be it - I've never found the need for that function anyway, just set it, leave it on and forget about it. Cheers... Ian |
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