'98 Marshall TSL100 no lights on channels leds

marshalltsl

marshalltsl

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Hi.
My '98 TSL100 has no lights on channels leds. I don't remember right now but I think I replaced all boards to issue 20 on 2010. Mother board, clean, crunch, rear and lead boards. I need issue 20 schematics. Let's see if I can find. Maybe I'll need mail Marshall for some help. I found two internal fuses melted. T250mA 250V. They are F1 and F2 from this picture. Footswith seems ok pin 3 and pin 6 are not shorted. This weekend I'll replace those fuses that I have on original '98 TSL100 rear board. I tested some diodes. Maybe just are this two fuses. Fingers Cross.
 

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I’m looking at your photo of the fuses. From my perspective, I don’t see “melted” fuses. Can you point out it out in more detail if possible?
 
syscokid said:
Also… What is that 33 ohm resistor (R21?) for? Current limiter for the LED’s?
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I don't know. I'll take a look on tracks from rear board tomorrow. Right now I have reassembled everything because I have to transport the amp to where I have the original amp boards. It is a better place to work with It.
 
syscokid said:
I definitely see the two fuses, but they look okay and not melted. Doesn’t mean that they’re good or bad, unless you can test them.

But R21 might be a problem. In the schematic I found, R21 should be 100 ohms and not 33 ohms. I still don’t know what R21 does to the circuit, though.

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I tested both fuses. They are open. The Switch Channels are different on TSL100 issue 20. I'll take a look on this resistor as well. Thanks for help. I apreciated it. I'll report what I find tomorrow. Now it's time to play with other Marshalls lol.
 
syscokid said:
I definitely see the two fuses, but they look okay and not melted. Doesn’t mean that they’re good or bad, unless you can test them.

But R21 might be a problem. In the schematic I found, R21 should be 100 ohms and not 33 ohms. I still don’t know what R21 does to the circuit, though.

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It looks like a voltage divider, taking the +/- 15V (30v at the resistor) and dropping it to 24v for switching.
 
Tomorrow I will test voltage on CON2 from rear board. I can't see R22 and R23 on issue 20 TSL100 rear board. This Issue 20 switching control works with relays I think. I never had an issue like this on others TSL's 100 that I owned. I was playing three hours with It yesterday. After I take a brake I realise that no light on channels leds. I love this amp. I bought It new and I have great memories with It. I was 20 years old when I bought It. I will report what I find tomorrow.
 
Hi all.
Good news. The channels leds lights on. Con2 rear board are 22vca from Power transformer. Con 2 is Pin 1 22vca , pin2 neutral, pin3 22vca. The circuit it's prety like others TSL100. R22 and R23 exist, they are 5W resistors but R21 it's a 33 Ohms resistor on Issue 20. Others TSL100's is 100 Ohms. On R21 I test 29 Vdc. Issue 20 Switching channels works with a 30vdc relay. The problem could be on the footswith pedal. Footswith cable is old and worn. Now it's time to test It properly without footswith pedal. I will report what happend. Thanks.
 
Amp is ok . I test 24,8vdc on R21. Before I tested 29Vdc because I didn't connected Con 5, Con 6 and Con 7 of rear board. I think it's the footswith pedal. I don't want try It with his 5 way footswith because I don't have any more PCB fuses like this. I'll try It with other TSL footswith.
 

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Thank you! I'm really happy. It makes me sad when I have a broken amp. Taking it to a technical service is hard work. I wish I had an official Marshall technical service near me. After all this job it made a little noise but it was a dirty FX Loop Jack output. Fixed. If you have a TSL 100/122 it is really important It have FX Loop jacks outputs in good condition. Also I use a triple shield isolation transformer (230 vca input 230vca output) that creates a perfect ground connection. Amps performance is excelent. No ground loop. No background noise. No noise from the electrical network. Highly recommended electric device.
 
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