TSL 100 no sound??? Schemo???

[Satamax]

Hi everybody!

Well, i have a tsl 100 on the bench, and i suspect the relay for output mute. Has anybody seen that happen, or anything similar, which could lead to no output. I have a litle with 12Vrms 440HZ on pin 7 of the PI and one of the pins of the octal sockets (there's seven pins on the circuit board, and the sound comes out when i touch pin 7) I gonna check schemoheaven for the schemo, but if anybody has a lead to the schemo and a few hints to troubleshoot this one. THat would be welcome.

Thanks a lot and best regards.

Max.

[Mark Black]

This wonderful fellow has that and many more Marshall schematics available for download:
http://www.drtube.com/marshall.htm#JCM2000

Most of what I have ever found on those is cracked solders. In fact what I usually do is retouch at all jacks, controls, switches, tube sockets, impedance selector, fuseholders, AC inlet, PCB interconnecting pins, and large and/or heat-producing components regardless of whether or not I can see cracks. Then at least I know what it's NOT, and the time before the next failure should be extended.

Also check the continuity of the normalling contacts in all the jacks, paying particular attention to the effects return and speaker jacks. I can't remember if this model does it, but some late-model Marshalls run the 8 & 4 ohm jacks through the normalling contacts in the 16 ohm jack so those contacts have to be in good shape.

Also those models use an underrated bridge rectifier to deliver DC heater voltage to the first 3 preamp tubes - they can fail or more commonly desolder themselves. See if the heaters are lighting up on those tubes.

I think the relay is for channel switching functions rather than output mute.

Oh yeah - there are some fuses on some of the PCB's in there as well, and they don't look like what you might expect. You will see where they are in the circuit when you get the schematic and should be able to find them for testing.

Good luck!

PS: I just looked at the schematic and it does appear that part of relay 3 is used for a muting function. I haven't seen a bad one yet but who knows? Also this amp does route the ground connection for the 4/8 ohm jacks through the ground normalling contacts on the 16 ohm jack...

[Enzo]

I don't think that rectifier bridge is under rated, after all, three 12AX7s only draw an amp. I thikn they don't unsolder themselves either. I think the problem with them is that ther solder never wetted to the legs in the first place. Remove the bridge, CLEAN the legs, and reinstall it. I have never had one come back after that.

If clicking the mute switch has ANY effect, then it is likely working.

Look over the schemo before coming back, but if there is nothing to the grids of the power tubes, there will be nothing coming out. The grids will be the ones with -50VDC if you can't figure out the tube pins.

I think the mute is just the switch - S3. The switch shorts the left and right power tube grids togehter. The pad switch nearby adds in the 680k resistors in series with the signal. I doubt your mute switch is shorted and won't open. Relays would be marked RL3.

Just approach it like any other amp that makes no sound: Are ALL the tube heaters lit? Is there B+ on ALL the tubes? Are any 12AX7 plates B+ voltage really high? In which case the associated cathode would be at zero?

[Mars Amp Repair]

you say when you 'touch' pin 7 of the power tube, you get the sound out....I am assuming you mean the buzz from your body injecting 60hz from the air & hopefully not the sound the tech makes when he hits the 450vdc ;-]
You could of course & probably have tried pumping a signal into the return jack to try to separate whether or not issue is pre or post preamp.
Also of course you could connect the send jack to another amp to see if any sound is getting that far.
I am trying to follow the signal from board to board using the schematics on the web & it's just about impossible. Could be something as simple as a spread switch connectors in the send/return jacks.
As far as the bridge rectifier for the preamp heaters...if I have gone as far to remove the old one or get the board up to resolder it, I just replace the bridge as I've seen some that get intermittent just from getting so hot. You also should stand the new bridge off from the board a bit as to allow a chance for the leads to cool a bit before the heat hits the solder. Personally for a couple of bucks, I sure don't want to do this repair 2wice ;-]

glen

[Satamax]

Hi Glen.

Thanks a lot for your rply.

Well, when i say pin 7, it's the "board pin", the octal sockets are conected via 7 stubs of wire to the PCB (and of course i haven't taken apart teh amp yet to know how, if it can be avoided would be best). And when i touch solder blob number 7 clockwise, with the probe of the sig gen, at 440HZ/12Vrms i get a litle sound. If i hit pin seven (real pin on teh socket this time) of the phase inverter, i get a fainter sound. Nothing if i touch the preamp before this. Actualy, i have three larch radiator covers to do on top of my day job (chairlift atendant in the winter), and a bass to repair, nother one to refret, the litle mars G15 to repair too. Kind of busy for the moment. I admit the marsh is in my lounge, but i haven't touched it again.

Thanks a lot for your reply, this gives me food for thought. Th epre heaters are glowing. I would suspect more a lack of HT on the preamp rail. Or as i said that bleemin mute switch acting funny. (why did they do this, there's already a standby switch!)

Thanks again.

Best regards.

Max.

[Matt T.]

FWIW, the schematic is several pages. When you encounter a connector on a particular page (labeled 'CON' IIRC) then there will be some text near it telling you what connector and which drawing it is on that it connects to. A little confusing at first but you'll see what I mean when you look at the schematics.

PS - I've had at least two different versions of this schematic and one was not complete...it didn't have all of the 'CON's right.

[Enzo]

I am a pretty experienced hand at tracing schemos around, and I think I am pretty good at it. This is STILL a serious pain in the ass to wade through. I would up making my own drawing of the TSL laid out as complete schematic rather than module by module. Worth the effort.

[Satamax]

Hi Guys, thanks a lot for your replies!

Well, the amp is gone to a more competent tech