Amp Troubleshooting needed

[ulijdavid]

Hey all,
I have a Marshall TSL60 which is having a major problem. I have had the amp about 10 years now. The tubes had been changed and biased about 3 months ago. I played the amp the night before for about 2 hours without any issues. Went to turn it on yesterday and no sound. Here are the observations:
1. Checked both fuses and both are good.
2. I didn't find any obvious tube problems - as far as the typical "burnt" look
3. The amp power lamp (power switch) lights up and you can here the amp "hum" as if it was on stand by.
4. The footswitch changes the amp channels and all channel lights work.
5. NONE of the tubes "glow". There seems to be no juice to the tubes.

Anyone got any suggestions? I am a DIY type guy, but electricity is not something I like to deal with. I am looking for some quick troubleshooting. I really don't want to go in blindly to an amp tech.
Thanks in advance for any help.

[jgcable]

Hey all,
I have a Marshall TSL60 which is having a major problem. I have had the amp about 10 years now. The tubes had been changed and biased about 3 months ago. I played the amp the night before for about 2 hours without any issues. Went to turn it on yesterday and no sound. Here are the observations:
1. Checked both fuses and both are good.
2. I didn't find any obvious tube problems - as far as the typical "burnt" look
3. The amp power lamp (power switch) lights up and you can here the amp "hum" as if it was on stand by.
4. The footswitch changes the amp channels and all channel lights work.
5. NONE of the tubes "glow". There seems to be no juice to the tubes.

Anyone got any suggestions? I am a DIY type guy, but electricity is not something I like to deal with. I am looking for some quick troubleshooting. I really don't want to go in blindly to an amp tech.
Thanks in advance for any help.

Bridge Rectifier. BR1. Replace it with either a BR62 or a BR64. Elevate it off of the board which is easy because they come with long legs. Easy repair. Don't quote me if its actually BR1 but there is only one large square bridge rectifier in your TSL60. Its easily found. That's your problem.
Be careful. Dangerous voltages inside your amp...even when its unplugged.

[ulijdavid]

Thank you JGcable. I will do some internet research on this to try and get in depth details on performing this. Really appreciate the help.

[Newc]

Gonna be "that asshole" and ask:
-are you sure the cable hasn't pulled out just enough to break the connection?


But then the tubes would glow regardless, I guess.

[jgcable]

Gonna be "that asshole" and ask:
-are you sure the cable hasn't pulled out just enough to break the connection?


But then the tubes would glow regardless, I guess.

On DSL's and TSL's, its pretty common for the amp to have all the indications that it should be working EXCEPT.. some of the preamp tubes don't light up.
When these amps have a rectifier problem that's what happens. Its common because Marshall uses a PC board that's just too thin to support the temperature. By elevating the rectifier off of the board it allows it to dissipate the heat. I replaced one in a DSL100 about 6 months ago. The part was around $5.00 on Digikey online and it took me an hour to take the amp apart... 10 minutes to remove and replace the rectifier and another hour to put it back together again. Worked perfectly from then on.

[ulijdavid]

I just ordered up a couple of the bridge rectifiers BR64 from Mouser electric for $1.75 each. I may get a small heat sink made up (maybe overkill??) I hope to try doing this over the weekend if the parts arrive. I figure I have nothing to lose but a couple of hours of my time and a couple of bucks. If it doesn't work - off to the amp tech.

[Twitch]

Yeah it scared me the first time I changed the power tubes in my tsl. The damn sockets are only board mounted and no stand offs underneath. The whole bored flexed putting the new tubes in.

[jgcable]

I just ordered up a couple of the bridge rectifiers BR64 from Mouser electric for $1.75 each. I may get a small heat sink made up (maybe overkill??) I hope to try doing this over the weekend if the parts arrive. I figure I have nothing to lose but a couple of hours of my time and a couple of bucks. If it doesn't work - off to the amp tech.

I bought the heat sink too but I didn't end up using it. Its easier just to make sure the rectifier is sitting high off of the board by not trimming the legs of it that much. Make sure you put it in correctly. Its square and polarized (+ and -) so you CAN install it wrong.

[ulijdavid]

Its square and polarized (+ and -) so you CAN install it wrong.

This will be noted!!!! Thanks.

[ulijdavid]

Amp is back up and running!!! Once I got into the "guts", I actually found it was a blown fuse on the main circuit board. A slow blow 6.3A 250V readily available at Radioshack. I did however, replace the existing Bridge rectifier with a BR64 and it is about 1/4" off the board now. I also didn't see any visual problems - no burnt traces or components. Actually everything looked to be in pretty good condition. Just before the amp stopped working, I remember not letting the amp cool down on standby before turning it off. One of those moments where everything goes slow motion and you're thinking to yourself stop - but you don't. I had seen some posts elsewhere that say this might be the reason for the blown fuse.
I will "burn" it in tonight to ensure everything is good.

Anyways, I appreciate the help JGCable.

[jgcable]

Amp is back up and running!!! Once I got into the "guts", I actually found it was a blown fuse on the main circuit board. A slow blow 6.3A 250V readily available at Radioshack. I did however, replace the existing Bridge rectifier with a BR64 and it is about 1/4" off the board now. I also didn't see any visual problems - no burnt traces or components. Actually everything looked to be in pretty good condition. Just before the amp stopped working, I remember not letting the amp cool down on standby before turning it off. One of those moments where everything goes slow motion and you're thinking to yourself stop - but you don't. I had seen some posts elsewhere that say this might be the reason for the blown fuse.
I will "burn" it in tonight to ensure everything is good.

Anyways, I appreciate the help JGCable.

anytime bro.