intermittent hiss and crackle JCM 2000 TSL 100

roly · 09-16-2009, 04:09 PM

Hi folks
I have a TSL 100 that came in with a cooked output transformer.
I replaced it with a Hammond 1750X.

So....now the amp works but there is an intermittent hiss and crackle.
This happens with all the preamp tubes pulled.

I am a fender amp guy, I build replicas and fix black and silver face amps.

These printed circuit board amps are quite foreign to me.

So....looking for advice.
cheers
Roly

MartyStrat54 · 09-16-2009, 05:28 PM

Well the TSL100 is a complicated amp to work on, because it is a combination of tube and solid state. If the amp is making this sound and all the preamp tubes are pulled, that's a bad sign.

When the original OPT fried, did you, or somebody else inspect the amp for any other components that could have fried? Just sticking a new OPT in doesn't mean it is fixed.

Other than swapping out the power tubes for a new set, I don't see what else could be easily checked. Do you know if the fx loop was ever working. Sometimes a dirty fx jack can cause sound problems.

roly · 09-16-2009, 06:57 PM

Hi Marty
Thanks for your help.

Voltages to the OT primary were good.
I did not see any evidence of heat anywhere in the amp.

That's as much as I did before replacing the OT.
I'll have a peek at the FX loop, but with all the 9 pin tubes pulled, don't you think it's unlikely to be a problem?

Whish I had some EL34s kicking around.
I'm definately not in Kansas any more...

cheers
Roly

MartyStrat54 · 09-16-2009, 08:41 PM

Maybe you could do this just long enough to rule out the power tubes. If you have a 16 ohm cab and the amp is on 16 for a load, pull the 2 outside tubes and set the load to 8 ohms. Turn the amp on and see if it is making the noise. If it is, turn off the amp, stick the two outside tubes back in and pull the two inside tubes. Turn the amp back on. If the noise is still there, this rules out the power tubes.

roly · 09-16-2009, 08:49 PM

Hi Marty
I have an 8 ohm test cab.
So...can I safely set the output to 4 ohms and test the tubes one pair at a time?
cheers

solarburnDSL50 · 09-19-2009, 08:52 AM

Quote:

Originally Posted by roly

Hi Marty
I have an 8 ohm test cab.
So...can I safely set the output to 4 ohms and test the tubes one pair at a time?
cheers

That would be correct but I bet you already tried it...?

TheShadowNinja · 09-19-2009, 09:07 PM

Marty please explain to my why you think the TSL100 is part solid state

I know you're probably right but it is an all valve head with extensive circuitry- is this what you mean?

BrotherJ · 09-19-2009, 11:59 PM

Hi Roly,

I know it's long and it tedious but it might pay to check everything from the PI onwards into the power amp for faults.

An area where you might want to check on is the bias supply. Check the caps C36, C37 & C42 (all 47uf 63v) the 33k resistor R68, and the 10k resistor R77. (All these items are on the main board)

handsandy · 10-21-2009, 09:24 PM

BrotherJ is on the right track I have a TSL 60 head and have had similar problem, having C36, C37 & C42 caps replaced as we speak, bit of a common fault there.....

Wilder Amplification · 10-21-2009, 11:18 PM

Did you check and make sure that the output transformer primary side isn't out of phase?

09-16-2009, 04:09 PM	#1 (permalink)
roly Junior Member Join Date: Sep 2009 Posts: 3	intermittent hiss and crackle JCM 2000 TSL 100 Hi folks I have a TSL 100 that came in with a cooked output transformer. I replaced it with a Hammond 1750X. So....now the amp works but there is an intermittent hiss and crackle. This happens with all the preamp tubes pulled. I am a fender amp guy, I build replicas and fix black and silver face amps. These printed circuit board amps are quite foreign to me. So....looking for advice. cheers Roly

09-16-2009, 05:28 PM	#2 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: intermittent hiss and crackle JCM 2000 TSL 100 Well the TSL100 is a complicated amp to work on, because it is a combination of tube and solid state. If the amp is making this sound and all the preamp tubes are pulled, that's a bad sign. When the original OPT fried, did you, or somebody else inspect the amp for any other components that could have fried? Just sticking a new OPT in doesn't mean it is fixed. Other than swapping out the power tubes for a new set, I don't see what else could be easily checked. Do you know if the fx loop was ever working. Sometimes a dirty fx jack can cause sound problems. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

09-16-2009, 06:57 PM	#3 (permalink)
roly Junior Member Join Date: Sep 2009 Posts: 3	Re: intermittent hiss and crackle JCM 2000 TSL 100 Hi Marty Thanks for your help. Voltages to the OT primary were good. I did not see any evidence of heat anywhere in the amp. That's as much as I did before replacing the OT. I'll have a peek at the FX loop, but with all the 9 pin tubes pulled, don't you think it's unlikely to be a problem? Whish I had some EL34s kicking around. I'm definately not in Kansas any more... cheers Roly

09-16-2009, 08:41 PM	#4 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: intermittent hiss and crackle JCM 2000 TSL 100 Maybe you could do this just long enough to rule out the power tubes. If you have a 16 ohm cab and the amp is on 16 for a load, pull the 2 outside tubes and set the load to 8 ohms. Turn the amp on and see if it is making the noise. If it is, turn off the amp, stick the two outside tubes back in and pull the two inside tubes. Turn the amp back on. If the noise is still there, this rules out the power tubes. __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.

09-16-2009, 08:49 PM	#5 (permalink)
roly Junior Member Join Date: Sep 2009 Posts: 3	Re: intermittent hiss and crackle JCM 2000 TSL 100 Hi Marty I have an 8 ohm test cab. So...can I safely set the output to 4 ohms and test the tubes one pair at a time? cheers

09-19-2009, 09:07 PM	#7 (permalink)
TheShadowNinja Junior Member Join Date: Jun 2009 Posts: 28	Re: intermittent hiss and crackle JCM 2000 TSL 100 Marty please explain to my why you think the TSL100 is part solid state I know you're probably right but it is an all valve head with extensive circuitry- is this what you mean?

09-19-2009, 11:59 PM	#8 (permalink)
BrotherJ Senior Member Join Date: Dec 2008 Posts: 267	Re: intermittent hiss and crackle JCM 2000 TSL 100 Hi Roly, I know it's long and it tedious but it might pay to check everything from the PI onwards into the power amp for faults. An area where you might want to check on is the bias supply. Check the caps C36, C37 & C42 (all 47uf 63v) the 33k resistor R68, and the 10k resistor R77. (All these items are on the main board) __________________ TSL100 - MM OT & Choke and some circuit mods - 1960AV Stiletto Deuce II - Traditional quad

10-21-2009, 09:24 PM	#9 (permalink)
handsandy Junior Member Join Date: Oct 2009 Posts: 2	Re: intermittent hiss and crackle JCM 2000 TSL 100 BrotherJ is on the right track I have a TSL 60 head and have had similar problem, having C36, C37 & C42 caps replaced as we speak, bit of a common fault there.....

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