Carvin TSL100 problem

[drewl]

Anyone have a schem for this guy?

Seems the 2 100ohm filament resistors to ground fried taking out the fuse.
I replaced them and they're fine until I turned the standby on ...POOF!
same thing happened....I'm guessing power tubes, whaddya' think?

[stokes]

Try it with the power tubes removed,if it doesnt blow the fuse or fry those resistors the problem is there.

[Mark Black]

Also take a careful look at the power tube sockets. Lots of times arcing from pin 3 to 2 can cook stuff in the heater circuit.

[drewl]

Yeah, I've seen that too!
Sockets look okay, it powers up fine without the power tubes and has signal all the way up to the power tube grids.
besides the 2 100 ohm dc filaments to ground, located on a preamp board, there are also 2 fried resistors from the power tube filaments to ground, which I'm guessing are also something like a pair of 100 ohms.

I assume they had a pair each for the dc heaters and also the regular ac heaters.

[Enzo]

And all you gotta do to get the drawings is call Carvin, they wil email them to you in a minute.

[stokes]

Sounds like your power tubes have a short from the cathodes to the heaters.Like Enzo says contact Carvin and get a schem.to be sure,but I dont think dc heaters would have the 100ohm resistors like an ac heater.

[drewl]

thanks I will!
they may not be 100 ohm resistors (guessing from a similiar schem) they're toast so you can't tell what they were!

[drewl]

Sounds like your power tubes have a short from the cathodes to the heaters.Like Enzo says contact Carvin and get a schem.to be sure,but I dont think dc heaters would have the 100ohm resistors like an ac heater.

~ 350ohms from the plate to the the filament on one of the tubes!
..............OUCH..........POOF!

[stokes]

Well that solves that,eh?While you're in there check your screen resistors,when tubes blow these have a tendency take them with them,just a precaution,they dont always go.

[Amp Kat]

Hey Drew try checking from the screen to the heater and see what you get. If it's around 80 ohms you most likely have a short there in the middle of the board. If this is the case the filter cap connected to that resistor will also be shorted from + to ground at about 80 ohms.

[Amp Kat]

Drew are you sure this is a Carvin ? They aren't showing it on the Carvin website ?

[drewl]

yes It's a Carvin!
called em yesterday and they sent me a schem.
I was right, there's 2 100ohm resistors to ground for the AC filament AND 2 100ohms to ground for the DC filament.

[Amp Kat]

hmmm that doesn't make sense for the dc as the reason for the 100 ohms to ground is to act as a hum balance for DC unless that DC is elevated but they wouldn't be going to ground it would be a voltage divider. Have you found the problem yet ?

[drewl]

~ 350ohms from the plate to the the filament on one of the tubes!
..............OUCH..........POOF!

Bad tube as stated above....