VTL tt25

[cobra]

hello all ,, can anyone point me I the right direction to find
schematics for my vtl tt22 (tiny triodes) ,I have one that pops
the main fuse

thanks

 

[TonyTecson]

check up on the filter caps and see if one or more got leaky....
that will blow fuses, also check the fwb rectifier if shorted...

 

[cobra]

vtl tt25

thanks for the reply.. I have changed the filter caps (that was my first
thought) FWB = ? all the rectifier diodes pass the basic diode test
the amp has 3 diode bridges ? it pops fuse with NO VALVES in and
gentle up on a variac

thanks

 

[Aleks1]

You need to work logically from source to loads. Power up the mains transformer in isolation from the amplifier, all secondary windings disconnected. Does it pop the fuse? If not reconnect the secondary windings one by one and power them up on each reconnection. Hopefully you will find which area of the amplifier is at fault.

Once you have the area at fault it's just a matter of elimination.

Eventually you will find the problem.

Circuit diagram would make this easier, but not impossible without it.

Regards, Aleks

 

[TonyTecson]

what is your line voltage and what size fuse are you using?
you can disconnect all secondary power traffo connections,
then test it again and see if the fuse pops...
what is your power traffo primary set to? if it is set to 120
and then you were tyring to load it 240, then fuses will surely pop...

 

[waltube]

Check the Rdc of transformer (primary and secondary) on both amps without tubes.

Maybe you have one issue on it


Walter

 

[cobra]

what is your line voltage and what size fuse are you using?
you can disconnect all secondary power traffo connections,
then test it again and see if the fuse pops...
what is your power traffo primary set to? if it is set to 120
and then you were tyring to load it 240, then fuses will surely pop...

thanks,, they are set up for 240 (I have used them for 6 months)
fuse 1.6amp (as per label on amp, secondary disconnected, 520 volts fuse ok
with ht insulated ,,valves in' heater also ok..
with transformer out off amp, no short to earth on ht, bias or heater

 

[cobra]

Check the Rdc of transformer (primary and secondary) on both amps without tubes.

Maybe you have one issue on it


Walter

RDC ?short term for

 

[TonyTecson]

thanks,, they are set up for 240 (I have used them for 6 months)
fuse 1.6amp (as per label on amp, secondary disconnected, 520 volts fuse ok
with ht insulated ,,valves in' heater also ok..
with transformer out off amp, no short to earth on ht, bias or heater

pk, so next step is to reconnect the psu one rectifier at a time....

 

[cobra]

vtl tt25

SORRY for slow reply !! with the ht onl,y powers up ok, with bias only also
ok ,with both connected (transformer out off amp, clip leads) pop !
I've taken the transformer out of the working amp, that will power up
both amps, the faulty transformer ( not connected) 520 v ht ,30v bias, 7.5
heater ,, with dmm shows no faults, I presume the trans has a shorted turn
ht to bias ,?

 

[Zen Mod]

ohm reading between HT and bias windings ?

 

[TonyTecson]

SORRY for slow reply !! with the ht onl,y powers up ok, with bias only also
ok ,with both connected (transformer out off amp, clip leads) pop !
I've taken the transformer out of the working amp, that will power up
both amps, the faulty transformer ( not connected) 520 v ht ,30v bias, 7.5
heater ,, with dmm shows no faults, I presume the trans has a shorted turn
ht to bias ,?

then better check downstream....

 

[cobra]

vtl

then better check downstream,, ?? sorry don't understand, the" good "
transformer will power up both amps (one at a time) the suspect transformer pops the fuse
in both amps is this not a transformer problem ??

 

[TonyTecson]

ok then, so you have two traffos, one good and one bad?
sorry i missed that...

 

[cobra]

vtl tt25

yes sorry my fault ,,VTL TT25 are MONO blocks,, both work on the "good" transformer,, the other trans, pops the fuse on both amps if its the transformer
probably the end off them

 

[Zen Mod]

if you made that sort of test , there is no doubt that xformer is blown