Fender "Custom" Vibrolux 'Power Drop'

[Pastortom]

If anyone is familiar with these newer amps, I have a strange gremlin........

For no apparent reason, the output power has just dramatically dropped...... Swapped the power tubes with no difference......tried different set of speakers, no difference..... load resistance (speaker) reads OK (these are 4-Ohm.....2-12's).......

Tried swapping pre-amp tubes.....no difference.......

It's just plain LOST a load of it's output power.....no real difference in distortion levels, etc......just power loss.

Any impressions ?  Certain caps perhaps?   

[rzenc]

Not familiar with these amps, however...

1- check bias voltage;
2- Check screen grid resistors/voltages;

I would check it right @ tube socket....I had some wied power losses on some new production amps that ended up being undersized G2 R's burning open...

[stratele52]

Custom Vibrolux are point to point or printed circuit board ?
If PCB, check connector, solder on printed circuit on power supply voltage.

if point to point, rznec have good answer, good to pcb too

[phsyconoodler]

Those are 2-10 amps by the way,not 2-12.

Yes you need to do basic tests like plate and screen voltages,bias voltage and current.Also make sure your speaker is plugged into the right jack(not the aux jack) and make 100% sure it's plugged in all the way and the jack itself is ok.

[plexi50]

You might check the plate resistors. I had one that went open on V1 a few months ago

[LooseChange]

We really need voltages and a schematic.

Is the lower power also distorted? Like Plexi, I too will guess it's a plate resistor and probably one of the phase inverter resistors... Seen many like that.

[phsyconoodler]

Hey Loose buddy! Love the new look of your 'loose' streaming video!

[HotBluePlates]

Custom Vibrolux Reverb schematic