Fender 68 custom vibro champ reverb - voltage

Modulus_Amps

Great, so just to be clear for those reading this in the future, you swapped the white wire with black stripe (230v) with the plain black wire (240v)?

godders

Modulus_Amps said:

Great, so just to be clear for those reading this in the future, you swapped the white wire with black stripe (230v) with the plain black wire (240v)?

Correct.

Before:

After:

idiotwindow

godders said:

Modulus_Amps said:

Great, so just to be clear for those reading this in the future, you swapped the white wire with black stripe (230v) with the plain black wire (240v)?

Correct.

Before:

After:

Thanks, that's helpful. I'll probably do the mod myself. Was it fairly easy to pull out the plugs (or whatever the correct term is) without feeling like you were about to break something?

godders

idiotwindow said:

Thanks, that's helpful. I'll probably do the mod myself. Was it fairly easy to pull out the plugs (or whatever the correct term is) without feeling like you were about to break something?

They aren’t too bad, a gentle wiggle from side to side as you pull up and they come off without too much of a fight.

bendugard

Hello,

I’m looking to do the aforementioned voltage tap change but before I stick my hand into the circuitboard I want to discharge the caps.

Having looked online it seems easy if the caps are sitting horizontal on the board but in this 68 cvcr they appear to be vertical with no access to the wires on the positive side.

I measured DC on the orange wire pin of the output tube (as mentioned by Psionic audio for testing for residual current). I got a measurement of 22 volts. I will test again tomorrow to see if it has drained any further.

I have some 100 ohm resistors for discharging but I don’t know where to place them.

 Any help would be much appreciated,
 Ben

ICBM

No need, 22 volts is safe and it won’t have increased if the amp has been off - it may have reduced further overnight. When you turn the power off most of the charge drains through the valves before they cool down. You won’t be handling anything in the HT circuit if you’re just changing the supply voltage connection anyway.

bendugard

Thank you,

It has gone down to 21 volts overnight. Is there anywhere else I can discharge the DC from? Just for future reference if I do want to do anything in other parts of the circuit.

ICBM

bendugard said:

It has gone down to 21 volts overnight. Is there anywhere else I can discharge the DC from? Just for future reference if I do want to do anything in other parts of the circuit.

If you have a 100-ohm resistor you can connect from that pin on the power valve socket to the chassis. Or connect directly from pin 1 on the V1 socket to the chassis if you don't have a resistor.

bendugard

Thanks for your hep ICBM. 

I did the change to 240v. The little clips were a bit tricky to get off as there isn’t much room to get your hand in and the board feels very fragile.

I was hoping the operating noise of the amp would reduce a bit but there is still a noticeable hum with no guitar plugged in. That will be something for another day.

i do love this amp but the one thing that bothers me is the noise floor. I’ve considered trading it for a tonemaster Princeton but gonna keep it for now.

 Cheers,
 Ben