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my 5f1 stopped working

telechamp
February 27th, 2012, 04:54 PM
I have a Marsh Amps Tweed Champ that has been working great. I turned it on a couple of days ago and no sound. I have power, the caps and resisitors all show they are still with me, the 12ax7 and 6L6 are glowing. the rectifier 5y3gt has no glow when I checked the 3 and 4 outputs I had 350vac If I remember correctly and 1.120 vdc at the 2 and 8 pins. I pulled all the tubes and tested again at the 5y3gt and got the same readings. would this suggest that my power transformer has passed on?

Dave

hackworth1
February 27th, 2012, 05:15 PM
With due care and Multimeter set for high voltage AC, with tubes removed, check for high voltage AC at pin 4 of rectifier tube socket.

If you have high voltage AC on pin 4, you should have high voltage DC on pin 2 and 8 when rectfier tube is installed. (Change meter to DC High Voltage setting). If you have high voltage AC on pin 4 (and 6) your PT is good.

If waht you say is accurate, your description foretells a bad rectifier tube.

telechamp
February 27th, 2012, 09:23 PM
I just double checked my voltages as my original post was from work. I removed the 5y3gt turned the amp on and checked pin 4 and 6 and I have 349.3 vac. then I reinstalled the 5y3gt and checked pin 2 and 8 I have very low voltage 1.125 vdc. That confirms your diagnosis and I will pick up a new 5y3gt. thank you for your help. :grin:

t-luxe
February 27th, 2012, 09:31 PM
Go NOS or JJ!