Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Searing on March 16, 2023, 06:37:46 pm
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I am refurbishing, and fixing a 67 Traynor Custom Reverb head. Everything is great except the reverb won’t work. The return is working, as I tap on the pan I get crashing reverb, but the guitar won’t drive it? The tubes are good and new. It’s a 12AX7 driver. I’m getting no reading of ohms between the red and the blue wires of the transformer? Is it bad? Thanks in advance!
Chris
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yes
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Would a reverb transformer found in a Fender Twin work?
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The current, bad, reverb transformer uses a 12AX7 as both a driver and a return. Would a Twin reverb transformer work even though uses a 12AT7 as a driver?
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Mayby. Post a schematic and we can probably say for sure.
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http://www.lynx.net/~jc/670113_YSR1.gif (http://www.lynx.net/~jc/670113_YSR1.gif)
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I think a Fender reverb transformer will work just fine ***IF*** the secondary dc resistance is pretty low.
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Thank you very much for your help! I am measuring 1.0 ohms on the current transformers secondary. Perhaps I could use a few 1 ohm resistors in series to knock the ohmage down a bit if needed?
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no need
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The new transformer is in, and it works. Problem now is too much reverb. Later I will change the pot to a 100kA. I will also try a 12au7 as a driver. Any other suggestions if those two changes don't work well?
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An easy thing to do would be...
1. Disconnect the wire from the middle lug of the reverb pot.
2. Connect a 470K resistor to the middle lug of the reverb pot.
3. Connect the removed wire to the other end of the 470K resistor.
Experiment with the value of the 470K resistor to give the amount of reverb you desire. Smaller value = more reverb.