I know it's a challenge working inside a 1484. This is not meant to be a permanent fix, but rather a quick way to patch a new resistor in. Simply tack solder the new resistor across the failed resistor. If voltages come alive on the tube (and I'm betting they will) then actually replace the resistor. It's easier if you cut the resistor leads as close to the resistor body as you can. Then deal with neatly removing the individual leads one at a time. Finally install the new resistor, making a good mechanical connection with each lead and finally solder in place.
Thanks for the advice sluckey. I did cut the leads, leaving the entire lead. But didn't bother removing the leads. Just soldered the new resistor right to the old leads. Seems mechanically sound. I keep my solder iron at around 730 degrees, don't know if that's too hot, but I always use a heat sink clamp for the component. This resistor was soldered directly to the very 'unique' multi-section cap can. Didn't want to risk it. I've attached a couple of pics.
Still working on removing R34 to measure. De-soldering with a 1484 is like working with a spaghetti dish... Plus the leads are around the eyelets several times. Don't know of a way to measure without removing...
Turn the power off and remove the 6CG7. Then measure R34. It could also be that there is a lack of continuity from R34 to the tube socket.
Thank you! Got me before I went through the hassle. For continuity, did a continuity test from underneath the socket to the lead of the R34 connected to pin6, and it shorted. When measuring ohms from pin 6 to the power input of the resistor, it was open. I have some 100K 1/2 watts, and will replace the resistor. Thanks so much. It will be one more thing out of the way. Fingered crossed. Thanks again.
I now have volume! Thanks 2deaf for pointing to R4. That did the trick. Also a lesson learned for me, when finding a bad voltage, don't trace through out the entire schematic looking for potential problem points, start with the closest component to the bad voltage. Especially if that component is the single resistor coming from a voltage supply into the plate. In hind sight seems obvious now.
And thanks again sluckey/Pete for the OT help.
The amp is working, including the reverb. Tremolo not. But I can't remember the last time I used a tremolo. I think I was fifteen, and just learned how to play gimme shelter. It was the only effect I had. So I really won't miss it.
Next project for this amp is a bias control so that I can up the bias to spec.
Once again thanks to all for the help. This forum really rocks!
Topic: Negative Low Voltage on 6L6 Plate Push Pull Amp (Read 6485 times)