Pulled my parents 500C out of storage today . . .

Are you using load resistors (or speakers) at speaker terminals? Tube amplifiers should not be powered on without load connected to output transformers. OPTs can get damaged.
Most receivers have dropping resistors for headphone output but I don't know if they are safe enough to rely on.
Yes, I have speakers connected. Thanks for the advice about relocating the CL-80 - seems like a good idea.
 
Based on post by Grind, I took another shot at powering it up, this time the bulb glowed dim, and after about 5-10 seconds . . . SOUND! Initially only from the right channel, but a wiggle or two on the (slightly sloppy) volume pot and i had two channels. I did not connect an FM antenna, so not sure how the tuner is working, but will spend more time on it over the weekend. After about 5 minutes running at low volume with a CD player into AUX, the output tubes got only slightly warm, and all three transformers remained cool to the touch. I did not take any voltage readings. Sound was OK. But there do not seem to be any major issues - even the meter bulbs worked. I will now proceed with a bit more listening tests, take and record some readings, and then begin the resto. Full cleaning, metalbone kit and Hayseed caps to start.

Other than a good cleaning with Deoxit, any advise for the pots? Volume, tone and balance all seem loose -- not the mounting to the faceplate but the shaft in the pot. Is there a way to tighten these up?
 
Clean them with DeOxit D-5 1st. This will get the grime out but leave no lubrication. CRC (EDIT 2-22-18 for part #) 226 Electronics Lube is good for these pots as it's heavier bodied than DeOXIT F5 (Faderlube) or DeOXIT SHIELD (S-5). You can tighten them up but if you do it wrong or get ham handed you could end up having the shaft off center from the pots, inducing binding and making things worse. The looseness is the shaft in the bushing it sits in. 55 years of lack of lubricant will tend to make things loose. I take my loose ones apart and pack the bushing from back to front with 2parts lithium grease and 1 part sewing machine oil. Mix well and pack in the bushing as tight as you can get it. Then push the shaft thru it until it bottoms out and re-assemble the pots. The shafts may wobble a little but not as much as before, and they';ll have close to that original feel.
 
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Home Depot next to the CRC QD Non Residue Contact Cleaner. The can for the 226 is a lot smaller (by 1/2). CORRECTION TO THE PART # FOR THE CRC LUBRICANT. ACCORDING TO HOME DEPOT it's 226 Lubricant. I'ts either sold in the RED CAN or the new style bluegreen can. But the # is actually 226. I don't know why I thought it was 626.
 
Connected a turntable to the 500C today and listened to it most of the day - in album sidelong stints followed by a break. Groovin' and Tubin'. I wanted to make sure the Phono/eq worked. Sounds great, no audible issues. Next step is to connect FM antenna and check out the receiver and MPX. Still have not taken any readings, as i have been running right side up. I know i should put it aside until resto, but it sounds too good to stop. But i know should clean it, replace the selenium recto, caps etc. before putting too much time on it. I unplug it whenever i turn it off, and have been running it through a 200W DBT. Do i still need to use the DBT it is is working OK? (yes i have installed the CL-80). It takes a while to warm up to produce sound (10 -15 seconds) is that the caps charging up? Will that go away with new caps?
 
The Warm Up time will not appreciably improve with new caps, etc. This is NORMAL TUBE WARM UP TIME. You should be so lucky. A TA-600 Takes about 50-60 seconds and sometimes in the winter even longer due to the way the tubes are wired for heater power and cathode bias. I have a '51 Coronet (R-3) chassis that in Phono takes almost 1-1/2 minutes to warm up. And this is in the middle of a Mid Atlantic Heat Wave.

You can take it off the DBT now. But when you start replacing parts again, put it on the DBT. It will tell you immediately if you screwed the pooch. Do 2-3 parts and test, repair if necessary, and rinse/repeat. Keep an eye /hand/IR or Laser thermometer on the CAN CAPS on top. You DO NOT WANT THEM getting hotter than the surrounding Transformers, or close by tubes (radiant heat soak). Turn it on and check 5 minutes into Warm up. If ANY are hotter than the surrounding parts, AND/OR the temp is increasing, shut it of and replace the can caps before powering up again. One has shorted.

You're playing with Fire but it's easily fixed NOW. Later may be too late. Knuckle down and leave it off, order the parts and replace it all. Do the Safety and Reliability Mods, (including the IBAM or IBBA Boards) and make it the best running FISHER in 3 counties. THEN you can run it for days on end with out problems. But right now, you're running a big block with a leaky Carter Thermo-QUAD 4 bbl with sunk floats and it's spraying gas all over. ........................................
 
If you're running it through the dbt, what's your input voltage as a result? Likely lower than normal, due to voltage drop of the bulb. You may be forestalling or masking a problem with the reduced voltage that may manifest itself after running at normal line voltage for a while. It's a crapshoot, but I'm kinda guilty of it too, although I constantly monitor for heating caps, red-plating tubes, etc. No problems with anything so far (knock on wood)! Larry speaks wisely from vast experience, pay attention. ..:bowdown:
 
I don't believe the voltage changes with DBT. It takes longer for voltage to ramp up when using DBT because it's limiting current flow. Once it's stabilized it should match wall voltage and drop shouldn't be significant
 
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FWIW, with my dbt, 150w bulb, 115v in, 85 volts at accessory sockets of one of the 500c's while powered/warmed up. Ymmv with bulb wattage. Voltage drop across each series load ,added up, equals voltage applied to circuit. Think series -wired Christmas light strings. The antique 8-bulb strings from decades ago, were 12-14 volt bulbs. They burned out regularly, but if one extended a string to 9,10, or more sockets, they lasted a helluva lot longer. They were a little dimmer with each added bulb due to less voltage available to each bulb. I've done a lot of these as I collect them. Bulbs haven't been available for decades, can only find second-hand & this keeps them alive.
 
Got it.
I have mine running on a relay with switch only seeing the relay coil winding current. I just did not want to chance the switch which would be a pain to source and replace.
Grind: Picking up on an old conversation here: Where did you connect the coil to pick up the low voltage for the relay coil? Can you reference nearest components? Also what was coil voltage. I've got some 5v relays, where would you suggest picking up the coil power?
 
Grind: Picking up on an old conversation here: Where did you connect the coil to pick up the low voltage for the relay coil? Can you reference nearest components? Also what was coil voltage. I've got some 5v relays, where would you suggest picking up the coil power?
I used 120v coil relay and energized it by original power switch. I don't see an easy way to use 5v relay for that.
 
I used 120v coil relay and energized it by original power switch. I don't see an easy way to use 5v relay for that.
That would reduce the current which is the culprit, but still put 120v through the switch. That works. If, or until, I put in a relay, I will send the output of the CL-80 through both sets of contacts on the switch.
Thanks.
 
That would reduce the current which is the culprit, but still put 120v through the switch. That works. If, or until, I put in a relay, I will send the output of the CL-80 through both sets of contacts on the switch.
Thanks.
Relay coil draws very little current. No danger for the switch, as long as transformer is powered by relay
 
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