Mike, I bought it that way. I originally bought it so I could repair it using parts from mine that got "moused", but I don't have the heart to knock any of those in the head, esp one that I know worked, so I am looking for a tranny for this one. It is a 500c. I may put an ad in the wanted section one of these days.
If I could find the place called "Somewhere", I could find "Anything"
John 14:6 Jesus answered, "I am the way and the truth and the life. No one comes to the Father except through me."
You know, seeing this thread is making me start to think about setting aside all of that solid-state stuff for awhile and maybe get started on something I've put off for too long...restoring my Fisher TA-600 receiver. Tubes and lots and lots of caps.
Его так просто не сломать
come on this is a PHILCO phorum
put that modern junk away
restore some thing nice and relaxing with warm bright glowing tubes
Some day, and that day may never come, I will call upon you to do a service for me. But until that day, accept this justice as a gift
Fisher 800, 500, 400, and TA-600 receivers do use warm, bright, glowing tubes...
Его так просто не сломать
02-19-2017, 09:26 AM
(This post was last modified: 02-19-2017, 09:29 AM by Mondial.)
Looks good. Check your AC line current draw with the new rectifier. I'll bet its a lot lower now due to the decreased output plate current
Yes, the bias on the output tubes is very important. With low bias the tubes overheat, liberating gas inside the tube. This causes the plate current to increase further resulting in a runaway condition. The final result is a meltdown of the power supply and/or the output transformers.
The line fuse should provide some protection, but make sure it is the correct current value (or lower!). Sometimes people replace the fuse with a higher amp rating which is a recipe for disaster.
You probably should replace the green molded line bypass cap with a safety rated type. There is another identical cap across the power transformer secondary.
Yes the safety rated Y cap should be fine in both locations. Its not really needed across the transformer for safety but they are usually rated for 240VAC so its a good choice.
I would go with a 2.5A slo blo fuse, or maybe even a 2A if your measured draw is less than that. Its better that the fuse blows before anything else expensive. In any case the fuse is easy to replace and if you find it blows under normal operating conditions you can up the rating slightly.
I forgot to mention the amperage draw. It was little over 2 amps and dropped down to 1.5amps.
with the new rectifier.
Don't be concerned about the exact voltages on the first half of V100. They are very much affected by the individual characteristics of the 12AT7 installed.
If you have 5V on the cathode and 112V on the plate that is in the range of normal operation. You can try another 12AT7 and see if the voltages get closer to those on the schematic.