Hi. I have a Model 71 Code 221 that I am restoring for a friend. I am wondering if there are any high voltage caps on there ( more than 630 volts). The service data I have doesn't give the voltage ratings. This radio had been worked on in the 60's with many caps replaced by just connecting them to the existing bakelite cap connections. without restuffing. Thanks for any help.
If there is one single cap that the mfr could potentially make to be of higher voltage, that would be the #39. Or, rather, both of them (one is permanently grounded, the other is wired via tone ctl switch).
But I always use 600V caps there.
Just don't unplug the speaker during operation.
Hi John and welcome to the Phorum,
Back in years gone by the common standard voltage values used in receivers for foil/paper caps were 100,200,400, and 600v. Every once in a while you might see a 1000 or 1200v job. These higher voltage one would be located across the primary of the audio output transformer or in farm sets used in the vibrator power supply. A lot of times those might be micas.
If you like for #39 you can use two .02mfd @ 630v in series for the .01, this will equal .01@1260v. For the .02 you can use two .047's @ 630v to equal .0235mfd @ 1260v.
In some circuits that cap is wired across the primary of the output transformer so if it shorted it doesn't really do any damage. In this one if it shorts it take the transformer w/it.
Welcome to the Phorum!
Thanks guys for replying. Just to be clear , which #39 is the .01 and which one is .02uf? Here's the pertinent part of the schematic. I added a shot of what I'm facing with this chassis. It was worked on in the 60's with the capacitors you see that have been added. You might notice the two yellow Aerovox electrolytics . They are the 8uf filter caps. Strangely they didn't disconnect one of the old filter caps completely and left some of its connections still connected and the only source of filtering for those connections. I have been going over the circuit from point to point to make sure that all the connections conform to the schematic. UPDATE: Looking around the forum I did find a post by Ron Ramirez that provides a schematic that has the values written on it.
I have one more question about caps on this radio. Are all the capacitors the same capacitance value for this model regardless of the the code? I know the main filter caps are higher on the code 221 ( 8uf vs 6uf).
Are you talking about the electrolytics? or all the caps?
I mean all the caps. My model is code 221 so I can see the extra cap there for the two speaker circuit.
Hi John and welcome also; it looks like the radio has a socket for the speaker connection (not hard wired). Are there two speakers? I am asking because I have a 71-225 in a cathedral case with one speaker. I thought that the leading number 2 in the code meant two speakers 71-121 one speaker; 71-221 two speakers etc. and that the single speaker models were hard wired.
Bob.
Yes there are two speakers. This is the floor model .
Thank you John. I have a floor model chassis in a cathedral case then (switched and not factory installed).
Bob.