Can ANYONE tell me what chassis this is?

[dieseljeep]

Originally Posted by rca2000

This is a cheap little Philco stereo chassis. It is a hot chassis, using a SE 25F5 output for each channel. It has three output transformers--looks like they are summing the pair of outputs for one center channel.

WHY did I get this--? For purely "sentimental reasons". I had one about 35 years ago. I played with it then for awhile...but I was forced to get rid of it about a year later "for my own good" along with that Admiral M20 set and many other thing

Well...i got one late last summer. I want to get it running. I plugged it in yesterday--the tubes all began to light...then a resistor on the side of that big 4 section cap began smoking. One section is a 425mf at 175v..could be easily replaced with a 470/180 or so.

I CANNOT find any sort of chassis # on it--to look up a sams for the chassis. I was hopong maybe someone here might recognize it--and be able to help me. I expect it is from 1963-1965, maybe a year older or newer..

Did you scan through the Beitmans schematics, for the years 1963-65?
It should be covered there.
The 25F5 tube is similar to the 35C5, but less power output. It's amazing to see that large of value electrolytic for filtering purposes.

[rca2000]

Quite by Accident...I FOUND this chassis. it is L-1652B on sams 652-12 I have a old, dirty but quite useable sams for it now. This set does not use a doubler--only a half-wave diode for a 140 volt supply. I expect less than 2 w/channel, maybe 5 or so from the sum channel.

It looks like the resistor that is smoking is on the 120 volt line. I checked with a meter for low resistance to ground--but it does not seem not be the case. There is a 50MF cap on that line--but it does not check shorted. This one is on the board--near the 25F5 tubes.

[old_coot88]

Sometimes if the first filter cap (the one coming off the rectifier cathode) goes open, the unfiltered ripple votage is large enuff to smoke the line resistor just 'downstream' of it.

[rca2000]

Turns out....that 50UF cap must be bad. With it in the ckt...the voltage to it drops to about 50 volts and the 1.8K resistor feeding it smokes. With it OUT...the voltage rises to about 120 or so volts and the resistor is OK. But it does NOT measure shorted on the DMM.. Must be badly leaky I guess...when voltage hits it.

Chassis DOES work--to some degree now. BUT...it does NOT seem to have much volume-- even on the sum channel--compared to that nice Silvertone I have here now--and showed in another post--the one with SE 6BQ5 amps. Also--the stereo light does not some on, blinks sometimes--but does not light steady no matter what. I realize the Silvertone is a lot more powerful...BUT this Philco seems REALLY weak. SOME him---but not a huge amount. Main B+ seems pretty close to the 140 volts shown on the sams. AND==when I finger the phono input...it is a LOT louder--for a couple of seconds...then fades--since the amp shuts down due to the power going off(must be switched by the phono in that position).

If that 50UF cap is not in the CKT...would it make THAT much of a difference?

[dieseljeep]

Originally Posted by rca2000

Turns out....that 50UF cap must be bad. With it in the ckt...the voltage to it drops to about 50 volts and the 1.8K resistor feeding it smokes. With it OUT...the voltage rises to about 120 or so volts and the resistor is OK. But it does NOT measure shorted on the DMM.. Must be badly leaky I guess...when voltage hits it.

Chassis DOES work--to some degree now. BUT...it does NOT seem to have much volume-- even on the sum channel--compared to that nice Silvertone I have here now--and showed in another post--the one with SE 6BQ5 amps. Also--the stereo light does not some on, blinks sometimes--but does not light steady no matter what. I realize the Silvertone is a lot more powerful...BUT this Philco seems REALLY weak. SOME him---but not a huge amount. Main B+ seems pretty close to the 140 volts shown on the sams. AND==when I finger the phono input...it is a LOT louder--for a couple of seconds...then fades--since the amp shuts down due to the power going off(must be switched by the phono in that position).

If that 50UF cap is not in the CKT...would it make THAT much of a difference?

Hang any 160 volt electrolytic in that place for now. Then check the performance. The 425 mfd, probably won't hold much of a charge, because of the leakage. A half wave power supply isn't good for reserve voltage. Having an input filter that large, the B+ current demand is rather heavy.