[murf]

Hi guy's,
I have had this Philco model 96 lowboy sitting around for a while and was thinking of restoring the chassis.
Looking at the chassis, it has model 76 written on the chassis in pencil.
Is there a way of checking to verify this is a 76 chassis instead of what originally came with the model 96.
Is this a tricky one to re-cap and replace electrolitics?
Don't really get into the older ones too much.
murf

[Arran]

The 76 has seven tubes whereas the 96 has nine tubes, the 96 also had a box shaped tube shield mounted at the back of the chassis. Sets this early don't use electrolytic capacitors they use large paper capacitors for filter capacitors, they are mounted in a potted metal can at the front corner of the chassis. I haven't got around to working on my model 96 yet but that potted can has a terminal board in the bottom so I have heard that it is possible to cut the internal leads off and remove the can without disturbing the chassis wiring.
Regards
Arran

[murf]

Thanks Arran,
Looks like someone must have switched this one to the 76 chassis.
When I feel ambitious, I will take the pan off and take a look at whats hidden under there.
Not to sure I want to get crazy with a $50 radio.
Probably worth $51 after re-capping.
Have a great day.
murf

[peteivan]

I restored an Atwater Kent model 60 for a friend. I measured the value of the capacitance of the filter capacitors, and they measured almost exactly the values stated on the schematic. They were obviously not electrolytic capacitors, as if they were, they would be shorted after many decades of not being used. I left them in place, and they worked fine. Perhaps they were impregnated in oil.

[Arran]

The paper filter caps in these sets, and A.Ks were not oil impregnated, but they apparently used a higher quality paper then the paper caps you typically run into in sets from the mid to late 1930s, plus the potting material does a good job of keeping the moisture out. In my opinion I would not trust 80+ year old paper caps no matter how good they test, even with voltage across them, age will degrade the paper dielectric if nothing else. Besides that the can not only has the paper caps it has most of the bypass caps in it as well which can also fail.
In short using the set as is is like playing Russian roulette (my apologies to Morzh) if you play on using the set on a regular basis. I have a Westinghouse model 89, a 1929 set with big block condensers, and while the filter caps have not shorted out the set does not work, in short they still need to be replaced.
Regards
Arran

[peteivan]

These capacitors are still working after being in use for over 1 year. All I can say is if they fail I will replace them for my friend. I found it amazing that the capacitance values measured almost exactly what they were supposed to. In other words, if it ain't broke-don't fix it.

[codefox1]

Old Capacitors are really time bombs ready to do real bad things to unobtanium. Your call.

[Phlogiston]

"In other words, if it ain't broke-don't fix it"

Those are the famous last words before you post the ad:

WTB: Power Transformer for Philco 76

Either way, good luck.

[Arran]

In this case Mr Peteivan was speaking about an Atwater Kent radio and not a Philco. If this was 1952 or 62 I might agree, or even as late as 20 years ago you could take a chance. However if it's a choice between changing under $20 worth of capacitors with some hassle, or spending $100-150 on having a power transformer rewound if I couldn't find a used replacement I would prefer to change the capacitors. After all if the old caps die and take out a power transformer, a filter choke, or a field coil, you would still have to replace them anyhow. If you want to take the risk I would at least connect a pair of fuses in series with the high voltage winding, preferably fast blowing fuses, then when (not if) a cap does short out you will get a second chance.
Regards
Arran

[codefox1]

Some of us will still be here when you need help in the future. Please do not leave a senior set on when you leave the room.