[mhuppertz]

Hello.
Can someone point me in the right direction for an electronics replacement part kit for my Philco Model 41-629?
I don't think I have the chops to figure it out myself, but removal and replacement are no problem.
Thanks!

Mark

[morzh]

There isn't much to figure out.

Myself, I do not even plan it: I go on the rule "see a cap - replace it".
Done.
WIth the exception of the mica caps, do not touch those.

So, to be a bit more organized, take the sch, go through all tubular/backelites and electrolytic caps, make the list, and buy it. And you are 85% there.
The resistors are rarely kitted as often times many do not need to be replaced.

Tubes....have to be tested, always, I make no exceptions.

And. People who sell kits tend to buy cheap no-name capacitors. You could for a little bit more buy good name caps through reputable vendors, like Mouser etc.

[mhuppertz]

Thanks. I did find a chart for converting mmfd to mdf, but those are the mica condensers.
Are you saying I don't need to worry about those?
Thanks, and sorry for asking dumb questions. Not a EE, or anthing resembling!

[morzh]

No you do not have to worry about micas, and try not to desolder them at all. Leave them be. Rarely it is that a mica cap fails. I have yet to see it.

mmfd is a picofarad, pF. "m" in the old notation stood for what "u" (which is a poor replacement of Greek "Mu") stands today, "micro". "mm" is "micro-micro" which is "pico-" today, or 10^-12, one-trillionth.

Today "mF" would mean 1,000 uF (microFarads), that is "milliFarad", and this is confusing for many folks, so one has to discern between old and new notations.

So, for radios:

m - Micro, 10^-6F, a microFarad
mm - micro-micro, or today's "pico"

And, despite "nano" being popular today, many local folks frown on it, using "0.001mf" instead of "1nF".
All the same.


So, to recap the recap:

- worry about any paper cap, whether a tubular or in a backelite case. Replave 100%
- Electrolytics. Replace 100%.
- - do not worry about micas. Only replace if find one bad in the troubleshooting process. Good luck finding one.
- Check the resistors, replace as needed; 20% tolerance is good. And even more in many cases.

[klondike98]

https://philcoradio.com/library/download...20Book.pdf

In case you have not seen it, the above link is for the schematic and parts info from our library. It should help you out along with the info Morzh has posted.

[bridkarl]

For resistors I try to check them first. 20 percent is fine. 
Assuming you get the radio working - I sometimes do everything else, get the radio running, let it run for an hour or two and then check the resistors.

I think these carbon resistors sometimes absorb water - especially if stored poorly like a basement - so running the radio heats it up and drives the water out. 

It may be an old wives tale, but I’ve measured out of spec resistors before and after and sometimes the resistor goes to its proper value. Lots of times they’re too far gone but sometimes this seems to work.

[GarySP]

Totally agree with these gentlemen on capacitors ... everything but the mica caps gets replaced. I differ with them a little regarding the resistors however. Resistors are the least expensive parts in the chassis that can go bad. Testing all of them takes almost as much time as replacing them, and you have the chassis on a bench anyway. I choose to replace them as well. I call it being proactive. Might be overkill ... just me. Take care and BE HEALTHY! Gary

[bridkarl]

I don’t disagree that replacing resistors is fine. There are people who prefer to keep some original parts - hence my suggestion.  If you like the original look new carbon resistors are available. 

I can think of situations where getting to a particular resistor is so hard that trying to replace it puts other parts at risk. People have different skill levels obviously in repair.

[GarySP]

I'm not that much of a purist. I did make dogbones for my model 20, but don't mind if the chassis on most other sets doesn't look "factory fresh" and period correct. I'm happy enough when it works! Take care and BE HEALTHY! Gary