I am working on my RCA 9k2 console and wonder about the resistors in the capacitor pack...the service data shows that the pack contains 3 caps and 2 27,000 ohm resistors...but it doesn't have a wattage rating for the resistors.

Can someone tell me if 1/2 watt resistors are OK?

I have only been learning about radio service for 9 months or so and all my sets so far have been newer, AA5 style. This one is older and more complex and has a few components I've not encountered yet.

Tom, I couldn't find a 9K2 listed on this board. Can you point us to a schematic?

If you do have a schematic, are you able to "guestimate" the voltage that will appear across the resistors in question? Then, the wattage dissipation can be figured by (V^2)/R. Upsize to the next standard resistor wattage.

Another approach is to go ahead and put in your half-watt resistors, and then measure the voltage across them with a voltmeter to make sure they're not overloaded.

Hi

RCA 9K2 can be found here:

http://www.nostalgiaair.org/Resources/350/M0015350.htm

Norm

:Tom, I couldn't find a 9K2 listed on this board. Can you point us to a schematic?
:
:If you do have a schematic, are you able to "guestimate" the voltage that will appear across the resistors in question? Then, the wattage dissipation can be figured by (V^2)/R. Upsize to the next standard resistor wattage.
:
:Another approach is to go ahead and put in your half-watt resistors, and then measure the voltage across them with a voltmeter to make sure they're not overloaded.
:
:
:

OK - this is a learning opportunity for me if you don't mind giving me some help Doug.

I have schematic and there are no voltages market on it...I have my formulas at hand, but, no practical skills in determining which info to plug into my equation.

One of those things I'd like to be able to figure out myself. Any guideance?

Tom, I pulled up the schematic referenced by Norm. The resistors in question, R21 and R22, are in the signal path leading to the grid of the 1st audio tube, 6F5. The volume control and the tone selector switch are all tied into this ckt.

Anyway, the current through those two resistors will be very small. How do I conclude that? Well, the current into a control grid will be small (mA?).

The half-watt resistors will be more than adequate. 1/4-W resistors would be fine, too. To demonstrate this, when you get finished, measure the voltage across those resistors.

By the way, this set is a little complicated, particularly if you past experience is with AC/DC sets. Is the radio now working, more or less? If so, you should check it after each cap or resistor is replaced to make sure you didn't make a mistake. If the set isn't working, you'd be well advised to troubleshoot first before wholesale cap replacement (maybe just replace the power supply filter caps).

Man, Doug, you are right...it is very complicated! So far, I have replaced the electrolytics and about 2/3 of the easy to reach caps. While the radio may have a "magic brain" I don't!

After the above changes, I did power it up and was rewarded with a big fat hum. So, back for more caps.

Before it was put away in the past, someone wrote "bad" on one of the e-cap cans, it was missing C64 entirely and had a 20mfd e-cap between C65 and ground. Three or four of the original paper caps had been replaced with molded plastic ones (1950s vintage maybe?). Also had wrong rectifer tube in it.

I've got all of the above corrected, plus a few other minor diagnostic checks for continuity, etc here and there.

Would you advise to replace the remaining 8 caps (including the 3 pack I initially asked about) and then doing a voltage check per the service data? Or how else could I move forward?

Tom, at this point, it's debatable what you should do next. I know it's tempting to think that replacing one of those 8 hard-to-reach caps will solve everything, but it's doubtful.

Usually, a loud hum comes from problems in the power supply area. You've replaced all the electrolytic filter caps? And you're sure that you got their polarities correct? (The most positive point in the set is the rectifer cathode.) When replacing multi-section cap cans with individual caps, it's easy to get polarities confused.

Go over that power supply section with a fine-tooth comb, checking everything against the schematic.

You are so right about the dream of having a few leftover caps solve my woes.

Tonight I'll really delve back into the power supply area and make sure everything is in the right shape. I'd be happy to get a sound out of it and at least know I'm in the right direction.

Thanks for the help and advice, as a new guy I sure do appreciate it.