Hey guys
I am missing some resistors, and have one 4000 ohm one that is not on the schematic. The ones missing are circled in red. Could anybody tell me where these could be. The Large one with the silver and yellow stripes is the 4000 ohm. The resistor is on pin 6 of the 12sk7 with the 2 next to it.

Kinda tough to see but the top appears to be the volume control-is there an arrow on 1 end?
That means an adjustable resistor,volume/tone whatever control.
Phil

Yes, there is an arrow but the way I learned it the arrow meant a diode. If you want here's a better schematic:
http://www.nostalgiaair.org/resources/385/M0016385.htm

You're thinking solid state-gotta think hollow state!
That is the volume control-the others look to be in the I.F. cans.
Phil

Edit:r2 and r3 ,1 meg,brown/black/green-you don't see them?

I saw all except those three. Thanks for the help. But that still doesn't explain extra resistor, the 4000 ohm? That appears to have been added recently, not original.

It's between pin 6 of the 12sk7 and what?Ground?
I didn't see it anywhere on the schematic and the pic is hard to see where the other end goes.
Phil

Take careful note of the IF's. Midwest used a Hammelund(?) IF and those had a terminal plate in the base of them. Within several of these, were hidden plate resistors & caps. & a few other resistors & caps. This may well be similar. Trace the wires.

Marc

Ya, one end is connected to pin 6 and the other is connected to the terminal strip which the two 100000 ohm resistors are connected to.

One of the 12sk7's has a 1k to ground,the other has a 300 ohm to ground-are those resistors there?
Some one may have replaced the 1k with the 4k that's in there.Does the radio work??
Phil

Hasent worked since I got it. The 1000 is there but the 300 isnt. The reason I had so much trouble with this is because I couldn't even fathom why anyone would think to interchange a 4000 ohm resistor with a 300 ohm. I could understand 500 and 300 but other than that, no.

May not have had the correct value or couldn't read a color code and winged it??
I'd put the 300 in it's place.
Phil

I've never seen a 4000 ohm resistor in a post-1940 radio-- the industry went to the standardized 20% resistor values sometime around then. Could the yellow stripe have been brown at one time, and it's really a 1000 ohm resistor? That would make sense.


Even if it is 4K, a 4000 ohm resistor will work just fine in that location-- it's just a B+ decoupler for the first two tubes, which don't draw more than 5 milliamps-- that would drop the B+ voltage a handful of volts more than usual but not enough to be a big problem. These AA5 circuits can happily run with 32 volts on the plates so going from 90 to 80 volts makes no noticeable diff.

Its definately a 4000 ohm, but I would like to find that other 500 ohm resistor before I replaced all. Problem is, I can't get the IF can metal casing off.it seems to be latched and riveted. I don't really want to cut leads and remove the whole unit. Btw the switch is the 500k resistor. Thanks phil.

Looking over the schematic, the first 500 ohm resistor may be left out by manufacturer. It's a B+ decoupling resistor and not necessary. Might have saved a cent during manufacture.

Pin #6 of 12SK7 is cathode. They might have wired this pin direct to B-? or to the other 12SK7 cathode. If they used this cathode resistor it should have bypassed with a cap, not shown. Again money saving figuring AVC would give 12SK7 enough bias.

If pin #6 is connected to B- then so will be the added 4000 ohm resistor. Agree with Ancient_Hacker, 4000 ohms isn't common. Was this measured or color coded 4000?

It was 4000 ohms when I measured it and the bands read 4000 ohms (yellow, black, red and silver). I didn't think 4000 was standard either

So what are the symptoms of not working/
Have you recapped it?
Checked plate voltages?
Phil