Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Stewart Warner 176 assistance
#1

http://www.nostalgiaair.org/Resources/885/M0029885.htm

I recently bought this Stewart Warner 176 locally and just wanted to get a couple of items cleared up. I’m new to this and this radio has been worked on before which complicates it for me. The fellow I bought from said he was new as well and gave up on the restoration. 

R8 is 100,00 and R12 is 500,000. Are they are both potentiometers and if they are, how to measure them properly? Should they be replaced if they’re too high/low?

How would I find a value for R20, it measures 9.600K, I traced it back to a resistor on a large terminal board, it’s brown black but the multiplier has been scrapped off. Is 10K a reasonable value for this resistor. 

The last item is there is a remote volume control on the schematic. It didn’t come with one so is that an issue? I haven’t plugged this in yet and won’t until I finish with caps and resistors.
#2

R8 is the tone control and R12 is the volume control. R12 is the audio gain vs R19 control the gain of the rf amp tube. Generally I find that controls don't drift in value much unless there's a is a large amount of current passing thru them. This can cause heating which in turn can cause drift in the value. This isn't the case in this application.
But wear, dirt, and cracks in the resistive strip could be a problem. This will make it intermittent. Best way the check it is to use an analog ohm meter connected from the wiper to ground side of the control. The needle on the meter should move smoothly as the full range of the control is adjusted.

9.6K or 10K seem reasonable for R20. It supplies the screen voltage for the osc section of the 6A7. I might revisit it if the there is a problem getting the osc running.

On the remote volume control ground the white. That will restore the circuit so that the rf amp will work properly. Without doing so the rf amp is disabled and the sensitivity will suffer badly.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry




Users browsing this thread:
[-]
Recent Posts
Philco Model 38-7: what caps & resistors do fail typically?
Hello Martin, Welcome aboard our little community what great Model 38-7 Sincerely Richardradiorich — 12:30 AM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum Martin. I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM
Part numbers to model cross
Jim, We have this index put together by Dale Cook but I don't think that is quite what you are looking for. The Parts...klondike98 — 09:37 PM
Philco Model 38-7: what caps & resistors do fail typically?
Yep the dim bulb test is OK but I'd definitely replace all those electrolytics before I did it. Since those #47 conden...klondike98 — 09:18 PM
Philco 42-345 Restoration/Repair
The resistor is a 2.2 Meg, it was the last one I hadn't replaced. The broadcast is coming in after replacing it.osanders0311 — 09:09 PM
Philco 42-345 Restoration/Repair
What does the resistor measure? I think it should be 3.3 Meg. If the oscillator coil has continuity and the resistanc...RodB — 09:03 PM
Philco Model 38-7: what caps & resistors do fail typically?
Good idea to check the coils... then I'll get hold of an incadescent light bulb and see what happens when the unit is sw...Musaeum — 08:49 PM
Philco 42-345 Restoration/Repair
I have that same set, ain't too much shortwave I like anyway.....it is a good AM DX set. PaulPaul Philco322 — 08:32 PM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum, Martin! Open a new thread in Philco Electronic Restoration when you begin working on your 38-7. ...GarySP — 08:28 PM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum! :wave: Here's the schematic for that radio from our digital library: Something to do bef...klondike98 — 08:05 PM

[-]
Who's Online
There are currently no members online.

>