R-30S chassis variations?

Would you know the values of the speaker crossover caps?
I know I have that written down someplace but a quick search of several suspect notebooks produced no results. Is the information on the caps illegible or are they mounted such that it cannot be read? I seem to recall that I had to de-solder mine to reveal their secrets.

On the subject of the AM antenna: perhaps you really do need the correct, Fisher-branded rubber band. Unfortunately, the service manual does not list a part number. I think it may be possible for a bad connection there to cause problems on FM. The way that thing sticks up there like a radar antenna on a WWII destroyer it would be quite susceptible to damage. The AM on my 10,000 series works exceptionally well using that antenna alone.
 
The crossover caps are wrapped in such a way as to hide any printing on them. I've been playing this now for several hours and the crossovers seem to be working fine so I'm tempted to leave them alone. Thoughts?

After playing for several hours the antenna problem seems to have dissipated and I can not replicate it anymore. ??

I have a 75' outdoor longwire and when I clip it to the AM connector on the power xformer the stations start to roll in. We only have one, low power, AM stations in the area so the longwire is almost mandatory. With it I can pull in stuff I can't even detect with a built-in antenna. I'm anxious to see how good it is in pulling in 740AM Toronto tonight.

Makes me anxious too, to get the TT going. Maybe one day if the gods smile on me I'll find a 560.
 
Well it's been a while but I finally decided to open up the back and remove the crossover caps to determine their values.
Here's what they read - the smaller one is 20mfd, 25vdc and the larger is 2.0mfd, 50vdc. Now I have to go find some replacements.

fisherc-810-9.jpg~original


fisherc-810-72-ccaps-a.jpg~original
 
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Just get 5% Dayton film caps from Parts Express. Don't worry about the voltage.

Also, I'd recommend replacing the tweeter. The classic Foster (Fostex) small horn, as used in some 70s Zenith speakers, works well and fits perfectly.
 
I have a pair of Daytons ordered. I placed the order about 5 minutes before I saw your post. Great minds think alike. :thmbsp:

fisherc-810speakers-1s.jpg~original
 
While I had the chassis out to replace the volume control I noticed one of the dial lamps was no longer working so I had a fellow on Ebay build a pair of LED replacements. The buggers on this chassis are really long (6mm X 58mm) but he built a pair to order.

fisher%20c-810-96-dial%20lamps---.jpg~original


fisher%20c-810-97-dial%20lamps---.jpg~original
 
It would be interesting to learn if the 0.1uF caps were the output tube coupling caps from the phase inverter stage. I wonder if the previous repair/modification had something to do with changing the value of the signal grid bias voltage resistors. In our mods to other Fisher amp circuits when the value of the bias voltage application resistors was decreased the value of the coupling capacitors was increased. Perhaps someone was trying to reduce low end response in order to combat a low frequency rumble from a record changer by decreasing the coupling capacitor value. It might also be good to make sure the output transformer is still the original Fisher part number. If it is, there should be no problem caused by using the original values that Fisher shows for this model and chassis.

Joe
 
Joe; Stock value on the R-30-S output coupling caps is 0.022uf. (C28 & C30). C33 and C36 are at the Channel "A" RCDR OUTPUTand Channel "B" Output RCA Jacks. I would presume Channel "B" out put is for connection to a 560 companion speaker box with the 30A amplifier. The "A" channel RCDR output is either for a tape deck or possibly a mpx setup but i don't see a mpx output off the ratio detector/discriminator. Here's a copy of the R-30-S manual.

Larry
 

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  • fisher r30s-1.pdf
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Larry;
So noted, and agreed. I notice an unusual difference in components around V8 & V9 (the 6BQ7 output tubes). At V8, R27 is 2.2K ohms while at V9 30 is 33K? Maybe, but the schematic I am looking at is difficult to read the R designations and I may be wrong, but those values we would normally expect to see equal for both tubes. 33K seems rather high for a grid stopper resistor. I agree that R23 is a stage gain control to help balance the gain of the console A-channel against the companion B-channel amp gain circuitry.

Being an older product, in order for best MPX performance, a wide bandwidth ratio detector from a later model would need to be installed in order to have the best signal going to a multiplex decoder.
 
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