> This is my own receiver. Last year it started taking longer and longer for the protection relay to activate and turn on the speakers I finally took it out of service. I recall that it had no other problems that were evident. I had posted this problem at that time and I think that it was Chuck up in Canada who nailed it immediately. He recommended changing C6 on the protection board and .that resolved the protect relay problem. Now however there is another problem that I never had before. Most of the dial lights including the signal meter light are out and that meter also seems to be inoperative as well. I never had any trouble with any lighting or the signal meter on this receiver. This is a big quadrophonic receiver. The switching is done through the main selector switch and it's a nightmare to get to. A real rats nest. Does anyone who has worked on these recall any common problems with lighting on one of these? I suspect a ground problem because so many of these lamps are in parallel but it's so crowded in that area you can't see anything. I Really appreciate any help. Lenny
Chuck
I'm embarrassed to say that I think I know what happened. The RF
section on this receiver is pretty hot and so for servicing it on my
bench I didn't bother connecting the old outside VHF/FM antenna that
is now used just for FM, throughout our house. I was getting what I
thought was a decent signal in my basement with just a short piece of
wire connected to the high side of the 300 ohm terminals. Apparently
in spite of the fact that the FM stations I was tuning in sounded OK
there must be a signal threshold that must be met before the signal
meter will move. With the unit connected to the outside antenna the
signal; meter is now working fine. I don't think that there was ever
a problem with it.
It was more aptly due to "operator head space"
So now I'm at the final stage of this repair. I have owned this
receiver for over thirty years now. I originally bought it from the
junk man at our town dump who was going to strip it, for 5.00 It has
been a great receiver for all this time,however the 4 channel
circuitry never seemed to work properly on it. I worked on it, John
Del, also a contributor to this thread worked on it as well, but we
never seemed to be able to resolve it. So for that time I have lived
with it.
A few weeks ago I was browsing Craig's List and found a guy about 30
miles from my house who had one of these for sale. I went out, and
looked at it and thought it might need a discriminator alignment, and
I picked it up for parts. So today, first I swapped out the 2048
board. I now have output on all 4 channel positions except the first
and last, which seems like it should be. I have 4 speakers connected
to speaker A front and back terminals. It seems to sound "OK:" but I
can hear a very slight "popping" way down in the mud in the rear
speakers.
So I was going to swap out the 2047 board, however in spite of the
fact that it would fit in the same slot as my original, the board from
the donor receiver is totally different. For one thing there are 7
potentiometers on the donor board and only three on my original board.
There are also two 8 pin chips on the original board but it seems to
be all discrete components on the donor board. So for boards that fit
into the same positions in the chassis are these boards forward and
backward compatible? After all this I would hate to make a swap and
because it was incompatible wind up destroying something.
Lenny