Gary L. Woodruff wrote:
David Farber wrote:
Gary L. Woodruff wrote:
David Farber wrote:
Gary L. Woodruff wrote:
Howdy all, I have a vintage Pioneer receiver. It will pick up
AM stations but is dead on FM. I do not get any deflection on
the tuning meters and no static. I do have a print. I do have
b+ into the board and have good voltages at the HA1156.
I do not see anything at the HA1137, with the exception of
13.8v at pin 11 (should be 5.6v). There is only a coil in
series with a cap to gnd between b+ and this pin. I do not
have a way to measure inductance on the coil but have
measured the cap .047 microfarads is spec and I get .055. I
am tempted to try to replace the IC (HA1137) but am
concerned about the amount of voltage I see on pin 11 of the
IC. Any and all advice is GREATLY appreciated.


Thanks, Gary
That 5.6 voltage should be for pin 10, not pin 11. Pin 11 goes
to the B+ supply and the 13.8 v is correct.

Good luck.
Gary L. Woodruff wrote:
Dave, thanks for pointing that out. the 13.8 is the only
voltage I see on the HA1137. I do not see the input signal of
1.9v on pins 1,2,3 of the chip. I do see the 12.6 v at F2 but
nothing after. I will try to replace this fuse? F2 and the
HA1137. Does this make sense?
Thanks, Gary


F1 and F2 fuse one of the pairs of wires coming off of the
secondary
of the power transformer. In the FM section, there is another
component which also labeled F2 which appears to be some sort of
I.F. filter. You need to tell me if by F2 you mean the fuse or if
you mean the filter. You cannot have the 13.8 volts at pin 10 if
the fuse is blown. Do you have the correct
voltages on Q4?

Good luck.
Gary L. Woodruff wrote:
Howdy, thanks Dave. Yes I do see 13.7V at the collector, 1.4v
Emitter .21v at the base. I do not see anything on the output of
the F2 filter (I missed the F2 listing in the tuner part list, and
found it listed as a fuse, thanks again).

Thanks, Gary



I believe we've found the problem. I am not in the office at the
moment where my schematic is, but if Q4 is reverse biased, that's
going to be a dead end for the signal right there.
Dave, thanks again. What do you think is causing q4 to be reversed
biased?

Gary

Sorry I couldn't get back to you sooner. Remove Q4 from the circuit
and test it with your multimeter. Also, check the voltage at the
base of Q4 were it still in the circuit.


Dave, I removed Q4 from the circuit and it is OK. I checked the
voltage at the base with Q4 out of circuit and get 2.1 V. I
resoldered Q4 and checked the base again and still get 2.1 at the
base. (I may have misread my previous reading of .21v) I do see 13.7v
on the Q4 side of the f2 IF filter but 0v at pin 1 of HA1137. i am
thinking I need to replace this F2 if filter?

Thanks, Gary

Well the difference from .21 and 2.1 is quite a difference. That means the
transistor is operating correctly. I would replace the HA1137 and see if the
voltages come back up. It's not very likely any of those filters are bad.
You could remove F2 and see if the voltage comes back up just to see what
happens though.

Good luck.
--
David Farber
David Farber's Service Center
L.A., CA