2325 FM Signal Strength Meter Issues

[rustyhusky]

I've been restoring a 2325 receiver and have run into a problem with the FM Signal Strength meter that has me stumped.

In the 2325, the FM Signal Strength meter doubles as a "Dolby Level" meter. The meter is working when Dolby NR is enabled, and also works when AM is selected. Unfortunately, the meter is totally dead in the FM mode. The "Center Tune" meter works, but even on the strongest station, there is no deflection of the Signal Strength meter.

I've done a deoxit treatment on the Dolby NR and Selector switches since the meter is routed through them, however there has been no improvement. I've also checked for broken wire wraps on the P200 FM IF and P300 FM MPX circuit boards and everything is still connected. Is there anything else I should be looking at?

 

[PE9ZZ]

Do you get any voltage on R374?

 

[rustyhusky]

Do you get any voltage on R374?

This morning, I checked the DC voltage at J316 (center tap of R374) and got nada with or without a station tuned in. I then checked voltages around H316 and got C=12V, B=0V, and E=OV, which matches what is shown on the schematic.

I moved upstream from J316 to J209 on the P200 FM IF board and checked voltages around H204; got E=3.1V, C=12V, and B=3.8V, which again agreed with the voltages shown on the schematic. Since I had just recapped this board a couple of days ago, I got suspicious and started examining the passive components downstream of H204. Checked the polarity of C261 and found it to be correct, however when I examined the foil side, I found what appeared to be a small solder bridge between R223 and GND. I resoldered the connection and voila!, the signal strength meter now works.

Thanks for the nudge in the right direction. That's what I needed!

 

[tonebells]

Tony