Im working on a Delco AM FM ETR from about 1982. I have no display unless a button is pressed, AM is switched to FM and vice versa and the tuning knob is turned. When the display is lit, for a few seconds after one of these actions, the radios audio is strong and clear. It then deteriorates and disappears until a button is once again pressed. Another symptom is that the clock will not display with power off unless the tuning knob is depressed. (Yes, orange wire is connected to 12v)

There’s what I believe to be a regulator on the board, that may feed the display. I took some voltages and It has 13.5v on the collector and nothing on the base or emitter until a button is depressed or station is tuned. Corresponding with the deteriorating audio and display going dead, about 6 volts is on both the emitter and base which then fades to milliamps until another action as above is taken. The collector voltage drops from about 13.5 volts to 10 when the display is lit.,

What am I looking at here? This regulator faulty and what may be a good substitute for it? Any advice from you Delco pros would be much appreciated!

These radios have problems with cold solder joints. They must be resoldered. Some boards are coated with a glue that must be removed with a solvent [I use Acetone in a well ventilated area]. With the board cleaned the cold joints and the pass-thru's will be visible. Both sides of the board must be re-soldered.

billk

This is not your problem, yet, but I used this info to fix a Delco S-10 truck radio that had garbled audio. There must be an issue with electrolytics in those units. http://www.howtoalmanac.com/Scott/HowTo ... Repair.htm

Is it wired correctly? I recall a separate wire to +12vdc to light the display.

Yes, thanks. It’s the orange wire for the clock.