SX 828 Stereo Indicator Lamp

[miklemke]

One last issue with an SX 828.

The Stereo Indicator lamp won't light. The bulb was bad and has been replaced, but still no indicator. There is no voltage going to the bulb. Any ideas?

Thanks

 

[markthefixer]

on the underside of the chassis on some terminal strips is a diode and axial leaded capacitor combination hooked into the lighting circuit to turn the ac lamp power into DC for the stereo indicator lamp. A shorted cap could have popped the rectifier, so ordering a 1n4004 replacement is appropriate.

c9 is an axial 470uf 16v cap. 647-TVX1E471MCD 470/25 670 in stock $0.87 ea
D1 is a sib01-01 diode - 512-1n4004

 

[miklemke]

Thanks Mark, I'll give it a try and report back. I have the diode, but not the cap.

 

[miklemke]

Mark, I think you nailed it. I found the cap/diode set-up you mentioned. 6VAC going into the diode, 0 DC out. I have a radial cap of the correct value and the diode. I'll give them a try.

 

[miklemke]

Still no indicator light.

Replaced the diode and cap. I now have 7.8 vdc off the cath of the diode. This feeds one leg of the bulb. The other leg connects to pin 5 of the tuner board, also 7.8 vdc on pin 5. Why no light???

 

[markthefixer]

Got voltage on pin 5 of the tuner board?

Then the transistor right next to the pin is either bad, or not turning on. Gotta measure the base voltage to see.

I think it's q12 a 2sc382. pin 5 will go to the collector. Follow that trace.

 

[miklemke]

The transistor is Q19 (2SC968). The Base voltage was 0; the Emitter voltage was 0. I went upstream to Q20 (2SC711); Emitter 0; Collector 4v.

 

[sregor]

Quick comment - make sure tuner is in FM stereo mode - there are two FM positions on the selector switch. There is one voltage which goes through the switch to allow stereo operation in that position only. Good Luck.

 

[markthefixer]

The transistor is Q19 (2SC968). The Base voltage was 0; the Emitter voltage was 0. I went upstream to Q20 (2SC711); Emitter 0; Collector 4v.

Quick comment - make sure tuner is in FM stereo mode - there are two FM positions on the selector switch. There is one voltage which goes through the switch to allow stereo operation in that position only. Good Luck.

The circuit isn't telling it to turn on.