1981 Delco radio repair

[billccm]

Hello:
A Delco radio from a 1981 Corvette came across my work bench. It must
be the top of the line for it's time; it is electronic tuned, and auto
reverse cassette. Unfortunately, all the stickers for model and serial
numbers have fallen off the radio's case.
The complaint is hiss, but no tuning, no display, no music.
I applied 12Vdc, and the complaint is correct. The display is dark,
and only a small hiss in the speakers.
I actually repaired Delco car radios back in the late 1970s when I
worked for a local service shop while in high school. I have forgotten
much about these, but remember that for the most part, Delco radios
were reliable, and generally simple to fix.
With this radio, I am not sure where to start. A schematic wouyld be
helpful, but I do not havethe model, and do not know where to get
schematics.
Any advice, and assisatnce is appreciated.
Thanks,
Bill

 

[Gary Tait]

Hello:
A Delco radio from a 1981 Corvette came across my work bench. It must
be the top of the line for it's time; it is electronic tuned, and auto
reverse cassette. Unfortunately, all the stickers for model and serial
numbers have fallen off the radio's case.
The complaint is hiss, but no tuning, no display, no music.
I applied 12Vdc, and the complaint is correct. The display is dark,
and only a small hiss in the speakers.
I actually repaired Delco car radios back in the late 1970s when I
worked for a local service shop while in high school. I have forgotten
much about these, but remember that for the most part, Delco radios
were reliable, and generally simple to fix.
With this radio, I am not sure where to start. A schematic wouyld be
helpful, but I do not havethe model, and do not know where to get
schematics.
Any advice, and assisatnce is appreciated.
Thanks,
Bill

Check the 5V regulator on the ETR board. Also, you need to feed it
continuous 12V on the separate two connector lead, on the orange wire.

 

[Tim]

Hello:
A Delco radio from a 1981 Corvette came across my work bench. It must
be the top of the line for it's time; it is electronic tuned, and auto
reverse cassette. Unfortunately, all the stickers for model and serial
numbers have fallen off the radio's case.
The complaint is hiss, but no tuning, no display, no music.
I applied 12Vdc, and the complaint is correct. The display is dark,
and only a small hiss in the speakers.
I actually repaired Delco car radios back in the late 1970s when I
worked for a local service shop while in high school. I have forgotten
much about these, but remember that for the most part, Delco radios
were reliable, and generally simple to fix.
With this radio, I am not sure where to start. A schematic wouyld be
helpful, but I do not havethe model, and do not know where to get
schematics.
Any advice, and assisatnce is appreciated.
Thanks,
Bill

It may be one of those "Corvette Special" radios as well. I believe
quite a few years of 'vettes had those in them. I would look at the
power supply for the front display and tuner. It is probably proprietary
logic, but it may still a simple defect.

- Tim -

 

[Art]

Look for a DC-DC inverter circuit that has failed. If memory serves me the
DC-DC developed supply voltages both for the tuning and display circuitry.

 

[Gary Tait]

Look for a DC-DC inverter circuit that has failed. If memory serves me
the DC-DC developed supply voltages both for the tuning and display
circuitry.

Tuning comes right from 5V or 12V. VFD displays would have a DC-DC
convertor, and I don't think they had them back then. It wasn't till
1985/6/7 or so when they went to VFD for their premium stereos, I think.
Before that, they used LED.