Sony auto CD player repair question

[tempus fugit]

Hey all;

I'm currently trying to get a Sony EXCD-21 auto CD player up and running.
The unit worked fine when it was removed from the previous car, but when I
tried to install it in another car, it was dead.

I pulled it back out, and hooked it up to my bench PS, and found that it
wasn't actually dead, but the display was flashing faintly (all the LEDs for
the panel as well as the LCD display). If I hit the reset button, it turns
off, but flashes again when I turn it back on. I noticed that when a ground
wire for the speaker touched the power ground, I got a steady display and
all the controls were now functioning; however, I get no sound out of it.
With the ground wire separated, I get a dit-dit-dit sound from the speaker.

Any ideas on what to do next?

Thanks

 

[[email protected]]

Hey all;

I'm currently trying to get a Sony EXCD-21 auto CD player up and running.
The unit worked fine when it was removed from the previous car, but when I
tried to install it in another car, it was dead.

I pulled it back out, and hooked it up to my bench PS, and found that it
wasn't actually dead, but the display was flashing faintly (all the LEDs for
the panel as well as the LCD display). If I hit the reset button, it turns
off, but flashes again when I turn it back on. I noticed that when a ground
wire for the speaker touched the power ground, I got a steady display and
all the controls were now functioning; however, I get no sound out of it.
With the ground wire separated, I get a dit-dit-dit sound from the speaker.

Any ideas on what to do next?

Does grounding the case fix the problem?

 

[tempus fugit]

Right now it's out of its case - just the circuit board on the bench. I
don't htink that could be it though, because the case is connected to the
board at various points.

 

[Nigel]

A lot of car audio equipment locks up as an anti-theft precaution when
disconnected from the 12v supply.

You may need to reprogramme it - and you'll need the proper manufacturer's
information to do that.


Hey all;

I'm currently trying to get a Sony EXCD-21 auto CD player up and running.
The unit worked fine when it was removed from the previous car, but when I
tried to install it in another car, it was dead.

I pulled it back out, and hooked it up to my bench PS, and found that it
wasn't actually dead, but the display was flashing faintly (all the LEDs for
the panel as well as the LCD display). If I hit the reset button, it turns
off, but flashes again when I turn it back on. I noticed that when a ground
wire for the speaker touched the power ground, I got a steady display and
all the controls were now functioning; however, I get no sound out of it.
With the ground wire separated, I get a dit-dit-dit sound from the speaker.

Any ideas on what to do next?

Thanks

 

[tempus fugit]

I checked for DC voltage at the output of the power amp IC, and got about
3v. Maybe the IC is cooked? I also tried grounding the IC directly to the
PS, which made no difference. Ditto for resoldering the connections to the
board from the IC.

Also, when the unit is doing the flashing thing, my voltage drops from 14.4
to about 8. With an ammeter connected, it's only drawing about 300mA so I'm
not sure what that is all about. I could go ahead and replace the IC, but
I'm not real familiar with car stereos, and there is a lot of logic and SM
components in there that I suppose could also be causing the problem. Add to
this the fact that I have no schematic, and you can see that I'm running out
of ideas. I suppose I could scope the output, but I can already hear what
I'm going to see (maybe I'll give it a try anyway).

Any other ideas?

Thanks

 

[tempus fugit]

Thanks Nigel.

The unit is maybe 10 yrs old, and was only about $100 installed. I've never
heard of the anti theft lockup you describe - how long have they been doing
that? Do you think it is likely they would have put something like this in a
cheaper unit as well?

Thanks again