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[LC0112G]

Dave,
I've got two Blaupunkt SQR88 Memphis tuners for the Omega A. Ideally I'd like one working for next Tuesday when I've got a 500+ mile return journey to Norfolk planned.

1) I know the code for it (1016), and it works for a few minutes till it warms up. Then it goes into an audio dropout cycle with about a one second period. You get radio for about a second, then a thump through the speakers, then quiet for a second, then radio for a second, then a thump etc. I suspect it's power supply related, but haven't opened it up (yet).

2) Got this off an ABS member, but no code. There is a code written on the label (0916) but that doesn't work. I've used an online serial number decoder, and that came up with a different code (1916). That one doesn't work either! The unit is now in a 1 hour lockout  - I've probably entered 5 'wrong codes'. I've looked at the circuit diagrams and the code appears to be stored in a MC68HC11 MCU - so not easy to desolder and read out.

Any ideas - or is it a post them to you job?
Cheers
Malcolm

[Dave DND]

Malcolm,

Not sure where you are, buts Friday today and next Tuesday may be a bit unrealistic unless you are proposing to swing by with them (ring me, we may be able to do something)

Audio dropout sounds like either a short, or depending on plugs on back, you may have a speaker misconnected if you are using a common earth block (the rear blocks were interchangeable)

Codeing  on the other one is no problem - but you won`t find a useable online solution as we never wrote software for that model - if you see anyone advertising it, its probably a scam !!  Get the unit to me, and no problems it decode

[LC0112G]

Not sure where you are, buts Friday today and next Tuesday may be a bit unrealistic unless you are proposing to swing by with them (ring me, we may be able to do something)

Thanks. I'm not too far from you (Yeovil) but I'm busy this weekend and as you say it's unrealistic to do it by post in the timescales.

Audio dropout sounds like either a short, or depending on plugs on back, you may have a speaker misconnected if you are using a common earth block (the rear blocks were interchangeable)

Pretty sure the wiring it Ok - It's worked for the past 25 years so unless something has decided to short out recently I doubt it's that. I'll give the speaker wiring a quick buzz with an AVO tonight.

When it happens, the display dims but doesn't go out, which again makes me think it's a power supply caving in. I was rather hoping that you were going to say a common fault is something like "That'll be C123 a 100uF 16V elecrolytic on the PCU card".

I've got the unit out and running on the bench here now playing a BoneyM tape. Typically - it's working OK, although I do only have one speaker connected, and it's the wrong impedance. I might go back to the car and when the fault occurs unplug the speakers in turn to see if that cures anything.

Codeing  on the other one is no problem - but you won`t find a useable online solution as we never wrote software for that model - if you see anyone advertising it, its probably a scam !!  Get the unit to me, and no problems it decode

Yeah - fair enough. Thought the internet option for £3.99 was worth a punt. I'll get it in the post to you soon ish. I've got 3 CDP09's too, and I need to get one working so I can enjoy Agnetha and Frida on the way up to Norfolk.

[Kevin Wood]

I've got the unit out and running on the bench here now playing a BoneyM tape.

 

Sounds to me like it might well be a speaker wiring fault that's loading the audio amp excessively and causing thermal shutdown. Maybe that's why it's not misbehaving on the bench. Could try it into a more realistic load on the bench with a 4 ohm resistor connected to each speaker output?

It's not a bridged  output stage where the speaker negatives have been commoned, I suppose?

[LC0112G]

I've got the unit out and running on the bench here now playing a BoneyM tape.

 

Sounds to me like it might well be a speaker wiring fault that's loading the audio amp excessively and causing thermal shutdown. Maybe that's why it's not misbehaving on the bench. Could try it into a more realistic load on the bench with a 4 ohm resistor connected to each speaker output?

It's not a bridged  output stage where the speaker negatives have been commoned, I suppose?

No - 4 independent differential outputs driven by TDA7241's. Thermal shutdown might affect one speaker driver, but unlikely to affect them all unless it drags the PSU down.

Loaded the outputs up with four 3.9R 3W wire-wounds and left it running. Found Kate Bush on the other side of the tape  Anyway, it ran and ran and ran and got hot enough for the internal fan to come on (and the resistors to smell toastie), and it was still working. So back to the car, and when plugging it in, I noticed sparks as I plugged the aerial connector in. Turns out the OV/Earth/Ground wire in the car side wiring loom plug isn't - and the OV is/was being supplied by the screen on the antenna/cable connector. So I bridged the wiring from the cigarette lighter ground to the 0V input to the radio, and it's all now working. Not sure what permanent fix to attempt (fault is in the car's wiring loom somewhere), but it's good enough for this weeks trip.

So, I'll give DAVE DND a call later in the week and arrange to ship the other SQR88 and CDP09 for brain surgery.

[Dave DND]

Yep - lack of an earth would do that