TIVOLI CD Player problems

[Old Sparky]

Basically this 10 year old CD player seems to have a faulty laser, since, at best, it will only read the first minute or so of some discs, but, besides that, the spindle motor sometimes doesn't run. Examining the PCBs, I've noticed that there are three 78 series regulator chips present. One is a 5v type (L7805), the other two, designated U6 & U7, are wired in series, U7 being a L7809, whilst U6 is a L7808. U7 & U5 are bolted to individual heatsinks, whilst U6 is just soldered to the board. I haven't attempted to trace the circuit in detail, but, why would anything need to have a regulated 9v supply further reduced to 8v. Surely nothing is that critical? Voltages on all 3 devices, measured with a DMM, are OK, but the heatsink to which U7 is bolted gets rather hot after only a minute or two, which I wouldn't have thought normal.
The player runs from 12vDC, from it's makers own 'wall-wart' supply. I haven't yet checked current consumption, but can do so via my bench PSU, but, could a failing regulator or associated circuitry be the cause of either or both faults?

[Mark Hennessy]

I assume you've cleaned the laser?

What happens after the first minute or two? Does it skip? If so, you might need to clean and re-grease the sled rails.

I wouldn't have thought that the 7809 could be supplying the 7808, as 78xx regulators have a higher dropout voltage than 1V. I think we need to see official schematics for this one...

It's definitely worth trying it from a decent bench PSU first. But if the CD player has been used most days for 10 years, then it's probably time to move on. Despite the clever marketing, these products were built to a price like everything, and 10 years ain't bad really.

That said, the laser assembly might be available for a reasonable price. A couple of years back someone brought me a Tesco special to look at - naturally I assumed that it would be fit for the bin, but it turns out that CPC sold the whole mechanism for about £5. Yes, just five pounds! Astonishing...

[Old Sparky]

I assume you've cleaned the laser?

What happens after the first minute or two? Does it skip? If so, you might need to clean and re-grease the sled rails.

I wouldn't have thought that the 7809 could be supplying the 7808, as 78xx regulators have a higher dropout voltage than 1V. I think we need to see official schematics for this one...

It's definitely worth trying it from a decent bench PSU first. But if the CD player has been used most days for 10 years, then it's probably time to move on. Despite the clever marketing, these products were built to a price like everything, and 10 years ain't bad really.

That said, the laser assembly might be available for a reasonable price. A couple of years back someone brought me a Tesco special to look at - naturally I assumed that it would be fit for the bin, but it turns out that CPC sold the whole mechanism for about £5. Yes, just five pounds! Astonishing...

I hadn't thought about greasing the sled rails, but it may be worth trying that. The mechaism is an enclosed type like those used in many car stereos, so a fair bit of dismantling is needed to gain access. Tivoli's service company has already stated that they don't supply circuit diagrams or manuals, but I'm 99.9% certain that the 7808 in in series with the 7809. Must double check that, too. Incidentally the Tivoli CD player retailed on it's own for £299, or as part of a system with a radio/amplifier, etc. for over £500, so it's in a different league from the cheap Chinese gear (although it was made in China!)

[tiv48]

Does it read the TOC ok ?
Does it play the first couple of tracks ok?
if so I would as others have said look at the sled.
On the other hand if it has trouble reading the TOC then suspect the LASER .
Rob T