cambridge 840C problem !

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Hello all,
I just finished repairing one AZUR 840C. It happened that the right channel is noisy, distorted, and lower amplitude.
I found the 10Vdc for the right channel DAC reads only 2.8V and the output of the 2.8V regulator reads only 2.65V. I checked the ESR of C217 is 6.5 ohm which may possible cause the 10V regulator U42. I had the capacitor and U42 replaced with new spare. I check other capacitors on the board and found many of them are having high ESR. I had them replaced as well.
After these works, the unit works fine and singing sweetly.

Johnny
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The capacitors being used for the power supply is polarized. Those four capacitor around the AD1955 DAC chip are bi-polar ones.

The capacitors should be rated for 105 deg C because of the high heat from the linear voltage regulators... it is about 40 deg C at the heat sinks.

Johnny
 
Hi, so I replaced the caps with new ones. And it fixed the problem, however, I'm worried a bit because as I was soldering, the little thin metal rings on the bottom of the board came unglued. I still got a good connection and solder through the hole.

Does anyone foresee any issues?

Thanks again!
Mike
 
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Pleased to hear you have fixed the basic issue.

Lifting print is a fact of life I'm afraid, although the more experienced you get, the more you can learn to recognise the signs that perhaps its not bonded to the board to well.

Ideally on single sided print, a dab of the iron (a large iron :)) and solder braid is all that is needed to cleanly desolder a part, and desolder it so well it will fall out under its own weight.

Double sided print is less obliging and you often have to heat and pull at the same time. When the part is free, the hole is often full of solder, particularly if it is a plated through 'via'. Here a thin piece of stainless wire can be used to poke through the hole at the same as you apply heat. The solder doesn't stick to the stainless wire and you can free the hole that way.

You won't have any issues as long as the connectivity is good.
 
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It will be fine.

Even if print comes away completely (and it happens) then a neat repair can be made with a few strands of fine twisted wire. The secret is never be afraid to remove a couple of millimetres of the lacquer to get a decent surface for the wire to solder to.
 
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Oh dear :(

I've no magic fix I'm afraid as I've never worked on these players. The golden rules of fault-finding are to check the rails both for correct voltage and also with a scope to make sure they are clean.

As you thought it was fixed, could the heating of that area with the iron be a clue. Perhaps a dodgy cap.
 
So I have an update. I ended up looking again last night at this page and lo and behold, I too, changed the wrong cap based on the circuit board numbering. Even though, one of the posts here says the same and he changed the other cap. I must've missed that or misunderstood.
Anyway, long story short, I opened it back up this am and replaced the #224 cap and it went rather smoothly. Plugged her back in and upon power up, no noise. So I powered down, waited again for 5 or so minutes, powered back up. Still no noise. :)
So I'm hoping when I get home after the kid's have sing along, ill power back up and there will still be no noise :)
Cross fingers for me!
Thanks everyone!
 
Well , my friend is having problems with skipping on this model . We replaced 3 drives and it still persist . Now , the play marker on the display dims (only the play triangle the rest is lit normally) the playback stops for a moment and it plays fine afterwards. Sometimes it plays a couple CD's without problem and sometimes it skips from the beginning on the same CD.
I know those $20 Ebay laser units are cheap junk. Do you know any reliable source so we can at least exclude transport as a cause?
TIA, L
 
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The player skips... you fit three 'new' drives and the same fault persists.

I think you need to look elsewhere tbh.

I've heard that the power supply caps can be suspect on many Cambridge products. As always a scope and service manual to see what is going on will be the most useful starting point.
 
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