Hi simon if you could come and have a look that would be great. How much would you charge. I dont have a meter but i have just orderd one off ebay as i drove my car over mine 😀
CHEERS MATE im good at that as well thats why my cd player and volt meter are no more😀 let me know when i its best for you sooner the better tried an old marantz cd player id got but it sounds very brown if if you know what i mean
Hi bent he as been tonight and no mushroom clouds😀 he did put some time in though and we still cant bottom it. Think i impresed him though with my little amp😉
I had a good look at Steve's player but I can't fix it. Here's a run-down of the facts:
* the 12V regs work fine
* both op-amps have +- voltages
* the 5V is fine and present at DAC etc. - not being dragged down
* no sound at left channel
* distorted sound at right channel
* right channel pulling + rail down to 11.7V
* left channel pulling + rail down to 10.7V
I changed the op-amps and this made no difference. I checked for cracks and splashes and cleaned stray flux etc away - no visible problems.
There's continuity from the op-amp output to the RCA jacks. The HDAM and muting is bypassed. Other CD players work on the same amp.
The output isn't shorted - measures 10k to ground on both sides.
It reads discs first time and goes between tracks etc.
I think the DAC is broken, though I don't know how it will have happened.
Any ideas guys?
Simon
* the 12V regs work fine
* both op-amps have +- voltages
* the 5V is fine and present at DAC etc. - not being dragged down
* no sound at left channel
* distorted sound at right channel
* right channel pulling + rail down to 11.7V
* left channel pulling + rail down to 10.7V
I changed the op-amps and this made no difference. I checked for cracks and splashes and cleaned stray flux etc away - no visible problems.
There's continuity from the op-amp output to the RCA jacks. The HDAM and muting is bypassed. Other CD players work on the same amp.
The output isn't shorted - measures 10k to ground on both sides.
It reads discs first time and goes between tracks etc.
I think the DAC is broken, though I don't know how it will have happened.
Any ideas guys?
Simon
bull041161 said:
Incredible that such a tiny and stone-cold box could make such dynamic high-octane sound, I was very impressed. It was a bit rough around the edges, but obviously we weren't using a modified CD player!
And another fan of Diana Krall - The Girl in the Other Room is born... 😎
The opamp supply is not supposed to be dragged down like that. I assume that's only caused by the load of the opamps? If the wrong caps were fitted, maybe the series inductors or resistors are damaged (if they are fitted), or maybe the regulators. Also, check the supply voltage before the regs. Does that also sag a lot?
Ray
Ray
We can look into those things but they sound like long-shots to me. The positive supply voltage is at about 22V (iirc) and the negative at -26V. So it is true to say the positive supply is being dragged down somewhat... but why? Judging by the large voltage drop across the left-channel 4.7R op-amp supply resistor I would say that op-amp is causing the current usage, presumably due to what the DAC is feeding it.
DC offsets, btw, were about -150mV left channel (156mV with metal hat op-amps) and about a third that right channel.
I'm stumped
Simon
DC offsets, btw, were about -150mV left channel (156mV with metal hat op-amps) and about a third that right channel.
I'm stumped
Simon
I dont understand all this its beyond me. Brent do think its the diodes then and not the DAC 😕
The problem seems to be around the +/- 12V rail which does not supply the dac. Diodes are cheap and easy enough to fit which makes it the first port of call.
Brent
Brent