Hi guys,
I have a Cyrus CD7 CD player that needs fixing. I'm pretty sure something is wrong with the clock as it works great with the Q DAC module fitted which includes a clock, but without that it has trouble recognising discs. It has two crystal cans in the thing, one on the control board for the laser mech and one on the main board.
Anyway I thought I'd replace both and I need some help to make sure I get the right replacements. Crystal 1 is labelled 'AEL 9.8304' and crystal 2 is labelled '8.4672 *logo*:12'.
I assume the numbers represent the frequency so 9.8304MHz and 8.4672MHz, right? AEL is a brand but I'm not sure what the other brand is, does anyone know the logo or what the ':12' means?
My main question is - is there anything else to picking the right item such as voltage or whatever? I know one is SMD and one is thru-hole.
Thanks for any advice!
I have a Cyrus CD7 CD player that needs fixing. I'm pretty sure something is wrong with the clock as it works great with the Q DAC module fitted which includes a clock, but without that it has trouble recognising discs. It has two crystal cans in the thing, one on the control board for the laser mech and one on the main board.
Anyway I thought I'd replace both and I need some help to make sure I get the right replacements. Crystal 1 is labelled 'AEL 9.8304' and crystal 2 is labelled '8.4672 *logo*:12'.
I assume the numbers represent the frequency so 9.8304MHz and 8.4672MHz, right? AEL is a brand but I'm not sure what the other brand is, does anyone know the logo or what the ':12' means?
My main question is - is there anything else to picking the right item such as voltage or whatever? I know one is SMD and one is thru-hole.
Thanks for any advice!
Crystals do not fail unless they were faulty at manufacture. I would suspect the electrolytic power supply filter caps are beginning to fail given the age of your box and now need replacing.
Sounds like power supply droop on the servo and DAC. Replace both the smoothing caps at the rectifiers and the smaller caps scattered across the board. Find types like Panasonic FC or FK with the largest capacitance that will still fit on the board (these types are tall but narrow making them ideal, also Nichicon or Rubycon).
Sounds like power supply droop on the servo and DAC. Replace both the smoothing caps at the rectifiers and the smaller caps scattered across the board. Find types like Panasonic FC or FK with the largest capacitance that will still fit on the board (these types are tall but narrow making them ideal, also Nichicon or Rubycon).
There was some PSU fault that blew out a few parts so I guess crystals could have been blown too? I've replaced all main smoothing caps. I guess some of the small caps around the clock could be buggered, but since it works with the Q DAC upgrade board in, the main PSU voltages are not the problem now.
Come to think of it I should probably check all resistors as one or two might have blown out. I did check transistors and diodes.
I have heard of crystals needing replacing.
Come to think of it I should probably check all resistors as one or two might have blown out. I did check transistors and diodes.
I have heard of crystals needing replacing.
We replace crystals with TCXO (temp compensated xtal oscillator) modules because they are lower noise not because of faults.
But news of a P/S fail is alarming - you still have faulty components on board and most likely the Decoder, Digital Filter or DAC since the box works when it is by passed by the Q Dac.
So where exactly in the signal chain does the Q-DAC insert? Downstream of this is your hint on where to begin searching for dead components. Plus, start your search on the semiconductors, these are the most susceptible to damage. Right now I suspect your decoder has failed and that's not really a DIY replaceable part.
But news of a P/S fail is alarming - you still have faulty components on board and most likely the Decoder, Digital Filter or DAC since the box works when it is by passed by the Q Dac.
So where exactly in the signal chain does the Q-DAC insert? Downstream of this is your hint on where to begin searching for dead components. Plus, start your search on the semiconductors, these are the most susceptible to damage. Right now I suspect your decoder has failed and that's not really a DIY replaceable part.
The Q DAC card has 2x DAC ICs, a VCXO plus an ATMEL AT90S1200 chip with crystal oscillator attached. So one of these things is making the difference. On the main CD7 PCB there is also a DAC IC and a VCXO and I have replaced both, so these are known fine.
Any idea what the ATMEL chip is doing and what its counterpart item on the main board is? The only 2 other parts with crystals attached to them are the SAA7378 and what looks like a proprietary part with a cyrus sticker on it, underneath it says HB3644 and 6AF3644H.
It doesn't look as though the SAA7378 is bypassed by the QDAC card as they are on completely different PCBs.
What do you think?
I'm sure I've heard of people fixing CD players that don't recognise discs well by replacing the crystals on the clock. I don't see why it couldn't be damaged by a PSU fault? Anyway they are cheap to replace and the SAA7378 doesn't seem available. So possibly this takes us back to my original question about picking the right replacements.
Any idea what the ATMEL chip is doing and what its counterpart item on the main board is? The only 2 other parts with crystals attached to them are the SAA7378 and what looks like a proprietary part with a cyrus sticker on it, underneath it says HB3644 and 6AF3644H.
It doesn't look as though the SAA7378 is bypassed by the QDAC card as they are on completely different PCBs.
What do you think?
I'm sure I've heard of people fixing CD players that don't recognise discs well by replacing the crystals on the clock. I don't see why it couldn't be damaged by a PSU fault? Anyway they are cheap to replace and the SAA7378 doesn't seem available. So possibly this takes us back to my original question about picking the right replacements.
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Do you have a scope?
Blindly replacing parts without knowing whether or not they are the problem is not necessarily going to lead to success.
Is it just possible that originally installing the QDAC required one of these clocks to be disabled? (Cut etch??)
Blindly replacing parts without knowing whether or not they are the problem is not necessarily going to lead to success.
Is it just possible that originally installing the QDAC required one of these clocks to be disabled? (Cut etch??)
99.999% certainty that the crystals are OK. You can't "blow" them in the normal sense. The only way to damage one is to exceed its dissipation limits which is running it in an oscillator where the crystal sees excessive voltage swing across it at its resonant frequency. Outside of this frequency it is just an open circuit so passes no current. Crystals can be damaged by physical shock and poor handling when soldering and removing.
You say the player has "trouble" recognising discs. Does that mean it sometimes does work OK ?
Whatever the problem, you need to do basic checks such as rail quality (ripple) and absolute values. And you need a "proper" scope of at least 30-50Mhz bandwidth for faultfinding.
You say the player has "trouble" recognising discs. Does that mean it sometimes does work OK ?
Whatever the problem, you need to do basic checks such as rail quality (ripple) and absolute values. And you need a "proper" scope of at least 30-50Mhz bandwidth for faultfinding.
Back in 1988, I had an interesting complaint from a customer with a top of the range Philips CD player. The described issue was, "Plays discs at the wrong speed".
Hang on I thought, it is crystal controlled and can't be wrong. The crystal was the wrong value, clocking out the data at the wrong speed!
Disco CD players, exploit this phenomenon for mixing the timing of the 'music' and does not affect the laser focusing on the tracks.
Hang on I thought, it is crystal controlled and can't be wrong. The crystal was the wrong value, clocking out the data at the wrong speed!
Disco CD players, exploit this phenomenon for mixing the timing of the 'music' and does not affect the laser focusing on the tracks.
Okay, i've replaced some SMD electrolytic caps around a regulator and it now seems to pick up discs reliably. However the sound is basically white noise. I can just about hear some music patterns in there but nearly all white noise. Any ideas what this might be?
I did replace the DAC, but I suppose it could have been damaged again by the unhappy regulator. Or perhaps I didn't make perfect connections. A couple of the pads came off, but it looked like they were not connected anyway. As you can see in the following pictures pins 4 & 6 in the first image are not connected. The DAC datasheet leads me to think this is correct as the player runs an external system clock (external from the DAC anyway). Additionally pin 12 is missing and the datasheet says this is NC. On the other side of the DAC pin 21 is missing. This is 'Zero Flag'. Could this me my problem?
Thanks!
I did replace the DAC, but I suppose it could have been damaged again by the unhappy regulator. Or perhaps I didn't make perfect connections. A couple of the pads came off, but it looked like they were not connected anyway. As you can see in the following pictures pins 4 & 6 in the first image are not connected. The DAC datasheet leads me to think this is correct as the player runs an external system clock (external from the DAC anyway). Additionally pin 12 is missing and the datasheet says this is NC. On the other side of the DAC pin 21 is missing. This is 'Zero Flag'. Could this me my problem?
Thanks!
There's a lot of ifs buts and maybes in there...
The player obviously has history. All you can do is check continuity of any suspect tracks by working to the service manual to see what goes where. SMD packages often have connections running under the chip too as I'm sure you know.
I don't know how you yourself work on SMD but it can be successfully done with standard soldering gear although once the pads are damaged then its a lot more difficult to resurrect using single strands of wire to link damaged print.
http://www.diyaudio.com/forums/parts/127924-working-smd-how-do-without-specialised-tools.html
The player obviously has history. All you can do is check continuity of any suspect tracks by working to the service manual to see what goes where. SMD packages often have connections running under the chip too as I'm sure you know.
I don't know how you yourself work on SMD but it can be successfully done with standard soldering gear although once the pads are damaged then its a lot more difficult to resurrect using single strands of wire to link damaged print.
http://www.diyaudio.com/forums/parts/127924-working-smd-how-do-without-specialised-tools.html
Crystals can fail. A well-made crystal used within its spec and free from mechanical shocks is unlikely to fail before some decades but you can't rule it out. You can't necessarily guarantee 'well-made' and 'used within spec' and 'free from shocks' in domestic equipment.
Having said that, the surrounding circuit is probably more likely to fail than the crystal itself.
Having said that, the surrounding circuit is probably more likely to fail than the crystal itself.
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