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Old 21st December 2009, 11:09 PM   #1
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Default Arcam cd8se help needed

Hi, My problem is that my 8se will not play cds. The laser goes to the outside end of rail and bobs up and down very quickly. I replaced the laser assy but it didn't help. Someone with a similar problem suggested it may have something to do with timing and the clock on the dac board. I replaced the reg that looked like it may have overheated, but to no avail. I have a Roksan dac and connected that up but it didn't help. Can I remove the internal dac or does the player need this even when using an external dac? If anyone can help I would greatly appreciate it. I'm a beginner so simple words please. Thank you. Barry
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Old 22nd December 2009, 12:09 AM   #2
poynton is offline poynton  United Kingdom
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It's unlikely to have anything to do with the DAC.

The clue may be in the "overheated" regulator.
What caused it to overheat ?
What part of the circuit does it supply?

Without a circuit diagram or service information, you are going to have a hard time !

Andy
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Old 22nd December 2009, 12:58 AM   #3
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Hello, The regulator may be a red herring. The circuit board was a bit browner under it and I was told it could cause the problem. It supplies the crystal which is on the dac board. I wondered if I could remove the board altogether and use an external dac to prove it is or isn't the dac board.
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Old 22nd December 2009, 02:01 AM   #4
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Usually, the crystal in the onboard dac provides timing signals to enable the rest of the player to work so removing the board would not be beneficial !

I would suspect a power supply problem or a fault in one of servos

Andy
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Old 22nd December 2009, 10:24 AM   #5
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Thanks Andy, Would my external dac have a crystal to supply the timing?
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Old 22nd December 2009, 04:35 PM   #6
Mooly is online now Mooly  United Kingdom
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An external DAC has no influence on the player.
I would imagine if there were a clock issue that more than just the sled running to the end would be seen.
Did this machine fail in use or has it been tweaked/worked on.
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Old 22nd December 2009, 07:00 PM   #7
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Hi Mooly, It hasn't been played with or tweeked. It just decided to run to the end of the sled and the laser jumps up and down very quickly. If I move the laser to the centre it just goes back to the edge. Two other people have now told me it has something to do with the clock which is on the dac board, that is why I wondered if I removed the dac board and used my roksan dac, would the clock on that make it work. Barry
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Old 22nd December 2009, 11:12 PM   #8
gfiandy is offline gfiandy  United Kingdom
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Hi.

These symptoms definately indicate that the transport is recieveing no clock. DO NOT RUN THE SYSTEM FOR ANY LENGTH OF TIME LIKE THIS! it will burn out the laser. When doing the check listed below avoid running the system for longer than about 10 seconds at a go.

The first thing to check is that the cable connecting the DAC to the main PCB hasn't come loose. So gently push it into its socket and see if there is any movement. Retest the system quickly. Then try removing it and replacing it carefully. Retest again.

If this doesn't work then, if you have acess to a multimeter check the output of Z11 on the DAC board this should be 5V. This is the power to the clock. If it is no good then and there is power to the input of Z11 then replace Z11.

If this is OK try to get hold of a scope off of someone. Then check the signal on C38 if you do not see a 16MHz signal here then either Q5 could have failed or the crystal could have failed. Q5 you can get from anywhere its a BC847B however the crystal will be difficult to get hold of as it is a 16.9344MHz crystal and they are only used in CD players with a 384x clock (and most have a 256x clock). If you contact ARCAM they will probably sell you one they are quite good like that, but expect to pay quite alot for it probably 10 or so.

Best of luck,
Andrew
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Old 23rd December 2009, 07:20 AM   #9
Mooly is online now Mooly  United Kingdom
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Without seeing a circuit it's guesswork really.

The fact the laser bob's up and down (you mean the proper focus search routine ?) to me suggests the clock is probably present. The disc (platter) often takes off at a million rpm too when that is missing which you haven't mentioned.

Having said that as gfiandy say's, you have to confirm it's there

An external DAC feeds nothing "back" to the player. The player at all times uses it's own clock etc.

Practical experience say's "look for parts that are stressed" which means anything that runs hot etc.
You MUST check every single rail from the PSU and any sub regulators or transistors used for power switching. "Safety" resistors are another common problem. These are low value (usually less than 10 ohm) that work as fuses but they can often go high in value.
If it is purely the sled problem, then an "H bridge" driver is suspect. That is a device (IC or discrete) that can apply voltage to the motor with either polarity form a singe rail supply.
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Old 23rd December 2009, 12:59 PM   #10
gfiandy is offline gfiandy  United Kingdom
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Hi Mooly,

I know you are trying to help but just dismissing my advice with no evidence isn't helping.

I am not guessing, I worked for ARCAM, and I know the symptom this player has (The laser doesn't usually bob in this situation it normally flicks up and down quite quickly, its different to the slower search routine of a laser focusing). When the Sony mech recieves no clock this is exactly what it does, there is quite alot of inteligence in the mech itself as it also contains all the digital servo control electronics, however it does not contain the clock as this needs to be placed near to the DAC, so it is passed back to the servos.

Without the clock the servo controller does not behave correctly and the symptoms described are the most common action it takes. So it could have been a problem with the servo control board but this is unlikley, it is much more likely that the clock is not getting to the laser assembly for some reason and the most likely reason for this is either the connector is loose or the clock has failed (the crystal can end up a little overdriven in this circuit so does sometime fail after a long time).

An external DAC cannot supply the clock signal that is required, you need to fix the on board DAC. It is possible that there might be a crystal in an external DAC board that you could remove and fix the internal DAC with however this would be a expensive fix and not guaranteed as most DACs use a 256x clock 11.2866MHz not the 384x 16.6344MHz used in the 8SE. This is a Sony "standard", so if you have an old sony CD player you may be able to use the crystal from that.

If you are lucky it is just possible that you have one of the 8 SE players that was made by modifying a 7 SE in which case the old 7 SE crystal will be on the main PCB (it looks identical to the crystal on the DAC PCB). If this is the case then you can remove the crystal and fix the 8SE DAC; if it is the crystal that has failed.

However I would not try any of this without investigating the problem as decribed first if it is not any of the simple problems then you need an oscilloscope. If you are not confident to try this then I would recomend either sending it back to ARCAM, although at this point it is probably worth less that they would need to charge to fix it, or find an electronic engineer who is happy to have a go and give him my description.

Regards,
Andrew
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