Arcam Alpha 9 - Help Needed

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Andrew Eckhardt

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Joined 2005
I have to admit I don't even see Z203 on the drawing, I was just going by that blurb you posted. Z208 is shown on sheet 2. It is a 7805 regulator with output, the interesting part, at TP2. The tab of the 7805 is at ground. I'm thinking that if the unit is obeying the front panel controls then the 5 volt supplies are probably good too.

Once again, did you unplug the cable for the pickup assembly?
 
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Andrew Eckhardt

Member
Joined 2005
Ok. The problem with the connector for the pickup, usually some kind of ribbon cable, is not that it often gets re-connected wrong. It's that the supply for the laser diode runs through it and in some designs those lines can be extremely voltage sensitive and need to be shorted before disconnecting to protect the diode from ESD, otherwise it's easy to flatten it.
 
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danza

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Joined 2004
I've checked the output on Z208 - 5V dead on. I can't find Z203 on the PCB anywhere!

Upon unplugging the DAC board and turning on, the disc span up as per before the repair.

I know what you mean about the laser diode, although it still gives out a beam (perhaps it's not that simple).
 
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danza

Member
Joined 2004
Sheets 1 and 4:

Alpha789CD1of4.jpg


Alpha789CD4of4.jpg


Not sure if sheet 1 is relevant given the title. 4 doesn't look like much use either.

Perhaps the DAC circuit is what you need (it's a separate file consisting of 10 drawings)?
 
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Andrew Eckhardt

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Joined 2005
I think I may have ran you around a little bit. Looking back at sheet 3 you can see at connector SK201 the FOK line at pin 18. The CDM14 mech seems to have all the servo and demodulator goodies integrated, and none of that stuff is in the Arcam drawings. (unless I missed something). The good news is unplugging that connector probably wouldn't have done anything. The bad news is I can't help you troubleshoot the other side of it.

See if you can get your meter on that FOK position and find whether it toggles when the player is trying to focus.
 
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danza

Member
Joined 2004
I changed 4 of the 25V 1000uF caps yesterday, the 4 closest the power supply (I replaced them with 35V 1000uF caps as suggested by mooly). Those were the only caps with bulging/leakage. I might change the other 2 or so that lurk in different areas to be sure.

Just re-posting sheets 2 and 3. I accidentally deleted them from my Photobucket account.

Alpha789CD2of4.jpg


Alpha789CD3of4.jpg


I'll see if I can dig up any info on that FOK signal for the Sony mech. I can't see anything on the Arcam layout diagram which looks useful.

Cheers
 
Mooly

Mooly

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Joined 2007
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This may sound like it's covering old ground or not relevant but let's be sure. We know it's had a PSU fault so let's be absolutely certain all is OK before moving on.
Also without having the unit in front of me... well that makes it more difficult just referring to a PC screen and not being able to actually see what's in there :)

On the PSU circuit top left is connector SK204. Check those 5 voltages are correct. Also on pin 8 there is something marked RLYV. What is the voltage on there ?

I notice regulator Z206 on the PSU has a switch ???? SW201C... Whats that ? It looks as though it's to cut power to the reg Z208. Check around there... is that 5 volts OK from that "switched" reg. Should be on that connector SK204. I guess that's if you use an external DAC etc.

Can you confirm that APART from the fact it doesn't spin a disc up it otherwise behaves OK? Is there anything that doesn't behave as expected? If so then the pickup is looking suspect ? Was it all "original" when you got it or has it been worked on before ?
If it's the KSS240 laser assembly these are readily available and cheap.
Don't know how easy it is to work on in situ but the FOK line is (appears to be) brought out on connector SK201 pin 18, on page 16 of the main manual although it isn't used. Can you measure there ? It's the flexiprint to the mech.

If any "clock" signals etc were missing then things usually take off, motors running at full speed etc, so I don't think anything like that is going on here.
 
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Andrew Eckhardt

Member
Joined 2005
Danza, just to mention: The signal on the FOK line is not real fancy. It will probably remain at around 0 volts until the focus servo achieves lock, then it will go high (5V) for as long as it can hold lock or until the control processor tells the mech to give up trying to read the disc. If you get lock then the laser is OK and the troubleshooting could get fancy. An oscilloscope may eventually be necessary.
 
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danza

Member
Joined 2004
Cheers for yet more input guys, my Alpha 9 may just work again!

Mooly said:
Does the lens move up and down slowly and smoothly when it does the focus search routine ?
Click to expand...

Yes, it seems fairly controlled - not 'spasming' or anything like that. It just illuminates, bobs up and down twice then rests. I'll try to measure the FOK signal later when I'm at home. I'll also check the various voltages mentioned at the same time, then reply later with the results (if I haven't blown it up).

Cheers
 
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