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Arcam Alpha 5 CD player - any experts?

Nic Robinson

Nic Robinson

Moderator
I have one of these (modified by Avondale). Some time ago the laser mech died. Les had a new one in stock which, after much fiddling, I got in. Now, everything seems to work...except for when I mount the audio board. So with the audio board out, CDs load and spin, but with it in place they just load and won't spin!

Before anyone advises me to call Les, Avondale don't support these any longer as the guy who used to work on them has sadly passed away.

Any thoughts?

Thanks,

Nic.
 
I'm sure you will get the appropriate help as people read the thread. Worth mentioning though, just in case the problem isn't solved, pfm member, ron, posts a lot in the photography section, has considerable knowledge of these CD players.
 
Hi Nic,

The first thing to do would be to remove and reseat the DAC board in case there's a dodgy connection.

If that doesn't work I'd be checking for a +5v supply to the SAA7220 and checking for a clock signal from the SAA7220 to the microcontroller IC on the main board.
 
Mike P said:
Hi Nic,

The first thing to do would be to remove and reseat the DAC board in case there's a dodgy connection.

If that doesn't work I'd be checking for a +5v supply to the SAA7220 and checking for a clock signal from the SAA7220 to the microcontroller IC on the main board.
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I’m surprised it will read TOC with the audio board removed. Iirc, the clock circuit for the whole player is on the Audio board!
 
Nic Robinson said:
I didn’t say it did. Just spins when it notices a cd. However it won’t spin with the board in.
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Right, I thought you’d said it read the CD, which I took to mean it was playing it. It does sound like you have a clock signal issue. As per Mike’s advice, it could be the +5v rail to the SAA7720 IC, this should be easy to check, there is a local regulator on the DAC board, if you have a voltage going into it but nothing out, that’s likely your issue (unless a short elsewhere is pulling it down), if that’s not the issue, you’ll need a scope, I don’t have a scope here at the minute otherwise I’d say to send it over, it could be the SAA7720 chip or the crystal itself, rare but they can fail... If you don’t have too tools or the experience, I’m sure Mike P could sort it if you, he does know his stuff.
 
The +5v power supply for the SAA7220 comes from Z402 (7805) on the main board and not from the regs on the DAC board. Check for +5v on pin 24 of the SAA7220.

The smoothing caps C403 and C405 are very often knackered.

Happy to take a look at it if you can get it to me.
 
Mike P said:
The +5v power supply for the SAA7220 comes from Z402 (7805) on the main board and not from the regs on the DAC board. Check for +5v on pin 24 of the SAA7220.

The smoothing caps C403 and C405 are very often knackered.

Happy to take a look at it if you can get it to me.
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I stand corrected, been a very long while since I’ve worked on one. I’ve extensively recapped a few of them, they run on the warmer side for a CD player so I always replaced the electrolytic caps with 105c rated Panasonics. I think I need to pick another A5/A5+ up to have a play with!
 
Sheffield Park in Sussex? Fantastic, just round the corner.

Oh...that Sheffield! Anyhow, I could risk posting it up if I don't get anywhere but I'll strip it down in the next day or so again and check those things.
 
Nic,

I have a Arcan Alpha CD player that plays CDs as long as it is from track two onwards. I'm considering getting rid of it, but I can't bring myself to throw it away as it has a flea fitted and has had a recap to Les's Spec. But I just don't use a CD player anymore.

IMG_20200510_195351 by Garf Arf, on Flickr

Interested?
 
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