Swapping parts in hope will never work, you will cause more problems than you solve.
From the pictures the player looks to have the transformer board, the main board down the side of the player, the front panel board and the mechanism. You know both players are faulty in some way and that they have different faults.
Decide on one player to try and fix and note exactly what the symptoms are. Now swap in turn the main board, the mech and then the front panel and at each point see if the symptom changes. If you swap a good board for another good board or a good mech for another good one then the symptom on that player should not change. You have to use a process of elimination to try and find where the fault is.
Doing that isn't the way I would work but you've kind of gone down that rabbit hole now
Agreed - I'll only make a further mess if i swap out components, scrap that idea.
Current situation to recap:
Player 1: absolutely dead and hasn't ever in my possession powered up - board has broken rails
Player 2: powers up for a moment and then powers off
Action taken - I swapped out the psu and main board from unit 2 and put it into unit 1. First time I powered this combination up the lcd remained lit until I pressed eject and since that point the player behaves exactly like player 2.
This video shows the behaviour:
Unless both players have the same problem with the disc carriage and additionally player 1 had a problem with the board - the issue must be that main board from player 2 that is now in unit 1 - if I am not mistaken. But remember this combination of parts did power up the first time I tried them. Something happened when I pressed the eject button - increased load that has blown something?
Current situation to recap:
Player 1: absolutely dead and hasn't ever in my possession powered up - board has broken rails
Player 2: powers up for a moment and then powers off
Action taken - I swapped out the psu and main board from unit 2 and put it into unit 1. First time I powered this combination up the lcd remained lit until I pressed eject and since that point the player behaves exactly like player 2.
This video shows the behaviour:
Unless both players have the same problem with the disc carriage and additionally player 1 had a problem with the board - the issue must be that main board from player 2 that is now in unit 1 - if I am not mistaken. But remember this combination of parts did power up the first time I tried them. Something happened when I pressed the eject button - increased load that has blown something?
Can you measure the voltage on Q3 collector as you press that power button. We know the 5 volts is OK when its not doing anything but does it drop even momentarily when you press that button? So you have to connect your meter carefully and then watch what happens to the voltage.
Also can you measure the voltage on R12 at the end that goes to the reset generator chip. Again measure the steady state voltage and then see if the reading changes momentarily when you press the button.
This is more scope territory tbh but your meter might just show something. The meter reading should stay constant for points. If the 5 volt supply dips it may be generating a reset pulse but whether your meter can capture that is another matter.
Also can you measure the voltage on R12 at the end that goes to the reset generator chip. Again measure the steady state voltage and then see if the reading changes momentarily when you press the button.
This is more scope territory tbh but your meter might just show something. The meter reading should stay constant for points. If the 5 volt supply dips it may be generating a reset pulse but whether your meter can capture that is another matter.
At face value those readings are all OK but as I say, its really scope territory because that would capture much shorter glitches.
I was wondering if the 5v rail was dipping under load momentarily which in turn generates a reset pulse from the reset generator chip and that reset pulse then sets everything back to standby.
Have you tried powering it up with the mechanism removed or disconnected in case there is an overload there (one of the motors) causing some issue.
(its a bit hard to keep track of tbh without having them all in front of me)
I was wondering if the 5v rail was dipping under load momentarily which in turn generates a reset pulse from the reset generator chip and that reset pulse then sets everything back to standby.
Have you tried powering it up with the mechanism removed or disconnected in case there is an overload there (one of the motors) causing some issue.
(its a bit hard to keep track of tbh without having them all in front of me
)Weird - so I tried unplugging both ribbon cables - no dice. Then as I plugged the cable for the mechanism it started to spin up and the head moved. I kept doing this and result were temperamental. Then all of a sudden I had the display working. At the moment display works and the buttons seem to function but the tray won't eject - I may have damaged the ribbon cable so need to swap it over from other unit. If I leave the player it goes into stand-by, but power switch turns it back on.
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This is just a thought...
Back in post #1 you began by saying:
Was the player working OK before and it has 'failed' or was it an acquisition that has never worked?
I'm just exploring the possibility (with you saying it seems to power down by command) that it might need to be part of the full system.
Back in post #1 you began by saying:
Was the player working OK before and it has 'failed' or was it an acquisition that has never worked?
I'm just exploring the possibility (with you saying it seems to power down by command) that it might need to be part of the full system.
It was just a thought, and one I should have realised earlier perhaps but I honestly don't know as I've no experience of these units. Against that theory is the fact it seems to have a remote receiver on the front panel board which often interconnected and dependent systems would not as they would use a single receiver on the main amp unit.
I don't know
I don't know
I also checked the manual and there is no suggestion that it is required.
This project might have hit the end of the road, As a last result I might try and switch out the larger transistors - the heatsink it a little warm just with the unit in stand-by. It's a last resort and after that if it's a no go I'll probably cut my losses and bin the units.
This project might have hit the end of the road, As a last result I might try and switch out the larger transistors - the heatsink it a little warm just with the unit in stand-by. It's a last resort and after that if it's a no go I'll probably cut my losses and bin the units.
I wouldn't just swap randomly, the voltages at face value are correct on those regulators and so no need to replace them. I had a look at the instruction manual as well and can not see anything relevant.
There is nothing obvious I can think of to try as it all becomes much more involved from here on in. When the laser assembly moves in to the centre all it does is close a microswitch to signal it is in the 'home' position but that should not cause a unit to shut down.
There is nothing obvious I can think of to try as it all becomes much more involved from here on in. When the laser assembly moves in to the centre all it does is close a microswitch to signal it is in the 'home' position but that should not cause a unit to shut down.
Maybe there is a common fault with these units that occurs on the mechanism - perhaps I have two units which have the same fault plus ooone also had the power fault. I guess I can't rule out that a seller may have repaired one with two units and sold me a cobbled together unit a bad mechanism and a bad board.
That can happen. There was an Akai thread recently a bit like that but its pretty rare.
https://www.diyaudio.com/community/threads/akai-cd-93.88356/
No problem, I'm sorry we couldn't find what was going on with this one.