I have a Onkyo DX-7333 CD player, which sometimes doesn't recognize CDs.
I don't think it's a laser pickup (KSS-213C) problem, because when it recognizes the CD, it plays it without a problem, even very scratched ones.
The next thing is, it should play CD-RWs, but it doesn't even recognize them.
I think it needs adjustment
There are two pots on the main PCB - Focus Gain R123 and Focus Offset R112.
Also there are two test points:
TP1 4 pins, first pair labelled Tracking Gain, second pair Focus Gain
TP2 2 pins labelled RF Out and VC
But in the service manual is no description, what should be measured on the test points and how to set Focus Gain and Focus Offset.
In the attachment is a cut out from the schematic, where the test points and adjustment pots are.
Please if someone knows, how to?
I don't think it's a laser pickup (KSS-213C) problem, because when it recognizes the CD, it plays it without a problem, even very scratched ones.
The next thing is, it should play CD-RWs, but it doesn't even recognize them.
I think it needs adjustment
There are two pots on the main PCB - Focus Gain R123 and Focus Offset R112.
Also there are two test points:
TP1 4 pins, first pair labelled Tracking Gain, second pair Focus Gain
TP2 2 pins labelled RF Out and VC
But in the service manual is no description, what should be measured on the test points and how to set Focus Gain and Focus Offset.
In the attachment is a cut out from the schematic, where the test points and adjustment pots are.
Please if someone knows, how to?
Attachments
This covers general alignment,
http://www.diyaudio.com/forums/digital-source/226288-sony-cdp790-kss240-restoration-project.html
http://www.diyaudio.com/forums/digital-source/226288-sony-cdp790-kss240-restoration-project.html
HW test: You may be using the same web site as below : ( I normally use HiFiEngine).
ONKYO DX-7711-SM Service Manual free download, schematics, eeprom, repair info for electronics
2 free download per day without login. Try your luck with these 2.
My DX-7711 Service manual only has adjustment pages but pretty clear for the Scope check/adjust, IMHO. See if that help to figure out yours. (My 7711 shows the similar symptom, I may adjust it a bit later.)
But I have the full service manual for DX-7911. pm me so that I can send you a copy of 7911 SM full.
ONKYO DX-7711-SM Service Manual free download, schematics, eeprom, repair info for electronics
2 free download per day without login. Try your luck with these 2.
My DX-7711 Service manual only has adjustment pages but pretty clear for the Scope check/adjust, IMHO. See if that help to figure out yours. (My 7711 shows the similar symptom, I may adjust it a bit later.)
But I have the full service manual for DX-7911. pm me so that I can send you a copy of 7911 SM full.
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I've downloaded a bunch of SMs for other Onkyo CD players, fortunately the procedure is (mostly) described there.
The CD player now recognizes only the Test CD and one music CD (not always), no other CDs, no CD-Rs.
The "eye pattern" on the RF test point is only 0,6-0,7V. According to other SMs it should be 1,2V+-0,3V.
Is the laser dying?
The CD player now recognizes only the Test CD and one music CD (not always), no other CDs, no CD-Rs.
The "eye pattern" on the RF test point is only 0,6-0,7V. According to other SMs it should be 1,2V+-0,3V.
Is the laser dying?
If the lens is clean then most probably yes.
The next step would be to check the laser current. Usually there is a low value resistor where the volt drop can measured and current calculated. KSS pickups often have the current for that pickup (that it was calibrated too) as the last three digits of the serial number on the pickup. eg 123456529 would be 52.9 milliamps. If its increased by more than a few percent then suspect the laser.
The next step would be to check the laser current. Usually there is a low value resistor where the volt drop can measured and current calculated. KSS pickups often have the current for that pickup (that it was calibrated too) as the last three digits of the serial number on the pickup. eg 123456529 would be 52.9 milliamps. If its increased by more than a few percent then suspect the laser.
I think it's R101 (22 Ohm) but now I have the problem that the player doesn't want to recognize any CD 🙁
I have to be patient and try ...
On the laser are two "numbers" printed:
10733
HA496
I have to be patient and try ...
On the laser are two "numbers" printed:
10733
HA496
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That would be 49.6 ma and mean a volt drop of around 1.09 volts across the 22 ohm. You would only see the voltage during play or if it won't recognise a CD, during focus search.
That figure is a guide that the laser diode itself is drawing the correct current and that the optical output power is correct.
There can still be many other causes of low recovered RF. Is the lens clean ? 🙂 Have to ask.
The focus bias (offset) pot can be tweaked when playing to get the highest amplitude RF.
You may just have a faulty pickup (photodiode array problem or internal contamination etc).
There can still be many other causes of low recovered RF. Is the lens clean ? 🙂 Have to ask.
The focus bias (offset) pot can be tweaked when playing to get the highest amplitude RF.
You may just have a faulty pickup (photodiode array problem or internal contamination etc).
I have cleaned the lens, in fact it was the first thing I've done.
I have tweaked the Focus Offset to get the mentioned 0,6-0,7V, it was off about 15-20° on the pot.
So the next logical step is to buy a new laser pickup?
Should I also buy a new flat cable?
What bothers me most is, that sometimes it recognizes a CD a then plays it without a problem. But to get a CD recognized is harder and harder.
I have tweaked the Focus Offset to get the mentioned 0,6-0,7V, it was off about 15-20° on the pot.
So the next logical step is to buy a new laser pickup?
Should I also buy a new flat cable?
What bothers me most is, that sometimes it recognizes a CD a then plays it without a problem. But to get a CD recognized is harder and harder.
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A new pickup has to be the next step.
This goes against a lot of advice but having made the diagnosis... why not try tweaking the laser power to see if the level comes up and what the new current is.
Final thought on the scope measurements. Are you using a divider probe (you should) to minimise loading on the signal. At these frequencies the capacitance of the scope/leads is a major factor.
No need for a cable if the old one is undamaged.
This goes against a lot of advice but having made the diagnosis... why not try tweaking the laser power to see if the level comes up and what the new current is.
Final thought on the scope measurements. Are you using a divider probe (you should) to minimise loading on the signal. At these frequencies the capacitance of the scope/leads is a major factor.
No need for a cable if the old one is undamaged.
I admit, I was thinking the same - boosting the power and see if it helps.
I'm using a divider probe (1:1; 1:10) but set to 1:1. Next time I'll try 1:10.
Must be on divide by 10 really because that cuts the capacitance down from typically 20 to 30pf or more (scope + lead) to around 3 to 5pf. Its very "test point dependent" how much difference it makes but on some players it can be very significant.
I've boosted the current gradually up to 54,5mA (1,2V), It didn't help. I'm still not able to get it to recognize a CD.
Strange thing - the current rises, when turning the pot anticlockwise, I expected it the other way.
Strange thing - the current rises, when turning the pot anticlockwise, I expected it the other way.
I guess you have to try a new pickup next. Internal adjustment pots often work the "wrong way" round. Maybe it suits the PCB design better.
I've ordered a new pickup.
If it doesn't solve the problem, at least I have a spare one for my Yamaha CD player 😉
If it doesn't solve the problem, at least I have a spare one for my Yamaha CD player 😉
I can't see what else it could be tbh.
The low RF is the big diagnostic clue. If your measuring at the correct place (with the 10:1 probe🙂) and its low then the pickup is prime suspect. Lets hope its a fix.
The low RF is the big diagnostic clue. If your measuring at the correct place (with the 10:1 probe🙂) and its low then the pickup is prime suspect. Lets hope its a fix.
Yes, I'm hoping too, because I'm out of ideas, what else could it be.
The test point is labelled RF, so I think it's the correct one 😛
If I would be able to get the player to recognize a CD, I would repeat the measurement with a 10:1 probe ...
The test point is labelled RF, so I think it's the correct one 😛
If I would be able to get the player to recognize a CD, I would repeat the measurement with a 10:1 probe ...
RF test point sounds good 🙂
There isn't much else really. A problem with the RF amp but I've never ever heard of that or come across anything like that... small signal electronics are supremely reliable as a rule. A problem with the focus bias... but you were able to adjust that "normally" in that I assume the best level was achievable without the pot being one-ended.
You have to go with the pickup being faulty.
There isn't much else really. A problem with the RF amp but I've never ever heard of that or come across anything like that... small signal electronics are supremely reliable as a rule. A problem with the focus bias... but you were able to adjust that "normally" in that I assume the best level was achievable without the pot being one-ended.
You have to go with the pickup being faulty.
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