First check that the DC voltages coming out of the DAC are correct and compare to the good channel. The two differential feeds should have the same voltage on them with the manual showing +1.4 volts
If those voltages are different between themselves then you will get a DC offset at the first opamp output. The opamp would really be the last suspect imo (although it can happen), more likely a DAC fault or a break in the print. I don't think any of those small caps could give those voltages even if one was failed short circuit.
And by 'different' I mean if one output is say +1.4 and the other is say -1 then you would get -3.4 at pin #1
If those voltages are different between themselves then you will get a DC offset at the first opamp output. The opamp would really be the last suspect imo (although it can happen), more likely a DAC fault or a break in the print. I don't think any of those small caps could give those voltages even if one was failed short circuit.
And by 'different' I mean if one output is say +1.4 and the other is say -1 then you would get -3.4 at pin #1
Measuring the op-amp inputs on pin2 and 3 i get 1,45V on right and 1,44V for the left channel.
Directly at the DAC output RO and RON, both measure 2,5V as does LON. LO output is at 5,0V though.
Directly at the DAC output RO and RON, both measure 2,5V as does LON. LO output is at 5,0V though.
If you measure the voltage drop over R613 and R615 this may give some hint. Even as IC failure is quite unususal, if this is too high it may point to the opamp being the problem.
Use the extremely convenient fact that one side is working OK. Just comparing left and right should making fault finding quite simple.
Use the extremely convenient fact that one side is working OK. Just comparing left and right should making fault finding quite simple.
That suggests the DAC is at fault to me. Make sure continuity is OK from the DAC outputs to the resistors feeding the opamp input.
If you lift the end of both RD21 and RD23 and tag them to the good right channel you should be able to prove that the opamp section is OK. You are then running both channels from the good DAC output.
I went with Mooly's suggestion and lifted RD21 and RD23 from the left DAC side and tacked them onto the right.
Now i have even level at the output terminals. Seems like the left side op amp stage is OK.
It's late now, i will continue tomorrow ( maybe re-flow the DAC joints ? )
Now i have even level at the output terminals. Seems like the left side op amp stage is OK.
It's late now, i will continue tomorrow ( maybe re-flow the DAC joints ? )
Interesting. Has the player a hidden history or is it one of yours that has just failed in use?
Worth just checking there are no shorts between the DAC output pins and the adjoining pins... looking like the DAC though I suspect 🙁
Worth just checking there are no shorts between the DAC output pins and the adjoining pins... looking like the DAC though I suspect 🙁
A relative gave me the player since it was skipping, which was caused by hardened grease.
He owned the player since new, but it sat unused for 1-2 years.
I fixed the skipping by cleaning and re-greasing. During the test run i noticed the channel imbalance.
I undid the test links from yesterday, soldered the left channel back to its corresponding DAC outputs and re-flowed all DAC legs and the surrounding parts. Well, that also broke the right channel 🙁
Both channels are equally low now, sound comes out though. Voltages in the op amp stage are all wrong now.
I checked the DAC outputs with the scope. RO and LON seem to work, but RON and LO don't work at all. Output does not look like in the service manual, just low level noise.
Maybe i can source a replacement board.
He owned the player since new, but it sat unused for 1-2 years.
I fixed the skipping by cleaning and re-greasing. During the test run i noticed the channel imbalance.
I undid the test links from yesterday, soldered the left channel back to its corresponding DAC outputs and re-flowed all DAC legs and the surrounding parts. Well, that also broke the right channel 🙁
Both channels are equally low now, sound comes out though. Voltages in the op amp stage are all wrong now.
I checked the DAC outputs with the scope. RO and LON seem to work, but RON and LO don't work at all. Output does not look like in the service manual, just low level noise.
Maybe i can source a replacement board.
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That all sounds very strange. Are you working (when soldering) with the player player totally unplugged from everything and that your soldering iron is correctly grounded. Just wondering if leakage or static from the iron is zapping the DAC.
Also just recheck your work for any obvious errors or solder blobs.
Also just recheck your work for any obvious errors or solder blobs.
So you didn't bother with my sugestion lifting one resistor now you have folk telling you to pull the DAC!!
Hi hotiron,
All he did was feed the decimation filter from a known good source. The left then was operating as it should.
It appears the DAC has an issue, so I would resolder the connections first. If the issues continue I would replace the DAC chip. The troubleshooting is solid. Mooly is an experienced tech, and he knows what he is doing.
All he did was feed the decimation filter from a known good source. The left then was operating as it should.
It appears the DAC has an issue, so I would resolder the connections first. If the issues continue I would replace the DAC chip. The troubleshooting is solid. Mooly is an experienced tech, and he knows what he is doing.
Absolutely nothing wrong with complicating matters.
Shadowlord initially said there was no offset at the inputs.
Which would lead me to believe something is pulling the output in the wrong direction.
Differential amp at the input inverting amp on the output.
Pulling said resistor would have confirmed where the offset was.
Ancient retired Tech at your service.
Shadowlord initially said there was no offset at the inputs.
Which would lead me to believe something is pulling the output in the wrong direction.
Differential amp at the input inverting amp on the output.
Pulling said resistor would have confirmed where the offset was.
Ancient retired Tech at your service.
Fair enough, but pulling R605 would only check if the second op amp stage was okay, that stage is inverting (which it was doing). Most likely working okay in that case. I understand you were trying to "half split" in troubleshooting. The question was really the first section of the op amp, or the input signal to that stage. That is what Mooly checked.
I will say it is very rare for a DSP/digital filter to go bad that way. I have seen more bad op amps than these chips.
lol!
"Should be retired tech" at your service.
I will say it is very rare for a DSP/digital filter to go bad that way. I have seen more bad op amps than these chips.
lol!
"Should be retired tech" at your service.
Aye well I was only trying to help.
Now the Shadowlord has likely destroyed His player!
As he initially said there was no offset at the input!!
So let's go straight to cancer and say the DAC is dead which it clearly is not.
Possibly the data stream is bad!?
Can Shadowlord check spdif output with an external DAC?
Then we can come closer to a fix..
Now the Shadowlord has likely destroyed His player!
As he initially said there was no offset at the input!!
So let's go straight to cancer and say the DAC is dead which it clearly is not.
Possibly the data stream is bad!?
Can Shadowlord check spdif output with an external DAC?
Then we can come closer to a fix..
We all are trying to help, all suggestions are welcome.
The DAC isn't totally dead, obviously. It may have a poor solder connection(s), it may in fact be defective at those output terminals. It could have been killed by static or current injection from a non-grounded soldering iron tip. There is always a risk of semiconductor death when non-trained people start poking around, we all know that.
Sometimes the input is more current than voltage, the output moves to make both inputs equal. Since there is feedback, input voltages at the IC don't always tell you everything. I suspect the op amp is fine. Mind you, the one input may have gone "funny", one of those odd faults you'll never see again. But the op amp was cleared completely by Mooly's test.
SPDIF will be fine in all probability, but a check wouldn't hurt. It is highly unlikely the data stream is bad. This would result in no sound at all or highly distorted sound (probably both channels). We had a non-distorted sine wave at approx 1/2 level. That looks more like one phase of the output drive is missing.
By the way, I'm the "should be retired tech". I should be lying on a beach somewhere.
The DAC isn't totally dead, obviously. It may have a poor solder connection(s), it may in fact be defective at those output terminals. It could have been killed by static or current injection from a non-grounded soldering iron tip. There is always a risk of semiconductor death when non-trained people start poking around, we all know that.
Sometimes the input is more current than voltage, the output moves to make both inputs equal. Since there is feedback, input voltages at the IC don't always tell you everything. I suspect the op amp is fine. Mind you, the one input may have gone "funny", one of those odd faults you'll never see again. But the op amp was cleared completely by Mooly's test.
SPDIF will be fine in all probability, but a check wouldn't hurt. It is highly unlikely the data stream is bad. This would result in no sound at all or highly distorted sound (probably both channels). We had a non-distorted sine wave at approx 1/2 level. That looks more like one phase of the output drive is missing.
By the way, I'm the "should be retired tech". I should be lying on a beach somewhere.
You should test the coax output. If it is still working, maybe just lift the resistors from the IC to opamp and close the hood.
I got a CD67 OSE, which sounded much better from the analog out with my Onkyo 818 AVR. Since I have a new Denon AVR, I must admitt there is no difference in sound, using the Marantz with it's own DAC or just the digital out. So maybe consider what you want to use it for. Most AVR and modern amps, by the way, digitalize analog CD player signal anyway.
Honestly I don't think you will be able to fix the analog stage with your tools, as you obviously did nothing good by "reflowing" the IC.
If you don't have a hot air station, special flux, solder (paste) and some kind of magnifying gear, working on this multi leg IC's is a sure path to desaster.
Replacing it will be expensive, time consuming and probably not successful.
Fixing a CD player is of questionable value. If you start to spend big on parts and postage for suspect defective components, you still don't get a new, reliable player.
IMO the most promising repair on such a player is to change the complete drive including laser. Combined with all new rubber belts, the unit will work for another decade if it was mostly used by the remote. If it was operated manualy, you can notice this on wear of the switches, so these may fail and make it useless soon. Or to say it in short: You basicaly need a plan. If you like to play around and don't mind wasting time and money, that is something else.
I repaired quite a number of CD players over the years, but only invest in units that can be put in mint condition. Often after a quick respray of the cover I may add, as these often look quite bad and completely devalue the player for "normal people". Some emery paper, a little spray can of primer and satin black do wonders... I'm satisfied when my wife get's angry, because she suspects "I bought some new, useless, expensive HIFI gear, again". not noticing it was used eBay junk, 29€ including P&P.
I got a CD67 OSE, which sounded much better from the analog out with my Onkyo 818 AVR. Since I have a new Denon AVR, I must admitt there is no difference in sound, using the Marantz with it's own DAC or just the digital out. So maybe consider what you want to use it for. Most AVR and modern amps, by the way, digitalize analog CD player signal anyway.
Honestly I don't think you will be able to fix the analog stage with your tools, as you obviously did nothing good by "reflowing" the IC.
If you don't have a hot air station, special flux, solder (paste) and some kind of magnifying gear, working on this multi leg IC's is a sure path to desaster.
Replacing it will be expensive, time consuming and probably not successful.
Fixing a CD player is of questionable value. If you start to spend big on parts and postage for suspect defective components, you still don't get a new, reliable player.
IMO the most promising repair on such a player is to change the complete drive including laser. Combined with all new rubber belts, the unit will work for another decade if it was mostly used by the remote. If it was operated manualy, you can notice this on wear of the switches, so these may fail and make it useless soon. Or to say it in short: You basicaly need a plan. If you like to play around and don't mind wasting time and money, that is something else.
I repaired quite a number of CD players over the years, but only invest in units that can be put in mint condition. Often after a quick respray of the cover I may add, as these often look quite bad and completely devalue the player for "normal people". Some emery paper, a little spray can of primer and satin black do wonders... I'm satisfied when my wife get's angry, because she suspects "I bought some new, useless, expensive HIFI gear, again". not noticing it was used eBay junk, 29€ including P&P.
Well, you can work with smt without a hot air station. It takes more skill and experience. That is how we started after all. Flux, absolutely required! Lead solder helps a lot too. 3 mm "screwdriver" tip on the station also helps.
I have some old CD players that sound better and work better than most new ones. Older transports had fewer read errors (watch the C1 and C2 flags that you can no longer access in modern machines). Some day I may direct the EFM signal in my Nakamichi OMS-7 into a more modern digital decoder and DAC (PCM1702 would be nice). That transport had the absolute best data recovery of any (OMS-5 is the same) of any player, ever. Worth doing? Absolutely!
Even the Denon DCD-S10 I have, with its toy Sony transport, performs way better than new machines.
I do share your lack of optimism for inexperienced folks successfully repairing a CD player. But, human nature means they will try. All you can do is help, or if you see it is for sure not going to happen, mention that fact.
I have some old CD players that sound better and work better than most new ones. Older transports had fewer read errors (watch the C1 and C2 flags that you can no longer access in modern machines). Some day I may direct the EFM signal in my Nakamichi OMS-7 into a more modern digital decoder and DAC (PCM1702 would be nice). That transport had the absolute best data recovery of any (OMS-5 is the same) of any player, ever. Worth doing? Absolutely!
Even the Denon DCD-S10 I have, with its toy Sony transport, performs way better than new machines.
I do share your lack of optimism for inexperienced folks successfully repairing a CD player. But, human nature means they will try. All you can do is help, or if you see it is for sure not going to happen, mention that fact.
Yes, lead solder is a must. Sometimes the only option to get that lead free gunk of a PCB is mixing it with a good leaded solder.
And, no, it is not forbidden to use it in a repair! So you can still buy it. You are only not allowed to build new things you want to sell with it.
And, no, it is not forbidden to use it in a repair! So you can still buy it. You are only not allowed to build new things you want to sell with it.
Yup, the higher temperatures you need to run at doesn't help PCBs and components either. Mixing in lead solder really helps.
Lead free is getting better. It still doesn't cut it. Solder is very expensive these days, 1 lb costs over $100 Canadian !!!!
Lead free is getting better. It still doesn't cut it. Solder is very expensive these days, 1 lb costs over $100 Canadian !!!!