Hi,
I have been working on improving a Philips CD730 (similar to CD920/910). Added spdif out and updated the usual caps.
The unit was working fine but now suddenly only outputs digital noise/garbage on both analog and spif out. I checked voltages to all ic's and opamps and no problem there. Even swapped the opamps (which i placed on sockets) but no change.
Is there anything obvious i am not seeing as a problem now?
Wouter
I have been working on improving a Philips CD730 (similar to CD920/910). Added spdif out and updated the usual caps.
The unit was working fine but now suddenly only outputs digital noise/garbage on both analog and spif out. I checked voltages to all ic's and opamps and no problem there. Even swapped the opamps (which i placed on sockets) but no change.
Is there anything obvious i am not seeing as a problem now?
Wouter
Hi Wouter,
It sounds like the DAC is receiving garbage or lost one signal. You did something by mistake somewhere, but in a section of the circuit you shouldn't be working in. Also, depending on your soldering iron / station, AC leakage may have travelled through to a sensitive point and caused damage. Or worse, if the circuit was powered up and you hit a supply rail with a grounded tip, you may have damaged stuff in areas where you weren't working.
Sockets for op amps. No! Sockets add capacitance to the connections and between pins. There are a few great op amps out there, and even the older ones perform better than can be tested in relation to the DAC. Select a good audio op amp and simply use that. Solder it and be done with it. Do not grab "the best" as people recommending them don't understand stability. The fast ones may oscillate or ring badly. That means you have to compensate the circuit for each different PCB layout. Most times you can't hear the difference between good modern op amps unless you picked one not suited to the circuit.
Electronics is neat stuff. You can't see what is going on. This also means you can kill things without even trying. Swapping op amps and capacitors seems easy and a no brainer. Well, it's what you don't know or understand that will get you. Not only that, but an engineer is needed to select the right part. There is too much to know, but if you don't know it seems easy ... right?
If you like that CD player I would suggest you get it to a good electronics technician, someone who works in audio (not computers or video). You problem shouldn't be in the filter or buffer sections. You have a digital problem.
-Chris
It sounds like the DAC is receiving garbage or lost one signal. You did something by mistake somewhere, but in a section of the circuit you shouldn't be working in. Also, depending on your soldering iron / station, AC leakage may have travelled through to a sensitive point and caused damage. Or worse, if the circuit was powered up and you hit a supply rail with a grounded tip, you may have damaged stuff in areas where you weren't working.
Sockets for op amps. No! Sockets add capacitance to the connections and between pins. There are a few great op amps out there, and even the older ones perform better than can be tested in relation to the DAC. Select a good audio op amp and simply use that. Solder it and be done with it. Do not grab "the best" as people recommending them don't understand stability. The fast ones may oscillate or ring badly. That means you have to compensate the circuit for each different PCB layout. Most times you can't hear the difference between good modern op amps unless you picked one not suited to the circuit.
Electronics is neat stuff. You can't see what is going on. This also means you can kill things without even trying. Swapping op amps and capacitors seems easy and a no brainer. Well, it's what you don't know or understand that will get you. Not only that, but an engineer is needed to select the right part. There is too much to know, but if you don't know it seems easy ... right?
If you like that CD player I would suggest you get it to a good electronics technician, someone who works in audio (not computers or video). You problem shouldn't be in the filter or buffer sections. You have a digital problem.
-Chris
I want to say that you must have screwed up somewhere.
failed solder, broken track, capacitor value error.
Everything requires method.
download the service manual and track your supply voltage from the transmitters to the consumers and you will certainly find your culprit, especially on such a simple but quite fragile pcb.
failed solder, broken track, capacitor value error.
Everything requires method.
download the service manual and track your supply voltage from the transmitters to the consumers and you will certainly find your culprit, especially on such a simple but quite fragile pcb.
Hi huggygood,
No offence, but your first line is blindingly obvious, yet put in a way that isn't too helpful. Something happened and it was not intentional. No need to assign blame.
The rest is pure speculation, again not very helpful at all. Wouter said he tested supply voltages. I already know they should be functioning from the description of the fault. However you need an oscilloscope to look at the quality of the power supplies. You need the same instrument to check the digital signals, plus be familiar with what to expect. I am - completely familiar with these circuits, but will not diagnose over the internet with a person not familiar enough. Too much to be misunderstood or go wrong.
"transmitters and consumers"? What kind of terminology is that? I know what you mean, but most would not. Yet the PCB is not simple, and it isn't extremely fragile compared to some I have seen.
Please don't post unless you have something truly constructive to add.
-Chris
No offence, but your first line is blindingly obvious, yet put in a way that isn't too helpful. Something happened and it was not intentional. No need to assign blame.
The rest is pure speculation, again not very helpful at all. Wouter said he tested supply voltages. I already know they should be functioning from the description of the fault. However you need an oscilloscope to look at the quality of the power supplies. You need the same instrument to check the digital signals, plus be familiar with what to expect. I am - completely familiar with these circuits, but will not diagnose over the internet with a person not familiar enough. Too much to be misunderstood or go wrong.
"transmitters and consumers"? What kind of terminology is that? I know what you mean, but most would not. Yet the PCB is not simple, and it isn't extremely fragile compared to some I have seen.
Please don't post unless you have something truly constructive to add.
-Chris
Sorry, I may have taken off a little too quickly.
I admit I'm a little tired of reading "blah blah optimization blah blah recapitulated blah blah it doesn't work anymore blah blah what should I do.
With my apologies again, I won't say anything more on this thread.
I admit I'm a little tired of reading "blah blah optimization blah blah recapitulated blah blah it doesn't work anymore blah blah what should I do.
With my apologies again, I won't say anything more on this thread.
Hi huggygood,
Thanks for the manual. Being lazy I added it to my collection as I didn't have to search for it.
Hi Wouter,
Anything from the DSP - memory - DAC can cause this problem. You're hearing data corruption. If it wasn't tracking you would also have problems reading the TOC or playing the disc. Of course, checking the HF pattern would be prudent.
Thanks for the manual. Being lazy I added it to my collection as I didn't have to search for it.
Hi Wouter,
Anything from the DSP - memory - DAC can cause this problem. You're hearing data corruption. If it wasn't tracking you would also have problems reading the TOC or playing the disc. Of course, checking the HF pattern would be prudent.
well thanks for the help... nice comments. I think somewhere a trace got broken, these players are very sensitive i have come to learn. so yeah i am not STUPID and know something was screwed, just asking for something common that someone has come to learn and not the partially discouraging replies that were given, go take your own problems out on someone else. thanks
Hi Wouter,
I was just thinking, these machines are famous for problems between top and bottom board connections. I didn't think you broke something, but just moving the PCB can cause this.
Try removing the PCB. Remove the solder from all links between the top and bottom of the PCB, add a touch of solder flux (liquid electronic type) and use some good 60/40 (normal) solder to resolder these connections on each side. Don't use too much solder, that will not improve the connection and only hide problems. Once you have done everything, reinstall and test. Look carefully as many top to bottom connections are hard to spot and often use a component lead, or what looks like a jumper wire. Take your time.
-Chris
I was just thinking, these machines are famous for problems between top and bottom board connections. I didn't think you broke something, but just moving the PCB can cause this.
Try removing the PCB. Remove the solder from all links between the top and bottom of the PCB, add a touch of solder flux (liquid electronic type) and use some good 60/40 (normal) solder to resolder these connections on each side. Don't use too much solder, that will not improve the connection and only hide problems. Once you have done everything, reinstall and test. Look carefully as many top to bottom connections are hard to spot and often use a component lead, or what looks like a jumper wire. Take your time.
-Chris
I have to motivate myself to go and look why and how.... Indeed you take the board out several times because you dont want to change too much at once, but that is working against you with these players because yeah moving something once too much or bending and stuff breaks... very frustrating. I do not make mistakes a lot, so i guess a broken trace indeed. Will put the DAC / RAM area under investigation plus these joints you mention. Thanks for the reply.
Hi Wouter,
My advice, I would give this to any tech working for me, in this case go brain dead and just do what I mentioned. The board comes out easily. Don't overthink it.
It failed and you were being careful by the sounds of it. It can happen to anyone and has to me. These days I resolder all that the first time the PCB comes out.
-Chris
My advice, I would give this to any tech working for me, in this case go brain dead and just do what I mentioned. The board comes out easily. Don't overthink it.
It failed and you were being careful by the sounds of it. It can happen to anyone and has to me. These days I resolder all that the first time the PCB comes out.
-Chris
Hi Wouter.
Nice machine! probably a transport mechanism & even the electronics made in Japan by Marantz (Philips laser diode tranport is not linear, but like a Vinyl turntable arm).
This may well be a tired laser diode PB, could be a pure coincidence. The laser diodes of this type of CD player were driven with quite a current and were aging due to the temperature
hence an automatic current control to ensure constant optimal exposure over time.
But there is a limit above which the current compensation doesn't work anymore, the signal received by the detector is too weak, and very depending on the quality of the reflective layer of the CD itself. The digital electronic error correction system (Reed–Solomon error correction) can not compensate anymore neither.
Plus, all CDs are not equal... For instance a CD ROM type of CD has a very much lower reflective factor than a genuine factory pressed one and also this varies with the thickness and quality of the layer material. So the player could well work with some and not anymore with others.
In addition, the signal coming from the transport mechanism is a high impedance low level (current) signal, so any additional electrical noise like a digital cable near the CDM Flexfoil ( see manual - the flex attached to the transport mechanism going to the main board) will drastically degrade the signal quality.
And then,, the servo mechanism of a CD player also relies on the same laser diode, as the position/focus of the reading mechanism as well as the rotation speed are closed loop systems controlled by the optical info. (cross photodetectors for the focus + disc pattern tracking & frequency for the speed). Those guys who invented this were very clever, but this makes it very complex too!
So, having repaired quite a few CD payers of this generation, my first reflex would definitively be to check the eye-pattern like in page 22 TP 17 or even on R3044 to avoid probe impedance problems.
If it's fuzzy, then the diode could be the source of the PB ... Beware ! this component is extremely sensitive to static electricity! Don't touch with a probe or anything.
I which you success!
Cheers
N.
Nice machine! probably a transport mechanism & even the electronics made in Japan by Marantz (Philips laser diode tranport is not linear, but like a Vinyl turntable arm).
This may well be a tired laser diode PB, could be a pure coincidence. The laser diodes of this type of CD player were driven with quite a current and were aging due to the temperature
hence an automatic current control to ensure constant optimal exposure over time.
But there is a limit above which the current compensation doesn't work anymore, the signal received by the detector is too weak, and very depending on the quality of the reflective layer of the CD itself. The digital electronic error correction system (Reed–Solomon error correction) can not compensate anymore neither.
Plus, all CDs are not equal... For instance a CD ROM type of CD has a very much lower reflective factor than a genuine factory pressed one and also this varies with the thickness and quality of the layer material. So the player could well work with some and not anymore with others.
In addition, the signal coming from the transport mechanism is a high impedance low level (current) signal, so any additional electrical noise like a digital cable near the CDM Flexfoil ( see manual - the flex attached to the transport mechanism going to the main board) will drastically degrade the signal quality.
And then,, the servo mechanism of a CD player also relies on the same laser diode, as the position/focus of the reading mechanism as well as the rotation speed are closed loop systems controlled by the optical info. (cross photodetectors for the focus + disc pattern tracking & frequency for the speed). Those guys who invented this were very clever, but this makes it very complex too!
So, having repaired quite a few CD payers of this generation, my first reflex would definitively be to check the eye-pattern like in page 22 TP 17 or even on R3044 to avoid probe impedance problems.
If it's fuzzy, then the diode could be the source of the PB ... Beware ! this component is extremely sensitive to static electricity! Don't touch with a probe or anything.
I which you success!
Cheers
N.
Hi NobuAk,
Did you read the first post carefully?
The unit appears to track correctly and did beforehand. What does that tell you?
-Chris
Did you read the first post carefully?
The unit appears to track correctly and did beforehand. What does that tell you?
-Chris
I pulled these two pages from the service manual.
the first gives an idea of the topology
the second allows you to go directly to check the values according to the problem encountered.
I promised to shut up but if I can help
the first gives an idea of the topology
the second allows you to go directly to check the values according to the problem encountered.
I promised to shut up but if I can help
Hi Chris,
yes I did. I was just mentioning the tracking/focus potential pb that would lead to 'fuzzy' eye-pattern without causing real lost of tracking as this is based on 'averaged' signals for the control rather that fine high frequencies discrimination as used for audio decoding. The controls are much less sensitive to noise or degraded signals. For instance a durty/scatched disc may skip and still play with some drop-outs/jumps...
Coming back to the first point, I'd suspect bad HF/RF (reading photo-diode) signal. This could also be caused by a bad offset in the mechanism control/servo system (either diode focus or tracking , as well as the so called E-F balance (symetry of the RF signal), &/ or PLL-center frequency adjustments).
Replacing all op-amps may also have been for the ones (if any) in the control/servo system... the parameters are then possibly altered and the control loops do not work propwrly or the PLL is unstable.
But not having the machine in front of my oscilloscope...
Cheers,
N.
Right.
Definitely replacing servo op amps could cause real instability, but people should know better. That is so obvious! The OP seemed to be on an audio upgrade only.
I do not believe there is any problem with the laser diode. Servo issues may make reading the TOC problematic, and skipping tracks will really show off servo issues.
Definitely replacing servo op amps could cause real instability, but people should know better. That is so obvious! The OP seemed to be on an audio upgrade only.
I do not believe there is any problem with the laser diode. Servo issues may make reading the TOC problematic, and skipping tracks will really show off servo issues.