A strange test for you to do...
does the crackling change in any way whatsoever if you hold the player at an angle or (if the Philips mech allows this without catching/scraping the disc), if the player is help upside down.
Ue an old CD so it doesn't mater if the disc gets marked.
does the crackling change in any way whatsoever if you hold the player at an angle or (if the Philips mech allows this without catching/scraping the disc), if the player is help upside down.
Ue an old CD so it doesn't mater if the disc gets marked.
cheers - will check out this morning - that is both the DAC relay and the 'holding at an angle test'
What will the latter tell me?
What will the latter tell me?
Jon, no clicking from the DAC relay
Mooly, no change when I move the player around (can only get it to about 30 deg from horizontal before it catches the disc)
Any other ideas - I noticed that the flat flexible circuit board tail from the mechanism flexible pcb that goes into a white connector is not that tight but I cannot see that being affected as the player gets warm - surely if it is a problem it would show fron the start
I felt as many caps as i could and they were all cold to touch. the chips TDA1541A and SAA7220P were both hot to touch - assume this is normal
Mooly, no change when I move the player around (can only get it to about 30 deg from horizontal before it catches the disc)
Any other ideas - I noticed that the flat flexible circuit board tail from the mechanism flexible pcb that goes into a white connector is not that tight but I cannot see that being affected as the player gets warm - surely if it is a problem it would show fron the start
I felt as many caps as i could and they were all cold to touch. the chips TDA1541A and SAA7220P were both hot to touch - assume this is normal
I noticed this when looking at the boards
Its a 6800uf 16V cap
does this look like electrolyte leakage? I don't know what part of the circuit its on
Also is it worth just changing the relay (if I can find one) to isolate that as an issue.
Is there a way of bypassing the mute section (I read that this might work on the 5 but will it also work on the earlier Plus)?
Its a 6800uf 16V cap
does this look like electrolyte leakage? I don't know what part of the circuit its on
Also is it worth just changing the relay (if I can find one) to isolate that as an issue.
Is there a way of bypassing the mute section (I read that this might work on the 5 but will it also work on the earlier Plus)?
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The gunge could be glue of some sort and there looks to be a strand "up" the cap. If in doubt and to be sure then take the cap out and look. Glue was common practice in all sorts of kit.
Next test... you say the player gets better as it warms ?
With it working and warm, very very very carefully try and "slow" the disc with your finger. Philips players tend not to lose lock when you do this but you do get and hear audible "drop out" as the error correction starts workin overtime. You can try lightly touching the edge of the spinning CD or the centre.
If you can do this is the noise like the original problem when it's cold ? I still think this is a signal/pickup issue really.
Muting relays can just be shorted out to prove. Being mechanical they can not physically cut in and out very quickly but if you suspect a fault then link it out. Unlikely for both channels to be duff though if a relay were faulty.
Next test... you say the player gets better as it warms ?
With it working and warm, very very very carefully try and "slow" the disc with your finger. Philips players tend not to lose lock when you do this but you do get and hear audible "drop out" as the error correction starts workin overtime. You can try lightly touching the edge of the spinning CD or the centre.
If you can do this is the noise like the original problem when it's cold ? I still think this is a signal/pickup issue really.
Muting relays can just be shorted out to prove. Being mechanical they can not physically cut in and out very quickly but if you suspect a fault then link it out. Unlikely for both channels to be duff though if a relay were faulty.
Mooly
I thought I had said that it gets worse when warm. From no use it will play two or three tracks then start with a quiet crackling in the background then slowly over one or two tracks til the crackling is louder than the music. So I believe it is something failing by getting too hot
cheers
Sorry, my mistake...
from cold then, if you touch the CD to slow it, does the noise you may get seem like the noise when it is warm ?
What I am trying to get at with these "odd" tests is that the noise you get when the player is on the verge of losing the signal is very distinctive. That can occur if the laser is low emission but you also get a similar sound if you slow the disc a fraction.
I know you have changed the 33uF cap. It's a long time since I have worked on these but I remember there were a lot of variations in production to the PCB under the laser to accomodate different motor types and so on. Can we be sure the correct cap has been changed.
Although it may well be an IC or transistor failing they are way down the list of suspects.
That said I seem to remember hearing of failure of the current regulator pass transistor for the laser diode on more than one occasion.
Another test that would be really worthwhile is monitoring the laser current as it warms up by rigging a DVM up across the resistor feeding the laser. You would need a circuit though and also solder test wires so as not to risk damaging the laser through "spiking" it with test leads.
Freezer spray is an option to drip (not blast) on suspect components.
I know you have changed the 33uF cap. It's a long time since I have worked on these but I remember there were a lot of variations in production to the PCB under the laser to accomodate different motor types and so on. Can we be sure the correct cap has been changed.
Although it may well be an IC or transistor failing they are way down the list of suspects.
That said I seem to remember hearing of failure of the current regulator pass transistor for the laser diode on more than one occasion.
Another test that would be really worthwhile is monitoring the laser current as it warms up by rigging a DVM up across the resistor feeding the laser. You would need a circuit though and also solder test wires so as not to risk damaging the laser through "spiking" it with test leads.
Freezer spray is an option to drip (not blast) on suspect components.
Really appreciate your suggestions
I will try the 'slowing down' test and then see if freeze drips make any difference
Where is the current regulator pass transistor for the laser diode located?
I will double check which cap I replaced but I used the earlier post as a guide - 'a 33uf 16v cap exists and is marked as 2532 on the copper surface. Right in between two yellow 220nf film caps'
Thanks for all comments and advice so far.....
I will try the 'slowing down' test and then see if freeze drips make any difference
Where is the current regulator pass transistor for the laser diode located?
I will double check which cap I replaced but I used the earlier post as a guide - 'a 33uf 16v cap exists and is marked as 2532 on the copper surface. Right in between two yellow 220nf film caps'
Thanks for all comments and advice so far.....
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I would have to dig a circuit out to identify the pass transistor.
Try the slowing down and if you have freezer spray handy then of course give it a go on any suspect parts. You have to just use a little and really just drip it on the part/s
Try the slowing down and if you have freezer spray handy then of course give it a go on any suspect parts. You have to just use a little and really just drip it on the part/s
This is the only circuit I have and it will be different to yours but you can see the 33uF cap and the transistor marked 6108. The 18 ohm resistor (3104) can be used to monitor the volt drop across it and therefore laser current calculated. The absolute value is an unknown and varies laser to laser and with temperature of laser diode but it should be fairly constant I would say.
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I had a similar issue with my cdp (cdm2) this week, crackling, as well as skipping and sometimes not reading disks at all. I did all the cap replacements on the transport PCB, rewired the connecting cables and replaced the cap (pictured earlier) as well as another 47uf cap on the same rail, all to no avail.
In the end I dropped the motor pcb off the bottom of the transport, it's held in place with a clamp. The spindle sits in the clamp on a bearing and this had completely dried out, a little drop of oil in there fixed all my problems!
I don't know if it helps but it's a 2 minute job to find out!
In the end I dropped the motor pcb off the bottom of the transport, it's held in place with a clamp. The spindle sits in the clamp on a bearing and this had completely dried out, a little drop of oil in there fixed all my problems!
I don't know if it helps but it's a 2 minute job to find out!
Mooly,
no impact in slowing down ...running player until warm to see if I can freeze the dac and learn something there
OK, here's an update
Ran the player tonight it took about 7 tracks to start crackling very lightly mainly from right speaker. After three more tracks the crackling got worse, but nowhere near what it was before 😕 I fiddled with all the amp input, volume and balance controls just in case but they made no difference which confirmed again it was the player.
So I then sprayed a tiny nit of freezer spray on to the TDA1541A chip and hey presto the crackling stopped!
I am now leaving the player running to see if I can repeat these steps!
OK with a bit of worry before I ask this question - does this mean the DAC chip has had it?
Ran the player tonight it took about 7 tracks to start crackling very lightly mainly from right speaker. After three more tracks the crackling got worse, but nowhere near what it was before 😕 I fiddled with all the amp input, volume and balance controls just in case but they made no difference which confirmed again it was the player.
So I then sprayed a tiny nit of freezer spray on to the TDA1541A chip and hey presto the crackling stopped!
I am now leaving the player running to see if I can repeat these steps!
OK with a bit of worry before I ask this question - does this mean the DAC chip has had it?
That's brilliant, sounds like you might have cracked it.
Cooling a good chip should not affect it. Try and confirm it and just drip a little freezer on the centre of the chip trying not to cool any other parts.
You can also use a fully heated hot soldering iron bit to place on the chip for a few seconds to see if the fault occurs. That's a recognised method too 🙂 It won't melt the IC. Remember an iron could be earthed so don't touch the tip on any live parts.
Cooling a good chip should not affect it. Try and confirm it and just drip a little freezer on the centre of the chip trying not to cool any other parts.
You can also use a fully heated hot soldering iron bit to place on the chip for a few seconds to see if the fault occurs. That's a recognised method too 🙂 It won't melt the IC. Remember an iron could be earthed so don't touch the tip on any live parts.
Well, if it did help it's not really a fix lol. It might work but it's not the answer 🙂
I'm surprised but really pleased you have found this... my money was on a signal problem. Guess you need a scrapper now as a donor.
I'm surprised but really pleased you have found this... my money was on a signal problem. Guess you need a scrapper now as a donor.
Just covering all bases now. Here's the data sheet for the TDA1541. Check (carefully, no twitchy fingers as that could spell disaster) all the supply voltages to it hot and cold.
If any were high the IC could be overheating. Very very unlikely but lets be sure.
http://www.datasheetcatalog.org/datasheet/philips/TDA1541A.pdf
If any were high the IC could be overheating. Very very unlikely but lets be sure.
http://www.datasheetcatalog.org/datasheet/philips/TDA1541A.pdf
Is there anything else I can check to confirm its the DAC chip or not - apart from the voltage checks in your last post
I am pretty sure its that as dropping some freezer spray on the chip stopped the crackling immediately BUT before that the crackling was more on the RH speaker than the LH speaker
I assume the chips alone are not readily available so a doner is needed
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Can you get hold of an external DAC? If that works then it eliminates the transport. There was a post recently detailing a distorting 1541 due to a failed PSU decoupling cap, one of three electrolytic caps closest to the TDA, but I don't see how this would affect one channel more than another. The other candidate is the filter (SAA7220?) but it's probably far enough away from the DAC to not be affected by the freezer spray. I'd try an external DAC first.
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