Hey,
I have a PDH500C Teac CD player and recently the problem occured that only if the amplifier is nearly on max volume the sound of the CD-player is heard including some cracking / noise on the output. Trying a new RCA cable did not help. All other devices operate without problems, also on the CD-channel of the amplifier. I'm not all an audio expert, but interessted in electronics and I can handle a soldering iron pretty well.
After quite a few hours searching various forums, I opened the player and cleaned the circuit boards and contacts. Although there was some oxidation here and there it unfortunately was not the solution. After some further reading I learned these kinds of problems often caused by a faulty dac. My player uses the PCM69AP and SM5841AP, of which (if I understand it correctly) the first is the DAC and the second is a digital filter.
Through Ebay I ordered the PCM69AP and replaced the original chip for a new one. Unfortunately, the problem is still the same. The SM5841AP was quite difficult to find, but I did find one and ordered it. Part is on his way..
Now, I realize my way of working is more like trial and error instead of actually knowing what is wrong with the player, so I hope there is someone here who can help me out ..
Is it possible that my problem is caused by a faulty digital filter or not at all? Yesterday I found out that another chip on the PCB, TA2092N, a bridge to supply power to various components, gets realy hot within a minute of operation. A little heat would not have surprised me but that soon and that hot? I thought the voltage differences wheren't that big but maybe I'm wrong..
Bottom line, I hope there is anyone here who is a real expert on stuff like this and is willing to put me on the right track.
Thanks in advance!
Bram
I have a PDH500C Teac CD player and recently the problem occured that only if the amplifier is nearly on max volume the sound of the CD-player is heard including some cracking / noise on the output. Trying a new RCA cable did not help. All other devices operate without problems, also on the CD-channel of the amplifier. I'm not all an audio expert, but interessted in electronics and I can handle a soldering iron pretty well.
After quite a few hours searching various forums, I opened the player and cleaned the circuit boards and contacts. Although there was some oxidation here and there it unfortunately was not the solution. After some further reading I learned these kinds of problems often caused by a faulty dac. My player uses the PCM69AP and SM5841AP, of which (if I understand it correctly) the first is the DAC and the second is a digital filter.
Through Ebay I ordered the PCM69AP and replaced the original chip for a new one. Unfortunately, the problem is still the same. The SM5841AP was quite difficult to find, but I did find one and ordered it. Part is on his way..
Now, I realize my way of working is more like trial and error instead of actually knowing what is wrong with the player, so I hope there is someone here who can help me out ..
Is it possible that my problem is caused by a faulty digital filter or not at all? Yesterday I found out that another chip on the PCB, TA2092N, a bridge to supply power to various components, gets realy hot within a minute of operation. A little heat would not have surprised me but that soon and that hot? I thought the voltage differences wheren't that big but maybe I'm wrong..
Bottom line, I hope there is anyone here who is a real expert on stuff like this and is willing to put me on the right track.
Thanks in advance!
Bram
I'm sorry to bump this old topic but I'm having the same problem and would like to know if you managed to solve it?
Manual here........
TEAC PD-H500 - Manual - Stereo Compact Disc Player - HiFi Engine
I'd start with checking the Muting Transistors and associated Power Supplies.
P.
TEAC PD-H500 - Manual - Stereo Compact Disc Player - HiFi Engine
I'd start with checking the Muting Transistors and associated Power Supplies.
P.
Last page (17) of the Manual (C Version) circuit at bottom left.
Q's 102 and 103 are the actual muting Transistors. Q's 104 and 105 are the Muting Drive Transistors.
Q's 102 and 103 will normally be made fully OFF with the -ve 15V. A Logic 'High' at the base of Q105, turning it ON will cause Q 104 to conduct making its Collector go Positive, applying a Positive feed to the Bases of Q's 102 & 103 turning them ON, putting a Short-Circuit (almost) across the O/P.
I would start with Q's 102 and 103.
Q 106 looks like it might be a Power ON Mute which should Mute the O/P at Power ON, then after a small delay, turn the Mute OFF. The delay set by the time constant of R 164 and C 186.
If Q's 102 & 103 are OK, check this little circuit. It could have failed causing permanent Mute.
If all above OK, you'll have to start 'scoping the O/P of the DAC (or after the first OP Amp) to see where the Signal disappears.
P.
Q's 102 and 103 are the actual muting Transistors. Q's 104 and 105 are the Muting Drive Transistors.
Q's 102 and 103 will normally be made fully OFF with the -ve 15V. A Logic 'High' at the base of Q105, turning it ON will cause Q 104 to conduct making its Collector go Positive, applying a Positive feed to the Bases of Q's 102 & 103 turning them ON, putting a Short-Circuit (almost) across the O/P.
I would start with Q's 102 and 103.
Q 106 looks like it might be a Power ON Mute which should Mute the O/P at Power ON, then after a small delay, turn the Mute OFF. The delay set by the time constant of R 164 and C 186.
If Q's 102 & 103 are OK, check this little circuit. It could have failed causing permanent Mute.
If all above OK, you'll have to start 'scoping the O/P of the DAC (or after the first OP Amp) to see where the Signal disappears.
P.
Q102 and Q103 seems to be okay but I think you nailed it with the Q106 as it conductive both ways when measured between the B and E.
I'll replace it and post the results.
Thank you
I'll replace it and post the results.
Thank you
Btw...how can I bypass Q106 to test if beside it everything else is okay?
Is there any known direct replacement for the Q106 (KSA1175YTA) transistor?
Thanks again, your help is much appreciated.
Is there any known direct replacement for the Q106 (KSA1175YTA) transistor?
Thanks again, your help is much appreciated.
Great !
Looking at the circuit again, I'm not certain I have described correctly how it works but still, if faulty will cause a permanent Mute condition. And if you've found Q 106 to be B/E Short then cool ! Swap it out and see.......!
Do post your results.
Cheers,
P.
Looking at the circuit again, I'm not certain I have described correctly how it works but still, if faulty will cause a permanent Mute condition. And if you've found Q 106 to be B/E Short then cool ! Swap it out and see.......!
Do post your results.
Cheers,
P.
I think you could just remove it. You may loose the Power ON Mute so turn the Player on with your Amp Volume on Zero and all should be OK.
P.
P.
Q 106 on that Sub Assy (Not the Main CD PCB) is a ?SA933S.
Any chance of a Pic or what does it say on it?
Could be a KSA933 (Can't find any info on-line about this) or a 2SA933 which seems to be a 100mA PNP Transistor.
P.
Any chance of a Pic or what does it say on it?
Could be a KSA933 (Can't find any info on-line about this) or a 2SA933 which seems to be a 100mA PNP Transistor.
P.
You are a legend !!!
I removed Q106 and it's working perfectly.
Any suggestion on a replacement for this transistor?
I removed Q106 and it's working perfectly.
Any suggestion on a replacement for this transistor?
I know the Manual says KSA1175 but I think the 2SA1175 will do, if it isn't the same thing (?)
2SA1175 pdf, 2SA1175 description, 2SA1175 datasheets, 2SA1175 view ::: ALLDATASHEET :::
Littlediode in the UK sell them (no affiliation to the company other than as a satisfied customer)...........
LittleDiode – Electronic Components for All
or of course there's ebay..........
2sa1175 | eBay
Cheers,
P.
2SA1175 pdf, 2SA1175 description, 2SA1175 datasheets, 2SA1175 view ::: ALLDATASHEET :::
Littlediode in the UK sell them (no affiliation to the company other than as a satisfied customer)...........
LittleDiode – Electronic Components for All
or of course there's ebay..........
2sa1175 | eBay
Cheers,
P.
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