Picked up a 1990 CD player. Noticed the audio sounds slightly distorted on loud passages. Almost like the output was too high. I started poking around and found a transistor getting very hot when the cd is playing. It doesn't get hot when not playing the cd. The part # on the pcb is TR103. The transistor beside it (tr 104) seems fine. Any ideas? I don't have the schematic.
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Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
It's likely those are spindle motor drive the transistors are for.
The CXA1182 IC drives many transistors in a bridge. The pairs drive the spindle servo, sled motor, tracking coil and focus coil. So four pairs.
Check the power supply voltages. Voltage regs IC501, IC502 look like they've been replaced. Guessing +/-12V from them.
Or the spindle motor is drawing too much current, the brushes do wear out.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
Originally posted by redwire View PostIt's likely those are spindle motor drive the transistors are for.
The CXA1182 IC drives many transistors in a bridge. The pairs drive the spindle servo, sled motor, tracking coil and focus coil. So four pairs.
Check the power supply voltages. Voltage regs IC501, IC502 look like they've been replaced. Guessing +/-12V from them.
Or the spindle motor is drawing too much current, the brushes do wear out.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
Originally posted by petehall347 View Postsee if a resistor is connected to the emitter .then calculate the current . then see what it connects to and see what current it should draw normally .
these things are impossible for me without a schematic .
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
That transistor is likely focus drive output, (try cleaning the lens) You say the transistor is getting hot but that is likely normal. TR107 seems to have a poor connection on its collector (resolder it) If you don't have a scope it might be hard to troubleshoot the problem.
If the problem seems to be with loud passages, its likely once the signal gets converted to analog.Last edited by R_J; 01-19-2021, 10:57 AM.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
Originally posted by R_J View PostThat transistor is likely focus drive output, (try cleaning the lens) You say the transistor is getting hot but that is likely normal. TR107 seems to have a poor connection on its collector (resolder it) If you don't have a scope it might be hard to troubleshoot the problem.
If the problem seems to be with loud passages, its likely once the signal gets converted to analog.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
TR103 & TR104 are the focus drive transistors, TR103 collector connects to +10vdc, TR104 collector connects to -10vdc, Check that the + & - voltages are correct. (check when the cd is operating)
Have you tried using the head phone jack to see if the audio is the same?Last edited by R_J; 01-19-2021, 11:45 AM.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
Originally posted by R_J View PostTR103 & TR104 are the focus drive transistors, TR103 collector connects to +10vdc, TR104 collector connects to -10vdc, Check that the + & - voltages are correct.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
Originally posted by JimBanville View PostThanks! Will do. So does it stand to reason that they should be the same operating temp? One is super hot. The other is just warm.
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Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER
Originally posted by R_J View PostThat transistor is likely focus drive output, (try cleaning the lens) You say the transistor is getting hot but that is likely normal. TR107 seems to have a poor connection on its collector (resolder it) If you don't have a scope it might be hard to troubleshoot the problem.
If the problem seems to be with loud passages, its likely once the signal gets converted to analog.
So that apparently a "fault" and isn't responsible for the distortion. Anyway, I reflowed the solder on several spots on both decks (since I had them open). I'll continue to investigate the distortion. I'll try it with another amp/speaker setup. Thanks!!
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