Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER

[JimBanville]

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.

[petehall347]

Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER

see 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 .

[redwire]

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.

[JimBanville]

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.

Thanks! Will check that. Could the overheating transistor have something to do with the slightly noisy/distorted audio during peak levels or maybe it's just another issue?

[JimBanville]

Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER

see 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 .

Thanks! I'll post a pic of the bottom of that section of the pcb to show what it's connected to

[JimBanville]

Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER

Underside of the board ...

[JimBanville]

Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER

By the way. I have a DENON dcd-910. It may use the same transport. I'll look at it tonight to see if I can swap transports to troubleshoot.

[R_J]

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.

[JimBanville]

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.

Thanks! I'll check that. I did clean the lens earlier yesterday. Luckily, the transports in my dcd-610 and dcd-910 look interchangeable. I think I'll swap drives this evening to see if that affects the slightly distorted audio. Most of the main board in the 610 and 910 are the same as well. I'll check to see if that same transistor in the 910 is getting as hot as this one was. If so, I'll be looking if for another cause of the distortion. I do have a little $30 digital oscilloscope I picked up from Amazon. Haven't had time to start learning how to use it yet.

[R_J]

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?

[JimBanville]

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.

Thanks! 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.

[R_J]

Re: Distorted audio and HOT transistor - Denon DCD-610 CD PLAYER

Thanks! 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.

It would depend on where it is focusing, it is likely driving the focus coil harder in one direction, there could be a number of reasons for this.

[JimBanville]

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.

Ok. Issue solved...partially. I opened up my DCD-910 and it's very similar to the 610. It has those same components we've been discussing. That one transistor does get so hot after a few minutes of playing a disc that you can't touch it for more than a few seconds.
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!!