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Birthday Present! Denon DP-1200

Went ahead and replaced it. Still no joy.

See attached pic.
 

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OK then, this makes me suspicious of diode bridge D3. If one of the diodes is bad it could put DC onto the motor and draw excessive current without turning the motor or just act as a partial short-circuit, a 1A/400V bridge should be an adequate replacement if it is defective.
 
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Pio1980 said:
OK then, this makes me suspicious of diode bridge D3. If one of the diodes is bad it could put DC onto the motor and draw excessive current without turning the motor or just act as a partial short-circuit, a 1A/400V bridge should be an adequate replacement if it is defective.
Click to expand...

I pulled the diode bridge and tested. Attached are the results. Should I still replace it?
 

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Pio1980 said:
Yes, cheap enuff to eliminate the possibility of failure under stress.
Click to expand...

Found that NTE167 (200V 2A) is a proper replacement for 1S2372A. So did a phone order and stopped by Mouser to pick it up.

Installed. Resistors R20/24 still get burning hot and no motion from the motor.
 

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fizzgig said:
Found that NTE167 (200V 2A) is a proper replacement for 1S2372A. So did a phone order and stopped by Mouser to pick it up.

Installed. Resistors R20/24 still get burning hot and no motion from the motor.
Click to expand...
I keep coming back to this thread praying to hear that the motor has turned. Such a long-running drama, could be a mini-series already! I sure am curious what is heating up those resistors as I can tell you there was no such thing going on with mine back when I had it.
 
I sure hope you guys are able to get this figured out and get this table back up and running. I really enjoy mine. Good luck!
 
I think we've done most of the quick-&-easy stuff and here we are.

I don't know for sure at this point if there is one problem or two, the motor can run/won't run and/or there is a high-current draw in the controller ckt.

There is a yellow wire going from the main board to the arm control board, lift this wire, power up and see if the resistors still get hot. If so try to isolate pin 15 on the controller IC TC955 and check again for resistor heating. This IC was used in other TTs and is not an exclusive rarity.

The motor ckt can be checked with a temporary quick-check direct connection, carefully bypassing D3 and controller ckt (jumper other diode leg points on board NOT marked + or - on the diode), and powering up momentarily with platter off. Getting the jumper wrong will cause havoc, take care!
 
Pio1980 said:
There is a yellow wire going from the main board to the arm control board, lift this wire, power up and see if the resistors still get hot.
Click to expand...

PIO, to confirm, you are stating to remove W-13 from the power PCB and then engage power and check the resistors for heat.

Pio1980 said:
If so try to isolate pin 15 on the controller IC TC955 and check again for resistor heating.
Click to expand...

In this step, what would be the best way to isolate the individual pin? de-solder the whole thing and make jumpers for the rest of the pins? Or, de-solder and put some rubber around it? lol. Not sure of best practice here.
 
fizzgig said:
Quote:

Originally Posted by Pio1980

There is a yellow wire going from the main board to the arm control board, lift this wire, power up and see if the resistors still get hot.

PIO, to confirm, you are stating to remove W-13 from the power PCB and then engage power and check the resistors for heat.

Quote:

Originally Posted by Pio1980

If so try to isolate pin 15 on the controller IC TC955 and check again for resistor heating.

In this step, what would be the best way to isolate the individual pin? de-solder the whole thing and make jumpers for the rest of the pins? Or, de-solder and put some rubber around it? lol. Not sure of best practice here.
Click to expand...
I use solder wick to "dry" them out until the leg freely moves, then ensure it is not touching the edge of the eyelet.



Posted from Audiokarma.org App for Android
 
Pio1980 said:
There is a yellow wire going from the main board to the arm control board, lift this wire, power up and see if the resistors still get hot. If so try to isolate pin 15 on the controller IC TC955 and check again for resistor heating. This IC was used in other TTs and is not an exclusive rarity.
Click to expand...

Removed yellow wire. Resistors still heating.

Removed pin 15 (verified no continuity with multimeter). Resistors still heating.

Moving on to motor tests. Will report back.
 
Pio1980 said:
The motor ckt can be checked with a temporary quick-check direct connection, carefully bypassing D3 and controller ckt (jumper other diode leg points on board NOT marked + or - on the diode), and powering up momentarily with platter off. Getting the jumper wrong will cause havoc, take care!
Click to expand...

PIO please verify from the pic that I have placed my jumpers correctly on diode D3. They are connected to "~" pins, not + or -.

These jumpers then connect to the motor via the yellow and black wires, correct?
 

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fizzgig said:
PIO please verify from the pic that I have placed my jumpers correctly on diode D3. They are connected to "~" pins, not + or -.

These jumpers then connect to the motor via the yellow and black wires, correct?
Click to expand...

The jumper leads look correct, they effectively bypass the motor control ckt. If the motor does not run we will have to look closer to the motor, again.
 
Johnny #5 is alive! :banana:

Well... At least for a moment he was. :thumbsdn:

I did get spindle movement (though VERY slow, possibly a bearing issue?) when I attached the leads according to the configuration in the attached picture. Then I believe the alligator clips moved and touched the metal plate...and flash...the fuse blew. The resistors of course got hot as well.

Now I have no power due to the blown fuse, so I will need to get a replacement. But we are tracking it down! I can taste success!!!

I'm excited!:thmbsp:
 

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