Pioneer DJM-500 mixer distortion

Thread Starter

signalnc

Joined Jun 30, 2019
20
Please measure the voltages directly at the 7808 and 7815 3-pin voltage regulators.



Input wrt (with respect to) Ground pin
Output wrt Ground pin

Pinouts for 7908 and 7915 are different.



Note that in your case the metal tabs are insulated and make no electrical contact with the heat sink.
Perfect info - I will check this. Thank you.
 

MrChips

Joined Oct 2, 2009
35,018
I don't know how you could have damaged the 7815.
Accidentally shorting pin-1 to pin-2 or pin-2 to pin-3 should not damage the 7815.
 

JoeJester

Joined Apr 26, 2005
4,390
Once you get the power supplies back. Test the amplifier using the Send output jack. If there is NO distortion, you can eliminate some of the circuitry. Repeat that test using every input and note the distortion. Do not exceed the input specified level.

Take copious notes as you check the effects of every function.
 

Thread Starter

signalnc

Joined Jun 30, 2019
20
I could only find one fuse. I took it out and tested it , and it's fine. Still have no power to the 7815. Unit powers on but produced no sound .
 

MrChips

Joined Oct 2, 2009
35,018
Can you go back and measure voltages on all three pins (1, 2, and 3) of 7808, 7908, 7815 and 7915 regulators with respect to GROUND?
This time without shorts.

 

Thread Starter

signalnc

Joined Jun 30, 2019
20
7915 : -25.18 in , - 15.19 out

7908: -25.19 in, - 8.13 out

7815: - .59 in, - .77 out

7808: - .95 in, -.97 out

No shorts/sparks/magic smoke today.
 

MrChips

Joined Oct 2, 2009
35,018
There are fuses on the power board that look like transistors in TO-92 packages, except there are only two leads on the device.

On the DJM-600 Service Manual the V+B line is protected with IC557, ICP-N15.

ICP-N15 is a 0.6A fuse.




DJM-600 Power,jpg.JPG
 
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