Help repairing a switching power supply out of a Pioneer DJ Disc Player

[jmibk]

I have a switching power supply, that isn't working anymore. I'm shure, thats the supply, because i crosschanged it between two cd player units.

Here's the schematic of it (also available in the service manual of the device):

http://audiowerk.at/djm2000_power.pdf

The problem:
The whole unit isn't working, nothing happens (no display, no leds, nothing).
I checked the power supply:
- fuse F1 is ok.
- voltage on primary energy store cap c5 is ok.
- voltage on output is around 7v dc (instead of 12V) on all outputs. It moves 1V up and down on a Fluke 87/V
- there is a very low klicking noise, around 1Hz, i think coming out of the transformer (i had no chance to localize it).

Anyone an idea to get it back working?

I have a multimeter and oscilloscope here at the bench and a camera for pics, if anyone needs more information. I haven't troubleshooted a switching supply before.

[mij59]

Prime suspects are C102 and C103, you could measure the ripple voltage, or swap the caps from the other unit.

[SeanB]

Picture of top and bottom of board, though the most likely cause is a few capacitors on the secondary that have died, along with one or two small electrolytic capacitors on the primary side as well.

[jmibk]

Hi,

1st, i checked the topic https://www.eevblog.com/forum/repair/focusrite-liquid-saffire-repair-help-needed!/, but it doesn't help in that case...

The pics of the board:





Here a few quick measurements:
yellow trace is output CN2: pin 6 to pin 1,2 (gnd)
blue trace is output CN2: pin 5 to pin 1,2 (gnd)

1) voltages, CN2, pin 3 open:


2) voltages, CN2, pin 3 shorted to ground:


3) i tried to capture the power on cycles of the supply. after 1,5secs i powered it on, it takes approx. 9 seconds to reach the final voltage ov 8 volts.


Check out the ripple, the clicking noise is exactly to frequency of that ripple. If I turn power off, the output takes around 1 - 2 minutes to reach 0V. All outputs measured open circuit.

I hope that helps - if not, i can do more measurements...

[PA4TIM]

Probably dead caps. What I do in such cases is look up the datasheet of the controller. They write how it should work and the voltages on the pins. Start up sequence/conditions etc.

But in your case just take the scope and measure the ripple voltage or swap the caps first. The jumpy DMM reading probably is caused by that ripple.

When testing, many SMPS need a minimum load to work good.

[mij59]

Ripple voltage seems to quite low, could you post a picture of the ripple voltage at a time base setting e.g. 10 to 100 usec ?
Edit : measure the ripple voltage of C102, C103.

Next suspect would be C11, since this capacitor is on the mains side of the circuit you can't measure the ripple voltage with an oscilloscope.

[cvanc]

Hmmm, I just realized I don't know how to post a photo here.

Anyway I took your pic of the underside and marked up a LOT of shaky looking solder joints.  And now I can't sort out how to post it - sorry.

In addition to the good advice you're getting about electrolytic caps, you might want to look real closely at all the soldering.  Good luck.

[jmibk]

Thanks for the answers...

First of all, I changed some caps:
C11, C102, C103. C11 the same capacity and voltage, for C102 and C103 the new ones are 50V / 470uF.

Now, thats the measurement (looks the same), but the voltage is slightly lower:


@mij59:
I tried to capture the waveform with the desired timebase.
1st pic is the rise of the "sawtooth" shaped voltage...


Here you can see the voltage between the sawtooth's...




Not easy to capture tue the low frequency AC parts of the signals...

@cvanc:
you can send me the pic to jmibk0{AT}gmail.com - i can post it for the others to see...

[jmibk]

Here the output voltage of the power supply with the cd player electronics connected to it. Its much lower than in open circuit condition.



Photo from cvanc:

[mij59]

Please measure the dc voltage of C11, maybe the regulator Z2 shuts down due to a low VCC, this could be caused by a faulty diode D7.
D7 may have a high internal resistance, this is not always obvious when measuring with the diode function of  your DMM,

[jmibk]

Voltage on C11 is around 10V DC, going up and down -> see video.

http://audiowerk.at/PioSupp/3/IMG_1976.MOV

The Diode D7 seems to be ok, diode test is ok (0,565V), resistance 4,5k (+ at A, - at K) and 200k (falling, + at K, - at A)

I also changed back C102 and C103, the voltage is now like on the first pics...

[joao2004]

Resistance and voltage from pin 2 to pin 3 (Z2) ??

also check R18 and D4

[mij59]

Last thing I can think of is a problem with the feedback, diode test  PC1,  pin 1 and 2 should give a voltage of about 1.1V.
Z101 is probably a TL431, check the data sheet.

[jmibk]

Voltage Z2 Pin 2 to 3: 0,4V
R18 = 10kOhm

Diode Test PC1 Pin1 <> Pin 2 = 1,05V

I'll check Z101 and the Diode later...

[joao2004]

Remove C7

Diode test PC1 4(+) to 3(-)

Z2 probably is faulty!

[jmibk]

Resistance Z2: Pins 2 to 3 = 340k / 500k depending on leads polarity.

Diode Test PC1 (4 and 3) = "OL" both directions, desistance also "OL"... maybe the damaged part....

[mij59]

Resistance Z2: Pins 2 to 3 = 340k / 500k depending on leads polarity.

Diode Test PC1 (4 and 3) = "OL" both directions, desistance also "OL"... maybe the damaged part....

The transistor ( pin 3,4) will not turn on unless there is a sufficient led current ( pin 1,2) flowing.

[funkyant]

[jmibk]

Optocoupler PC1 works very well, tested it on a breadboard with help of two resistors and one red led...

Diode D4 also OK, tested with external power supply... 23.8V

[joao2004]

Faulty Z2... any way measure the resistance between pin 1 and 2 of transformer

[jmibk]

Okay...

I tested the feedback thing with simulated voltages out of a power supply and a waveform generator...

ground: secondary ground and primary negative (eg. PC1 / pin 3) to one ground
yellow: voltage on RC101 cathode simulating a wavy 12v voltage...
blue: voltage on PC1 / pin 2 (shows switching on/off the led of the opto
purple: voltage on PC1 / pin 4 (pulled up with a 2k2 resistor to 10V external supply)
Everything seems to be working well.

[PTR215]

Hi, this is a long shot. This thread is more than a few years old....

I have the same PSU , Pioneer P/N (DWR1463) that was pulled from a S9. I had an older DDJ-SZ2 parts unit, that shares the same part (PSU). I swapped the PSU in the S9 with the working one one from the SZ2. Everything has been working great in the S9 no issues and back to normal. I would like to try to repair the PSU that was removed though, so i can get back to restoring the SZ2.

The PSU is DWR1463-A (SanKen)

I also believe I have a faulty Z2 (SCC6210A). The newer service schematic for the SZ2 does not show the part value or name for Z2. I am having a hard time finding info on it. In addition I have discovered Pioneer labels the same PSU BOTH DWR1463 AND DWR1566 as compatible , which is about a hundred dollar difference between both.

I have voltage at C11 & D7 but Z2 is very low on Pin 1 (Vcc) and nothing out Pin 7. Just tested the IC out of circuit on a bench power supply. Any help would be greatly appreciated.

Confirm what Z2 is
and anyone with a successful repair?