Sony HCD-DZ880W

[ortiko]

I have this sony receiver and it doesn't power on at all...

Power Supply model: 09DAV-POWER-MR-MP-13
I started looking the power supply and fuse on it are ok.
At rectifier output i measure 32V dc

The red circle the output is 8V and on pcb it reads 32-0 32-0
So i suppose this is the problem but don't know how to find the defective part
Every part on pcb looks ok...

Any suggestions will be appreciated

 

[Nigel Goodwin]

If it's any help. here's the service manual.

Oops! - it's too large for the forum to accept, do you have a proper email address that will accept large attachments? (PM me if you do).

 

[ortiko]

Thanks alot for your help.
I have found the service manual earlier today !

Will try to take some measurements and study it later on

Thanks again!

 

[ortiko]

I have the PS circuit below.
Will take some measurements later today and come back

 

[ortiko]

With my voltmeter i read 320 Volts DC at D901

At Service manual it is marked 15.2 with red color ?
Is this Volts?

Also there is only 1.6 Volts at Q901 emitter and from the readings must be 20V !

 

[ortiko]

Have changed the capacitors with new ones and problem remains
Strange thing is that volts at emitter of q901 is 1,6V
Before i replace the caps it was 15,8 V

Is the transistor defective? (Q901)
Any idea what to check ?

 

[ortiko]

Can not find datasheet for the IC MR4020-7103 (IC921)
Anybody know where to search ?

 

[tunedwolf]

Try here:

https://lib.chipdip.ru/923/DOC000923032.pdf

 

[Nigel Goodwin]

Have changed the capacitors with new ones and problem remains

Which capacitors?, and why change them? - it's almost unknown for capacitors to fail in Sony products.

There should be about 340V across the large reservoir capacitor.

 

[ortiko]

Try here:

https://lib.chipdip.ru/923/DOC000923032.pdf

Thanks !!!

 

[ortiko]

Which capacitors?, and why change them? - it's almost unknown for capacitors to fail in Sony products.

There should be about 340V across the large reservoir capacitor.

I have replaced C926; C912; C908;
Found out today that FR929 is open.
Can i replace it with simple 1 ohm 1 watt resistor?

 

[Nigel Goodwin]

Found out today that FR929 is open.
Can i replace it with simple 1 ohm 1 watt resistor?

That would make me suspect IC921 - but you could certainly try a simple 1 ohm resistor (leave it stuck up on long wires) - the original is a special safety type, but while working on it a normal one will be fine (it will get destroyed in a much more 'exciting' way ).

 

[ortiko]

Well i am back with not so good news
I powerd on the PS with 1,2 A fuse in place of FR929 and fuse blown and burned smell came from IC921 MR4020-7103

After that i replaced fuse (FR929) and without mains power connected i tested the resistance of IC921 and it is 28 ohms...

So this IC is dead i suppose and hard to find for replacment ?

In a store i looked i found only the one in first picture below(the burned out is second pic with long legs)

Will this work for replacement if i use wires to connect all legs as the old one ?

 

[ortiko]

Have MR4020 (pic 1 above) installed after long and hard soldering of the pins it is ok and think it is working fine but reciever dosen't power on again

I need the datasheet of IC 901 STRF6138
Could not find anything about it...

 

[rosbif]

EDIT: To avoid confusion I underline that I am not the original poster but I have repaired a virtually identical power supply with similar symptoms.

Thanks to your help I fixed mine: C912 had failed (short circuit).

More details :-
I have a DAV-DZ280 with a 09DAV-POWER-MR-MP-12 (instead of -13) power supply board which is virtually identical.
The symptoms were similar: it didn't power on and mine had 0 V on all outputs.
I checked the resistors suggested in another forum and all were OK.
However there was only about 200 mV on the emitter of Q922 and even less on VCC of IC921.
The 320 V rail was OK and I noticed that the heatsink of IC921 was pretty warm.
I measured the resistance from VCC to GND of IC921: only about 7 ohms so obviously something was very wrong in the vicinity.
I read above that capacitors in Sony products rarely fail so I thought "****, IC921 must be dead".
(Particularly as, while searching for IC921's data sheet, I saw that someone was trying to sell them on Amazon at £71.00 + £12.00 shipping )
Otherwise C912 seemed the most likely to fail so I unsoldered it and found with relief that it was indeed short circuit.
I replaced it and my DAV-DZ280 came back to life

Thank you all for your invaluable help.
I hope that this account of my experience helps others in turn.

 

[Fulvio]

i have the same problem about 8V output and not 32V. Can i have the user manual please, i can't find online. Thanks

 

[rosbif]

i have the same problem about 8V output and not 32V. Can i have the user manual please, i can't find online. Thanks

There is the same post with more information and with links to manuals with similar power supplies on the BadCaps.net forum.