Sony HCD-DZ880W Receiver Dosen't Power ON

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Also the Voltage at the two legs of C912.
https://www.badcaps.net/forum/attach...0&d=1415908730

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Tthe resistance reading between the two legs of C908 starts with 39 Mohms and slowly it decreases...

OK, no shorts or low resistance.

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

theres a post here but its in spanish showing that chip in use and some voltages maybe worth a read
http://www.dtforum.info/index.php?to...prev_next=prev

It looks like it has the same setup and it is running at around 20VDC, we are getting around 11V which I am not sure if that is enough startup Voltage or not to run the IC.
Thanks Vince.
According to this STR-6600 series it needs 16V to start.

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Voltage of c912 is 9~12 V

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Voltage of c912 is 9~12 V

OK, that does not make sense since the output Voltage at the Emitter of Q922 is reported at 11V, this is fed into 5.6V Zener diode DZ904, that means the Voltage drop on the Zener will be 5.6V so the load which is the VCC of the IC921 should be only 11-5.6 = 5.4V at the VCC pin 4, but you are getting 9~12V.
Can you measure the Voltage on the two legs of the ZD904?
There are measurement error some where here or the meter is not right.
https://www.badcaps.net/forum/attach...6&d=1415317397

http://www.digikey.com/product-detai...DKR-ND/1919975

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Voltage on DZ904 changes from 0~2,2V

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

OK, please take the resistance readings between the two legs of the ZENER? no power applied to the unit, you may have to test it off the board, so far it looks like it has low resistance and not working like Zener diode any more.
Also the Voltage reading on C926, per SCH it should have around 28VDC.
https://www.badcaps.net/forum/attach...6&d=1415317397
As you can seein the SCH, that Zener is there so that the Emitter Voltage at Q922 has to be around 20V to have 15V VCC for IC921, if it is too low, the circuit will not run or not run properly.
Also check DZ902, 22V Zener.

[vinceroger69]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

please ignore wrong thread.

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

the resistance readings between the two legs of the DZ904 on the pcb is 40 kohms and changes to 60 kohms 30 kohms...
Must i remove it ?(it is very small )

Voltage at C926 is 11V (10,9~11,5)

[vinceroger69]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Have you got a second multi meter you can try just incase its faulty what does your meter read if you test a brand new 1.5 volt battery or 9 volt battery if you have any.

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

"Voltage at C926 is 11V (10,9~11,5)" that cannot be right since you are getting aROUND 11V at the Emitter of Q922, and the Collector is at 11V which is fed from C926, that means the Q922 has shorted E to C, or shorted DZ901.
So basically the Voltage readings are all bad and too low.
You need to test Q922, DZ901, the cap C926 capacitance.
As you can see in the circuit and the Voltages as shown in the diagram around Q922, your voltage readings are way off.
It is the meter or the circuits are bad.

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

meter is ok. i used a second one and same volts...
DZ902 has 11V like DZ904 and same resistance readings

Do you suggest i take of the Q922 first ?

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

DZ901 with multimiter on diod test it reads 0,563 and if reverse the meter terminals it reads 0,730(on pcn)

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Check the resistance reading between E and C on board and off the board by taking the transistor out.
We are looking for resistance leakage so use the meter in Ohm mode

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

At E and C of pcb resistance readings are 1,2 Mohm and q922 removed from pcb

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

With Q922 on pcb E and C resistance readings are 5.5 Mohms and rises slowly

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Well, the whole thing does not make any sense, the Voltage feeeding the Q22 is way too low, the input Voltage and the output Voltage on Q922 are the same.
We need to get that Voltage on C926 up to 28V as shown in the SCH. Can you solder in another 22Uf 35V or more in parallel with C926 to see if the Voltage will come up?
One way to find out if Q922 LINEAR REGULTOR circuit is working or not is to use external DC power supply to feed the Voltage to the two legs of C926 and see if if it is regulating or not when turning up the output voltage of the variable power supply, nothing else will be connected to the board.

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

We need to get that Voltage on C926 up to 28V as shown in the SCH. Can you solder in another 22Uf 35V or more in parallel with C926 to see if the Voltage will come up?

Have done it with 22uf 100V but voltage is as before

One way to find out if Q922 LINEAR REGULTOR circuit is working or not is to use external DC power supply to feed the Voltage to the two legs of C926 and see if if it is regulating or not when turning up the output voltage of the variable power supply, nothing else will be connected to the board

Done this to with my external power supply and attached 28V dc on C926.
At Q922 E was 20V, C 28V and B 21V so i suppose it is ok?

[budm]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

OK, the regulator is working, it is just getting too low of the voltage to work properly.
So the IC that you replaced is the same as the original one? I am surprise that it runs on 11 V.

[ortiko]

Re: Sony HCD-DZ880W Receiver Dosen't Power ON

Well i am back with not so good news
I powerd on the PS with 1,2 A fuse in place of FR929 as budm told 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 ?

I have replaced it with same IC but diferent pins
Picture below is the replacment ic i used