sony KDL 40D 3500 DEAD PSU

[jimbofz]

Hi all and happy new year
this oldie was given to me to look at ,
no red led ,no secondary volts from psu,
no relay click, no blown ceramic resistors,
theres no 3.3v sby volts .
first i changed most psu caps ,
theres no s/c on any secondary supplies the main s blocks are charged to around half of normal around 190v as theres no s/c on the primary of psu i linked the contacts on the relay ,still no o/p,removed link, and checked resistances .
so i need to know how the primary is switched on,i thaught it may be some protection cct shutting down the psu outputs.
i sourced a cct but there seems to be more than one version of this psu
and it seems to be over complicated
so bottom line is you need 3.3v to start the psu ,without it the psu wont run
has anybody got any ideas ,as im now scratching my head ?
i believe its a WAX3F chassis
i will post pics of both sides of psu

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

heres the pics of the psu board

[budm]

Re: sony KDL 40D 3500 DEAD PSU

What did you use for ground ref for the meter when you check the DCV on the Hot side of the circuit?

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

What did you use for ground ref for the meter when you check the DCV on the Hot side of the circuit?

chassis earth ,not primary earth,
when i check directly across the main smoothing blocks measures 340v raw dc

[dick_barton]

Re: sony KDL 40D 3500 DEAD PSU

You don't say if you have the schematic for the power supply. There is a manual at https://www.manualslib.com/download/...dl-40d340.html

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

heres some futher voltage checks in primary of psu,using primary earth not chassis earth :the mip2h2 ic ,ic6200
pin1 =6v,
pin2= 2v,
pin3= 1.4 to 3.5v pulsing,
pin4=1.9v
pin7/8 joined =0v
pin 5 drain=340v
on ic6500 l6562 no vcc volts on pin8
on ic6100 cdx9841p vc1 pin8=0v
pin1 vsen=.4v
after searching the net cant find what the start up sequence should be
but i feel sure that no 3.3v will mean no secondary supplies produced

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

You don't say if you have the schematic for the power supply. There is a manual at https://www.manualslib.com/download/...dl-40d340.html

thanks this is much better than the one i d/loaded.
i printed and joined the pieces together but there were sections missing ,and no voltages shown so now i have more of a chance thanks

[dick_barton]

Re: sony KDL 40D 3500 DEAD PSU

The PFC voltage across the capacitor is given as 400V. So if that's not there then it looks like the PFC circuit is not working or being switched on.

The KDL32XBR4 available from the manualslib.com shows a G3 power supply on page 94 that may be more complete with some voltages given.

https://www.manualslib.com/manual/79...dl-32xbr4.html

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

looks like i will have to read up on power factor correction,in my experience faults in the primary of psu ,s usually results in s/c components ,o/c ceramic resistors with blown fuse
today i had hitachi vestel with low o,p secondary volts caused by o/c smoothing block? good old vestel keep us on our toes.
one question ,
can you work out how the vcc voltage is produced for ic6500 pin8 ?

[dick_barton]

Re: sony KDL 40D 3500 DEAD PSU

Quite briefly and happy to be corrected if I make an error.
Using the 32XBR4 schematic

IC6200 oscillates the transformer T6200 which results in 3 seperate voltages being generated.

(T6200 pin 8 has the 400V supplied to it.)

T6200 pin 1 produces the 16.4V which is fed to Q6303. This transistor is switched on via the Opto-isolator PH6300 (Power ON) and then the 16.4V feeds through Q6303 to RY600 (to turn on the Relay) and IC6500 VCC pin and also IC6100 Pin 8 (VC1)

T6200 pin 3 provides the 11.9V for IC6200 pin 4 (VCC) to maintain the IC oscillation.

T6200 pin 10 provides the 3.3V standby voltage

At switch on IC6200 charges C6204 via current flowing from the Drain supply at pin 5

Once the voltage on this capacitor (C6204) reaches a certain point the IC starts to drive the transformer and Pin3 of the transformer then provides the voltage needed for IC6200 to sustain oscillation.

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

Quite briefly and happy to be corrected if I make an error.
Using the 32XBR4 schematic

IC6200 oscillates the transformer T6200 which results in 3 seperate voltages being generated.

(T6200 pin 8 has the 400V supplied to it.)

T6200 pin 1 produces the 16.4V which is fed to Q6303. This transistor is switched on via the Opto-isolator PH6300 (Power ON) and then the 16.4V feeds through Q6303 to RY600 (to turn on the Relay) and IC6500 VCC pin and also IC6100 Pin 8 (VC1)

T6200 pin 3 provides the 11.9V for IC6200 pin 4 (VCC) to maintain the IC oscillation.

T6200 pin 10 provides the 3.3V standby voltage

At switch on IC6200 charges C6204 via current flowing from the Drain supply at pin 5

Once the voltage on this capacitor (C6204) reaches a certain point the IC starts to drive the transformer and Pin3 of the transformer then provides the voltage needed for IC6200 to sustain oscillation.

wow thanks, great cct discription,
the diode d6506 connected to coil/tx l6501
has 340v on both sides not 102v and 400v as shown on cct ,
does this mean the power factor correction is not working?
as a consequence the 16v on pin 1 ic6200 measures low at 6v.

[dick_barton]

Re: sony KDL 40D 3500 DEAD PSU

The 340V is correct on one side of the diode ( UK 230V AC full wave rectified = 340V DC) and the PFC circuit should boost it to 400V on the other side of the diode.
I would initially do a thorough check of the components around IC6200

[budm]

Re: sony KDL 40D 3500 DEAD PSU

chassis earth ,not primary earth,
when i check directly across the main smoothing blocks measures 340v raw dc

When taking Voltage measurement in the HOT side of the circuit, you need to use the negative leg of the main filter cap as the ground ref. for the meter.

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

thanks ,all volts shown in above posts are measured that way

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

fixed.
i ordered MIP2H2 when fitted symptoms same (that sinking feeling)
but as luck wiuld have it another similar sony came in with poor hdmi connections .
this was quickly sorted
then i could put both psu side by side and do cold checks.
on the faulty one there was 250k resistance across optocoupler pin 3 and 4 ,
on the good psu it was o/c ,
when i unsoldered the pins ,it proved opto ph6200 was the culprit
after replacement ,the relay clicked on and the 3.3v was produces and all the supplies were restored when brought out of sby.
thanks to all especially dick barton for your help

[dick_barton]

Re: sony KDL 40D 3500 DEAD PSU

Glad you got there in the end.

Curious, you say another Sony came in? Do you have access to circuit boards?

[jimbofz]

Re: sony KDL 40D 3500 DEAD PSU

not really but i usually fix one or two ,just to keep my hand in since i retired ,
i closed my shop 10 years ago but still get asked to do repairs ,
also so many people prepared to just buy new these days ,
rather than have existing tv repaired .
as you know some of the older models were so well built with decent sound ,they are to good to scrap .
i still enjoy the challenge of repairing,
and this site is a great help thanks again