Philips 65PUS6521/12 voltage fluctuation

[Gabriel]

This tv had a blow C9145 1KV capacitor and a U9101 3S121 on the back that reached ~70C within a few seconds after connecting to 230V.

I replaced C9145 with a similar type cap and ordered a 3S121 on aliexpress and the chip now is at 30C but vcc on 3S121 goes up to 14v dc and down to 8v and up again.

I did check Q9109 K13A65U in a transistor tester, I think it is fine.

I can't seem to find other faults on this board, what is blown since the voltage is going up and down ?

My psu is a 715G7831-P01 and I found a service manual that has almost the same psu at this link.

https://www.electronica-pt.com/esque...qm16.3e-37202/

[R_J]

Re: Philips 65PUS6521/12 voltage fluctuation

Check R9101, check the components in Q9101 gate circuit, Replace C9103 and check R9114, R9127, R9113

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

R9114, R9127 measures 2.2 - 2.7 Ohm in circuit - R9113 measures 5.1ohm som they seems fine, C9103 measures ok out of circuit.

I have measured R9101 before and it was ok but after moving it out of circuit now I can't get a measurement on it.

Weird it won't measure anything now - perhaps it was 'half alive' if there is souch a thing in resistor world.

[Davi.p]

Re: Philips 65PUS6521/12 voltage fluctuation

Check under R9109 + R9104 on the mosfet source, if both ok replace shunt regulator U8607 and check photocoupler U8606.

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

R9109 is 10Kohm and R9104 measures 150ohm so ok, U8607 measures ok in transistor tester I guess. Photocoupler I will remove and test out of circuit.

I have an order for new 0.2ohm resistors R9101 and will report back when they arrive.

[R_J]

Re: Philips 65PUS6521/12 voltage fluctuation

If R9101 is open, U9101 can get damaged, ocp input can see a very high voltage if the modfet turns on with R9101 being open. as for C9103 I would always replace it, you can't check it with a component tester

[Davi.p]

Re: Philips 65PUS6521/12 voltage fluctuation

U8607 is an IC, must be replaced not tested..

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

If R9101 is open, U9101 can get damaged, ocp input can see a very high voltage if the modfet turns on with R9101 being open. as for C9103 I would always replace it, you can't check it with a component tester

Thanks for taking your time to explain this to me, I will replace C9103 too.

U8607 is an IC, must be replaced not tested..

Yes, I saw it was a TO-92 ic , I thought if it was ok it was no need to replace.
I just put in an order for new AS431 so I will follow your advice.

Thanks to both of you for helping with this problem, I will report back when parts arrive.

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

I fitted a new R9101 and U8607 and now tv turns on and shows picture but a few gremlins is still here.

Laptop does find the Philips is connected but tv won't show any picture on any of the 4 hdmi ports and screen message is 'no input' - it does show all menus and reacts to remote just as it should. I did test all 3 usb ports and all show 5.18v, ambilight also works as it should.

I fitted a pad under the K13A65U since I did not have contact paste, the
K13A65U and C9145 is ~100C almost instantly, why would it be so hot ?

Added some pictures for you.

[Davi.p]

Re: Philips 65PUS6521/12 voltage fluctuation

have you tested the PSB outputs? for the u8607 what was the marking of the original one and what is the new one? Both AS431? Or the new one is TL431?

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

Yes both are AS431, I did put back the one from Philips and tv still behaves the same. u8607 was marked 3S121, 8k642a, 381l and the new was sourced form Aliexpress and it's marking are 3S121, sk6d1a, 230l.

What is PSB ? do you mean voltages of the small signal board with hdmi, network and so on ?

[lotas]

Re: Philips 65PUS6521/12 voltage fluctuation

PSB - Power Supply Board.

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

Yes, 12v measured 12.46 - 5v measured 3.5v I dont remember if this was in standby or on.

I'm not sure if 5v marked pins are supposed to measure 5v or not as a service manual for the 55" tv of similar Philips type tv listed 3.5/5.

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

Screenshot of manual is from Philips+55PUS6401+Chassis+QM16.3E service manual.

[Davi.p]

Re: Philips 65PUS6521/12 voltage fluctuation

in the first post you said U9101 is 3S121 not u8607...
let me understand, you put back original as431 and tv turns on with only defect hdmi/temperatures or you put back the u9101?? some confusion here..
what happens if you replace original R9101 and the new as431?
if hdmi still disappears try to reinsert Opcodes from back of tv to the SAM service mode..

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

Yes I mixed up chip names, yes I did put back the original as431 and it did not get picture on hdmi back, temps are still high.

Just to be clear I did also replace U9101 3S121 earlier as it measued ~70C within a few seconds after connecting to 230V.

Original R9101 is open so it is defect, I don't know what Opcodes are - I'm not familiar with this sorry.



Ok, I saw this - https://factory-reset.com/wiki/Philips_Service_Menu
I can see if I can get to work.


Thanks

[Davi.p]

Re: Philips 65PUS6521/12 voltage fluctuation

option codes are usuallly written on the back label, must be inserted.in SAM, to enter : “062596” + info/Ok

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

There is written 'Set Option: 061' on the label, perhaps thats it ?

[Davi.p]

Re: Philips 65PUS6521/12 voltage fluctuation

No it is a long set of numbers, 2 rows. Q9101 might be passed through by too high current this because of a not proper value of R9101. Are you sure new C9145 is at least 1kv? It seems not to hold tension applied... Another higly possible culprit could be the transformer in short on primary. Do you have spare old/unuseful Power supplies to grab transformer wire from and re built old one? maybe you need new kapton tape..

[Gabriel]

Re: Philips 65PUS6521/12 voltage fluctuation

R9101 measures .01 -.02 ohm in circuit - in service manual it is listed as 0.2R 2W so I think it's ok.

Yes C9145 is 1kv but I see I fitted a 102K (1000PF) instead of 100PF - perhaps the reason for high temp and no hdmi ?

I'm not experienced enough to rewire a transformer, I normally work with much simpler things then this tv hehe.