Toshiba 55ZV650U

[Danstona]

Troubleshooting my brothers set. So far I have visual sign of blown cap at location C820, C821 looks like it may be going to blow. I know I'm not suppose to read uf while connected, but they both read 280uf (rated 450v 150uf) Next I have open R850 low resistance fuse? R897 and R898 both give 1.2ohms and seem to be ok. Given my limited knowledge, but after reading numerous threads, would I be safe to order and replace those parts only. Or should I also order and replace the Q880 voltage regulator to be safe?

[budm]

Re: Toshiba 55ZV650U

I think up load good clear pictures of your whole top and bottom side of the board will be a good starting point.

[Danstona]

Re: Toshiba 55ZV650U

The board is a PE0702A fairly common along a series of sets from my reading. I'm only having trouble finding the voltage regulator given the numbers on the chip with mouser or digikey. Does anyone know if its one of the IC's that come with the SJ kit? Other than that, the LARGE caps 450v 150uf are approx 30x27mm, with a 15mm lead spacing. All I can find is a 10mm lead spacing, so hopefully that will work?
See attached pics.

[budm]

Re: Toshiba 55ZV650U

PCB P/N PE0702A is the part number of a blank PCB, that blank PCB can be stuffed to make more than one PCBA (PCB ASSEMBLY) as needed for particular TV model as you can see here:
http://www.shopjimmy.com/catalogsear...ult/?q=PE0702A
R850 inrush current limitter will go open circuit if the bypass relay SR81 is bad due to not being turned or or burn out contacts, very common failure.
ALL the red round fuses are good? you need to have that R850 replaced otherwise there will be no AC feeding the bridge DB820 to run the circuit in standby mode.
You should remove at least one of those big cap and test if off the board first.

[Danstona]

Re: Toshiba 55ZV650U

ok, I'll have a look at the for sure blown cap, off the board in the morning. I opened the SR80/81 relays and the contacts do look a bit black. I was going to see about cleaning them up... if that will suffice? All the red round fuses checked good for continuity when I tested.
Any idea if the Q880 is included with that SJ kit?

[budm]

Re: Toshiba 55ZV650U

Clean it as good as you can, what will happen is that if the contacts are not good, you will burn up the resistor again when full power is drawn.
You should also check the resistance between the two legs of either one of those two caps to see if it shows very low resistance or not.
There are 3 devices (Q821, Q820, D821?) mounted on that big black heatsink next to the two bog caps to see if they are shorted or not, they are for the PFC Voltage booster circuit.
You have 3 power supplies on that board. I do not know it has in the repair kit.

[Danstona]

Re: Toshiba 55ZV650U

So the worst cap is reading 135uf, the other beside it reads 143uf. Both are rated 150uf... I have plans to replace them, but don't believe both are kaput and cause of issue. I'm going to go out on a limb and suspect the SR80/81 contacts and R850. I'm going to order up the rectifier and regulator to have on hand.

The large caps are giving me 640 and 650 mega ohms. How do I test the other transistors?

[R_J]

Re: Toshiba 55ZV650U

Do you have any d.c. voltage across C880? If you have voltage there, check the voltage on plug PJ90, Do you have 5v1, 12v 18v_audio

[Danstona]

Re: Toshiba 55ZV650U

I have both c820 and 821 removed. waiting until new ones arrive then I can test.
budm, how do I test those 3 devices for a short?

[budm]

Re: Toshiba 55ZV650U

Look up the P/N as printed on the MOSFET to get the pinout then check the resistance between S and D pin. Look up the diode spec sheet then check the resistance between A and K pin to see if shows conduction on both directions.

[Danstona]

Re: Toshiba 55ZV650U

So far from what I am understanding I am getting the proper readouts from the mofsets and the diode. I have some of the new pieces form mouser... and will be installing them now. Those pieces are the large caps and the ohmite wirewound fusible resistor. Locations C820, C821 and R850. I will then clean the contacts on SR81 and SR80. I have a new bridge rectifier but not the new voltage regulator as of yet, but I'm not installing it. Will post results when reconnected to panel.

[Danstona]

Re: Toshiba 55ZV650U

Sorry it took so long to get back with this message, tis the season for being busy busy. After replacing the two main caps, and the R850, along with using electronics cleaner and a mild abrasive paper to clean SR81 and SR80. I put the power board back in the set for a test and everything is back up and running. Thanks for all who helped me diagnose and test the various circuits for issues.

[budm]

Re: Toshiba 55ZV650U

Thanks for the follow-up on the repair.

[zape]

Re: Toshiba 55ZV650U

I observe the same symptoms and I already ordered caps and resistor on digikey.
The issue is I dont have any special tool or cleanser to clean relay contact.
So I ended up using just regular paper with isopropyl alcohol. Will this work?

Upd: added two relays to my order. will probably just replace them.
Will these work?

[zape]

Re: Toshiba 55ZV650U

Replaced two main caps, R850 and relays.
Old caps were slightly bulgy and measured 135uF
Replaced with higher capacity and lifetime rated Rubycons (made in Japan)
This TV will now work for another decade or two

Here is the digikey part list just for information:

Index Quantity Part Number Manufacturer Part Number Description Customer Reference Backorder Unit Price Extended Price
1 2 TWW5J2R0E-ND TWW5J2R0E RES 2 OHM 5W 5% RADIAL 0 0.91000 $1.82
2 2 1189-2032-ND 450VXH180MEFCSN30X25 CAP ALUM 180UF 20% 450V SNAP 0 5.10000 $10.20
3 1 255-3350-ND LKT1AF-12V RELAY GEN PURPOSE SPST 5A 12V 0 1.73000 $1.73
4 1 255-3499-ND LKT1AF-5V RELAY GEN PURPOSE SPST 5A 5V 0 1.73000 $1.73
Subtotal $15.48

[Simcoe]

Re: Toshiba 55ZV650U

I hope I am replying correctly. Our television decided not to power up. It is the model listed on this thread. I am a long time putterer and newbie, see profile. So here we go. I watched a youtube video by Tempatec.
https://www.youtube.com/watch?v=ttrSsgkI5TE
Ran the diagnostics with the same results. I found the shopping list from member Zape on thread
https://www.badcaps.net/forum/showthread.php?t=66276
very helpful. it directed me to digikey.
Like the youtube video by tampatec and Zape I require the resistor TWW5J2R0E-ND TWW5J2R0E RES 2 OHM 5W 5% RADIAL 0 0.91000.
Like the video test I require the voltage regulator STR Y6456 by Sanken.
Here is my immediate problem this regulator / MOSFET is now obsolete.
I am thinking of using a Sanken STR Y6754 in its place.
https://www.digikey.ca/products/en?keywords=STR-Y6754
looking at the absolute Maximum rating the numbers vary. example IDpeak for the original Y6456 was 17.6A the replacement I am considering the Y6754 has an IDpeak of 11.0A. This continues. my biggest concern lies with the Control Circuit Electrical Characteristics, under the heading Operational Start Voltage the values are exactly the same and perhaps worse the identified terminals vary. Seeking advise, thanks

[nicholas1110]

Re: Toshiba 55ZV650U

When the resistor opens its due to dirty relay contacts. You most likely won’t have to replace that regulator. Order both relays and a resistor from digikey and give it a try. Hope this helps. There is other posts about this model and the 46” versions as well with this same info

[Unspun01]

Re: Toshiba 55ZV650U

Like the video test I require the voltage regulator STR Y6456 by Sanken.
Here is my immediate problem this regulator / MOSFET is now obsolete.
I am thinking of using a Sanken STR Y6754 in its place.
https://www.digikey.ca/products/en?keywords=STR-Y6754
looking at the absolute Maximum rating the numbers vary. example IDpeak for the original Y6456 was 17.6A the replacement I am considering the Y6754 has an IDpeak of 11.0A.

Hi:

The STR-Y6754 does not appear to be pin-for-pin replacement for the STR-Y6456. Datasheet shows differences in pinouts.

Also, the 17.6A on STR-Y6456 exceeds the ratings of STR-Y6754 and may cause the replacement to run hot and fail again prematurely. Voltage specs are both 650V peak, but Y6456 has lower Rds(ON)=0.76ohm versus Y6754 with higher Rds(ON)=1.4ohm which will run hotter due to higher losses.

I would source a STR-Y6456. Available on aliexpress.com for cheap. ebay is a bit more expensive for many of the same sellers on Aliexpress.com. Expect to pay less than $6 with shipping to US or Canada.

[R_J]

Re: Toshiba 55ZV650U

The voltage regulator is likely ok and there is no need to replace it, the resistor opens because of the bad relay contacts. If the relay is not replaced, the resistor will just open again.

[Unspun01]

Re: Toshiba 55ZV650U

On my tv, Q880 (STR-Y6456) was shorted, and fuse F880 5A/250V) was open. Both needed to be replaced.


I'm not sure if the poster measured their Q880 as a short, but if theirs is bad, the STR-Y6754 will not work as replacement, so my reply was regarding their part substitute.

My relay was ok.