TH-P50G15A - 6 Blinks- Bad TNPA4782

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Well--Not certain models for sure!

The older series like the TH-p42/50/PX/PZ/70/80/81 series are brilliant long lived reliable sets.
--Just a shame they double as room-heaters!

For sure, i think the PZ series are solid enough bar the PSU. I must admit I like the 2011 panels now I've seen them , the 2 I've done I'm happy with just transistor replacements, at least we know how to fix these cheap, not good for the average consumer I guess

[tom66]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I suspect that the 2011's would be fine with the heatsink-free boards but there's a software or hardware design flaw that causes them to fail early. Thermally speaking the transistors only run warm to the touch.

[Alastair E]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Maybe Tom, --Could it be that issue concerning the ERC Cap circuit being fully discharged at turn-on, demanding twice the normal current (Or thereabouts) to flow through the SUS_Up pair--which eventually say--sod it and go short, taking the SUS_Dn pair out and whatever else happens to be around at the same time....?

Just recalling something you mentioned a while back....

This 50G10B has been fine now for two days, --Dunno why it had those SOS7 and SOS4 codes logged....

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Progress!!! I decided to put back the original IC563 and finally it stays on! So it seems it does run without the Q604 FET.

Now I just need to make sure there are no problems with the buffers before I put them back on.

this is a new 4782AB on Ebay. the box has a date of march 2014, not sure if that's manufacture date or picking date but note the Vset cct removed.

second picture is from SJ

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

My 2SJ281 P-FETs (10) just arrived from Poland. 2.49GBP + ship. took 3 weeks from order date to Australia. Works out at $1.30 ea for me.

HFO Elektronik

http://www.ebay.com.au/itm/261478252...%3AMEBIDX%3AIT

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Picked up a broken Rev AC 46" board. virtually no diiference between this and an AB 50" (G10) except placement of the inductors and a couple of caps.

Q601, RJK6026 shorted
Q661, RJP6065, shorted
Q441, 45G127 shorted
Q451, 45G127 _ shorted but not the same as 441, I suspect that when 441 is out this may be ok
Q701, MMBTA92 blown out
Q702, 2PD601 blown out
Q818, 2SK3018 could be ok
Q604 2SJ281 no short but i'm unsure still what they should do in cct. Not cracked apart like the last one
Q551 CPH5524_ shorted
D608, MA8120M, MAZ81200ML 12V 150mW zener(DIODE ZENER 12V 150MW SMINI2) _ open cct

D618 RF101L4S 400V 1A blown apart
R613 47K reads ok but burnt.
IC771 showing short O/P , 724,725 78L05 _ seem ok

IC773(bad),564 ok, 464,465 suspect_ TC7SH14F

IC521 M81707FP blown out

R521,522 100ohm 5% metal _ visually look ok but R521 is high at 108ohms, R522 appears open at 5.6K so both will need replacing.

IC561,562 appear to have not been shorted this time

New for me , opto PC601 has exploded

Usual scorched tracks

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Picked up a broken Rev AC 46" board. virtually no diiference between this and an AB 50" (G10) except placement of the inductors and a couple of caps.

Q601, RJK6026 shorted
Q661, RJP6065, shorted
Q441, 45G127 shorted
Q451, 45G127 _ shorted but not the same as 441, I suspect that when 441 is out this may be ok
Q701, MMBTA92 blown out
Q702, 2PD601 blown out
Q818, 2SK3018 could be ok
Q604 2SJ281 no short but i'm unsure still what they should do in cct. Not cracked apart like the last one
Q551 CPH5524_ shorted
D608, MA8120M, MAZ81200ML 12V 150mW zener(DIODE ZENER 12V 150MW SMINI2) _ open cct

D618 RF101L4S 400V 1A blown apart
R613 47K reads ok but burnt.
IC771 showing short O/P , 724,725 78L05 _ seem ok

IC773(bad),564 ok, 464,465 suspect_ TC7SH14F

IC521 M81707FP blown out

R521,522 100ohm 5% metal _ visually look ok but R521 is high at 108ohms, R522 appears open at 5.6K so both will need replacing.

IC561,562 appear to have not been shorted this time

New for me , opto PC601 has exploded

Usual scorched tracks

tracks blown off at D618, R613

Of the 3 inverter ICs 773,464,465. 464 on this occasion had 3.3ohms vcc-gnd. normally 773. all 3 are on the same 5v rail IC771

[Nick's Tvs]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I am currently attempting to repair my board, TNPA4782ab and I found that a lot of the components you talked about were also faulty on my board as I followed the same measurements as you showed in previous replies. However, I don't usually do many board repairs unless its basic Diodes caps, and or certain surface mounted components such as EEPROM chips, or fuses.
Because of the above statement, I have no idea where to buy these spare surface mounted diodes, IC's and or transistors. A few of the IC's I was able to find on ebay, but some of the transistors when typed in show up with a few different options. For example, RJK6026, I get RJK6026 and RJK6026DPP. What does the DPP at the end mean, and is there a difference? If so, which would I need?
Also I have no clue where to buy the surface mounted diodes. I have about 8 of them registering shorts, and the only symbols on them are K696 for 4 of them and the other 4 say 8897.
Thanks for the help.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I am currently attempting to repair my board, TNPA4782ab and I found that a lot of the components you talked about were also faulty on my board as I followed the same measurements as you showed in previous replies. However, I don't usually do many board repairs unless its basic Diodes caps, and or certain surface mounted components such as EEPROM chips, or fuses.
Because of the above statement, I have no idea where to buy these spare surface mounted diodes, IC's and or transistors. A few of the IC's I was able to find on ebay, but some of the transistors when typed in show up with a few different options. For example, RJK6026, I get RJK6026 and RJK6026DPP. What does the DPP at the end mean, and is there a difference? If so, which would I need?
Also I have no clue where to buy the surface mounted diodes. I have about 8 of them registering shorts, and the only symbols on them are K696 for 4 of them and the other 4 say 8897.
Thanks for the help.

DPP is merely the package type in Renesas speak I guess. needs to be TO220 Full Plastic casing.

As for the diodes, a little suprised you have not correlated 8897 which is actually marking 88 as the same as D618 mentioned in previous posts.

That also means K696 is in fact marking K6 made by Shingenden.

before you rush off and start getting bits, I'd remove the suspected shorted IGBTs first. then recheck the diodes, i suspect the K6 you refer to are in front of Q661/660.

Watch out for open cct pcb tracks where ever there is evidence of burning.

You could try UTSOURCE (will take weeks to arrive)or a kit but not just any kit. get a list together of what you find.

8 diodes sounds more than what i found but there's a number of ways these can fail I suspect. I would be more specifc with the info like exact locations.

i've only done 2 and only a small amount of info shared on self repair here.

[Nick's Tvs]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I took out

Transistors labeled 30G123 at locations Q421 Q422 Q423 all tested short

Transistor labeled RJP6065 at location Q661 and it tested short.
After taking it out, my SMDiode D673 and D674 labeled K696 are now working properly.

I have not taken any other transistors or diodes out. However the 6 SMDiodes that I am still registering as bad are the following:

D503
D522
D524
D711
D618 is physically burnt
D865 is located in front of, and is also shorted with D621 and D622 so it more than likely is ok, I just have to take D621 and D622 out of circuit to make sure. However the other 4 diodes were all located near the Q421 Q422 and Q423 that I already took out, and they are still acting weird.

Here are the following readings I get with the SMDiodes in circuit with my DMM on diode setting.

D503 Black on cathode red on anode .348v red on cathode, black on anode .353v
D522 Black on cathode red on anode .473v red on cathode, black on anode .726v
D524 Black on cathode red on anode .473v red on cathode, black on anode .726v
D711 Black on cathode red on anode .459v red on cathode, black on anode .641v

Back to non surface mounted diodes, I have D401 and D402 registering shorts,

I have Q401 on diode setting registering 0v between the emitter and collector, and .037v between the gate and the emitter and since the emitter is shorted to the collector, I get the same result on the collector. Measuring with both cathode and anode on gate, I am getting .037 both ways. On ohms I am getting 59.1 ohms between gate and emitter/collector.
Q402 right next to it is the same thing except I am getting .044v on diode setting between collector/emitter and the gate, and with ohms I am getting 70.8ohms.
Q403 emitter and collector shorted as well, but is giving me with anode on gate .568v on diode setting, and with cathode on gate, .993v.
In ohms I get about 47Kohms.
So I am not 100 percent sure what the deal is with those, but I am assuming Q403 is good but Q401 and Q402 need replacement.

D641 is showing on diode mode .338v going both ways.
Q601 shorted
Q441 shorted

So far this is what I found. I tried looking at some of the resistors near the transistors that went out, all tested good, I tried testing the IC's but then I realized I had no clue how to and decided to do that tomorrow once i have a chance to look over all of your back and forth replies once more to see how you tested them and what results you got so I can compare from there.

That's where I am right now, but I am going to take it slow and for sure will not plug this thing back in until I have a chance to test every single component on it haha.
However, I was able to find a few of the fets/diodes, and unless I want to pay $10 per component, I need to order from china, so I was hoping to start ordering some of those parts ASAP so I don't have to wait to long.
Also I have 2 of these exact same TV's with similar problems. This is the board that I have found has less problems, the other seems to have way more components that have gone bad, so I wanted to start on the easier one first.

Lastly here are all the locations and part numbers that I have found to be bad or think they are bad.

Driver IC M81707FP IC521 IC501 no clue how to test, but every repair kit has them and it seems like it went bad for you guys as well.
30G123 Q421 Q422 Q423
45G127 Q441
RFUS20-TM6S D401 D402
2pg011 Q401 Q402 Q403 these I am not 100 percent if all bad or if q403 is good
RF2001-TM3SW D621 D622 D641
RJK6026 Q601
RJP3034 Q621 Q622
RJP6065 Q661

Let me know what you think.
Thanks for taking the time to even read all of this, I know it's very confusing the way I presented it, I barely understand it when it's all separated out, but I have no idea how to properly organize it and what is connected together.

Thanks again

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I took out

Transistors labeled 30G123 at locations Q421 Q422 Q423 all tested short

Transistor labeled RJP6065 at location Q661 and it tested short.
After taking it out, my SMDiode D673 and D674 labeled K696 are now working properly.

I have not taken any other transistors or diodes out. However the 6 SMDiodes that I am still registering as bad are the following:

D503
D522
D524
D711
D618 is physically burnt
D865 is located in front of, and is also shorted with D621 and D622 so it more than likely is ok, I just have to take D621 and D622 out of circuit to make sure. However the other 4 diodes were all located near the Q421 Q422 and Q423 that I already took out, and they are still acting weird.

Here are the following readings I get with the SMDiodes in circuit with my DMM on diode setting.

D503 Black on cathode red on anode .348v red on cathode, black on anode .353v
D522 Black on cathode red on anode .473v red on cathode, black on anode .726v
D524 Black on cathode red on anode .473v red on cathode, black on anode .726v
D711 Black on cathode red on anode .459v red on cathode, black on anode .641v

Back to non surface mounted diodes, I have D401 and D402 registering shorts,

I have Q401 on diode setting registering 0v between the emitter and collector, and .037v between the gate and the emitter and since the emitter is shorted to the collector, I get the same result on the collector. Measuring with both cathode and anode on gate, I am getting .037 both ways. On ohms I am getting 59.1 ohms between gate and emitter/collector.
Q402 right next to it is the same thing except I am getting .044v on diode setting between collector/emitter and the gate, and with ohms I am getting 70.8ohms.
Q403 emitter and collector shorted as well, but is giving me with anode on gate .568v on diode setting, and with cathode on gate, .993v.
In ohms I get about 47Kohms.
So I am not 100 percent sure what the deal is with those, but I am assuming Q403 is good but Q401 and Q402 need replacement.

D641 is showing on diode mode .338v going both ways.
Q601 shorted
Q441 shorted

So far this is what I found. I tried looking at some of the resistors near the transistors that went out, all tested good, I tried testing the IC's but then I realized I had no clue how to and decided to do that tomorrow once i have a chance to look over all of your back and forth replies once more to see how you tested them and what results you got so I can compare from there.

That's where I am right now, but I am going to take it slow and for sure will not plug this thing back in until I have a chance to test every single component on it haha.
However, I was able to find a few of the fets/diodes, and unless I want to pay $10 per component, I need to order from china, so I was hoping to start ordering some of those parts ASAP so I don't have to wait to long.
Also I have 2 of these exact same TV's with similar problems. This is the board that I have found has less problems, the other seems to have way more components that have gone bad, so I wanted to start on the easier one first.

Lastly here are all the locations and part numbers that I have found to be bad or think they are bad.

Driver IC M81707FP IC521 IC501 no clue how to test, but every repair kit has them and it seems like it went bad for you guys as well.
30G123 Q421 Q422 Q423
45G127 Q441
RFUS20-TM6S D401 D402
2pg011 Q401 Q402 Q403 these I am not 100 percent if all bad or if q403 is good
RF2001-TM3SW D621 D622 D641
RJK6026 Q601
RJP3034 Q621 Q622
RJP6065 Q661

Let me know what you think.
Thanks for taking the time to even read all of this, I know it's very confusing the way I presented it, I barely understand it when it's all separated out, but I have no idea how to properly organize it and what is connected together.

Thanks again

Ok, straight up, that's a lot to digest and the 30G123 being shorted straight away that's more damage than i've been exposed too so would explain the additonal diodes bad gong by what's in the kits. It may be worthwhile analysing all the kits available as that can give some clues what's needed. Sounding like a large repair in terms of number of items needed.

may be worth looking at a repair service as it's a big task to take on but you don't learn if you don't try.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

D503
D522
D524
D711

I can get similar reading for forward but reverse i either get OL or it starts charging then OL

normally these fail short

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

D618 , seems typical and the tracks are probably fused too
D865 , I've seen this one mentioned in kits so i expect it will be bad
D621 , D622 if they're shorted I'd be rechecking Q621,622

reading the rest of the post, this is a big job, and this is the easy one!?

there's still a lot of stuff you have not mentioned that will be bad. hombre has a post on 1 he battled with

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

[QUOTE=Nick's Tvs;560507]

I have Q401 on diode setting registering 0v between the emitter and collector, and .037v between the gate and the emitter and since the emitter is shorted to the collector, I get the same result on the collector. Measuring with both cathode and anode on gate, I am getting .037 both ways. On ohms I am getting 59.1 ohms between gate and emitter/collector.
Q402 right next to it is the same thing except I am getting .044v on diode setting between collector/emitter and the gate, and with ohms I am getting 70.8ohms.
Q403 emitter and collector shorted as well, but is giving me with anode on gate .568v on diode setting, and with cathode on gate, .993v.
In ohms I get about 47Kohms.
So I am not 100 percent sure what the deal is with those, but I am assuming Q403 is good but Q401 and Q402 need replacement.


Traditionally these are in parallel so you'l just have to pull them out to see.

I tried testing the IC's but then I realized I had no clue how to and decided to do that tomorrow once i have a chance to look over all of your back and forth replies once more to see how you tested them and what results you got so I can compare from there.

If in doubt, replace. you'd be better off replacing the fet drivers, schmitt inverters, and voltage regulators etc than not. looks like optos and get blown on this board too


Driver IC M81707FP IC521 IC501 no clue how to test, but every repair kit has them and it seems like it went bad for you guys as well.
30G123 Q421 Q422 Q423
45G127 Q441
RFUS20-TM6S D401 D402
2pg011 Q401 Q402 Q403 these I am not 100 percent if all bad or if q403 is good
RF2001-TM3SW D621 D622 D641
RJK6026 Q601
RJP3034 Q621 Q622
RJP6065 Q661

don't forget about the pfet and the zener plus the opto that drives it. The 100ohm resistors for the signals to fet driver ic521, the octal buffers that send the signals through those located near sc20

[Nick's Tvs]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

tw2005, Thank you for the replies.

I will be ordering the parts listed above for now along with those SMDiodes to start with once I have removed them from circuit and made sure they are indeed bad.

As for the other information, I am not 100% sure what all the other components you mentioned are. You said I would be better off replacing the Fet drivers, schmitt inverters, and voltage regulators. Could you give me their location code on the board so I know where to look for those. I am not sure what they are supposed to look like.
What is optos? is that a component?
What are Pfets? Locations?
The zener diodes, well I honestly checked every component with the letter D in front of its numerical location, so I think I checked those unless they have a different prefix.
The octal buffers? never heard of that before, what is than and how do I check it?

Thanks for everything.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

tw2005, Thank you for the replies.

I will be ordering the parts listed above for now along with those SMDiodes to start with once I have removed them from circuit and made sure they are indeed bad.

As for the other information, I am not 100% sure what all the other components you mentioned are. You said I would be better off replacing the Fet drivers, schmitt inverters, and voltage regulators. Could you give me their location code on the board so I know where to look for those. I am not sure what they are supposed to look like.
What is optos? is that a component?
What are Pfets? Locations?
The zener diodes, well I honestly checked every component with the letter D in front of its numerical location, so I think I checked those unless they have a different prefix.
The octal buffers? never heard of that before, what is than and how do I check it?

Thanks for everything.

I think you better have a good read of this thread then because if you don't pick up on those parts which are identified and I've given part numbers you have no chance with the list you have now.

2 posts above your first I even have a list of some bits you don't have .

This is in an earlier post as a guide. If you miss the schmitt inverters, any bad voltage reg and smd transistors it will just blow

I'd jot down every part mentioned throughout this thread and any others, I'd also look at Glitchers threads to his work on the same board and also Hombre, search his thread, collate all the info and you'll have a more complete picture. I'd also search on Ebay and see what are the the really large kits, sometimes they give locations of the bits. Optos - opto couplers

Q661 RJP6065, shorted_..I've used a RJP63F3A which is the newer version .
replaced Q818 2SK3018, used 2N7002
Q702 2PD601 was short, IC773 TC7SH14F was shorted Vcc-gnd(41ohms),
Replaced Q701 MMBTA92

Replaced all 78L05 regs( they appeared ok) IC724,725,771
Replaced all TC7SH14F _ IC773 bad , others looked ok, IC464,465,564
Replaced TC7SH00FU - IC691 NAND
Replaced IC521 M81707FP, used M81737FP which is same pinout higher current output
Replaced Q551 ( looked ok)

Replaced Q660,601, RJK6026 ... I had none and used STP10NK60ZFP 600V 10A N FET.

Replaced D618,652 .. RF101L4S 400V 1A super fast rectifer.

[Nick's Tvs]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

tw2005

I had a chance to re-read every post and have a better understanding of this board now. Some of the info given earlier about certain bad components was wrong due to certain components shorting out others. Here is what I have replaced so far.

D618, and D865 located on the top left near Q622

Q661 Q621 Q622
Q601 Q401 Q402
Q421 Q422 Q423
Q441

Q451 registers a short between G and E. However it registers a short between those points even with the transistor out of circuit. I have checked D451 and get .455v and OL. I have checked R451 and get 5.6 ohms. Not sure what could be causing this one to do this.
I have replaced all the above, and now every component that is screwed into a heat sink is good to go, and every single larger surface mounted diode is also measuring good.

I have checked IC561 and IC562 and am getting 10 Mega homs between pin 10 and 20 and slowly the ohms decrease. So those should be good.

I checked R521 and R522, they measured about 49Kohms so I think they need replacement.

For the following, what measurements should I get:
Q876 Q647 Q701 Q702 Q818

Q551 I don't know how to measure it, all I can tell you is that the side with 3 pins are all shorted to one another.
Q604 has D and G shorted with it in circuit, I have not taken it out yet. I will update on this.

For the following I have no idea how to measure:
IC521 IC771 IC464 IC465 IC691 IC724 IC725 IC773 IC564

R613 and R869 measure at 42Kohms,
Zener diode at D608 measure good .706 and OL

Now to the Opto, I think that PC601 might be bad but I don't know how to test it. PC461 you mentioned how to test it, but I have no idea what pin is pin 5 and which pin is pin 6 and 7 and so on. How do I know which pin is which? I have tried 4 different scenarios with pin 1 being on each end, and none of the times could I get the same numbers as you did, so I think mine might be bad not sure.

I know I am throwing a lot at a time, and also requesting a lot of information, but I have browsed through this post several times, and got as much info as I could without losing my mind.
Thanks in a advance for the help.

-Nick

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

tw2005

I had a chance to re-read every post and have a better understanding of this board now. Some of the info given earlier about certain bad components was wrong due to certain components shorting out others. Here is what I have replaced so far.

D618, and D865 located on the top left near Q622

Q661 Q621 Q622
Q601 Q401 Q402
Q421 Q422 Q423
Q441

Q451 registers a short between G and E. However it registers a short between those points even with the transistor out of circuit. I have checked D451 and get .455v and OL. I have checked R451 and get 5.6 ohms. Not sure what could be causing this one to do this.
I have replaced all the above, and now every component that is screwed into a heat sink is good to go, and every single larger surface mounted diode is also measuring good.

I have checked IC561 and IC562 and am getting 10 Mega homs between pin 10 and 20 and slowly the ohms decrease. So those should be good.

I checked R521 and R522, they measured about 49Kohms so I think they need replacement.

For the following, what measurements should I get:
Q876 Q647 Q701 Q702 Q818

Q551 I don't know how to measure it, all I can tell you is that the side with 3 pins are all shorted to one another.
Q604 has D and G shorted with it in circuit, I have not taken it out yet. I will update on this.

For the following I have no idea how to measure:
IC521 IC771 IC464 IC465 IC691 IC724 IC725 IC773 IC564

R613 and R869 measure at 42Kohms,
Zener diode at D608 measure good .706 and OL

Now to the Opto, I think that PC601 might be bad but I don't know how to test it. PC461 you mentioned how to test it, but I have no idea what pin is pin 5 and which pin is pin 6 and 7 and so on. How do I know which pin is which? I have tried 4 different scenarios with pin 1 being on each end, and none of the times could I get the same numbers as you did, so I think mine might be bad not sure.

I know I am throwing a lot at a time, and also requesting a lot of information, but I have browsed through this post several times, and got as much info as I could without losing my mind.
Thanks in a advance for the help.

-Nick

The answer to this

Q451 registers a short between G and E. However it registers a short between those points even with the transistor out of circuit. I have checked D451 and get .455v and OL. I have checked R451 and get 5.6 ohms. Not sure what could be causing this one to do this.

I feel is answered by this

Q551 I don't know how to measure it, all I can tell you is that the side with 3 pins are all shorted to one another.

Replace Q551 & IC521. once Q551 is off, check those shorted q451 points, expect that will clear.

[Nick's Tvs]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Yes, once I removed Q551 the Q451 was no longer shorted. Perfect, and thank you for that tip. I also have purchased IC521 and am about to instal it in, however I do not have a Q551 available to replace it, I do want to make sure that I am correct on this, but CPH5524 is the proper replacement for it correct?

As for the Q876 Q647 Q701 Q702 Q818 transistors, how would I check them to know if they are working properly? I am assuming Diode mode, but what kind of readings should I be looking for with which lead on which pin?
Can anyone help me with this??

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Yes, once I removed Q551 the Q451 was no longer shorted. Perfect, and thank you for that tip. I also have purchased IC521 and am about to instal it in, however I do not have a Q551 available to replace it, I do want to make sure that I am correct on this, but CPH5524 is the proper replacement for it correct?

As for the Q876 Q647 Q701 Q702 Q818 transistors, how would I check them to know if they are working properly? I am assuming Diode mode, but what kind of readings should I be looking for with which lead on which pin?
Can anyone help me with this??

I usually just bell them out for shorts , but, not everything shorts.
pretty sure I'm repeating myself , but Q701 Q702 Q818 I would replace

Q876 I would leave, at worst it will just cause a blink code but will not damage anything as it's in the detection cct.

Q647, IC461 I'm not sure if they're likely suspects, I know I was clutching at straws and did them but on my second board, never touched them.

sometimes it's more efficient to replace than to try and work out if they're good and make an error.

With IC562, if r521,522 are open cct from high voltage back feeding from IC521 then it's a good chance although Vcc-gnd on ic562 is ok that it could be damaged.