Another Sanwa 29E31 gone

[davidcoolman]

Dear All,

After leaving my racing cab on for three days, i realized that screen was off.
Now i can hear a faint magnetizing noise on power on however screen does not produce static electricity or noticable neck glow.
Bets open monitors gurus: where to start please, dead flyback?

Btw, I would trully love to have a diagnose flowchart as for ms9: https://gamerepair.info/images/62_nanao_ms9_29 but although "popular" monitors, documentation on these is scarce.
Thanks for insights.

 

[Mukuro_W]

First of all go check the HOT, 2sc5143, this often fail as well as a voltage regulator and a fuse resistor 039 ohm near the flyback. Unluckely the 2sc5143 often become very hot due to an error in the original chassis project, basically they not calculate well the H stage and it go easily open and It Is Not the Flyback wich fail in another way but not taking the HOT! ....

 

[davidcoolman]

thanks for thre input Mukuro_W. will check after office hours and report back.
Would you mind contributing to the troubleshoot flowchart if i start a thread? this step is amongst the most upstream but we could start to populate...

 

[davidcoolman]

So HOT was bad. shorted all the ways.
@Mukuro_W i guess you mentionned the R456 tha is 0.39 Ohms neear the Flyback.
Reads ok (0.4-0.5Ohms) in circuit but will desolder a leg "just in case"

i need precisions on the voltage regulator that could be faulty. i dont want to blow another HOT.
is it the Q408, a 2SK525 Mosfet, Q435 a 2SC1959or Q346 a 2SA562?
thanks again


EDIT: if R546 was blown? what would be causing that besides HOT failure? any other possibilities. (I have another junk chassis that has this resistor swaped by previous owner and still showing severe signs of burn)

 

[davidcoolman]

Damn CRTs.
after putting back chassis under a monitor heard a small bang noise.... non noticable damage but i fear something left...
now heater is on but screen wont magnetize. after plugging input nothing but after removing it a sort of Horizontal collapse shows up.
so next... FMV-3GMR or flyback

any other tests that would prevent (me) blowing more IC's would be greatly appreciated. Thx

 

[davidcoolman]

need precisions on the voltage regulator that could be faulty. i dont want to blow another HOT.
is it the Q408, a 2SK525 Mosfet, Q435 a 2SC1959or Q346 a 2SA562?

hello @Mukuro_W and others, any inputs would be appreciated... gaming night planned

 

[davidcoolman]

dear all, i changed the flyback with new one and get nimilar results black screen with source followed by vertical line when i remove the source.
The only thing i know is flyback was ok. can anyone give me correct readings for c5143 please?

 

[davidcoolman]

First of all go check the HOT, 2sc5143, this often fail as well as a voltage regulator and a fuse resistor 039 ohm near the flyback. Unluckely the 2sc5143 often become very hot due to an error in the original chassis project, basically they not calculate well the H stage and it go easily open and It Is Not the Flyback wich fail in another way but not taking the HOT! ....

Dear @Mukuro_W I installed a new hot which instantly got fried so i really want to identify the othe component that causes that.

In summary overheat -> HOT gets bad and fries something else that will in turn short the HOT again....
thanks again for your help

 

[Mukuro_W]

Check the polyester capacitor on the HOT collector, sometimes those test good but they are not once the power is on. Also check the diodes and resistors in this line.

 

[davidcoolman]

will check D401, The FMV-3GMR and the plastic capa C416 / C417 and R417.
I noticed on the underneath of the pcb, traces of heating from power supply all the way to the HOT

Firstly nearby R810/C810 then on the secondary at R842 and Q827

more intensely again on the secondary near the P901 connector

and from Q827 leg "1" one can pretty much follow a smoke trace to J31 then to J40 and J36 that leads to flyback, D401 and Q412

Doest it provide any hints?
After fixing the damn monitor i plan to install it with a 12v Fan on top of the large heatsink

 

[davidcoolman]

Check the polyester capacitor on the HOT collector, sometimes those test good but they are not once the power is on. Also check the diodes and resistors in this line.

C416 C417 and C422 tested fine, so is D401. another HOT is down...