Main > Monitor/Video Forum

29" Makvision monitor shutdown and leaking capacitors?

<< < (3/3)

mamenewb100:
Thanks Shawn. Figured I could swap out the transistors and diodes in the same circuit as the FBT like Q40, Q41 and D43 in case they were weakened by the overvoltages. But I suppose that could be unnecessary other than the replacing the HOT. Maybe just flowing new solder to improve the joints would be best? I can get the flybacks meant for the Trisync monitors but have to order them from dodgy Chinese sites like AliExpress. Which could be a real gamble with unknown quality. Almost desperate enough to try though haha.

Still not 100% on which component is actually the HOT. Is it the small transistor to the right of the large one in front of the FBT? Been getting schooled on things like Snubbers, Damper Diodes, and Transformers. I'll probably need to fully learn all components on the board to really get a good idea of what's going on.

lilshawn:
the HOT is going to be the big one you linked in your photo above. (q40)

it basically takes the raw B+ (190vdc some odd volts) and switches it off and on to ground...through the flyback, producing the highvoltage for the tube. see super simplified pic.

it's a good idea to swap out the snubber diode, the flyback and the HOT. it appeared to kind of work in one of your pics, so i wouldn't worry about any pre-driver transistors upstream to the HOT, as they are behind a layer of protection.

Zebidee:
That is a great explanation lilshawn :D

Jomac:

--- Quote from: lilshawn on February 08, 2022, 11:24:42 am ---the HOT is going to be the big one you linked in your photo above. (q40)

it basically takes the raw B+ (190vdc some odd volts) and switches it off and on to ground...through the flyback, producing the highvoltage for the tube. see super simplified pic.

it's a good idea to swap out the snubber diode, the flyback and the HOT. it appeared to kind of work in one of your pics, so i wouldn't worry about any pre-driver transistors upstream to the HOT, as they are behind a layer of protection.

--- End quote ---

Just for future reference:
Nice simple explanation pic but you might want to flip the diode around, you have B+ going into the flyback and directly to Gnd through the diode, the HOT isn't going to be seeing anything.

Heken:
Hey OP,

Did you ever figure this out or have success?  I have the exact same problem with my makvision.  I know it's about to be a 3 year old post, but wanted to know if you had progress before I dig into my monitor.

Navigation

[0] Message Index

[*] Previous page

Go to full version