Toshiba 30HF84

[luke9511]

hello everyone my girlfriends parents have this tv and when you first turn it on there is no picture and there is a hissing sound coming from the inside of the tv, if you turn it off and on a few times the picture is awesome and there is no hissing sound.

im thinking the problem is the flyback as i have seen problems kinda like that in arcade monitors and i want to just make sure thats what it is. thanks for all the help and advice!

[randtek]

Re: Toshiba 30HF84

I doubt if it is the flyback itself, intermittent flybacks are very uncommon. They are generating about 30,000 volts, and from that level of stress, when they fail, they fail. I would look at the solder connection at the flyback, and I would also be looking at the input filter capacitor, C530, 1000MF 200V.

[RON_CET]

Re: Toshiba 30HF84

From what your describing sounds if your not hearing some issues coming from power supply noise i check and repalce c541 (2200 UF 10V) c542 (1000 UF 25V) attached is picture of 2 capacitor circled in red ...hope this helps

[luke9511]

Re: Toshiba 30HF84

From what your describing sounds if your not hearing some issues coming from power supply noise i check and repalce c541 (2200 UF 10V) c542 (1000 UF 25V) attached is picture of 2 capacitor circled in red ...hope this helps

sorry for the late reply but thanks for that when i get a chance i will take a look

[luke9511]

Re: Toshiba 30HF84

ok i just checked c541 and c542 and they are fine is there anything else i should look at?

[luke9511]

Re: Toshiba 30HF84

hey everyone i thought i would update this post, i still have the tv and have started to try and figure out the problem after being busy for so long,

i plugged it in and made a recording on my phone of the sound it makes and maybe someone might know what it might be,

also the picture is shaky when it is turned on, which makes me believe it is the flyback unless someone else says its something else after hearing the sound,

i can also record a video of anything on the tv if you need me too

http://www.mediafire.com/download/39...2/tv_noise.zip

[stj]

Re: Toshiba 30HF84

shaky horizontal or vertical?

[luke9511]

Re: Toshiba 30HF84

Horizontal

[R_J]

Re: Toshiba 30HF84

Try c407 ? there should be a cap. off the horz. drive transformer T401 primary, they sometimes caused problems. If not check the caps in the power supply, These usually don't buldge and leak they just drop in value. probably a lower uf one, like c518 c522

[luke9511]

Re: Toshiba 30HF84

What about the sound though that's something else that could cause major problems later

[stj]

Re: Toshiba 30HF84

check the connector to the scancoils for bad soldering.

you have a psu generating about 90-140v, called B+
this goes through the horizontal scancoil to the lopt via the horizontal drive transistor - probably a bu508a
that transistor is driven by an oscilator - often using a smaller pulse-transformer to obtain the current to drive the base of the transistor.

damn - love this retro-thread, not worked on crts for years!

[luke9511]

Re: Toshiba 30HF84

check the connector to the scancoils for bad soldering.

you have a psu generating about 90-140v, called B+
this goes through the horizontal scancoil to the lopt via the horizontal drive transistor - probably a bu508a
that transistor is driven by an oscilator - often using a smaller pulse-transformer to obtain the current to drive the base of the transistor.

damn - love this retro-thread, not worked on crts for years!

Off topic last CRT I worked on was a color vector monitor for a arcade game

[stj]

Re: Toshiba 30HF84

i'v done those, the wells-gardner ones.
and the b/w ones for battlezone etc.

[luke9511]

Re: Toshiba 30HF84

offtopic the one i worked on was for space duel i had alot of fun fixing it and learning how to solder

ontopic, ok i have the tv with me and have managed to look at the board, the sound is coming from either the flyback or some place really close to it, its real hard to pin point, here is a couple of pictures first one is just some stuff on the board with some black mark under them and second is something on the flyback might be normal im not sure also sorry for the bad pics i took them the best i could

[txsolutions]

Re: Toshiba 30HF84

hi everyone I don't know if this right way to post a question please can anyone help me, I need the bios for the Toshiba A300d.

thanks

[luke9511]

Re: Toshiba 30HF84

ok im guessing it might be a power supply problem which is hard has it is on the same board as the flyback, anyway i plugged the tv in and pressed the power button and for a couple of minutes tried to find where the sound was coming, well i couldnt find it, so i unplugged the tv and plugged it back in and right as i was about to hit the power button, it powered on on its own

[luke9511]

Re: Toshiba 30HF84

ok i had my fiancee listen for where the noise was coming from and she says it sounds like its coming from the part in the picture does anyone know what this is and where i can get a replacement?

[tom66]

Re: Toshiba 30HF84

That's the HOT (horizontal output transistor) for driving the flyback and horizontal scan of the TV. 2SC5904 is the full part #.

[luke9511]

Re: Toshiba 30HF84

That's the HOT (horizontal output transistor) for driving the flyback and horizontal scan of the TV. 2SC5904 is the full part #.

well there is a bit of a horizontal shake, could this be my issue? and do these go bad from time to time?

edit does anyone know of a suitable alternative replacement for it as i cannot find a place that sells this part

[tom66]

Re: Toshiba 30HF84

I wouldn't expect it to cause that fault, maybe some ripple on the B+? Don't know much about CRTs myself.