Toshiba TP48D51 proj TV dumpster find

[stj]

Re: Toshiba TP48D51 proj TV dumpster find

on the board F701 = fuse701

if in doubt - use a fast type.

[tom66]

Re: Toshiba TP48D51 proj TV dumpster find

F701/F702 is just the PCB "refdes" the same as calling a fuse "Charlie" or "Fred" it means nothing.
I would follow the manual rating if available, but if the fuse is printed differently, then I would use that over the manual.

T = Time-delay/slow blow
F = Fast blow

Fuse characteristic is important: replacing T fuse with F, while not harmful, is likely to result in nuisance fuse blowing.

[R_J]

Re: Toshiba TP48D51 proj TV dumpster find

If one of the fuses is open, one of the stk ic's is bad, The reason that all 3 colors are effected is that there is no voltage to one side of the convergence amp, either the plus or the minus is missing) Replace both ic's and the fuse (2amp) fast blow pico will work just fine.
f=fuse, r=resistor, c=capacitor

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Thanks. I do know the difference between slow-blow and fast fuses. I'm just not sure how things are designated these days and some terminology has changed since I was a bench technician.

I'm unable to find a service manual or schematic for this TV or for this board (Toshiba PB4613-2) although I found some related info for other models using similar boards. Nothing I've seen so far defines the fuses as F nor T type so I will err on the side of safety and use a fast fuse.

I did find some old info from another forum stating that a similar Toshiba 2-IC board (PB4613-1) using two STK392-020s do spread all three color channels across the two ICs:

"Q702 controls Green H & V and Blue Vertical."
"Q701, does Red H & V and Blue Horizontal."

http://www.tv-forums.com/forum/TV_Eq..._Shift_P12136/

If that's valid info it would explain how one chip blowing out could affect convergence on all three color channels. This is in reference to:

The fact that your distortion affects all three channels (six deflection channels) would, to me, suggest both ICs are bad. but I am not sure why both would go bad at once, it is odd.

I just saw your reply R_J. Thanks. And I mis-read that thing I pasted so nevermind. Maybe I'm getting too old for this.

Oh yeah, I forgot to say I will replace both chips and the fuse and update.

[R_J]

Re: Toshiba TP48D51 proj TV dumpster find

I looked for the manual but don't have it, only repaired one back in 2002. this is a bit of an odd model. Repaired a lot of 50h71, 50h72, 53hx71, 57hx81 etc.
This set uses a TAC9491 chassis.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

I appreciate the effort R_J, thanks. And thanks for the chassis # it may come in handy.

Any suggestions who to buy the STK392-020 chips from? I don't want to deal with ebay. I see them down around $10 and as high as $66.

[R_J]

Re: Toshiba TP48D51 proj TV dumpster find

You can also replace them with STK392-040, if you want, they will handle a little more current may be easier to find.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Thanks. I found them at Suburban Electronics in MD for $6.99 each and a box of five 2 amp picos for $2.99 and of course shipping is the biggest cost and I threw them an extra $1 for faster shipping. Total is $25.92 and should be here in 2-3 days.

I read at another site that sub'ing an 040 for an 020 might require changing the resistor values and to consult service info for the TV, which I don't have, so I went with the 020s.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

I got the parts delivered yesterday and am ready to work on the board. I think I can get the big chips out and new back in without removing the heatsinks. I've got some ceramic thermal paste I can use for the heatsinks. It looks like they used the white silicone thermal goo.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Success! The TV works perfectly fine now! Well, as perfectly as a rear projection TV can work anyway and much better than I thought it would. Thank you all for your help. You have made this much easier for me than I'm sure it would have been without your help. My daughter and wife are in love with this TV now and are making room for it in the living room.

[stj]

Re: Toshiba TP48D51 proj TV dumpster find

just so you know,
a lot of those things get thrown out by the arcade operators.
they get replaced by large plasma or lcd monitors.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Yeah yeah yeah ok, I'm not a tech snob or an arcade operator, so what do I care? I know it is old and obsolete but it was still fixed and is useful here and I'm just thanking the people here who helped me fix it quicker than if I tackled it alone.

[vinceroger69]

Re: Toshiba TP48D51 proj TV dumpster find

its another item saved from landfill etc so why not make use from it for a few while i like the challenge of fixing things myself and if i learn something whilst doing it even better i would of never been able to afford a plasma tv myself being out of work but a free one came up with the help of this site i fixed it for about £1.00 in parts and my time now its in my sitting room.

[stj]

Re: Toshiba TP48D51 proj TV dumpster find

Yeah yeah yeah ok, I'm not a tech snob or an arcade operator, so what do I care? I know it is old and obsolete but it was still fixed and is useful here and I'm just thanking the people here who helped me fix it quicker than if I tackled it alone.

i didnt mean it like that.
i meant if you ask operators they may give you some panels or tubes.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Oh, ok. I'm sorry I misunderstood. No worries. That's good advice actually and thanks. I wouldn't have though of that.

In test mode to align the convergence the green over shoots the red and blue by a tad on the outside edges when they're all ok in the center. I'm guessing that's fairly normal. There's no adjustment for the green. It isn't terribly noticeable with moving pictures and I've seen regular CRT TVs worse than that.

[R_J]

Re: Toshiba TP48D51 proj TV dumpster find

Doing a convergence on these sets can be a pain in the A55, I don't have this manual so I can't provide information on how to do it, it might be the same as a simular model. Its done through a service menu with the original remote.
If you do try adjusting, You must be carefull, It is possible to reset all the data and then you would not be a happy person.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Thanks for the info. It doesn't look that bad as is but if I find info on how to get it adjusted better I'm not afraid to try it.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

Being very curious I tired some things I read online to try to get into service mode on Toshiba TVs and got into some mode that displayed 4 lines of code at the top left of screen that meant nothing without the appropriate service info, there was no menu of any kind. I may be curious but not stupid, so I turned the TV off. No damage was done, it works the same. The convergence is not that terrible but I'd still like to be able to tweak it if possible.

Otherwise, in Test mode to set convergence I noticed at the bottom of the cross-hair pattern about 1/4" above the short horizontal line appears to be a reflection(?) of the short horizontal line. Could that be caused by dust on the lenses and/or mirror? I tried to get a pic but it didn't come out well enough to see.

[SteveNielsen]

Re: Toshiba TP48D51 proj TV dumpster find

BTW, in case anyone is interested the display showed:

ADDR DATA
160H 0EH
BINARY
00001110B

I know enough about programming to tell that it's saying 160 hex is the address location and 0E is hex for the 00001110 binary data.

How I got there was by pressing Mute on the remote 3 times, pressing and holding Mute and pressing Menu on the TV. According the the instructions I followed (some generic stuff for Toshiba TVs) that is supposed to produce an "S" at top right and one more Menu press takes you to the Svc Menu. Pressing Menu or Mute at the point I got to only displays RESET at lower right and nothing else.

[R_J]

Re: Toshiba TP48D51 proj TV dumpster find

Here is an excerpt from a TP48E50,I'm not sure if its the same but might help. Use at your own risk