Need help with a TV... - Videokarma.org TV - Video

PioneerGuy75 · #1 08-31-2007, 06:35 PM

Maybe someone can help me......

Just got a Hitachi BigScreen TV that has issues.

Hitachi 50" diagonal CRT rear-projection model from about 1993.
Great condition but...

Color doesn't seem to work properly. Mostly black & white and very dark during normal operation. However, in Picture in Picture mode the color works great in the small screen! Also in setup mode the colors appear fine.

I have been through the setup and picture menus and cannot seem to "adjust" it out.

Also it acts the same regardless of input...Tuner, Aux input are the same.
This tells me that is in the TV itself and not tuner etc.

Is this fixable? If so, what would it take?

Any input much appreciated!!

Cheers

Geoff Bourquin · #2 08-31-2007, 11:03 PM

I'm going to guess it is in the module in the middle of the signal board, About 6 inches long and an inch thick, enclosed in a metal case. There are some surface mount electrolytics in there that are probably bad. (4 of them I think).
Unsolder this module and remove it from the signal board, then open it up and replace these 4 caps. I usually just use a good quality radial lead cap rather than putting in new surface mount jobs. There is enough room if you are patient.
I hope I'm thinking of the same chassis as you are.

rcaman · #3 09-01-2007, 12:35 PM

geoff you are right about the comb filter board. but those caps can be a real pain to replace. a good tech has to be carefull with those tiny traces. steve

PioneerGuy75 · #4 09-01-2007, 01:50 PM

Thanks for the input

However, the color does work fine in the little PIP screen....and anywhere the little screen is moved looks fine.

I will look for that board today and see if I can see what you are talking about.

Many thanks!

PioneerGuy75 · #5 09-01-2007, 09:47 PM

Does anyone know if there is a way to switch this unit into a "Tech setup" mode where I can fine-tune convergence etc?

I have been through the setup mode in the main menu but no help.

Findm-Keepm · #6 09-02-2007, 07:46 PM

What's the Model/Chassis? Hitachi's Service manuals were free a few years back - HitachiServiceUSA website. I mirrored their website and got 19 Gigs of PDF manuals and training information for their TVs from 1983 to 2000. I may have the manual or training info in PDF here somewhere with all of the maintenance info.

Cheers

Findm-Keepm · #7 09-02-2007, 09:36 PM

I uploaded two 50" Hitachi models from 1993 to my website - I'll keep the link active until Tuesday evening, as I have to pay for excessive d/l bandwidth. Both chassis are in one manual and are large - 25megs or so.

Both are AP31/AP32 chassis, to my recollection the only projection chassis that year. Convergence information is in there, as is the rest of the service info. I'm no projection tech - just a resource for Hitachi Manuals.

Cheers

Findm-Keepm · #8 09-02-2007, 10:41 PM

Thanks for the quick PM - it's posted as listed in the PM.

Cheers

Duane · #9 09-04-2007, 02:44 PM

Quote:

Originally Posted by PioneerGuy75

Does anyone know if there is a way to switch this unit into a "Tech setup" mode where I can fine-tune convergence etc?

I have been through the setup mode in the main menu but no help.

This link states that the adjustments are inside the set vs. digital,onscreen menus.If you get a service manual, then it would show those controlls.

http://myweb.accessus.net/~090/how2adj.html#5.7

PioneerGuy75 · #10 09-08-2007, 09:01 PM

Quote:

Originally Posted by Geoff Bourquin

I'm going to guess it is in the module in the middle of the signal board, About 6 inches long and an inch thick, enclosed in a metal case. There are some surface mount electrolytics in there that are probably bad. (4 of them I think).
Unsolder this module and remove it from the signal board, then open it up and replace these 4 caps. I usually just use a good quality radial lead cap rather than putting in new surface mount jobs. There is enough room if you are patient.
I hope I'm thinking of the same chassis as you are.

Thanks Geoff

Well, now I am in DEEP.....I took comb filter module out, opened it up but don't recognize the caps you are talking about. If they are the "little metal cans" with a black stripe on one side (These are the closest cap looking components on here.), I count 20

How do I determine the value of these and more importantly, where would I get replacements ?

Thanks so much for your help, I am pretty familiar with electronic stuff but this is like "Micro-Surgery"

Thanks again for your assistance and hope to hear back soon.

PioneerGuy75 · #11 09-08-2007, 09:08 PM

A couple of pictures if it helps...

andy · #12 09-08-2007, 11:53 PM

Those are the caps you need to replace. They are labeled with their value and voltage, but it may not be very clear. Typically, the top number is the value and the bottom is the voltage. Use common sense 4.7-35 would be 4.7uF 35v (4.7 is a common capacitance, but not likely to be the voltage, and 35 is a common voltage rating). Similarly, 10-50 would be 10uF, 50v. The black stripe is negative.

You can replace them with ordinary caps if there's room. There's almost always a way to fit them in.