CurtPalme.com Home Theater Forum

[JustGreg]

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Old(er) Hitachi RPTV, chassis p/n: AP73X-028201.

I first started having jumping image problems about 6 months ago until the set warmed up for 10 mins or so. I figured it was just a bad solder joint because it worked fine after warming up so let it go for lack of time to get to it.

Last week the set started doing something new. It would power on but the image would only pop up for a split second every 60 seconds or so. The image wasn't distorted in any way and came up immediately as opposed to coming back slowly out of focus or shrunken.

I benched the chassis, inspected it thoroughly (Manuf'd 1997 and there isn't one bad/bloated/leaking cap!!) and reflowed a couple hundred joints; focusing on the PS area and the signal input daughter board. I was happy when the set powered up to a stable good looking image; but....everything is in black and white regardless of what input I use. (S-VID, composite, rear or front panel) The onboard menu color is right and the Magic Focus (convergence) converges each color as it should.

I'm going back over the input board (Terminal PWB p/n JK03591-D) with a magnifying light to look for whiskers or bridging while waiting for (hopefully) someone to post.

I only have to keep this thing alive a little bit longer (a couple months) as the wife is leading the charge to get a 21st century replacement, but the $$ won't be there until early spring.

Thanks in advance folks.

EDIT: I have a schematic now.

[macgyver655]

Start with c719 and c724.

I'll check Hitachi later for any bulletins.

[macgyver655]

According to Hitachi this chassis did have some common video issues including what you are describing.

The culprits are:C719, C724 (as already stated), IY01, IX01, XX02 and XX03.

Those parts should fix it if you didn't find any bridged solder.

[JustGreg]

Hi Mac how are ya?

Thanks for replying...I was hoping you would.

I didn't find any solder bridges or whiskers. I did find a couple poor solder joints (my bad...did it on the kitchen table and the lighting isn't great). Still no joy after however. Still B&W.

From what I read pin 13 at I501 is resonsible for providing chroma. The svc manual said to check for a signal there to work through the troubleshooting flow chart. I don't have an Oscope so not much I can do in that regard. I'll check the caps you suggested and parts availability for the others tonight when I get home from work.

BTW, I501 is a Toshiba TA1222AN on the Signal Sub PWB, an obsolete part. I suppose the heat from quick soldering could have been enough to push it over the edge given the age of the set.

Thanks Mac! I'll let you know how it goes.

[macgyver655]

The parts i listed should be the problem. Of course like everything else, you wont know until you replace. Some of those parts aren't cheap either. 33.56, 20.82, 4.82 and 1.83. So you have some deciding to do. You could always try the cheap stuff first.

[JustGreg]

Man it's sure easy to see that you're IN with pricing...I just spent an hour looking for the IC's and got lucky only with IY01 (IC CXA1545AS) from audiolabga.com for $12.00. No luck checking the usual vendors (DigiKey, Mouser, etc) for the TC90A13N.

One interesting thing to note: The TC90A13N (as you know already) is a Y/C Seperation IC, to seperate Y/C from NTSC composite signals. The cable box we just got from TW is HD but dumbed down to composite to feed the 'ancient' Hitachi set. The new box doesn't offer S-Vid and the set is to old for component. I just went out and fed the set an S-Vid from a Panny DVD player and it's still lacking chroma so not sure if this info would cause/help tunnel down more.

(Researching chroma was more than my tired brain could get itself around but XX02 (LC Filter @3.58MHz) is definately married to NTSC chroma via very old television 'rules'.)

Where did you find the parts/prices you noted earlier?

Thanks again. This is fun!.. and because the wife is wanting a new set a lot of pressure is off me not to hose this thing while putzing with it.

[macgyver655]

Greg. The fact that there is still no color with S video merely helps confirm a possible problem in the ABL circuit, which is where those 2 caps I posted apply.

All the parts I listed were confirmed fixes for problems like yours on this specific chassis. The parts were also actually listed on Hitachi's pro site for techs as confirmed repairs. And Hitachi does not normally list repair solutions unless it is a wide spread and common issue. There are very few solutions on their site.

The caps you can get from where ever you want. Here are the other parts if you decide to go forward.

CXA1545AS: http://www.partstore.com/Part/Hitachi+Ltd/Hitachi/2020452/New.aspx

TC90A13N: http://www.partstore.com/Part/Toshiba/Toshiba/B0410800/New.aspx

BJ00141: http://www.partstore.com/SearchResults.aspx?q=BJ00141&SearchTerm=True

BJ00112: http://www.partstore.com/SearchResults.aspx?q=BJ00112&SearchTerm=True

[JustGreg]

Thanks for all the legwork Mac. It's sure appreciated.

I've also been fishing for myself and found a couple of the components but they're mostly in China...with shipping taking anywhere from a week to 6 weeks. My attention span isn't long enough for those delivery times.

The caps I already have so I'll go ahead with them first obviously and let you know. I need to get it fixed because I've run out of black and white jokes to keep the wife entertained; for food commercials I used variants of "Yeah but it looks bland honey", or Minolta and HD TV commercials, "Yeah but their stuff is so old school; it's all in B&W".