Best Source for TV Schematics??

Hello Jim,

Hey, since you kill bugs with freeze spray I guess it's time to try it on the TV. It could be as simple as an electrolytic having become marginal. Freeze spray is how I found out what caused our little PAL standard TV to lose PLL lock. I really had to fix that one because we can't buy them here and it's our sole source to watch old European tapes.

In the old days (meaning >20 years ago) I had good luck by writing directly to the manufacturer. Nowadays many schematics are sold via "service manual providers". Don't know what the fees are but a pdf download shouldn't be too bad.

Probably a defective electrolytic capacitor. Buy a can of freeze spray too cool down components and start cooling down electrolytic caps near heatsinks. I bet the culprit is close to the HV transformer.

Does slamming the TV help? If yes, check for loose soldering joints.

A schematic is not going to help. A basic understanding on how a TV works and a not so expensive analog oscilloscope are more usefull.

HV? In an LCD flat-screen ?:-)

I have been known to completely re-solder a board... successfully ;-)

Duh! I grew up in a radio/TV repair shop ;-)

Finding things on a dense board becomes problematic.

It has an external 15V/4A "power block". I'm beginning to be suspicious of that.

...Jim Thompson

There is no reason to be leery of the rusky sites. Get your schematic, and move on.

Televisions are wonderful devices. When they fail, it is almost always a bad solder joint, or a bad electrolytic. Some times there is some collateral damage that results from the failure.

Get an ESR meter, and you can check all of the electrolytics quickly.

Freeze spray sometimes helps, but for intermittent, I usually use a fiberglass stick, and tap here and there until I get a response. I found a bad solder joint in a 25 year old sony just yesterday, that way.

-Chuck Harris

Hello Jim,

Well, they generally do have a high voltage converter for the CCFL tubes. Not tens of kV but a few kV. I don't know what you mean by "washed out" though.

Same here. And certainly not with RoHS compliant solder. I can already see myself resoldering RoHS stuff to get it back to non-RoHS performance.

And figuring out what that highly unobtanium full-custom chip does that reacted to the cold spray.

Easy. Hook a digital scope to it and let it log the 15V in slow motion. Or use a bench supply and see if the TV repeats the error.

Loss of contrast.

Doesn't seem to (at least coherently) respond to "slamming".

Bought this set the day of 9/11 so I could keep track of happenings without leaving my desk... I was in the midst of a big project. So I doubt if it was built to RoHS.

Natch. I probably should just go buy a new set and forget about it. The replacement AC adapter alone is $126 :-(

Unloaded it's bouncing around. I'm going to rig up a "T" so I could watch it while loaded.

I'd use a bench supply but, in my world, 4A is unheard of. All I have is small supplies good to 300mA.

...Jim Thompson

Hello Jim,

That could be a CCFL tube going (or the switcher feeding them).

I just meant the stuff that's coming. With the EU having gone crazy about RoHS there will be lots of electronics gear shoved onto our market that is compliant. And that might not be a good thing.

I have seen a small LCD 14-inch TV at a big store (Walmart?) for about $250. It didn't quite have the contrast that our outdoors tube set does.

That is not a good sign. Either shot or of poor design.

A fully charged car battery might work if the set is happy with about a volt less. Assuming this is a 15" set I am surprised it needs a 60W supply.

My two cents: Toss the TV. The world of network TV that you and I grew up with is gone. The last universally shared experience of US culture was watching the 9/11 damage over and over again, and we saw enough of that 5 years ago. What we're left with is a bazillion channels of HDTV nonsense.

Use the space formerly taken up by the TV to buy some ex-soviet military technology (maybe not the same sites, but maybe adjacent ones!) to sit in your office. On E-bay there's a lot of interesting stuff coming out of Ukraine/Georgia/Russia right now.

Tim.

It's 16" letter-box.

...Jim Thompson

What? And not be able to watch Fox News ?:-)

...Jim Thompson

Hello Jim,

Wow, wonder why it needs so much more juice than a CRT set.

Regarding power, check this out:

It's our CA power grid supply-demand situation on a scorcher day (by non-Arizonian standars). Under our previous governor the green supply side line would often have continued flat at 11:00am and it seems we would have lost electricity by 12:30pm.

Hello Jim,

There is always Rush...

Is that the channel that the Huntley-Brinkley report is on now?

Tim.

I dont have a TV, almost 4 years now, but I see the UK is going even more down market with imported US crap

OK well, it is Arnulds pitch

martin

I'm old enough to remember Chet and Dave as *the* standard for news casting.

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

I allways ran over to the local library. There is one not too far that had a pretty complete Sams on hand. A couple of dimes in the machine and I was off.

Cheers

Looks like the Conserv-o-meter is saying something. Maybe its time to turn off the Christmas Lights?

Cheers

I remmber when they won some award, and Carol Burnett was hosting that particular presentation, only weeks after they'd had a "Huntley- Brinkley" parody on the Carol Burnett show, and when she opened the envelope, she grinned from ear to ear, as only she can do, and proudly announced, "Buntley-Hinkley".

Cheers! Rich

Not a lot, *all* will be RoHS. Every electronics component manufacturer on the face of the earth is in the process of converting over. Anyone that introduces lead products into their factory supply stream is going to be assumed to be making non RoHS compliant parts.

The Euronation is going to be single handedly responsible for the destruction of electronics. We are going to see reliability shoved all the way back to where it was during the tube era.

Tin whiskers were fun when they first showed up in through hole electronics. Imagine how much more fun they are going to be with the fine lead pitches used today! You used to have to wait until the whisker grew about 1/10th of an inch before you had a problem. Now, it has to grow only 1/8th that far.

-Chuck Harris