RCA Proscan PS27123

[Phil Nelson]

We have an RCA Proscan 27" PS27123 TV, purchased new in 1997. Worked fine with no service for 15 years and now the picture suddenly went dark. Audio still present.

I'm more familiar with 1940s TVs than this new-fangled stuff, but last year I was able to resuscitate my 1980s Sony KV-1311CR without setting the house on fire, so if this one's repairable, that seems preferable to recycling it.

If anyone is familiar with this critter, are there any obvious weak points or gotchas to look for?

I have the Sams manual, set 3864.

Thanks!

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[radiotvnut]

Do you have HV at the CRT? Also, is the CRT filament lit? There is a small resistor in the CRT filament line that will open, causing a loss of voltage to the CRT filament.

[Phil Nelson]

Thanks, that gives me a starting point. Now I need to figure out how to lug this whale down the stairs and into the workshop!

Phil Nelson

[Phil Nelson]

Originally Posted by radiotvnut

Do you have HV at the CRT? Also, is the CRT filament lit? There is a small resistor in the CRT filament line that will open, causing a loss of voltage to the CRT filament.

You may be correct. I have plenty of HV, no filament voltage to the CRT. I found that resistor: 3 ohms, 3W wirewound, at the rear edge of the main board, so I may be able to sneak in my iron and replace it without pulling the board.

The challenge will be finding a local place that sells such a resistor. I hate making an online order for one 20-cent part!

Phil Nelson

[Phil Nelson]

I saved the 20 cents after all. That resistor wasn't open, just intermittently attached on one end. Resoldering did the trick.

Thanks for the tip!

Phil Nelson

[holmesuser01]

Isn't it fun when it's something incredibly simple?

If it was mine, I'd be looking at the soldering allover the board, especially around the flyback transformer, horizontal output transistor, and yolk plugs. Anything that looks discolored and dull. I love soldering. I HAVE the patience!!

[radiotvnut]

Looks nice! There's something else I should have told you to replace while you had it apart. On the front right hand corner of the chassis (power supply area), there are four electrolytic caps. When they fail, the B+ will run high and the horizontal output transistor will sometimes short. I'm not certain of the values; but, I think they were 2.2, 10, 47, and 470 uf. The 2.2 and 10 uf caps are located next to the regulator driver IC. The 47uf cap is located close to the heatsink mounted chopper transistor and the 470 uf cap is located in front of the IC.

[Eric H]

Phil, do you have GWTW going 24-7 at your house?

Speaking of the CTC169 I repaired one with some guidance from the people here (radiotvnut was that you?) it was the IC and caps mentioned above as I recall.

[Phil Nelson]

I didn't have it all the way apart, just removed the top & back covers and sneaked my iron under the edge of the main board to resolder that resistor. I haven't really bench tested the set yet. If it fades or looks funky, maybe I will pull out that board and deal with those electrolytics.

GWTW is great for a quick screen shot because there's a big closeup of Scarlett one or two minutes into the very first scene. It's not even my favorite movie -- I'm just lazy!

Phil Nelson

[old_coot88]

I forget what makes of sets were involved, but at least twice in my illustrious career, i either jumpered or reduced value of that resistor to boost emission on a weak gun.