1990 Zenith Sentry SS2505TR - Videokarma.org TV - Video

AUdubon5425 · #1 03-09-2009, 10:34 PM

I brought home a low-end Zenith console TV last week, an SS2505TR9 made in Aug. 1990. It uses the 9-914 module and an A63ADG31X crt. The lady who gave it to me said it was working until a power surge earlier this year.

The first thing I noticed was that the fuse was blown. Replaced it and when I plugged it in I heard a pop. The fuse didn't blow but it's dead to the world. I tested the fusistors and the diodes around the power supply and they check out okay. The 117v ac is coming through the cord to the board, but I have very low voltage at the fuse.

I got this set to fool with because I have never worked on anything this new. I ordered a Sams for it ($22) since no libraries around me subscribe to their service. I'm looking forward to figuring this out.

Ironically, an ad popped up this evening for a free non-working Zenith that looks identical to this one in the picture. I'll probably get that one too and hopefully make one good set from the both of them.

radiotvnut · #2 03-09-2009, 11:06 PM

I just sent you a PM; but, I just made another observation. There appears to be a burn mark behind the white degaussing relay, close to two power resistors. I believe that is where the power supply driver transistor is located. If it's blown, you can bet that the STR53041 regulator (on the heatsink) is gone as well. Also, there are three low ohms resistors in series that are in the regulator circuit. IIRC, one is a 47 ohm, the other is a 15 ohm, and the other a 10 ohm. I'll have to dig up the schematic to double check. I think MAT electronics sells a kit that contains the regulator, the transistor, the resistors, and a couple caps.

Another thing that can cause power supply failures in these sets is a shorted CRT. Bad CRT's were very common on these sets and got to be very, very, very common by around '93.

Carmine · #3 03-10-2009, 09:29 AM

Expect everybody and their brother to chime in and tell you the set is junk because of the CRT... I contend that the bad CRTs had to start at sometime after 1990, based both on my own daily-watcher since-1990 set:

And the number of late 80s monitor-style Zeniths that I've trash picked with good CRTs and bad power supply caps. I think these sets produce an excellent picture with nice dark blacks.

No doubt the CRTs were junk at some point in the early 90s. I'm going to guess 1992-ish.

bgadow · #4 03-10-2009, 12:21 PM

Coincidence! Sunday I was given a Sentry 2 console from '92. I don't recall the chassis # off the top of my head but it is very similiar in build. The owner said it had become intermittent, and would work if slapped hard. It was dead to me; found a blown fuse. I am concentrating on the area around that largest capacitor; to the left there is a transistor and mine, no lie, is blown apart! Half of it is missing. There is a small resistor adjacent which looks a little crisp. My thought is to replace that cap and the resistor/transistor-but I'm not sure if I want to bother with it. I will certainly have to give this TV away even if it works perfectly. AUdubon, if I was in your neighborhood this would be a third set for you to use! Anyway, I'll follow this thread and see what I can garner from it.

radiotvnut · #5 03-10-2009, 12:37 PM

Quote:

Originally Posted by bgadow

Coincidence! Sunday I was given a Sentry 2 console from '92. I don't recall the chassis # off the top of my head but it is very similiar in build. The owner said it had become intermittent, and would work if slapped hard. It was dead to me; found a blown fuse. I am concentrating on the area around that largest capacitor; to the left there is a transistor and mine, no lie, is blown apart! Half of it is missing. There is a small resistor adjacent which looks a little crisp. My thought is to replace that cap and the resistor/transistor-but I'm not sure if I want to bother with it. I will certainly have to give this TV away even if it works perfectly. AUdubon, if I was in your neighborhood this would be a third set for you to use! Anyway, I'll follow this thread and see what I can garner from it.

I suspect that the intermittent problem was a shorting picture tube. I suspect that the STR53013 regulator is shorted along with the blown apart transistor and smoked resistors. You'd probably be better off to toss this one. I used to get a lot of these sets from the local Zenith dealer with these parts blown. I'd replace them just to sell the set and have it come back in a week with the parts blown again due to an arcing or shorted CRT. And, those CRT's usually will not check shorted on a CRT tester. I just finally got to the point where when a Zenith came in with those parts blown, it went straight to the trash.

AUdubon5425 · #6 03-10-2009, 04:46 PM

I have downloaded the schematic from Sams, and am having a friend of mine print it out on 11x17 paper so I can read it. I'll have it tomorrow and will keep y'all posted on what I find.

bgadow · #7 03-11-2009, 02:10 PM

Quote:

Originally Posted by radiotvnut

I suspect that the intermittent problem was a shorting picture tube. I suspect that the STR53013 regulator is shorted along with the blown apart transistor and smoked resistors. You'd probably be better off to toss this one. I used to get a lot of these sets from the local Zenith dealer with these parts blown. I'd replace them just to sell the set and have it come back in a week with the parts blown again due to an arcing or shorted CRT. And, those CRT's usually will not check shorted on a CRT tester. I just finally got to the point where when a Zenith came in with those parts blown, it went straight to the trash.

Glad to hear your experience...I'll give it one more once over and probably junk it. If anyone wants the chassis, etc, just let me know.