NAP must have used some excellent CRT's in their sets - Videokarma.org TV - Video

radiotvnut · #1 01-29-2011, 07:38 PM

When I say NAP, I mean the Magnavox, Philco, and Sylvania brands of the '80's and '90's.

Today, someone gave me a '92 BPC 19" Magnavox stereo TV with A/V input jacks. It was dead and removing the back revealed a very nasty chassis, with 12 pounds of dirt hanging off the HV lead and nicotine all over the insides. I could also tell that the PC board had been very hot and there were many heat related loose solder connections in the set. That tells me that this TV has about 20 billion hours on it. This is the chassis that has the 100uf,200V cap, located behind the flyback, that always fails. This one was no exception and it took out the HOT, the TIP47 transistor in the regulator circuit, and the B+ fuse. Also, for some reason, one of the side plastic chassis mounting rails was missing. Replacing those parts (from junk boards) still didn't power up the set and there's a chance that the STR30130, which I don't have, may be bad and I seem to remember a small resistor and some other transistors in the power supply that would fry; but, since it's such a high hours set and knowing that no one would buy it even if I fixed it, I've decided not to go any further on repairing it.

Just for kicks, I decided to test the CRT on my B&K 470. Despite the high hours, the CRT still checks well into the "GOOD" area.

I actually have a little newer, and cleaner, Magnavox that was a victim of a fall and sustained damage to the shadowmask. Otherwise, the set works fine. I think I'll use the tube out of the nasty set in order to fix the better looking one.

Come to think of it, out of all the NAP sets that I've fixed, I don't recall seeing too many with an unusable CRT. I've seen a few weak ones that would come back after a light jolt. Most of these tubes have the EIA code for Sylvania on them and I think I remember reading somewhere that the main reason NAP wanted Sylvania was for it's CRT plant.

I'm certainly not complaining about the TV. It lived a hard life for 19 years and could probably be made to live a few more years if I wanted to go to the trouble of finding out what's wrong with it. Let's see if these new flat screen TV's can hold up as well.

DaveWM · #2 01-29-2011, 07:55 PM

my 91 WGPC maggie also has a great pic, gets mega hours on it. I too tested the CRT, very good and excellant tracking. Being a non smoker, the set is remarkably clean inside but for some dust that I blew out. this is the one that had the bad HOT. the pcb looked perfect, and I tested most of the E caps (out of circuit with old school cap tester) all tested like new. I guess I got lucky and got one before the big decline.

radiotvnut · #3 01-29-2011, 08:04 PM

NAP held it together until the late '90's; and, by the early 2000's, they had really gone down the toilet. If you ever see a silver cased Magnavox TV on the curb, it would be best just to leave it there.

bgadow · #4 01-29-2011, 10:36 PM

The older Sylvania crts didn't seem to hold up well, but I too have noticed the EIA # and the fact that the NAP-era stuff holds up well. Now: NAP consolidated TV production in Greenville, TN. Was the Sylvania crt plant in Batavia, NY, and was it moved right away to TN? Maybe things improved with the move? Inquiring minds!

radiotvnut · #5 01-29-2011, 11:16 PM

Quote:

Originally Posted by bgadow

The older Sylvania crts didn't seem to hold up well, but I too have noticed the EIA # and the fact that the NAP-era stuff holds up well. Now: NAP consolidated TV production in Greenville, TN. Was the Sylvania crt plant in Batavia, NY, and was it moved right away to TN? Maybe things improved with the move? Inquiring minds!

I've noticed the same thing. I have a '79 Sylvania Superset console that uses a delta gun black face CRT; and, it is weak. This was a very low hours set that I got from a Sylvania dealer (probably a warranty return). I've got a good Zenith CCII CRT to go in it.

And, Sylvania made a lot of B&W tubes for Zenith. I've seen a lot of these that were either weak or dead.

I think the old Sylvania plant in Batavia was closed right after the NAP buyout in '81 and production was moved to Greenville, TN.

ctc17 · #6 01-29-2011, 11:28 PM

I don't know if this has anything to do with it, but the filaments in those crts glow very dim. You can barely see them where as the old round color and bw filaments are like light bulbs.
I notice the round tubes I had rebuilt by Hawkeye also glo very dim. He told me his rebuilds would last 50,000 hours like those 90s tubes.

AUdubon5425 · #7 01-30-2011, 12:08 AM

I think Batavia was closed or perhaps just doing final assembly by the time of the sale to NAP. Chassis were being built in Juarez - tubes, transistors and yokes were made in Penna. They had a big CRT plant in Ottawa, Ohio that (I'm pretty sure) stayed under GTE. How long the CRT plant in NY survived i"m not sure - there were heavy layoffs there in the mid-70's.

analog · #8 01-30-2011, 01:06 AM

Our daily watcher is a 21 year old 27" Philips that I believe came off the Magnavox assembly line. It has had 2 minor repairs but still has a great picture and is going strong. I seriously doubt a new flat screen would last anywhere near as long...

rcaman · #9 01-30-2011, 10:37 AM

r432 1k ohm will be burnt. steve

radiotvnut · #10 01-30-2011, 01:31 PM

Quote:

Originally Posted by rcaman

r432 1k ohm will be burnt. steve

Thanks for refreshing my memory!

radiotvnut · #11 01-30-2011, 05:28 PM

The resistor was the problem. And, I remember replacing that part in the past. I guess I just had a memory lapse combined with not really wanting to work on it in the first place.

At first, the picture was too red; but, it looks decent after adjusting the CRT bias and drive controls.

Now, I guess I'll add it to the collection of other BPC sets that no one is making an effort to buy.

mbates14 · #12 01-30-2011, 06:13 PM

i have a magnovox TV with the same chassis as a bedroom TV. with the 100uf 200v cap, etc etc. had to replace that cap twice, and then rebuild the regulator circuit after it fried.

And there was a 3.3uf 63v cap i think it was, it was dried out as well .

But you are right. the picture still looks like new, and looks better than any LCD/Plasma i have seen thus far.

jeyurkon · #13 01-30-2011, 07:49 PM

I must be the only person who doesn't know this. What's NAP?

radiotvnut · #14 01-30-2011, 07:55 PM

North American Philips

eberts · #15 01-31-2011, 09:19 PM

EIA 312 tubes.
Slyvania manufactured their own electron guns in Ottawa, Ohio. Their guns were different from RCA and Zenith's.
Slyvania used what is called a "soft" cathode coating, designed for fast and easy processing on Delta and 36mm inline guns. They were not designed for long life.
The Zenith and RCA electron guns used a "hard" 4% tungston cathode coating which required better processing techniuqes.