Here's all the info listed on the back of the TV:
http://i40.tinypic.com/b4iaoj.jpg

I press the power button, and I hear the degaussing circuit, as well as a faint hum in the speakers. I do not hear the CRT scanning. The TV shuts itself off a few moments later.

Doing a google search, it appears this problem is fairly common with this model, but alas, there are quetions but no answers, other then "buy a new TV".

Do you guys have any ideas?

Sounds like a shorted HOT.

Okay. I'll check the HOT as soon as I can... having a 36 inch Sanyo that also had a bad HOT, I believe you... and I'll check the caps around the HOT.

Sounds like a shorted HOT to me as well. If it uses an STR30130 or similar voltage regulator IC, it may be bad also. You could also have a bad flyback; but, they are inexpensive and this set would be worth a new flyback if it's not beat up.

Yeah, try to find out what blew the HOT if it is indeed bad. Radiotvnut has it right, the regulator could also be bad.

OT: Interesting how my '85 Sanyo and your '94 are both built in USA with Japanese parts. I know Matushita Quasars were the same.

I forgot to mention that there's a resistor in the regulator circuit that may be open. Years ago, I fixed a 19" Sanyo from the same time period that had a shorted HOT and voltage regulator. After I replaced the parts, the set played; but, the B+ was low and unregulated. There was a 1 or 2 watt power resistor connected to the regulator that was open. I don't remember the exact value; but, there are few parts in those STR30xxx based regulator circuits, so finding the problem shouldn't take too long. Frankly, they should have stuck with that type of regulator. They are simple, cheap, and easy to troubleshoot. I can't say the same for the much more complex switching power supplies used in newer electronics.

All right. I'll check the HOT and everything around the HOT that I can.

I see an STR30130 IC How do I test to see if it's bad?

You can check between all of the pins with an ohmmeter to reveal a shorted device. Otherwise, you'll have to get the set to stay on and check the B+ voltage.

One other thing. If there's an electrolytic cap in B+ line, check it. It will have a voltage rating of at least 160 volts.

The HOT (D1879) is certainly bad. low ohm readings on all three pins. Good news is I'm certain I have a better HOT to throw in.

If the IC's bad, that might be another story, unless i can substitute another IC...

I'll check the caps and the IC and see what i find.

I found a 47uf@160 volt Rubycon cap near the flyback that tests at... 55.3uf Isn't that a little high, and is this an issue?

tested the IC, and I'm getting high ohm readings on at least 3 of the pins, with a couple others reading infinite ohms. I doubt its shorted.

I'd be worried more if the cap was lower in value. At this point, I'd throw a HOT at it and see what happens.

Changed the 47uf cap anyway, and a bad 220uf@ 16 volt cap that was in the flyback area.

Tonight was a good night for TV's. I have two more that I'm gonna get to after I deal with this one...

Threw in a new HOT, no joy. still can't hear the CRT scanning.

Also check for an open fuse type resistor. It will probably be a white ceramic low ohms 5 or 10 watt resistor. There may be a smaller size fusible resistor between the voltage regulator output and the B+ input pin of the flyback. When the HOT shorts in sets that use the STR30xxx based power supply, it usually opens a fuse or fusible resistor.

There are three large ceramic resistors near the HOT. None of them have any info on them though.

I'll check all the resistors in the area in a bit...

Okay, so far I haven't found any "bad" resistors. The two larger 10 watt ceramic resistiors in the regulator circuit have seen some heat... so much that their casing is cracked. The info on them was worn away, but my multimeter identified them as 220 ohm resistors. I'm sure as hell going to replace them, but they tested good, so i assume they aren't why the TV still won't get a picture.

Okay I took out the third ceramic resistor, and it measures about 10 ohms. I don't know if its good or bad because the information on it is cryptic.

The info is: RY8GJ 6R8K I assume the K stands for kilo ohms, so that would indicate the resistor is bad, but I can't be certain.

I think that may be a 6.8 ohm. All the bad ones that I've seen were open. I've never seen one of those go up or down in value.

Okay, I'll replace it anyway since it's out of spec.

I also found a 2.5K ohm resistor in the flyback area that reads only ~175 ohms. Pretty sure it's supposed to be a 2.5k ohm resistor. Here's a pic of it.
http://i40.tinypic.com/2hmgi07.jpg

To me it reads red green red gold, which comes out to 2500 ohms at 5% tolerance.

It's in Sams 3466. I'll see if I have a copy so we can make sure of the resistor values.

Oh that would be great. :) I HATE resistor color bands. Can't ever tell with 100% certainty what one of those little 4 band bastards is. So i snap a pic of it and use Photoshop's color sampler to get a best guess.

I found the Sams. What are the board location numbers of those two resistors in question?

As far as the shorted HOT blowing something, I'd suspect R007 (5.6 ohm, 2 watt) and/or R001 (1 ohm, 6 watt). One end of R001 connects to one of the contacts on the power relay and the other end connects to the cathode of D002 and the anode of D004. These are two of the four diodes that make up the bridge rectifier in the power supply and the cathode is the end of the diode with the white or silver band.

R007 connects to pin 3 of the regulator.

If these resistors are good, measure the B+ voltage. Take your voltmeter ans set it to measure at least 200 volts DC. Connect the negative lead to one of the heatsinks and the positive lead to pin 4 of the STR regulator IC or pin 2 of the flyback. Turn the set on and you should measure around 130 volts DC. If the voltage is much higher, like in the 160 volt range, either the regulator circuit is not operating properly or the horizontal circuit is not operating. These types of regulators must have a proper load in order to regulate properly.

If the voltage is lower than 130, unsolder pin 2 of the flyback and check again. If the voltage jumps up, the flyback is most likely bad.

Okay, the supposedly 6.8 ohm ceramic block resistor is R473

The supposedly bad 2.5k ohm resistor is R459

R473 is a 6.8 ohm and R459 is a 180 ohm, 1 watt.

Okay, so they're both essentally good... R473 might be a tad high. Thanks a lot! Saved me from spending money on the wrong parts, getting frustrated and junking the chassis.

I'll check R001 and R007 when i can.

R007 is BAAAAD!! Infinite ohms! Finally found you motherfucker!

And of course it's hidden between the big 220 ohm resistors and the heat sink, so were it not for your help, I may have never ever ever found it.

While you're in there, check C474, a 47uf, 160 V cap.

All right. I've been shotgunning the jamicons anyway. The rubycons seem to be holding up nicely.

Oh, C474 was one of the first caps I replaced. So that's already been replaced.

Still waitin on the parts I need.

Well, I replaced the bad resistor, put it all back together and... nothing! same problem.

I went through all the trouble of getting the needed parts for nothing!

I think I'd check the voltage at the collector terminal (center pin) of the HOT. Just set your meter to measure at least 200 volts DC and clip the negative lead to one of the chassis heatsinks. Attach the positive lead to the HOT collector and hit the power button. You should have around 130 volts DC. Since the set is dead, you'll likely either read very low or zero volts or a high reading of around 170 volts. If the voltage is low or zero, you'll have to trace the B+ line back to the STR30130 to find the problem.

I did that, and got a whopping... 2 volts.

So I assume something's bad between the center pin of the HOT and the regulator IC?

Take out the HOT and recheck the voltage. If it jumps up, the flyback is probably bad and loading down the voltage.

Seeing as there isn't much between the center pin of the HOT and the flyback, can I just assume the flyback is bad? This TV's quickly turning into more trouble then it's worth.

I guess I could take the HOT out and test again, but where would i clip the positive lead to?

Trace the foil back and connect it to the flyback terminal that goes to the HOT.

Okay, I removed the HOT, and connected my positive lead to the flyback pin, which was easy enough to find. Turned the TV on, and still only read about 2 volts.

WTF...

OK, I'll dig out the schematic again. The problem has to be somewhere in the power supply.

I just had another thought while I re-locate the schematic. Locate the main filter cap in the power supply. That's the huge cap with a value between 330 uf and 680 uf at 180 to 200 volts. Connect your voltmeter to the positive terminal of that cap and the negative lead to ground and see what you get. Should be around 165-170 volts.

It's a 470uf@ 200 volt cap. Okay I'll do that.

Okay, doing that got me a reading of about 150 volts. This is with no HOT in the TV

Now what?

That voltage sounds fine. I think you can reinstall the HOT at this time. Now, check the voltages on the STR30130.

Pin 1 is connected to ground (0 volts).
Pin 2 should have approx 136 volts
Pin 3 should have approx 155 volts. This is the raw B+ input from the big filter cap.
Pin 4 should have 130 volts. This is your output pin.
Pin 5 is not connected to anything in circuit and should read 0 volts.

So I know ahead of time, what if I get either too low or too high voltage readings?

I think it would be better to measure the voltages and we'll go from there.

All right. I'll get to it later tonight. If this yeilds no answer, I might very well junk the set. Tomorrow's trash night and I'll probably find another one anyway.

Okay: Here's the voltages for each pin. They're all way too low...

Pin 1 measures at 0 volts

Pin 2 measures at 0.75 volts

Pin 3 measures at 0.18 volts

Pin 4 measures at a whopping 2.0 volts

And pin 5 measures at 0 volts.

All these measurements were taken with the HOT reinstalled.

Check the voltage at both ends of R007, the 5.6 ohm, 2 watt resistor that I think you replaced. If you have roughly 150 volts on one end; but, nothing on the other, the resistor is open. If you have little or no voltage on either end of the resistor, recheck the voltage at the positive terminal of the large 470 uf, 200 V cap. If you have voltage there but not on resistor R007, there is a problem between the cap and resistor. Maybe the trace is broken.

Did you check the new HOT to make sure it didn't short when you first powered up the set with the new parts?

The new HOT is good, the new resistor is good. I tested them both before they went back in. I doubt the trace is broken. is there anything between R007 and the main filter cap?

Not on my schematic. If you use your ohmmeter to check between pin 3 of the regulator (which one end of R007 connects to) and the plus side of the big filter cap, you should read around 5.6 ohms. With the set off and unplugged, I'd measure the voltage across the 470 uf filter cap to make sure it's not holding a charge. If the cap is holding a charge, (and it very well could be) it will get your attention in a most disturbing way if your not careful.

Okay, 470uf cap showed no voltage, so I measured between the plus side of it, and pin 3 of the regulator IC, and got around 11k ohms.

OK, now I'm starting to get confused and that ain't good. It sounds like you are checking from pin 2 instead of pin 3 of the regulator. There is a 10K resistor between pin 2 and the filter cap. One end of R007 should connect directly to pin 3 of the regulator. Did you check R001, a one ohm, six watt resistor? It's in the power supply area.

I took R007 out of circuit after following the trace from the positive cap lead to the regulator, and finding that it was the only resistor in the circuit.

r007 is bad.

now I'm confused, as that resistor tested good two hours ago.

Recheck the HOT again to confirm that it's not shorted. If it's good, the only other thing I can think of is to change the STR30130. They should only cost a few dollars. If you don't want to order one, just sit the TV back. It's a common IC in '90's TV's and I'm sure one will turn up in some junk real soon.

So, if it's not the HOT, then it has to be the STR30130?

I have more then a few boards from 1990's TV's maybe I have one....

Nope. no STR30130 IC's in my stockpile. Guess I'll have to scrape enough together to order one. One of my Zenith chassis has a big regulator IC, but were i to guess, they aren't as interchangable as HOTS are...

The Zenith will probably have an STR53041 and it won't work. If you have any STR30xxx series IC, you could try it to see what happens. The last three digits of the STR30xxx line indicates the output voltage. There were STR30120's, 125's, 132's, etc.

No STR30xxx IC's. The Zenith IC is an STR 60XXX IC

Just tested the HOT again and it's not shorted.

And, when you order that STR30130, try to get it from a place like MCM or tritronics. Many of those $1.99 discount house specials are not worth the effort. Many won't work at all and others will work for a while and then bite you in the butt.

Yippie.

First I'm going to try the two local TV repair shops around here. It's apparently a common IC. I might get lucky.

Of course I need the cash first. I already cashed in the pop bottles to get the 5.6 ohm resistors.

It's too damn bad those 2003/2004 JVC chassis I have don't have the right IC... nothing wrong with those chassis. Just pulled them cos the CRT's were weak.

Well, I sold that POS Zenith and now have the cash needed to order the IC. MCM has them, $3.79 each, apparently including shipping. I think I'll order two. Always good to have a spare.

I hope you told whoever bought it that it was theres and you didn't want to see it again.

Yep, even threw in one of my better universal remotes, which alone is probably worth what I charged him for the TV.

DAMN IT!!

New STR30130 regulator IC ordered from MCM electronics...

New HOT

New 5.6 ohm resistor.

NOTHING!!

I turned it on, same shit. quickly unplugged it because I only had enough cash to order one regulator IC, and if I blow it, that's it.

This TV is turning into a moneypit, and I'm getting close to pitching it.

You could very well have a bad flyback and, unfortunately, there is really no way to test it (except for blowing money on parts) without special test equipment. I used to never give up on a TV; but, that was back when a 13" knob tuned color TV was worth a quick $50 or $60, 19" color knob tuned sets were worth a quick $75 or $100, and 19" remote sets were worth a quick $125+. I lost much of my motivation when 13" remote color TV's started bringing a slow $15-$25, 19" color remote TVs started bringing a slow $35-$50, and 27" remote sets a slow $75-$100. I had a brief good luck streak at selling used TVs when the expensive flat screens took over; but, now they are back to not moving again. I've had ad's in a local classified paper that's sold at convenience stores, etc. for the past month and have not gotten a single call. I just blew $17 on an ad that's supposed to go in one of those "mailbox stuffer" papers for the next two weeks. If that don't do it, I'm probably done! Let them go to wherever and buy a Chinese flatscreen if that's what they want. Given all of this stuff that I'm ranting about, there comes a time when you have to draw the line and say "forget it". I've got a 31" CTC203 with a brand new flyback and HOT sitting on top of it. I've had the new parts for over a week and have not even opened the box. I just can't get motivated to try and fix the set because I'm afraid that the set still may not work properly after I change the parts and that, even if it does work, everyone will turn their nose up at it when they find out it's just a "regular old obsolete TV".

Sorry for the long rant but I can certainly feel your frustration. Nothing ticks me off more than to spend money on parts for a TV only to have the set not work and, in some cases, destroy the new parts where I can't use them in something else.

Yeah I think its time to junk this TV. Pull the chassis and at least keep the parts I put into it.

I can still sell TV's. That Sanyo could have easily gotten me $35 if it fucking worked!

I found a little 19 inch Philips TV that I could probably sell if the channel buttons weren't messed up.

And, you've probably got close to $35 in it right now.

Right now, I've got a cheap sylvania 20" CRT flatscreen that was in a major accident. It broke the RF connector, broke most of the buttons, and scratched the cabinet. I fixed the RF connector and the set plays well; but, you have to stick your finger in the hole to control most of the functions. I sent it up to the flea market for my friend to sell and they just act like it's not there because it's beat up. They want a new flatscreen HD set with a 2 year warranty for less than $50.

It wasn't long ago that I could have gotten $75 for your Sanyo in good working condition; but, like I said, used TV sales are recently falling off around here. I always said that if I had to sell color TV's for a B&W TV price, it was time to stop. Well, I find myslef selling some color TVs for less than what I used to get for a B&W. So, I guess it's time to stop. It's simply not worth pulling my hair out and using language that I shouldn't use over something that nobody wants to pay a decent price for.

That Philips TV is unsellable by me because of one crack in the front bezel and the channel buttons which I fixed well enough for them to function, but are crooked and not flush with the other buttons. That Philips was made cheaply... and I found metal tweezers in it, and a pen and pencil, which had been used to change the channel. I'm amazed it still works. Tiny chassis board, made in 2000.

But back to the Sanyo, chassis is junked now. Ended up just ripping the flyback off, and taking a small piece of the board with it.

I thought that the used TV business might pick up for you guys, but I went in a couple of stores this week and I don't know. The nearest Wal-Mart Zoo and Reform House (the same one the cops were looting shoes from live on CNN during Katrina) had a 20" RCA flat-tube for $137 and a Vizio (?) 19" LCD tv for about $200. But man they look cheap. The larger flat-screens (about 27") were in the $300s & up - maybe there'll be a market for used 27" & 32" sets, i don't know.

I watched my uncle go through the same thing in the late 80's with his radio/stereo shop. By '92 or so he closed the doors and just fixed things in his garage now & then until a year before he passed. Toward the end he was fixing a lot of BSR turntables. His family ran radio repair shops for over 70 years starting with his grandfather.

Ring the flyback, Tony! :D