The people I got it from said it flickered once, then went out for good. I plugged it in and heard a faint, high pitched sound coming from it. Pressing the power button did nothing.

Don't know when the TV was made, but it seems to be pretty new.

That set probably uses a switching power supply. If it's making a high pitched noise, that probably means there is something shorted on the B+ line, loading down the power supply. My first checks would be the horizontal output transistor and the big diode in the B+ line.

You can probably get some semi-decent $ for that if you fix it. Around here, 36" sets still fetch $200+ in good condition. Don't know how long that trend will last, though.

It's in Sams 4404 (too new for me). That set was probably made in the early 2000's.

I found another answer that said it might be a bad HOT...

Crap...

Well, I dunno... I've been saving boards from 36" TV's... maybe I have a spare HOT on one of them.

...

Yep. Found a large 3 pin transistor near the flyback. (Q 404 ) It reads as a dead short on all 3 pins.

I can't really make out the numbers on it. I'm wondering if I can substitute another HOT from the board of another 36" TV?

Hell, what do I have to lose?

Since I couldn't obtain a part # off the old HOT that I removed. I went and put in another HOT from a different TV chassis. However, I have NOT plugged the TV in yet.

What's the worst that could happen? My guess is the worst that could happen is the new HOT would short. Should I take some precautions before plugging the TV in?

...

I made sure the new HOT got a good amount of heat dope before mounting it to the heatsink.

Hoo... Okay. I guess I'll find out in a little while...

Okay. Plugged it in, and the TV worked!... for about a minute.

The picture was concave, but it was there. After a minute, the TV shut down and that noise came back. The second it did, I unplugged the TV.

So all this TV needs is a better HOT...

If the picture is concave, you have problems in the horizontal circuit. Probably bad caps around the flyback and HOT. These won't be electrolytics. They will be low value capacitors probably rated at a high voltage. If there are any diodes in that area, check them also.

Could the pic have been concave from a HOT not rated for the TV? I used a hot labeled D1554 that came from a 19" TV.

There are mostly lytic caps around the flyback. There is one disc cap, but it looks fine.

I've scavenged another HOT from a Magnavox chassis. I'll try it after I test the caps.

...

I checked tritronics website and the HOT should be a 2SD1880. An NTE2353 is the generic sub. This HOT does have the damper diode built in. The 2SD1554 is the same as an NTE2331, which is not as heavy duty as the NTE2353.

2SD1880 sounds about right! I can make out "880" on the old one.

That'll help if I can find specs...

EDIT: The HOT from the Magnavox chassis apparently won't work. (BU2508DF), no damper diode.

I may try to scrape some cash together and visit a TV repair shop to see if I can obtain the right transistor.

Okay. I put in a Zenith 121-1141-01 HOT from a 19" TV. From what I've found, it crosses with an NTE2302, which after looking up the specs seems very close to what I need.

I put it in the TV and tried it, and the TV's alive again! However, I've only run it for about 30 seconds out of fear of shorting this HOT. The picture was VERY concave...

Can I run the TV like this, to see if this HOT will hold up?

...

Okay, I ran the TV for 25 seconds and turned it off. The heatsink that the HOT is attached to was almost too hot to touch. I guess that means the 121-1141-01 is an inadequate replacement.

...

Could you, or someone else compare the 2SD1880 that this TV needs, to a Zenith 121-1141-01 and see if the specs are indeed similar? If they are, I can rule that out and start looking for what's causing the HOT to overheat.

i have been in the repair business for almost 30 years you are spinning your wheels putting anything but what was originaly in the set. dont waste your time with those other outputs put in a 2sd1880 and do the finger test on the heatsink. steve

put in a 2sd1880 and do the finger test on the heatsink. steve

Feel like shipping one to me? I'm flat broke, otherwise I'd have ordered one by now.

I also try to stay away from NTE/ECG transistors, especially in power supply and deflection circuits. Sometimes they work and sometimes they will blow up in your face. Many times, it's actually cheaper to go with the original part than an NTE sub. Like rcaman said, put an original back in there. Another word of caution: Many parts houses sell inferior transistors at a cheap price. Many of these will short instantly. I think places like Tritronics, Mouser, and B&D sell decent parts. I remember finding some STR53041 Zenith voltage regulators at a "good" price. It turned out that every one of them were bad!

You might want to order 2 or 3 HOT's. That will give you some "play room" in case you blow one while troubleshooting.

I'm sure whatever is bad in the pincushion circuit is causing the HOT to blow. If I had a schematic, I could probably tell you some things to check.

Okay... When I can, I'll order the correct HOT, and I'll try to get more then one. I'd prefer to order one with higher ratings to have some wiggle room, but I don't know what I'd order.

I'll just have to hope that the 2SD1880 isn't some value engineered POS designed to fail inside of 5 years...

Ohhhh... I was working on my Samsung TV (cleaning the remote sensor), and I looked at the HOT it has... it says "D1880" on it!

Gah it's tempting to sacrifice it... but I like that Samsung TV. I'd just go and buy a new HOT, but a certain douchebag who owes me money is making up excuses not to pay me. :mad:

I'll see what I can do about obtaining a new HOT first.

I staved off the temptation to cannabilize my Samsung TV, and ordered two Sanyo 2SD1880 HOT's

I've been checking the TV for other shorted transistors and can't find any so far. Any idea on where to look?

All right! Got some good news!

I ordered two 2SD1880 HOT's a few days ago, and they arrived today. I put one of them in, and the picture on the TV is no longer concave. I ran it for 25 seconds like before, and the heatsink barely got warm.

What should I do now? Run it for longer?

I'd resolder the horizontal driver transformer (the little transformer that connects to the base of the HOT) and any other connections that look bad around the flyback. I'd also check the B+ and make sure it's not running high. It shouldn't be over 130-135 volts. Other than that, just play the set and see what happens.

Don't know how to, and unsure if my multimeter can handle checking the B+ voltage.

I'll check the transformer's solder connections, and I think I'm going to beef up the heatsink that the HOT is attached to, as it's rather inadequate in my opinion. I'll take one of my small computer heatsinks and attach it to the HOT's heatsink.

Set your multimeter to DC volts and use at least a 200V range. You can connect the negative lead to the tuner can, vertical output heatsink, etc. Don't connect it to the heatsink with the power supply regulator transistor, as this is hot ground. There should be a pin on the flyback leading back up into the power supply area where you can measure the B+. Also, look for a capacitor in the power supply area rated between 47 and 100 uf @ 160 (or higher) volts. You can also measure the B+ here. You can use clip leads to connect your meter (with the set unplugged) if you don't feel comfortable probing around with the chassis on.

You certainly can't hurt anything by adding the heavier heatsink. I've seen some modern TV's that didn't even have a heatsink on the HOT!

Okay, before I do that, I have another issue.

TV seems to be playing fine. Picture is good, but the channel numbers will not disappear, and I can't find an option in the menu to disable this "feature".

I let the TV run for about 10 minutes, then turned it off and felt the HOT's heatsink. It was very warm, almost too hot to touch. Since this transistor is rated for 150 degrees celsius, I'm wondering if this is normal.

The original Sanyo remotes had a recall or display button to remove the channel number from the screen. I think the Philips and One for All remotes have the same button.

I am a little concerned about the heatsink getting that warm. OTOH, I've seen sets that the heatsink would almost get too hot to touch but would work fine. It could be that you have a failing flyback that is causing the transistor to overheat and short. A flyback shouldn't be all that expensive.

Sencore made a special oscilloscope for TV work that would handle the collector pulse on the HOT. This collector pulse is high enough to burn up most ordinary oscilloscopes. Heck, I don't even own a oscope that will handle the collector pulse. From what I've read over the years, a lot can be gained by examining the collector pulse on the HOT.

If I need a remote control to remove the channel number from the screen, that might be an issue. I want to sell this TV, and i don't need the customer calling me and complaining that the channel number won't go away.

My multimeter doesn't have a voltage range setting that I know of, so I don't know if it can handle the ~130 volts that the B+ voltage is.

We have a little 13" Samsung in the bedroom with a GE universal remote. The channel display will only go off if you push a certain button-I can't recall just which one but it is labeled for another feature. I don't use that set much myself so I don't recall.

If I need a remote control to remove the channel number from the screen, that might be an issue. I want to sell this TV, and i don't need the customer calling me and complaining that the channel number won't go away.

My multimeter doesn't have a voltage range setting that I know of, so I don't know if it can handle the ~130 volts that the B+ voltage is.

Your meter will probably handle it. Most will measure up to at least 600 volts. If you have the instruction book, it should tell you for sure.

I'm pretty sure one of those cheap one for all or philips remotes will get rid of the number. Those are the brands that I've been using and was able to get the display off a Sanyo I recently had.

This has nothing to do with the horizontal problem; but, resolder the vertical output IC before you wrap it up. They are prone to have loose connections and will cause intermittent vertical sweep.

Okay, I won't worry about the channel number for now.

Set your multimeter to DC volts and use at least a 200V range. You can connect the negative lead to the tuner can, vertical output heatsink, etc. Don't connect it to the heatsink with the power supply regulator transistor, as this is hot ground. There should be a pin on the flyback leading back up into the power supply area where you can measure the B+. Also, look for a capacitor in the power supply area rated between 47 and 100 uf @ 160 (or higher) volts. You can also measure the B+ here. You can use clip leads to connect your meter (with the set unplugged) if you don't feel comfortable probing around with the chassis on.

Okay, I could clip the negatve lead to the tuner can, but where would I clip the positive lead? Would I have to clip it to the body of the cap, or to one of the pins?

Would the TV need to be on?

Would any 100uf @160 volt cap suffice?

PS: resoldered the vertical output transistor already.

This might be a little easier. Unplug the chassis and set your meter to ohms. Look at the collector (center pin) of the HOT and if you trace the foil back, you'll notice that it connects to one pin on the flyback. Connect one of the meter test leads to that pin on the flyback that goes to the collector of the HOT. You can also connect the meter lead to the collector terminal itself. Now, take the other meter lead and touch the probe tip to the remaining pins on the flyback. There should be continuity to at least one other pin. There will probably be two other pins that show continuity to the collector terminal. One pin will be the B+ input and the other pin will provide the 200 V for the video output stages. You should be able to trace the foil back and determine which pin connects back to the power supply. On some of the newer Sanyo's, there is a large Zener diode connected between the B+ input pin of the flyback and ground.

Once you've found the B+ input pin, set your meter to read DC volts. Connect the negative test lead to the tuner can, vertical output IC heatsink, etc. Connect the positive lead to the pin on the flyback where the B+ enters. Make sure the clip leads are not shorting to other terminals, plug the set in and turn it on while watching the meter. The B+ should be around 130 V.

EDIT: I meant unplug the chassis from the AC outlet. Leave the yoke, HV, and other connections in place.

This might be a little easier. Unplug the chassis and set your meter to ohms. Look at the collector (center pin) of the HOT and if you trace the foil back, you'll notice that it connects to one pin on the flyback. Connect one of the meter test leads to that pin on the flyback that goes to the collector of the HOT. You can also connect the meter lead to the collector terminal itself. Now, take the other meter lead and touch the probe tip to the remaining pins on the flyback. There should be continuity to at least one other pin. There will probably be two other pins that show continuity to the collector terminal. One pin will be the B+ input and the other pin will provide the 200 V for the video output stages. You should be able to trace the foil back and determine which pin connects back to the power supply. On some of the newer Sanyo's, there is a large Zener diode connected between the B+ input pin of the flyback and ground.

Once you've found the B+ input pin, set your meter to read DC volts. Connect the negative test lead to the tuner can, vertical output IC heatsink, etc. Connect the positive lead to the pin on the flyback where the B+ enters. Make sure the clip leads are not shorting to other terminals, plug the set in and turn it on while watching the meter. The B+ should be around 130 V.

EDIT: I meant unplug the chassis from the AC outlet. Leave the yoke, HV, and other connections in place.

All right. I'll try this tomorrow.

In the meantime, I modified the heatsink for the HOT. (had lots of holes so it was easy), screwed on part of a computer heatsink. I put heat dope on the computer heatsink to ensure a good thermal contact. It's not much, but it should help.

Put some heatsink compound on the new HOT if you have not done so.

Did that already. (I treat the HOT like a CPU in a computer, NEVER run it without a heatsink and always use heat dope)

I let the TV run for about 10 minutes, then turned it off and felt the HOT's heatsink. It was very warm, almost too hot to touch. Since this transistor is rated for 150 degrees celsius, I'm wondering if this is normal.


It's hard to say if it's getting too hot. Some TVs run cool, but others run very hot. For what it's worth, 150 degrees C is literally scorching hot and would result in an immediate burn. I've never seen a semiconductor get much hotter than about 60-70 degrees when everything is ok.

Okay I found a large diode near the flyback that had continuity with the center pin of the HOT. I connected the positive lead of my multimeter to the diode and the negative lead to the tuner can. Plugging in the TV gave me a reading of 129 volts. Turning the TV on gave me a fluxuating reading of 118 to 126 volts.

What do you guys think?

That sounds about right to me.

I think when it cools down outside, I'll try running the TV for a half hour or so. My multimeter has a temperature probe, and I might actually get to make use of it if I can figure out how to attach it to the heatsink.

A conversion webpage told me that 150 degrees Celsius is 302 degrees Farenheit, so if it gets close to that, I guess thare's still a problem.

I'm starting to think this TV was designed to blow HOT's. The HOT was the only problem, and when it blew, the TV went into some kind of protected mode, complete with a ringing noise.

No TV is designed for the "long haul" anymore. Companies want to keep you coming back for more and this will not happen if their TV's last 30 years. I still like Sanyo TV's and I think they are the best buy for the money, given what else is out there. But, even the newer Sanyo TV's are not as well made as the ones from the early to mid '90's.

I believe that all you need to do is touch the temperature probe to the heatsink and it should register a reading.

Well, the new HOT shorted. Here's the details:

Played the TV for over a half hour. I watched maybe half of America's Funniest Home videos, and about 5 minutes of the Simpsons before it went.

I attached my multimeter's temperature probe to the heatsink, about maybe an inch away from the HOT (close as I could safely get it), and it got up to a high reading of 198 degrees Farenheit. This was with the back of the TV off and some mild air movement, not to mention the extra heatsink I put on.

Also, I noticed that the TV's picture concaved slightly when the picture had a lot of white in it.

PS: Got rid of the channel number staying on screen. Thank you giant universal remote!

195 F is MUCH too hot for a transistor. Anything above about 70 C would make me worried. That 150 C rating is probably the junction temperature which will be a lot hotter than the heat sink, or case. It's also probably the absolute maximum rating, not the idea rating.

You either have a problem in the HOT collector circuit, or a problem with the drive to the base. A HOT needs to be turned on and off quickly and fully by the base signal. If it's not, it will over heat and fail quickly. The fact that the sides were pulling in is a definite problem. I'm not familiar with this set, so I can't really give you much advice there.

Anything above about 70 C would make me worried.



So, 160 degrees farenheit is the absolute highest I should let it get to? I'm glad I bought a spare HOT, as it's the only other compatable HOT I have now, I'll do my best to make sure it doesn't get even close to 160.

Could there be a bad cap causing the HOT to overheat and short?

I have seen bad caps in the horizontal drive circuit cause this type of problem.

As a general rule, no transistor or IC should ever get too hot to touch. Certainly nothing in a TV should be able to boil water.

Look for any small electrolytic caps in the horizontal drive circuit. Also, trace that B+ input pin of the flyback back to the power supply and I'm sure you'll find at least a 47 uf, 160V cap in the circuit. Pull that cap and check it. I had a sharp come my way with a shorted HOT. I replaced the HOT and the set still had some picture pulling and shifting. It turned out to be a defective electrolytic cap in the B+ line.

Look for any small electrolytic caps in the horizontal drive circuit. Also, trace that B+ input pin of the flyback back to the power supply and I'm sure you'll find at least a 47 uf, 160V cap in the circuit. Pull that cap and check it. I had a sharp come my way with a shorted HOT. I replaced the HOT and the set still had some picture pulling and shifting. It turned out to be a defective electrolytic cap in the B+ line.

All right, I'll start hunting!

EDIT: Found a bad 4.7uf @160 volt cap in the power supply. As I have no boards with a suitable replacement, I'll have to suspend the hunt until I can get a new cap.

That's probably the culprit. If you've got a local electronics parts house besides ratshack, you should be able to get it locally. Remember, you can go with a higher voltage rating on the new cap if a 160 V is not available.

Oh I know just the place!

I just need some money... blew my budget on the HOT's and shipping... Damn I hate being poor.

Also, I'd probably go with higher voltage anyway.

With caps, I like to go with a voltage well above what is needed, and 105c caps, even if the old cap was an 85c one. Less wear on the new cap.

Oh I know just the place!

I just need some money... blew my budget on the HOT's and shipping... Damn I hate being poor.

I know what you mean. Here lately, I've been blowing my budget on TV's that wind up in the trash anyway. That really burns me up! I need to find a few that are fixable out of my junk pile so I can come up with bill paying and flea market money.

My local electronic store wanted $10 for a 100 uF, 350V cap. I told them no thanks. I can order the same cap for probably $3.
This is one of those stores that used to cater to the the radio & TV repairmen. Now, they cater to mostly commercial needs and I don't think they're making too much money at that.

I could probably get the cap for $5 at my local electronics store (NOT Radio shack)

... I just need the $5...

Hopefully I'll either get paid what I'm owed by a "friend', or someone will buy a TV off me.

Most of my replacement caps come from junked TV boards that I save (I test them beforehand) However, i don't have a single board with a 4.7 that's rated for 160 volts.

I could probably get the cap for $5 at my local electronics store (NOT Radio shack)

... I just need the $5...

Hopefully I'll either get paid what I'm owed by a "friend', or someone will buy a TV off me.

Most of my replacement caps come from junked TV boards that I save (I test them beforehand) However, i don't have a single board with a 4.7 that's rated for 160 volts.

Oh boy, you're owed money by a "friend". I've been in a few of those situations myself. Good luck!

Do you have any low cost / free means of advertising your TV's? Around here, we have a classified paper that's sold at the convenience stores and we have a call in swap and sell program on a local AM radio station. There's another paper that reaches more people; but, it cost $17 for an ad. I'll sometimes go that route if I have many TV's. In some ways, the DTV transition is hurting the sell of ordinary TV's. People would rather spend their money on a modern set. In other ways, there are people that can't afford a FP set; so, they are happy to give $100 for a nice 27" analog set. I just wish the days of getting $100 for a 19" rotary tuner TV would come back; but, I know that's not going to happen.

Yep. It's called Craigslist. It's how i've been selling most of the TV's I fix. :)

I'll get the cap I need, even if I gotta break some thumbs to do it :)

Well I finally got the cap I need, after I solder in a new HOt, I'll see how things go. I'll have the temperature probe attached, and if it even gets near 140, I'll shut it down.

your 4.7mfd cap will more than likely fix this set. i have done a lot of them. sanyo is a good set. steve

No concave picture anymore, and the HOT is at about 110 degrees. Sets been running for maybe 15-20 minutes...

Edit: Sets been running for maybe 30-45 minutes now and the temperature seems to be holding at around 120 degrees. Now i know that 122 degrees is 50 degrees celsuis, so that's only 33% of the HOT's maximum rating.

So far so good I'd say.

Edit 2: TV's been running for well over an hour and the temperature is still holding at around 120 degrees! I dare say it's FIXED!! I can even touch the HOT with my finger.

Edit 3: Put the back back on the TV and watched two DVD's on it. TV didn't give me a lick or trouble. Amazing how one bad 4.7 Jamicon lytic cap can cause the HOT to blow. I think, especally with my heatsink mod, that this new HOT will last a long time!

It sounds like you got it going. I'd play it a few days and if all goes well; it should be safe to sell. And, yes, those electrolytic caps can cause some weird problems.

Meh, it'll give me an excuse to watch TV in the garage...