Found a 36" Sanyo AVM 3659G Won't power up.
 

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

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.

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.

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.

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.