Hey everyone, our main TV in the living room is having trouble. It's a US-made 1992 Fisher (Sanyo) PC2525, with a G3F-25250 Chassis. A few years ago, the built-in speakers started crackling and sometimes not working, until they both just quit. We hooked up our stereo using the AV out on the back of the TV, and we kept on trucking. After several years of this, now the rca sound out is failing too. A few months ago, the volume started going up and down, and now the right channel intermittently drops out and comes back. When the right channel drops out, it stays that way for anywhere from a few minutes to an hour, then it starts working, then it drops out again, etc. etc. The problem is not the stereo. I cracked open the set, and right in the middle of the Audio section of the PCB is a burnt up resistor. The resistor is green and 2W, but the code on it is unreadable. The area on the PCB around the resistor and the resistor legs both look burnt. I would really appreciate it if you guys could help me out with this, since I've already fixed two TV's before, my parents expect me to fix this one. If anyone has a Sams for this set, the burnt resistor is R608.

Thanks a ton.

The Sams is 4893. I'll look tomorrow to see if I have one; but, I don't think mine go that high.

That resistor may not actually be open. I've seen these get very hot and over time, the solder would break loose from the PC board and the resistor would look overheated. You might try resoldering that resistor and see if it helps. Your problem of audio cutting in and out sounds like a loose connection. Usually, when something shorts and opens a resistor, it will kill that particular circuit.

Thanks radiotvnut. The area around the resistor wasn't just kinda brown from running hot all these years, it was burnt and there was black stuff on top of the pcb and the foil side of the PCB was warped. I actually lifted a trail when I tried putting the resistor back in. The resistor leads to the middle pin of a 3-pin transistor, so I hooked it up to there with a wire. No change.

The problem was incorrectly described to me (I don't watch much TV in the living room), the right channel is good for about 30-40 seconds if you turn the TV on cold, then it starts popping in and out until it drops out completely, and sometimes it comes back but usually doesn't. If you turn off the TV, let it sit for a few seconds, then turn it back on, the sound on the right channel comes back for a few seconds before dropping out again.

I resoldered the RCA audio-out connector pins, no change there either.

Get a can of freeze spray and when the audio goes out, start spraying parts with the freeze spray. When the audio comes back, you've found the bad part. I'd suspect that transistor that connects to one end of the burnt resistor. Resistors just don't burn up that bad on their own. Something had to short, drawing too much current through the resistor and burning it up.

Those Sanyo/Fisher sets are loaded with ceramic mini-modules, which have primitive foil-side mounted components. You might try tapping each one and see if you find a bad connection. If so, you can unsolder and remove the mini-module, and resolder all the connections on it carefully. Those caused a lot of audio and CRT drive problems. Also, the table model stereo Fishers with speakers mounted on the sides of the cabinet had problems with the speaker foam surrounds dry-rotting and ripping apart.

Charles

kx250rider, would those be on the bottom of the PCB? There was nothing there. Also, this TV is stereo but the speakers are mounted under the tube, not on the sides.

The resistor was connected to a three-pin transistor that crossed to an NTE 373, I replaced it and also replaced a 10uf 25V capacitor right next to the resistor that got so hot the shrinkwrap on it shriveled up. I didn't replace the resistor because I can't read the colors on it (picture tomorrow).

After replacing the capacitor and the three-pin transistor, the TV worked beautifully for about 20 minutes. For the first time in years, there was full sound out of both the internal speakers, and the RCA-out was working great on both channels. All seemed well.

Now, it's back to how it was before. When the internal speakers are enabled, the right one makes no sound and the left one sounds all crackly. The right channel on RCA-out is dead, but I noticed if you put your ear up right next to the speaker you can hear sound very faintly, but it sounds muffled and buzzing.

Do you guys think the NTE373 might have burned up again since I didn't replace the resistor? If it did, I'm SOL because Fry's only had one 373 and they probably won't be restocking for a long, long time.

BTW, I tested the resistor and it is not open, however the reading I get kept rising, started at around 220 Ohms and kept going up from there.

I'm sorry to report that I don't have that sams.

220 ohms is a common resistor value. What worries me is the fact that yours rises when you check it. It could be that your resistor is increasing in value under load. I think you'd be safe to replace the resistor with a 220 ohm. That just might take care of it.

Here's a pic of the resistor (the one on the left that's all burned), does that look like a 220? I've never been good at reading the color codes but the spacing on this one is very strange, so it has me stumped.

Perhaps the value of the resistor goes up under load like you said, and once the value goes up too high the sound dies?

A 220 ohm should be red-red-brown. It's hard to say what this one is since it's burnt. Those color bands can become unreadable when the resistor burns.

You may also want to check the resistor on the right. Stereo TV's generally have two identical circuits for the audio (one for left and one for right). You can trace the resistor on the right to see if it connects to the same parts as the burnt resistor. If it does, check it with an ohm meter to see what it reads. It looks like a 68 ohm.

BTW, when you check a resistor, always unsolder it from the circuit to prevent false readings. If you measured that burnt resistor in circuit, you could have easily gotten a false reading and the rise in resistance could have been due to an electrolytic cap that was charging.

I would check some of those caps near the resistors, and any other hot areas.

I replaced the small cap right below the burnt resistor, it had gotten so hot the plastic wrap on it was warped at the top and bottom.

The resistor was measured out of circuit when I got those readings.

I'll check what the other resistor is hooked up to tomorrow morning.

Looking at that board, it's newer than I thought it was. They had done away with those ceramic modules by then. Sorry for the false tip :(

Charles

Hello,

I have one of these televisions that I'm basically giving away (the listing below starts at a penny). Before the listing runs out, I thought I'd alert the audience here.

http://www.ebay.com/itm/141107167688

Given that I'm trying to find a good home for this (as it doesn't have much in the way of value and profit isn't my intention), I hope this post isn't considered to be rude.

Thank you...

Try turning the volume all the way down. If it still crackles
its the audio out IC. The resistor & cap may be a red herring.
At best its feeding B+ to part of the audio but then both
channels would be affected the same.
Also look for bad PC cons at the audio IC's, RCA & headphone jacks.
I will also check for a Sams but I dont have many that new.

73 Zeno:smoke: