Hey guys.
A journey I took very recently
The Picture shows a 21" Philips TV. This belong to some relative of a good friend of mine, who is same field as I am. But he is a little down in TV trouble shooting. I think he is scared of HV.
Anyways, he called me and asked for my help so I went and it took a few hrs before I realize wht the problem was. I never take too much time to fix TV, but this blew my mind.
Another thing is tht I have fixed TV's of the same type with the same issue, but this thing was giving me too much trouble
Initially the problem was a blown H-OUT, a BUT11AX. He replaced it and the set does not seem to power up. My checking revealed the sync shutting down, and the supply sagging. So naturally I assumed it was Flyback fault. Told him to get a new one and it will be OK.
Next day he called, I went and still the same with new flyback. But this time supply sagging was not as it was before.
Instead sync is too weak to start the horizontal. And of course this lead me to a leaky horizontal sync coupling cap. Replaced and viola.
The TV came to life.
After around 15secs, the TV started squeaking. The noise of horizontal or supply shutting down due to over load. Checked the tube, TV is dead.
I touched the sinks and the H-OUT sink can boil water.
Damn it...transistor blew. So hurried and bought another but this time I did not kept it powered up , instead I held the H-OUT between my fingers to check for heat. Powered up and this thing heats up in seconds.
So I have to keep shutting down and checking to prevent the H-OUT from blowing.
So as usual I checked every single component tht could heat up the H-OUT and found nothing...Checked the supply and found it was at 125VDC. To my knowledge a 21" Philips usually has a B+ of 95VDC.
Which even made me more confused. Cause I though the high B+ is causing the heat up.
Now it's time to check the service manual. I have almost all the Hitachi and Philips service manuals tht came out at the beginning of the LCD era.
So I have around 25GB of schemas, but could not find the one I was looking for. So I searched for a similar chassis. Found something close enuf with the numbering and all.
This schema shows all the part numbers and components exactly and also has the after market modification shown.
The supply is 95VDC. HA!! I though, high supply.
So fiddled around the feed back and found a way to lower the B+ by increasing opto feedback.
Did it, satisfied and powered up. The Picture came with a limited horizontal width ( an indication of low B+) and went blank.
I was like ... What the.......
Now what.
Again switched off and on, over and over, still the same.
Poked around, when on. All Voltages are OK, assuming a B+ of 95VDC. But why tht small H-width. This does not make sense. A lot of useless Hrs passed with my head banging on it.
Finally decided to increase the B+ to see the width effect. But first touched the H-OUT sink, it was hot, not warm.
It didn't blew, so I thought I will increase the B+ to it's original value.
So fixed the feedback, powered up and guess what. Width was OK. Good picture, and then, Squeeeeeeeeeeeeeeck!!!
Touched the H-OUT, it was boiling. Checked again, shorted.
So, now thinking that the previous leaky cap was the culprit in the first place and H-OUT is blowing due to a faulty new DOA flyback, I put the old FBT back, bought a new H-OUT and powered up.
Nice picture and then ..Squeeeeeeeeeeeeeeeeeeeeck!!
Aye! yai! yaaaaaaaaaaaaa!!
That's the third one.
Blowing without a reason I can think off.
I got pissed off, so took a break and next I decided to find the fault by soldering a bad ASS H-OUT, like 250W, 25A ones tht I had, which are used in Hi-def monitors earlier. So by the time this one blows I can get a descent amount of minutes to probe the PCB.
So, going thru my item I found a 14"Sony H-OUT, 2SD1877, which is a different package but has close rating as the BUT11.
Switching H-OUTs is not a problem for me. So I thought instead of blowing a big one, I will first try with this, as I had plenty of it.
Next day, I soldered it and had it between my fingers. I powered up.
TV came to life and stayed,
Guess what. This H-OUT is not even mounted on the heat sink but between my fingers and yet it is only warm. Minutes passed by, B+ at 124VDC and, stable picture and a cool H-OUT.
Replaced the Old FBT, this guy too was OK but a little leaky as I can here the static discharge but works.
So I mounted the D1877 instead of the BUT11.
TV is good as new.
Below are the ones tht gave me this whole trouble
A journey I took very recently
The Picture shows a 21" Philips TV. This belong to some relative of a good friend of mine, who is same field as I am. But he is a little down in TV trouble shooting. I think he is scared of HV.
Anyways, he called me and asked for my help so I went and it took a few hrs before I realize wht the problem was. I never take too much time to fix TV, but this blew my mind.
Another thing is tht I have fixed TV's of the same type with the same issue, but this thing was giving me too much trouble
Initially the problem was a blown H-OUT, a BUT11AX. He replaced it and the set does not seem to power up. My checking revealed the sync shutting down, and the supply sagging. So naturally I assumed it was Flyback fault. Told him to get a new one and it will be OK.
Next day he called, I went and still the same with new flyback. But this time supply sagging was not as it was before.
Instead sync is too weak to start the horizontal. And of course this lead me to a leaky horizontal sync coupling cap. Replaced and viola.
The TV came to life.
After around 15secs, the TV started squeaking. The noise of horizontal or supply shutting down due to over load. Checked the tube, TV is dead.
I touched the sinks and the H-OUT sink can boil water.
Damn it...transistor blew. So hurried and bought another but this time I did not kept it powered up , instead I held the H-OUT between my fingers to check for heat. Powered up and this thing heats up in seconds.
So I have to keep shutting down and checking to prevent the H-OUT from blowing.
So as usual I checked every single component tht could heat up the H-OUT and found nothing...Checked the supply and found it was at 125VDC. To my knowledge a 21" Philips usually has a B+ of 95VDC.
Which even made me more confused. Cause I though the high B+ is causing the heat up.
Now it's time to check the service manual. I have almost all the Hitachi and Philips service manuals tht came out at the beginning of the LCD era.
So I have around 25GB of schemas, but could not find the one I was looking for. So I searched for a similar chassis. Found something close enuf with the numbering and all.
This schema shows all the part numbers and components exactly and also has the after market modification shown.
The supply is 95VDC. HA!! I though, high supply.
So fiddled around the feed back and found a way to lower the B+ by increasing opto feedback.
Did it, satisfied and powered up. The Picture came with a limited horizontal width ( an indication of low B+) and went blank.
I was like ... What the.......
Now what.
Again switched off and on, over and over, still the same.
Poked around, when on. All Voltages are OK, assuming a B+ of 95VDC. But why tht small H-width. This does not make sense. A lot of useless Hrs passed with my head banging on it.
Finally decided to increase the B+ to see the width effect. But first touched the H-OUT sink, it was hot, not warm.
It didn't blew, so I thought I will increase the B+ to it's original value.
So fixed the feedback, powered up and guess what. Width was OK. Good picture, and then, Squeeeeeeeeeeeeeeck!!!
Touched the H-OUT, it was boiling. Checked again, shorted.
So, now thinking that the previous leaky cap was the culprit in the first place and H-OUT is blowing due to a faulty new DOA flyback, I put the old FBT back, bought a new H-OUT and powered up.
Nice picture and then ..Squeeeeeeeeeeeeeeeeeeeeck!!
Aye! yai! yaaaaaaaaaaaaa!!
That's the third one.
Blowing without a reason I can think off.
I got pissed off, so took a break and next I decided to find the fault by soldering a bad ASS H-OUT, like 250W, 25A ones tht I had, which are used in Hi-def monitors earlier. So by the time this one blows I can get a descent amount of minutes to probe the PCB.
So, going thru my item I found a 14"Sony H-OUT, 2SD1877, which is a different package but has close rating as the BUT11.
Switching H-OUTs is not a problem for me. So I thought instead of blowing a big one, I will first try with this, as I had plenty of it.
Next day, I soldered it and had it between my fingers. I powered up.
TV came to life and stayed,
Guess what. This H-OUT is not even mounted on the heat sink but between my fingers and yet it is only warm. Minutes passed by, B+ at 124VDC and, stable picture and a cool H-OUT.
Replaced the Old FBT, this guy too was OK but a little leaky as I can here the static discharge but works.
So I mounted the D1877 instead of the BUT11.
TV is good as new.
Below are the ones tht gave me this whole trouble
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