Flyback replacement for a Mitsubishi AM-1401R

[Electronic M]

Originally Posted by StarquestMan

Just now getting back to this neat little TV after being busy for a while with other work. I checked out the heater voltage for the CRT, it is sitting at 6.19 volts. I used the TV for a little while just to check it out. After I turned it off I noticed a small splotch of colors on the screen that was sort of rectangular shaped and had a shimmering effect like a candle burning or a flag waving in the wind. I was very curios to what the HV was running at so I bought an old HV probe on ebay and when I got it I checked it for accuracy on another working TV that I knew the specification and it read right on. So I checked the Mitsubishi and it checked spot on 22.5 Kv as per the service manual. what would cause this strange effect on the screen after the set is powered off and is this harmful? I still need to correct the width deficiency but I'm guessing this isn't related although I have never seen this before on a TV so I don't know what to think.

That's probably normal. It takes a few seconds for HV to bleed down on most sets and the same way it takes the CRT heater ~11 sec to warm up to full emission from cold it takes about as long to stop emission when turned off from warmed up. Capacitors in the sweep and gun drive circuits don't fully discharge immediately either so the set will still be semi-running off of stored charge and stored cathode heat for a few seconds after power off.

Each different circuit design will behave differently on switch off. Old monochrome sets would often have a lingering white dot in the center of the screen for the same reasons.

[StarquestMan]

I hoped it was something normal, it lasted about 30-45 seconds, maybe a full minute.

[damen]

I know someone who did RCA warranty work back in the day and he said some customers complained of this happening with solid state sets. RCA said to inform the customer that it was caused by an "above average quality picture tube". Longer the glow, the better the tube. Customers stopped complaining.

[StarquestMan]

That's good news about the picture tube being good. This TV seems to be a low hour set so that would make sense. I tried looking for the retrace capacitor and tried subbing what I thought was it with a slightly higher one. After I noticed no change i reread the post from earlier and realize that the retrace capacitor is supposed to be across the horizontal deflection coil although I can't find any cap across it in the schematic. I then decided to try adjusting the horizontal hold pot which didn't yield any good results. It was glued at the factory so I swapped out the trimmer for a new one and since it is buried towards the front middle of the chassis I had to be very careful snaking my hand in to adjust it. I wasn't quite careful enough and brushed my hand over the horizontal output transistor heatsink and got bit pretty good, got a nice little burn and a cut from my hand jumping up into a support bracket. Once my heart rate dropped I decided to be smarter than the TV and use some gloves and got it dialed in. I was able to stretch the picture a bit but then I realized the picture wasn't centered properly so I centered it out properly and was back to where I was before in terms of width.