Packard Bell Color TV

[bhegges]

I am not sure what exact part fixed the rising horizontal output tube current but a combination of the following let me run the TV for 30 min, after which I turned it off. Here is what I fixed:

• Replaced all of the parts from the horizontal osc. plate to the horizontal output grid
• Replaced the horizontal osc tube with a NOS tested tube
• Replaced the boost rectifier and C119 capacitor which brought up the 1000v boost to a measured 1020 volts, thank you Zeno, I did use a NOS ECG 119 selenium rectifier
• Replaced the horizontal AFC diodes
• Replaced the remaining film capacitors located on the bottom chassis, note I still need to go through the other circuits

One remaining concern - the horizontal sweep circuit adjustment recommended adjusting the horizontal efficiency coil to keep the horizontal output tube current under 225ma. When adjusting the horizonal hold to get a stable picture the horizontal output tube current ran at 240ma. Are there other settings or other parts to check so I can bring the current down. I suspect the horizontal output tube and flyback transformer will not like running hot long term.

NES source, playing Legend of Zelda:

[zeno]

The trouble is this set has something thats just off. Odds are
its not a wide open resistor or dead shorted cap. If you have
a scope look at the drive. Should be one ( or 2) BIG spike
& otherwise clean.
One thing that gets missed is the hoz blanking tube. That can cause some
strange problems. Change it & check around that area. It may be transtorised
also.

73 Zeno
LFOD !

[bhegges]

More measuring and also fired up my new Tek scope. The best part of a project is getting to acquire new tools:

• AC line voltage 123 volts
• 390v source measured 405 volts
• 275v source measured 294 volts
• Horizontal output grid 2,6 spec -46v measured -43v volts
• Horizontal output grid 2,6 spec less than 225ma. The best I could adjust for was 240ma current at 24k high voltage
• Horizontal output grid 1,7 spec 130v measured 130 volts
• Horizontal output grid 8 spec 37v measured 42 volts
• Horizontal output grid 2,6 drive. Scope setting 50v per division, 10us per division
  
  

Zeno, thanks again for your advice, the horizontal blanking amp is a 6GH8A. Other than replacing all of the electrolytic caps on this set I have not checked any parts in this circuit or other remaining circuits.

[bhegges]

Been working on a home improvement project so not much progress but I did pick up a Sencore CR70 and was able to test the 2 CRTs I have. Both are Packard Bell labeled 25xp22 which makes me think they are original to the TVs.

Naturally the tube in my project TV has no cataract or discoloration but measured almost no cutoff on red or green and barely any for blue. Emission is very poor for red, marginal on green, and fair on blue.

Now the CRT out of the large parts console I picked up measures good all around but it is quite discolored under the safety glass. I have watched shango066 pull off the safety glass on several CRTs so I see it is possible. What does everyone think for this one? Also let me know if anyone has a CRT they want to sell and ship to me (I will post a separate thread in the classified section).

[dieseljeep]

Originally Posted by bhegges

Been working on a home improvement project so not much progress but I did pick up a Sencore CR70 and was able to test the 2 CRTs I have. Both are Packard Bell labeled 25xp22 which makes me think they are original to the TVs.

Naturally the tube in my project TV has no cataract or discoloration but measured almost no cutoff on red or green and barely any for blue. Emission is very poor for red, marginal on green, and fair on blue.

Now the CRT out of the large parts console I picked up measures good all around but it is quite discolored under the safety glass. I have watched shango066 pull off the safety glass on several CRTs so I see it is possible. What does everyone think for this one? Also let me know if anyone has a CRT they want to sell and ship to me (I will post a separate thread in the classified section).

That CRT shown is a Zenith/Rauland sourced CRT, with the famous halo.
There's a few entries on this forum dealing with this. It's an easy fix.