Solid State TV CRT Tip...

[rrrhre2s]

Got a solid state TV with a weak CRT, or color smearing ?

Something you can try:

Get a fast switching diode rated at 300 volts or more PIV, the old GE 300 would work in most cases.

General Purpose Switching Silicon Diode, 50 nSec, 300V, 250mA

Connect the cathode (banded end) to the collector of the offending (NPN) driver transistor (Red, Green, or Blue) have the other end connected to the ~20 to 28 volt source with as short a lead as possible.

Be sure to get the polarity correct or that color will over saturate, run wide open with no control.

This clamps the collector of that transistor to the voltage source and helps the smearing.

I have seen it done on all three transistors...

If the tube is that far gone, there is no harm in trying ?

rrrhre2s

[zeno]

Nice ! a few more tips,one much the same.

Sears / Sanyo 19" sets were getting H-K shorts left & right.
They used Sylvania jugs but Sylvania didnt have the problem.
Rewire filament so one side DOSNT go to ground.
Put 1.5 meg between the F & the K of the shorting gun.
Also added a cap .001 IIRC but cant remember where !
Worked good. Also did it to a few other brands. I could tell
when it shorted but it made the TV usable again.

For low E
If the filament comes off the FBT and its an opened core FBT add a
winding or two in series with the filament. Best to use a scope
doing this.

Or you can jump out the low ohms resistor in series with the
filament. Again use a scope to be sure not to over do it.

73 Zeno

[old_coot88]

Originally Posted by zeno

Nice ! a few more tips,one much the same.

Sears / Sanyo 19" sets were getting H-K shorts left & right.
They used Sylvania jugs but Sylvania didnt have the problem.
Rewire filament so one side DOSNT go to ground.
Put 1.5 meg between the F & the K of the shorting gun.
Also added a cap .001 IIRC but cant remember where !
Worked good. Also did it to a few other brands. I could tell
when it shorted but it made the TV usable again.

I ran into the same problem on those Sanyos with H-K shorts again and again. I didn't add any parts or change anything, just cut a single trace in the neck board to isolate the heater winding so there was no path to ground at all. With the heater winding thus 'floating', there was not enuff capacitance-to-ground to affect the picture at all.