color drives

[timmy]

how is it that there could be so much color content with the r,g,b, drives counter clockwise and just a small adjustment to the b,g drives to clean it up alittle.

[Electronic M]

Were you expecting a black and white image or a more uniform gray-scale than you have?

With the drives down you will still get a color picture unless you turn the color knob (located among the front user controls) down.
Gray scale adjustment consists of both the drives and the screen/G2 adjustments so if the gray scale is off adjust those controls. Drives fix tinted whites, and screens fix tinted blacks.

[old_coot88]

If the set lacks a setup switch, the best way to set the grey scale tracking is (with the color control off) is: turn the brightness down till the image is almost extinguished, just barely visible. Set the screens to make the image white, then bring the brightness back up. Then use the drives to un-tint the pic (or tint it to your preferance). Usually one drive will be near max with the other(s) slightly reduced.

[Findm-Keepm]

Originally Posted by old_coot88

If the set lacks a setup switch, the best way to set the grey scale tracking is (with the color control off) is: turn the brightness down till the image is almost extinguished, just barely visible. Set the screens to make the image white, then bring the brightness back up. Then use the drives to un-tint the pic (or tint it to your preferance). Usually one drive will be near max with the other(s) slightly reduced.

+1 - that's EXACTLY how I was taught by my dad.....a 43-year TV repairman.

One caveat - Motorolas with the 23EGP22's - let em run for several hours and re-adjust as necessary. They always seemed to shift considerably.

Cheers,

[timmy]

well its just the never ending problems i have with this 63 silvertone as it seems as if the r,g,b drives are being driven to hard and loading down the hv. or the crt is bad in some way with the blue mark that formed on the glass. im grasping at straws at this point, im out of possible causes here.

[zeno]

Measure all the CRT voltages & if you can post the CRT
area of the schematic. Should be easy to figure out.
( dont need focus voltage)

Be sure the kine bias is not to high. It may be a switch.
You should be able to turn the brightness anywhere from
total black to normal without any retrace lines.

Another test put all G-2 ( screen) down & all other controls on normal.
No signal needed. Turn up one G-2 at a time, should turn that
color brightly. If the all come up you can grey scale it by eye.

73 Zeno

[timmy]

Originally Posted by zeno

Measure all the CRT voltages & if you can post the CRT
area of the schematic. Should be easy to figure out.
( dont need focus voltage)

Be sure the kine bias is not to high. It may be a switch.
You should be able to turn the brightness anywhere from
total black to normal without any retrace lines.

Another test put all G-2 ( screen) down & all other controls on normal.
No signal needed. Turn up one G-2 at a time, should turn that
color brightly. If the all come up you can grey scale it by eye.

73 Zeno

the problem has always been the hv wont regulate on certain scenes the hv dips to low. the bias is all the way counter as well as the r,g,b drives i cant raise the bias it blooms because of the hv. the drives show the color by turning up one at a time. grey scale i can get ok but the hv dont allow for it all to stay the same scene changes like white will turn reddish because of the lack of hv to support it and voltages were checked reg currant checked cathode, screen voltage, g1, g2,cathode everything is within range but yet the hv refuses to regulate. reg cap off the hv runs away at over 30 kv and its got a new flyback several 3a3 tubes including a solid state 3a3, no difference. either something in the chassis is causing the loading down or this mysterious blue mark that formed over time is the cause. the mark goes from the anode button down to the exterior dag, the mark is inside the glass yet the tube shows very good.

[andy]

...

[timmy]

Originally Posted by andy

Have you checked the regulator cathode current? It should be about 1mA with a black screen, and gradually decrease as the brightness is increased (check the Sams for the correct value). When it goes to zero, that's when the HV will start sagging.

If it starts out too high, it will drag down the HV, and could mean the HV is set too low. If it's too low when the screen is dark, it's a sign that the HV supply is weak, or the HV control is set too high. If it changes unpredictably, it's a sign that the regulator circuit isn't working.

well if its not the crt at fault then its obvious the hv reg circuit is not working as it seems now but the cause has got me puzzled. the reg currant with dark screen and hv adjust low is 1.64 and hv adjust high is 0.93 bright screen hv adjust low is 1.16 and hv adjust high 0.20 ma. to get any decent hv the hv adjust pot has to be maxed. the 2 1.5 meg resistors are within range as well.

[timmy]

at this point i dont know what else to look for as far as a problem in the hv regulator circuit as there is not much at all to this circuit to begin with. the focus voltage is ok along with all the other voltages comparing to the sams.

[andy]

...

[timmy]

the 0.2 is the bright up and hv adjust pot clockwise all the way and this is with the bias pot counterclock wise, and it was not blooming during that test.

[timmy]

so if the beam current is to high or to low would this effect the hv in a negative way by keeping the hv low or not regulating at all ? if that were the case then this may be the ticket i have been looking for to fix this set then where to look for a problem or check beam current or the reason for it and fix it.

[Alastair E]

If the Beam Current Limiter isnt working--or mis-adjusted, that would upset the EHT Regulation....

The (assume shunt-reg) can only regulate so far, and if the beam-current goes above a certain level, the regulator will be effectively cut off completely and no regulation can occur. The EHT will then be lower than it should be, and ballooning pictures/de-focussing will happen....

I would recommend you set up the drives, grey-scale, any extra screen or drive adjustments or voltages, the BCL and the EHT Regulator to the service-manual settings, then try again....
--If no good, doing the set-up procedure should indicate where the fault lies, maybe check the shunt reg, the EHT Rectifier and the Flyback Overwind for problems

[timmy]

this has all been done already several times voltages , ect are good it just makes no sense i posted the reg current findings above.