All tube, weak greens. I checked the CRT and indeed the Green was weak, but further checks with the scope on the green grid so very low drive like 5v PP vs 28vpp shown on a cope of a SAMs I found online.

I am going to start by checking the voltages on the color amp tube. it looks like the grid is driven by a couple resistors that come from the B-Y and R-Y drive circuits. I suppose the resistance values there are somewhat critical, but that is just a guess. I used a color bar vectorscope, it looked horrible.

anyone with exp on these pls chime in. I know the green can produce since I get a decent gray scale, so I am guessing its the grid drive that is the primary reason for the weak greens.

I am hoping for a service manual that gives a bit more than what I have (which was just the schmatic).

I did try subbing the color tubes but that did not seem to make much of a difference. The pic is ok as far as flesh tones, but anything requiring a lot of green is not that great.

Am not sure if your set falls under this scenario, but I remember a period of time when manufactuers were producing color sets that reduced the amount of green a color picture would show. In an effort to reduce the green faces complaints of color sets owners had. The later rectangular tube sets and earlier solid state sets had buttons to turn on or off the "auto color corrector", the effect was to lessen the green and broadened the tint range so there wasn't any purlpe or green faces. Everything in my opinion looked orange and blue, so I always turned off the auto color switches. Just my 2 cents worth!

My restored HC PortaColor complete with a NOS rebuilt tube also has week greens. I think it was a feature.

-Matthew

Even when they were new, if you sat a GE Portacolor next to any other properly working color set, it looked terrible in comparison. The colors were never the same.

If you aren't comparing it to another set, but just watching it, then most owners found the picture acceptable, and that is what sold them because you didn't have many choices if you wanted a small screen color portable.

I have never seen one with a sharp, clear picture or what I would consider proper color. They always lack detail and in many cases the green seemed to be poor.

I'll bet you could get it to work better than what you are describing, though.

The tint control goes from blue faces to pretty much normal looking tint. keyed color bars go from Blue to sorta grey to Red.

yikes getting an occasional loud pop from the pots adj the CRT drives, guessing tin whiskers. Sure wakes you up...

The degauss switch is open in the charge position, But even when I worked around that it did nothing, at least that I could hear or see.

charges a .22 uf cap, then discharges thru the degauss coil, I assume its some kind of a tank circuit that is supposed to ring a few times. For fun I think I will scope the coil and see if I can see the ringing. I don't think the coil is very big so I should not have any problems with a big inductive kick back hurting my scope.

I had a PC new in the 60s and green was never satisfying and sometimes missing altogether. The chroma path is highly compromised for cost reduction. I believe it's matrixing not-R and not-B with non-DC restored Y that causes weak G. Might be fixable with an elegant piggyback but cannot be fixed by adjustment or component replacement that I know of. I think you'd find a little better green presentation on NTSC/SMPTE bars than on gated rainbow.

The Porta-Color didn't have a great color picture, even when it was new! It was even worse than the infamous Silver-Scenic and 8168/9168/4168 that Sears sold back then.

well this thing has NO green, the B&W is ok so the Y signal is working, I suspect the green G1 is just not working right.

As a test I have reversed the B and G G1 drive wires so IF the CRT is ok I should get a Green sky since the Blue drive was working fine. I just want to see that the CRT Green gun and control grid are working.

Put it on a good print of Bonanza. The grass will be green. The green bar of gated rainbow will be grey. It has to do with the luminance value of the 'pixels' that are supposed to be green. The grass in Bonanza was highly exposed, gated rainbow is not.

Was the result of the test that there was still no green? If the B&W is OK then the green gun has to be working.

yea still no green, I tested again, NO cutoff and weak gun, plus a weak green signal to start with. There is enough emissions that the screens can be set for a decent B&W, but I fear a new CRT is the real fix. when a swapped the green/blue drive I could get a green bar but only with the screen set so high that the black bars were light green. I think the blue drive is clearly better hence the ability to generate the green bar, but again the cut off does it in. I went ahead and did a auto restore, better now on the color bars, will check bonanza tomorrow. The CRT reponded well the the rejuv, all guns about the same now, ok but not great.

I should have conducted the G/B swap after the restore, but already reconnected everything. The tint control works a bit better, I can now get a greenish tint, I just need some really saturated greens (football/baseball is good for that as well).

I putzed around with the Blue balance and the Green balance pots (not the drives but the trim pots mounted on the main board under the CRT. Was able to get a nice spread of green, blue and red bars. I am getting tired, and that is when mistakes get made so stopping now. The sams has a rather through color AFC setup that includes the correct procedure for adjusting those pots. I just used the keyed rainbow and tweeked a bit. will check an actual pic later and then review the correct procedure. I double checked the CRT after the auto restore still looks good so it was not just from the extreme heat put on the filaments hopefully it will last.

My guess is the balance pots control the output of the demodulated R and B, if not balanced then the G matrix will of course not work, (but the R and B can still be forced to work with tweeking of the drives and screens, but still the input to the G difference amp will be messed up.

Anyway looks promising....

I think what I really need is just a broad cast of a fully saturated green, then I could setup those balance pots to max out the green. Have to think about how to do that.

Hi DaveM.
i had a few tricks to get a weak/unbalanced color crt looking acceptable.
1st, if the set has a setup switch, i would use that to initially adjust the rbg cuttoff(screen,g2)for a dim white line.(adjust rgb cuttoffs(screens,g2s) to min so crt is black,turn up red cuttoff(screen,g2) to get a dim red line,then turn up green cuttoff(screen,g2) to get a dim yellow line,then turn up blue cuttoff(screen,g2) to get a dim white line).
Watching a b&w picture(color at min and tint centered), i would adjust the brightness/contrast for a dark picture and adjust the rgb cutt off(screen,g2) for grey in the dark areas.
then i would crank the brightness/contrast up and adjust rgb drives to get gray in the bright areas.
sometimes i would have to go back and forth a bit.
also ,bumping up the red cuttoff(screen,g2)to make the dark picture slightly red helped a bit too.
i hope this helps,
RonL

I don't remember a green reproduction problem with the with the early sets... The Goldensenic chroma was very similar to that of RCA CTC15/16 used in Warwick's high B+ chassis... The 41681 with the 4MK8 color demodulator was when they started to slip, though they were still better than the GE Porta Color... The 41682 with the hybrid chassis was worse still, at least the reliability was up slightly...

The solid state Medalist had a some of the poorest green of anything Sears sold, well 'cept maybe for the Silversenic...

Tom

I always thought that the early Zenith color sets had better green reproduction than the RCAs and their clones.

They did, but Zenith used different type of color circuitry than RCA and its clones. One of the few brands using the 6JH8 and 6ME8 dual plate tubes. Makes a big difference in the color.

Some stores would not put Zeniths right next to RCA's on the sales floor because the color reproduction on the Zenith sets would often blow the RCA's right out of the water. In a customer's home, both looked good as long as you didn't have anything else to compare it to.

Just like the GE portacolor. You had to keep them separated from larger screen sets on the sales floor if you expected to sell any of them, they just didn't look that great particularly in a well lit room.

I went back and started all over, returning the balance pots to the orig settings, after futzing with them I noticed that B&W would change colors if I detuned the fine tuning. So I returned the orig starting points then re did the entire grey scale setup. The sams as a odd g2 setup, has you setup so at least one gun is set at maximum. This is a little different from what I am used to.

anyway I reset everything, with the tint control set in the middle I touched up the G1 blue/green and the G2 RGB screens.

end result is I can get good green if I let the flesh tones suffer a tiny bit, or if the flesh tones are good the green is a bit weak, but much better than before. Of course the set has to be reset constantly for different programming, as the old stuff shown on MEtv,ANTtv, and THIStv tend to be somewhat washed out (and look BETTER for this set after adjusted for).

The extreme contrast and deep saturation of modern programming seems to overwhelm the CRT which admittedly is weak.
There does seem to be a problem with the chroma and Y signal, like the delay is not correct, the color seems to lag the Y signal (you can see it when the fine tune is detuned or the color is turned down, the lag goes away).

one other thing, the color signa is VERY strong, even with the color control fully CCW you get some color info. and less than 1/4 turn is too much. I don't know what the deal is or if that is a problem.