Hey, you posted the solution just as I was typing a reply.

Did you fill the dug-out path with epoxy (I have used JB Weld), or just leave it open?

Phil Nelson

excellent picture!those philcos had a look all their own.love that set and happy for your good fortune

I just left it. After thinking about it, I figured I'd better not give it another path to track through. No idea if the stuff I would have put in there would have formed another path for current or not. If it does it again, I can just remove the small trace on the right, and sub in a wire.

Thanks sampson, it does feel good to get an easy one every now and then. I think the main fliter cap does need replaced though, the picture has a barely perceptible 60hz wave rolling through it. I'll leave that for the future though, for now it runs just fine.

Looks great! I see it isn't any warmer in Chicago than it is here. Where the heck is Spring.

I think the 67 & 68 model years used them, both round and rectangular. Of course, it was the higher priced models.

The Sams sheet (and sticker inside the set) list the tuning eye as a part, but they also note that they were not installed in all models. I suppose I could add one, but I'm not sure where it goes.

This stupid thing has the best convergence of any roundie I currently own, makes me want to go through the CTC-7 again. :scratch2:

when you get a chance would you check a few things and let me know

HOT current

CRT HV



after running for say 30 min just a ruff idea of how hot the fly is

as in warm to touch, pretty hot, stone cold etc... or if you have an IR temp gun, say the temp at the top of the doughnut.

I ask since mine seems to be running a bit too warm. I am going to double check the HOT and KV tomorrow.

for comparison, 25kv 200ma brighness turned down all the way. Horz bias set too near min. FYI, could not get the KV lower than 25kv with min brightness.

Normal viewing has it bouncing around 220-240, kv jumps around a little in scene changes, but not too bad. No blooming or other issues.

I still have a soft focus. coil is turned all the way in, but that maybe due to some early work I was doing to it when I played with different focus coils, I plan to reinstall the old one. Right now in never goes thru a focus point just gets close until it bottoms out. All the way out is not better.

Sounds like the VDR in yours has drifted or something, it's part of the feedback mechanism which regulates high voltage. Same principle as the circuit used in the Portapotty.

Also Motorola's and some Admiral's. Did Philco use second anode voltage for the focus? If not, it might have a focus rectifier. No schematic handy!

The schematic I have shows a SS focus diode.

Edit: I can email you the schematic I have, a forum member sent it to me.

I'm not currently able to read HV because I gave the meter back to Mark, but I just checked HOT current and grid voltage. I have spot on -60 VDC on the HOT grid just like Sams says, and I get anything from 210-240ma depending on picture content. Seems pretty normal to me. :thmbsp:

thats about the same current I I am getting.

one thing odd about mine, if I set the setup switch to serv, and adj the screen G2 for just being able to see the lines, I end up with a pretty dim pic(not bad just not as bright as some of my other roundies). I have a feeling the bias is off, I need to check the voltages at the cathodes.

I can of course increase the cathode bias to get a decently bright pic, but I have always read that is not the correct way to set it up, and that the bias pot should be fully CCW unless a gun can not produce a line, in which case you max that drive and then turn up the bias until it can produce a line.

IIRC my CRT tested fine, so I am back to thinking I must have something off in the overall bias of the CRT, esp considering I am at 25kv (even when fully loaded, it only drops a bit).

Here's what Sams says:

"Tune is a B&W picture or a color one with the color control at minimum. Set CRT bias and all screens to minimum, and put the switch into the service position. Advance screen controls one at a time, until each produces a barely visible line.

If one or more screen control fails to produce a line, leave that screen at max and advance CRT bias until a dim line appears. Then adjust the remining screens to match the brightness of that line. Put the switch back into the normal position. Adjust blue and green drives to eliminate coloring in high and lowlight areas."


FWIW mine seems to track perfectly, but the pots in this cheap chassis are horrible. In particular, the AGC pot is really bad. It causes the screen to flicker randomly, and the front panel pots could use a cleaning as well. Have you tried cleaning your pots yet?

Beautiful set! Is it acceptably safe for the fly that the horiz linearity is off a bit? Looks like the right side is very slightly more narrow. I have thought that imperfect horiz width and or linearity indicates a potential problem to make the fly temp hotter.

yea I think I am getting close to the issue on my setup, see my post in the noisey pic thread. pretty sure it is cathode voltage issue from the video out tube (plate V to high, look like the video out 12GN7 tube cathode bias resistor/pot drifted up, causeing the tube to not conduct enough, resulting in the high plate voltage).

Yes I did clean front panel control pots, but for the IF trim pot on the video board (missed that one), and yes I agree the pots on the back are cheap a$$ stuff.

I am pretty sure this last resistor (the R61 100 ohm on the bottom of the brightness control) is going to be the one that fixes my dim pic. I did check the cathode bypass cap, its ok, so that being ok and the resistance check of pin 1 of the 12GN7 (like 500 ohms was the MIN I could get, should have been 100 with the pot cranked fully towards ground) I think I got it.

I don't see anything wrong with the linearity on this set, it looks exactly the same on my HD set. It was slightly off-center in the pic though, I recentered it since then.

That's a possibility, high plate voltage on the video tube (presumably from being more cut off than it should be) would also result in higher CRT cathode voltage, which would in turn cut the CRT off more. Worth looking into, IMO.


Sure are!

6GH8's will replase 6U8's in many applications. 6U8's replace 6GH8's in very few. :(
Doogie

I know, it's a shame.

Fortunately for me, this set's GH8's are all good (for now). They are Philco branded 'cool chassis' tubes,butif they start acting up I'll definitely buy a sack of 6U8's to replace them.

Are 6GH8's that hard to get? I wouldn't sub the 6GH8's or the 6BL8's with 6U8's. Just not a good sub.

No they are easy to get, they just have a bad reputation for going failing.

I think in the RCA's they were driven for all they good for. 6EA8 would be a better sub.

Update on this set.

It's been working pretty well for some time now, I gave all the pots a good cleaning and deoxit'ing so they aren't scratchy anymore. The pots up front are pretty cheap looking parts, it's easy to understand why these sets were 'price leaders'.

I got bored with it pretty fast though, and it had terrible 3.58 dot crawl in the Y line anyway. The dot crawl could probably be fixed with a few tweaks, but in the end I decided to go a different route- component video! Turns out the circuit is easy to change to accept component video, I repurposed the R-Y and B-Y demods so the pentode section acts to amplify the incoming signal. They don't provide enough voltage output though (or more accurately the incoming signal is far too weak), so an additional stage of gain will be required. Also the red info is getting to the pix tube too soon, so a short delay will be required to make everything line up. I'll probably unwind a Y delay from another set, till I end up with the right amount of delay.

So far I got it to display a color image with the mods I've made, so it's definitely possible to get working correctly. Only question at this point is to add a tube stage for R/B gain or use transistors? I figure varying the gain of the R/B signals will form a 'tint' control of sorts, and that would be easier to do with transistors.

Here's the testing situation.

Demods modded to act as voltage amplifiers, and the chassis sitting on the DVD player which provides test signals.