I've been blessed!

[zenithfan1]

Originally Posted by bgadow

The power transformer in my -5 lost a lot of wax, too, but it hasn't given me any trouble and doesn't seem to be losing any more. Not many sets put the transformer in a box like that.

Yep, I've only seen them in RCA color sets but are probably found in a few others. I wonder why some leaks out and then it is fine? Maybe it did it when the transformer was new and it stops when it is broken in. I'm glad other people have seen this, I was a bit bothered by it at first.

[old_tv_nut]

Thx for the FAQs on wax

[old_tv_nut]

Tonight I chased down the horizontal waveform and hold adjustments, which interact a lot. I now get a solid horizontal lock and can adjust the AGC for the specified 2Vp-p detector output. For some reason, the p-p amplitude at the video output is low (plenty of blanking, and the brightness control works, but max contrast seems anemic on the scope), so more trouble shooting remains.

[old_tv_nut]

I hooked up a color bar DVD tonight, and it appears the video output is OK after all - I'm getting the peak-to-peak reading specified in SAMS, although it's lower than I guessed it would be. Also, the color circuits locked right in and are producing classic-looking waveforms on the G1's.

Also, the vertical hold seems to work OK.

I checked out the action of the contrast control, and I can see why there is a suggested change. There is quite a bit of quiescent current in the video output tube, which is changed by the DC coupled contrast control setting. This results in wide swings of black level (brightness) when the contrast is adjusted. The change to capacitive coupling will eliminate the DC shifts.

I have got to get the CRT mounted somehow now, because it looks like the chassis is fully functional.

[old_tv_nut]

Hi - "Chuckles" the TV restorer here--

Today I put in the contrast control fix (see attached diagram). However, I didn't study it very carefully and just wired it as shown. If you pay attention, you will see that this reverses the action of the contrast control, so max contrast is now counterclockwise. I plan to leave that way, as the chassis is very crowded in that area, and completely disconnecting and rewiring it seems like asking for trouble.

The contrast control now acts like it should, without the huge shift in DC level - should be much easier to set up and adjust the background controls now.

A second look at the color controls inidicates that the hue is not centered - more work.

[old_tv_nut]

By the way - anybody have spare tube shields? I'm missing a couple.

[bgadow]

I have at least a shoebox full. If I can remember Sunday I'll dig out some clean ones. Drop me a line with your address. Enjoyable to read the progress!

[old_tv_nut]

Originally Posted by bgadow

I have at least a shoebox full. If I can remember Sunday I'll dig out some clean ones. Drop me a line with your address. Enjoyable to read the progress!

email sent!

[old_tv_nut]

"...and the smoke it encircled his head like a wreath..." - no, not Santa, but me, wondering what that smell is - something died suddenly in the tuner (although I didn't realize it for a few seconds, because I was working on adjusting the chroma oscillator, and thought at first I killed that) but it turned out to be the B+ dropping resistor on the tuner. Now I'll have to track that down. The burned resistor is supposed to be 1k/2W, now measures 270 ohms. A secondary dropping resistor that should measure 6k (6.8k in parallel with 56k) now measures 1k in the circuit - I haven't figured out where the parallel path is, if any. But all the B+ points measure about 2M to ground, which they should - no shorts evident!

That's enough geeking around for Christmas Eve - heading for some eggnog and carols on TV - Merry Christmas all.

Oh - and thanks to Brian for the tube shields - just the assortment I needed.

[old_tv_nut]

I finished the mods to mount the glass CRT (21FJP22) today. Steve McVoy provided a complete set of mounting hardware from a junker CTC-7 (intended for the 21CYP22, which has the same shape as the 21FJP22, but a different anode connection location).

Thanks, Steve!

It turns out that this hardware fits the CRT perfectly, but is exactly wrong for the CTC-5 bezel. For example, the CRT rim insulator is corrugated just enough to prevent it fitting in the CRT well molded into the bezel. Also, the metal shield, while it looks similar to the shield in the RCA adapter kit, is actually just the same size as the CRT well, so doesn't fit either inside or outside. Since the manual says it's not used in metal cabinet sets, I know it's only purpose is magnetic and not structural. Therefore, I did the CRT mounting without it, and will cut it as required to mount it over the other hardware.

Despite the mismatch to the bezel, it was possible to use the mounting ring by extending the bolts that are built into the CTC-5 bezel. This saved me from what would have been a difficult construction for me. After I extended the bolts, I called a friend to see what I had done (before standing the set up), and he suggested that the bolts would probably bend and let the CRT shift if not supported. Fortunately, I had bought one of each kind of padding material offered by American Science and Surplus, just in case I needed it, and the foam rolls you see did the trick.

The anode button is a bit close to the mounting ring, but I plan to use silicone grease and also to put the smaller rubber insulator from the CTC-7 between the HV cup and the ring.

Now, I have to find and fix whatever burned the B+ dropping resistor for the tuner, and work towards pictures!

[old_tv_nut]

Replaced the burned resistors on the tuner today. Couldn't find any particular cause though - guess they just got tired.

Then I almost got into trouble trying to align the color oscillator drivers to see if I could get the tint control centered better. At one point I stuck the tool into the bandpass transforner by mistake and really messed up the tint. Then trying to follow the instructions, I found that the so called "touch up" of the drive transformers actually could move the tint by 90 degrees, that is, tuning for the peak demod current according to the instructions, (R-Y) was coming out of the (B-Y) demod, and minus (B-Y) out of the R-Y demodulator. Anyway, after wasting an hour, it's now back to normal tint. I probably should be doing a complete IF and color bandpass alignment, but I'm going to move on to more basic things like hooking up the HV and CRT dag grounds and installing the chassis. Then I'll see if I basically have a picture and sync instead of just scope traces.

[old_tv_nut]

Started to install the chassis and only got as far as you see, because the clever (?) bolt extensions and mounting pads I put in for the glass CRT interfere. Second pic shows the vertical tube about to be decapitated.

Back to the drawing board

[jeyurkon]

Still, it was a pretty clever idea and you've made a lot of progress. Keep the faith.

John

[eberts]

Take a hacksaw and cut those bolts until the straps fit perfect.
Move that padding towards the face of the tube for support.
You have the pads on cone, not good, the glass in that area is very thin.

[zenithfan1]

Also, if that edge purity magnet assembly is in the way, you can remove it when using the 21FBP22. I would take it out and save it with the other stuff in case you find an AXP. Mine is removed for cleaning right now and that is where I got the idea. Just a thought....