Ge 21c2465

[Glenz75]

Great find on that NOS control...Guess Murphy was 'out to lunch' in this occasion How often does that happen

[bandersen]

I just received my order of a few caps and resistors from Digi-Key. What the heck did they send me

[bandersen]

I turned out to just be some 4' lengths of heatshrink tubing. Why not just roll it up or bend it ? I wonder if that would damage the tubing in some way

[Kevin Kuehn]

I doubt if rolling would hurt it, in fact I've seen heatshrink sold in rolls. Probably just the shipping person had to make the call and decided better safe than sorry. Last thing they need is a call from an angry TV guy.

[bandersen]

Originally Posted by Kevin Kuehn

I doubt if rolling would hurt it, in fact I've seen heatshrink sold in rolls. Probably just the shipping person had to make the call and decided better safe than sorry. Last thing they need is a call from an angry TV guy.

LOL - could be. I picked up a couple rolls of heat shrink from Mouser, but it's a much smaller diameter.

I noticed Digi-Key carries the Rubycon BXW series (105C, 10,000 hrs, and small) and decided to give them a try. Also got some 1600 and 1250 VDC Panasonic poly caps.

[bandersen]

I decided to start recapping the sweep board and cleanup the HV cage.


It's fairly easy to work on the PCB in place. I just hard to untwist a few tabs holding the pots down and unwrap a couple wires.


It's even easier if you go a little farther and dismantle the HV cage.


That also gave me a chance to remove the corrosion. Here it is ready for reassembly.



I noticed this set specifies a 1J3 HV rectifier although I found a 1B3 installed.
The only difference between the two tubes I could find in the specs is the plate drop. It's a couple 100 volts more in the 1J3. It makes me wonder why the 1J3/1K3 even exists. Why not just always use the 1B3/1G3

[ohohyodafarted]

Bob,

I have a 21DSP4 NOS Chanel Master rebuilt for sale if you are interested. I am not far away from you in Milwaukee.

[bandersen]

Thanks, but the 21DSP4 is 90° while this set uses 110° 21CEP4.

[Reece]

Funny about that full-length shipping box. I keep all my different shrink tubes rolled up in a glass jar and it doesn't hurt them at all.

[ohohyodafarted]

Originally Posted by bandersen

Thanks, but the 21DSP4 is 90° while this set uses 110° 21DEP4.

Sorry Bob, I must be getting senile. I misread the original post and though it said DS. I think I need to take a break. To much going on and I am having obvious issues handling it all. Sheesh! My Bad!

[bandersen]

I finished recapping the sweep board and HV cage. I powered it up before moving on to the IF board. It's working fairly well and I can adjust the volume now

I decided the best way to tackle the second board was to undo the wires and unmount it just like in a Predicta set.


Interesting how the tubes are mounted on the foil side.

[wa2ise]

My RCA TV set (the one I Beltroned the CRT in) has boards like that. I cheated when recapping: instead of unmounting the boards I just clipped the old cap's leads, and J hook soldered the new cap leads to the old leads. Ugly, but if you keep the new cap leads reasonably short, but not so close to the old leads where they connect to the foil of the circuit board, works. IOW, I wanted to avoid melting the old lead's solder connection to the circuit board foil, by having around 1/3 or more inch length of old lead from the board to the soldered junction of the old lead to the new cap's lead.

As you can see in the picture, you don't see the ugliness...

[bandersen]

I spent sometime this afternoon removing the dead CRT.

Working with it face down on a blanket seemed safer than keeping it upright.


I quickly realized the speaker would have to come out so I could get at some bolts. That gave me a chance to finally get a good look at it and the second speaker hiding inside.
That's one huge speaker




The aquadag coating had worn off the new 21ESP4 (on the right) in a few areas so I'm giving it a coat of Slip Plate before installing it.


I made an attempt at touching up the damaged top but ended up striping it. Just the top that is. The rest of the original finish is in good condition.

The damage is still faintly visible on the right side. I figure some sanding and stain will take care of that.

[Phil Nelson]

Cool. I didn't realize there was a tweeter mounted in front of the big oval speaker.

Phil Nelson

[davet753]

Banderson: I think the 1B3 was developed as an improvement on the 1J3. Seems like I read somewhere that the filament on the 1B3 tubes were designed a little huskier than the 1J3. Because the tube usually takes it's filament voltage from a loop on the flyback, the voltage varies quite a bit. Adjustment of the horizontal drive control, brightness, or even variations in line voltage can have quite an effect on filament voltage for the HV rectifier. In other words, plenty of voltage variation for a filament rated for 10% variation.

I have read that in cases with high failure rates, you can change sockets (and filament resistor) and use a 1AX2 tube. The 1AX2 is a much more rugged tube with a tougher filament and a shielded cathode.