Here's that 8T241 again. I picked up the resistor yesterday, but didn't get around to installing it until this morning. I didn't like the looks of the HV Rectifier filament winding, so I re-wound that while I had the cage apart. Here's the picture of the set working with the cabinet fully put back together. Unfortunately, my cheap camera and shop lights don't do it much justice. At least the picture looks nice and sharp. This set has one of the brightest and sharpest 10BP4's I've ever seen.

1958? GE
 

OK, I admit this set is boring compared to some of the 40's sets posted here but...

Here's the guts of the GE I posted earlier over in the B&W Portables thread.
I have only replaced a half dozen caps and already the picture is looking pretty good :D
The CRT shown in the pic is the original or the first replacement more likely since it has a 1961 date code, It is shot and is only being used for test purposes.

I have obtained a brand spanking "new" GE tube, still in it's original box dated the 30'th week of 1957!
It's been waiting 46 years for it's chance to show a picture :eek:

Ion Trap
 

Here's a pic of the itty bitty lil' Ion trap.
The tube is a small neck 110 deg job but still has a trap, didn't think they went that late!

Eric,

Does the CRT you put in have an aluminized screen AND a bent gun? Aluminized screen CRT's do not need an ion trap. If the gun is straight it doesn't need an ion trap either....but you know all this. :)

I too am surprised. I thought ion trap/bent guns went out with the switch to small neck tubes and higher deflection angles.

Rob

The advent of the aluminized screen was the last step toward eliminating the ion trap and bent gun construction and you're right that the small-neck tubes were the first to eliminate the ion trap. There were, however, some large-neck test CRT's that didn't use ion traps, but I have yet to see one of those without a burn in the center of the screen. The burn could be from ions, but it could have also resulted from operation of the tube without deflection. I always take my test CRT out of its case and install it through the yoke of the chassis that I'm testing, but some previous owner of the tube might not have done that. It only takes one time to burn the phosphor.

Here's my latest non-customer project. It's the Fada TV30 that I bought from Tim last year. I started recapping it shortly after I bought it, but found myself too busy to finish it right then. Before I started recapping, I ran my usual preliminary tests on the circuitry and reviewed some notes that Chuck had written about his experience with the set before Tim owned it. This set has been passed around like a groupie ... lol. I'm about 90% finished with recapping it and have been firing it up at several convenient points to check my progress. So far, it appears that I've corrected all the issues from Chuck's notes and I have a recognizable picture and some sound that keeps getting better as I recap more stages. By the time I'm done with the recapping, my second B&K 415 should be arriving and I'll re-calibrate that unit for 21.25 MHz IF work, leaving my first 415 set up for 39.75 MHz. Here's an under-chassis picture of the TV30. Note the Amprobe inductive ammeter and the divider coil fitted to a "cheater cord" that I use with my Variac when I'm powering these old sets up.

Here's how the picture looks at this point. It's not great, but at least it confirms that I'm making meaningful progress with each step.

John,

I was the previous owner of Tim's Fada TV-30. This is the one that had some minor grey paint splatter on the front. I had a raster on it briefly until one of the wax caps under the chassis in the Horizontal section started to crackle and bubble. At lkeast that is what I guessed it must have been. The raster went out as the cap shorted I'm guessing. I never pulled the chassis to investigate. Nice to see someone finally doing this set!

Rob

John,

In my experience screen burns from deflection failure are small, sharply defined burns. Phosphor burn from ion bombardment are larger sized darkened smudges. I have a Dumont 15AP4 that has no aluminizing and a straight gun (no ion trap). It is like new for emission and has no ion burn. When I tested it for emission when I got the set home it had obviously not been run for decades. It immediately shot up to perfect emission without delay, clearly a low mileage CRT. Many of these old CRT's read good, but only after taking a while for the emissive coating on the cathode to reawaken. It is in a very rare Sightmaster 15-S-1 set.

This tube is kinda crude, has some shape distortions, probably from almost colapsing in the baking process. If I own a vintage CRT that I'm afraid might blow up in my face from merely handling, this would be the one.

Rob

Yes, and the paint came off nicely with a small amount of denatured ethanol and soft cloth. The finish and lettering survived intact. I'm going to have the set's few cosmetic flaws fixed at some point during the repair. Actually, the blanking out of the raster was from a cold-solder connection. It looked as if it had been serviced a few times through the years, and one of the techs didn't quite get the solder flowing when he put a new cap in the video output stage. The voltages on the CRT drifted way off, cutting off the beam. The CRT in that set is absolutely incredible, definitely in the top two of all the 10BP4's I've seen so far. I have 6 sets in my collection that use 10BP4's, five good tubes and one rebuildable dud. My 630TS lost its CRT thanks to the Postal Service -- bonk, snap. hiss. Luckily, I had bought a good tube on eBay for a spare, but my Fada 899 has a dud tube. I guess the dud goes in the 630TS until I can get the other massive damage repaired. By then I hope to find another good spare or the extra cash to have the dud rebuilt.

Here's the Fada 799 that will be the next set from my personal collection to be recapped when I find time. I finished the initial evaluation last week. Aside from a snapped detent spring in the tuner and the need for recapping, the set is otherwise in mint condition. I got sound and something resembling a picture when I put in the 5AXP4 test CRT and put the Variac to it, but then I set it aside to finish the work I'd started on the TV30.

My latest project is this Hallicrafters 505.

Like my T-54 it was a basket case, I had to have some knobs made and I bought a back and CRT off eBay a while back.
I have started recapping it but ran out of .1's and .22's so I wil have to wait till I restock to finish.

Here's the recapped TV30 working much better. Rob, you were on the right track with the HV after all. The 1M/1W filter resistor had changed value, causing very poor regulation. HV was present and would produce a raster, but increasing beam current would start to drag the HV down as the Brighness control was turned up past 90%. With that cold solder joint that I had fixed earlier throwing the CRT's bias out of whack, it turned out that the increase in beam current from the grid going positive would cause an increasing drop across the filter resistor with a resulting sag in HV output that would ultimately blank the raster.

I'm waiting for a B&K 415 that I'll be re-calibrating for efficient alignment of 21.25 MHz IF systems and will be aligning this set with this "plug-and-play" system. For now, I'm setting it aside until the 415 gets here.

I may have a couple of brown original Halli knobs around if you need em.

...

Thanks Tim but I have a complete set of repros. :D