#16
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You got a great score with that one. How about some glam shots a la Banderson for the rest of us to drool over.
__________________
John |
#17
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Quote:
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#18
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This
http://www.themineralgallery.com/silver.htm (first few) is what happens when lumps of silver encounter sulfur at relatively high temperature. These wire grow out. The ones in the pictures have, mostly, been cleaned of the sulfide tarnish. Straight from the mine, or straight from the fake-producing oven, they are black. They are easy to fake. Last night I got to 75% recapped. I've done all the electrolytics (restuffed) and HV caps (canned ones restuffed, the four non-canned ones not restuffed, as the only vertical coupling ones I could find are too large in diameter by about a millimeter.) I'm still working on the paper ones. There were several ones replaced in the late 40s or early 50s, and these I have not restuffed but just installed new ones. I also will not restuff the two on the RF oscillator socket as I want to disturb it as little as possible, as it seems to be working fine. I'll use clip and hook. Edit: oh yes ... I also collect such mineral speimens, though very few as pricey as that first one (though mine have appreciated a LOT.) Last edited by dtvmcdonald; 05-17-2016 at 08:28 AM. |
#19
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The routine recap is finished. I did a few simulations and tests on the
vertical oscillator circuit and discovered that what I thought were filter caps were in fact energy storage ones. I had in stock plenty of 0.33 uF axial ones to replace the 0.25 uF ones, plus plenty of 0.22 uF rectangular Panasonics, but no 0.27 uF ones, so I went with the 0.22 uF ones, unrestuffed. Everything except the vertical still works fine; I checked the RF oscillator frequencies and they are in good shape, well within nominal range for modern frequencies, unlike my TRK-120. The whole video and audio chains work fine. I have not yet ascertained whether the audio detector is correctly reset to slope detection, though with modern frequencies it should be. However, the response looks too symmetrical. The vertical osc transformer is on the mail delivery truck right now. Perhaps a picture tonight! |
#20
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The vertical oscillator transformer arrived and was installed, and works correctly.
A CRT was installed and produced a picture. However, width was inadequate and position unstable. It was also dim. This was one of two I bought reasonably cheap on Ebay. It had had its base "repaired" which was why it was cheap. A test of the capacitance of the 4 deflection plates to all the other electrodes showed one was open. So I tried another tube (the original) and it was even dimmer. It didn't last long ... the filament died. The third tube, the better one I bought on ebay, produced a dim but correct picture. I attempted to fix the broken lead SUCCESSFULLY! REPAIR BAD CRT 5BP4 (search bait line) I removed the "repaired" base. Sure enough, pins 5 (connected to a getter carrier, not used afterwards) and 6 (the deflection plate) had wires broken off at the glass tube base. The wires come out of little "teats" with dimples in them, so the wire cannot be easily resoldered. I got a Dreml tool cutoff disk, a metal disk 2 cm in diameter encrusted in rather coarse diamonds. I used this BY HAND to grind down the glass of the two bad connections until the metal of the lead was exposed and flush with the glass. It was easier, with the tool I had, to do both at once, a diamond encrusted file could easily do just one. I then tinned the two exposed leads. This was easy. I then soldered very thin tinned wires (from some stranded hookup wire) to the tinned teats, and soldered them to the tube base leads. Capacitance measurements showed the correct values! So I used sensor safe silicone to hold the wires firmly on. This morning the glue was set so I tested the tube and it works normally. Then I reattached the base. The ebay seller had used cable ties, which won't fit in the magnetic shield, so I just used a few layers of tightly wrapped tape. The set works OK. The sync is a little touchy but stable. The picture is very dim. I carefully looked at the TRK-5 at the ETF at the convention, and it too was dim, but not this dim. The B+ is normal at 300v. (AC line at 117 v.) The HV is 2000 volts or so from cathode to 2nd anode., maybe a bit less. However, the main filament supply is a bit low at 6.1 volts. I forgot to measure the CRT filament voltage with the CRT running. I will do that tonight. |
Audiokarma |
#21
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The resistor to ground from the brightness control had risen from 150k to 320K.
Since the control had been set all the way to highest brightness, one would have hoped fixing that would increase brightness. It didn't do much since the "correct" setting when fix, while in the center of the range, was almost the same voltage as before the fix. Raising the line voltage so the bulk of the heaters were 6.3 volts and the CRT was 6.65 improved the brightness just a bit. 5BP4s are cheap, compared to the set's value. I'm ordering more to try. |
#22
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I tried ordering a couple more 5BP4s from Surplus Sales of Nebraska, which claimed to
have them, but they were all DuMont except one Philips, so I cancelled the order. The better one I have has awakened quite nicely when running at 6.75 volts, and seems to stay awake at 6.2. Its watchable in a dark room. The set is now in "cooking" mode, outside the cabinet. Tonight I will take chassis pictures and post them. I did try putting the chassis in the cabinet last night to see if the properly adjusted RF slugs would fit (they stick out the front a lot), and they did, barely. I glued a bit of loose veneer back on the cabinet. It still has some small areas of veneer chipped off and a few bad scratches and lost lacquer, but I'm not fixing these at this time as it looks OK. The CRT has really truly awful astigmatism. This and nothing electronic limits the resolution. This must depend on the relative DC voltages on the two sets of plates. I will investigate either on the Web or with a simulator program a colleague has. |
#23
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As promised, photos. There is one "before" of the HV section of the chassis, and two "afters". Note the big white HV caps. They are the only visible caps that were not restuffed if original. Caps I believed to be non-original were not restuffed,
though I may have made a few errors. I still have the old ones. The cabinet has only been cleaned with Goop and delaminated areas of veneer and the plywood were reglued. If it cooks OK tonight I will put it in the cabinet tomorrow. This design set did not DESERVE to sell well. It needed 4kV on the HV. |
#24
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Here are images from the screen, with the set all
wrapped up in the cabinet. Neither TV nor camera settings were changed between shots. These are unadjusted manual settings at ISO 6400, 1/20 sec f/5.6. That means they are DIM. The relative brightness of different scenes is accurately rendered. Remember that this set has DC restoration (done at the grid of the video amp, which is DC coupled to the CRT. I'm surprised that the shots with text look as sharo as they do .. at the real dimness they are much harder to read. |
#25
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I accidentally put the post with screen pics in the other (wrong)
thread (this forum) Moderator: could you move it? |
Audiokarma |
#26
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I can merge the two threads if you like.
BTW, very nicely done!!! Amazing work you do
__________________
"Restoring a tube TV is like going to war. A color one is like a land war in Asia." |
#27
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Here is the set, next to its matching RCA U10 radio-phono with specific
Television input, showing Happy Days on OTA (digital) TV. |
#28
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Thanks, for posting the pictures. Glad to see you got the TV working.
I'd never seen a picture of the radio/ phono for the set. The wiring for your set looks more cramped than I realized for a TT5. Ed |
#29
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Happy days indeed!
__________________
John |
#30
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The U-10 is not "the" radio-phono for the TT-5. Its merely "a" suitable one. Many were
sold with "Television" jacks on them. However, while only a transformer AA-5 radio, it does have a mode/tone switch similar to the radio for the TRK-9 and TRK-12. The radio for the TRK-5 does not have a tone "switch" but rather a very conventional tone pot. The U10's preset station pushbuttons are more reliable than the motor system on the TRK-120. They are a rather elegant solution. Now I have to get the phono pickup for the U-10 rebuilt. The turntable works. And then buy some jazz 78s and more steel needles (it came with a pack of 20). |
Audiokarma |
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