tt-5 5BP4
 

I got the TT-5 I won at the ETF auction home and inspected it.

The CRT plug, if it is a socket, is falling apart. The wires are
100% OK however. It can be fixed.

BUT .. I can't figure out how the socket comes off! There is no
groove between the socket and what would be the plug if it were intact.

It is not the normal Bakelite plug! Its a very thing shell which appears
to be in two sections. Its hollow inside the the wires just flop
around. How does this thing work? It looks like I could grab
the shell and push of the inner keyed piece ... but I'm very afraid to try this.

What should I do?

Otherwise, the set look in good shape.

Photos might help so we can see what is odd about it.

.

Ill do that tomorrow. Tonight I finished
the project I was working on before the convention: a
set of switchable filters for Sw SDR radio. They make
a lots of aliases go away.

I figured it out with help from photos of tubes on the 'bay. Its a very bad socket
design, as you can't grab the actual plastic base to hold it as there is a lip
on the socket covering it up. I had to slowly pry my socket off with two screwdrivers.

The HV wires to the socket are dangerously old ... they are beginning to crack.

I have ordered new wire.

But how do I remove the contacts from the socket? My guess is that I
unsolder the old wire and pull it out, if it comes out. Then there are likely
little "spurs" on the contact that I need to push out to get it to came out.

Has anybody redone the wires on the CERT socket on one of these?

On the other hand, they are all clearly good enough and at close enough voltage,
that I could just wrap the whole bundle with cut-open vinyl tubing and cable-tie
it together, to protect me.

Where did you find the wire? I tried looking for replacement wire a while back and could not find anything.

Up to 10 kV Mouser has it. Odd place.

Go to manufacturer Pomona. Then search for wire. They have it
in 5 and 10 kV red and black, 50 foot lengths.

Above 10 kV I can find the manufacturers but no distributors.

and, of course, there's ebay

Above 10KV there is always the old rob the HV wire from a BPC CRT set sitting by a curb or in a field method...

Automotive spark plug wire (the non-resistive type) is another option, and should be available at the local auto parts store of your choice.

Argggggggghhhhhhhh

Abysmal soldering job throughout this set ... right from the factory.

Big blobs of 50-50 or worse solder!

I can't even use a solder sucker without first adding 60-40 solder.

Sorry, should have been more specific, I was looking for an exact replacement for the multicolored rubber coated wire. I know I can get a functional replacement.

Well, there is black, white and red on ebay. They are quite close looking.

I found all the other colors, at their manufacturers. But no distributors.

TT5 restore thread
 

My tt-5 restore proceeded well until this evening.

I recapped the HV section and all electrolytics plus a few
critical paper caps.

I then turned it on using a variac and dim bulb. Nothing sparky or
smelly happened. The HV section works ok as tested with my new HV probe.
The B+looks OK at slightly reduced line voltage.

The horizontal works fine.

The vertical is dead, apparently due to an open oscillator transformer
primary (plate) winding. This needs to be verified and if so checking
for bad wire connections.

Its supposed to be an RCA 32898. Can these by found? If not,
the circuit looks rather common, I've seen similar circuits
with different transformers. Is it possible to use a different replacement,
or find the specs to have this one rewound? would a generic 4:1 one with
appropriate resistances work (properly)?

Doug McDonald

An attempt to fix the transformer failed. Indeed there was a break at the small-wire
lead junction. However, the fine wire broke off at the paper.. Further investigation
showed that there were multiple patches of
corrosion in the few of layers of wire. Something
corrosive was there from the day of construction.

Sulfides from the paper? May be just an old wives tale, but several radio collectors that I know claim this is a real problem on pre war radios.
Coin collectors also seem to avoid paper envelopes for the same stated reason.:scratch2:

jr

I don't think it was from the paper. On the windings it was patchy and seemed
to be coming in from the edges.

Another symptom was that it was impossible to solder to the lead wires using
just solder and flux! Period. No matter how hard I tried. There was some sort
of coating that resisted heat so well that even my hottest soldering iron
setting and liquid flux could not beat it. It had to be scraped off. A sulfide
would dissolve in flux.

You got a great score with that one. How about some glam shots a la Banderson for the rest of us to drool over.

One of the worst things for coin collectors was the high sulphur content of the materials used in the blue Whitman coin albums of the late 60's-early 70's era. They could turn your choice BU set of 1941-1958 wheat pennies into severely spotted coins in less than a year.

.

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.)

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!

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.

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.

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.

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.

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.

I accidentally put the post with screen pics in the other (wrong)
thread (this forum)

Moderator:
could you move it?

I can merge the two threads if you like.

BTW, very nicely done!!! Amazing work you do :)

Here is the set, next to its matching RCA U10 radio-phono with specific
Television input, showing Happy Days on OTA (digital) TV.

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 :yes:

Happy days indeed!

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).

I'd recommend looking for saphire styli for it. They last ~2000 plays, and are lower wear to the records. I don't know if anyone makes them for 40's carts now, but they did make them in the 40's. I've found 2-3 in phonos I've acquired, and I don't plan to let them go.

I stupidly forgot to photograph the decals on the back of the TT-5 chassis
before cleaning it, they got ruined. Too bad as they were quite legible.

Does anybody have really good high res photos of these? One of them I have
a low res photo of and a good original of a similar one from my TRK-120 that
I can photoshop into the desired form if necessary, but the other one I
don't have anywhere near good enough.

Also I need a photo of the rubber stamo with the modified frequencies:
mine was very dim.

As a general issue: when redoing these, what does one do about the
condition? Do you try to match the old color, use nice clear white, or
something in between? I personally don't care ...