Tech-Master NIB TV Kit #5516

[Electronic M]

It looks like they broke flush...
If you can CAREFULLY chip enough glass away from the leads to have something to solder to then you can use the really fine phono hook up wire Rat Shaq sells toconnect to the stub....I've had success with that method, but it takes a high watt iron and speed to get a good joint, without cracking the glass.

[WISCOJIM]

Originally Posted by Electronic M

It looks like they broke flush...
If you can CAREFULLY chip enough glass away from the leads to have something to solder to then you can use the really fine phono hook up wire Rat Shaq sells toconnect to the stub....I've had success with that method, but it takes a high watt iron and speed to get a good joint, without cracking the glass.

I've had luck doing the same with a Dremel rotary tool to carefully grind the glass away.

.

[Eric H]

The Focus wire could probably be fixed with some conductive glue (rear defroster glue for instance) since it carries little current, the heater otoh will probably need a more direct connection.

[dtvmcdonald]

Originally Posted by WISCOJIM

I've had luck doing the same with a Dremel rotary tool to carefully grind the glass away.

.

So have I, as I described earlier. BUT PLEASE ... don't use it on a power tool.
Dangerous to your CRT!

Do it right ... go to store like Lowes or Menards and buy a nice, new
DIAMOND encrusted tool of suitable shape. I used a cutoff disk. And use
it BY HAND. Slow but safe.

However those wires look very close to being long enough as is.

If they stick up at all, they are long enough. Clean them with #0000
steel wool or fine sand paper. Tin them. Then solder on tinned #30 or so
wire ... I get it from #22 tinned stranded wire. Finally stabilize them
using sensor-safe silicone. Make sure they are long enough to go throush
the base pins.

With ordinary care, your tube will live just fine. Don't worry about breaking an extra wire ... I broke a filament wire on one of my 5BP4s fixing
a broken deflection plate pin, and it works fine.

[Crist Rigott]

I managed to tack on some wires with alligator clips on one end. Then I tested the CRT.

Viola! I didn't take any time to do any adjusting of the picture.

[Crist Rigott]

Thanks guys for the tips on fixing this CRT. Seeing it does test good with the wires hooked up I'll try and save this thing. Stay tuned.

[old_coot88]

You may now claim the official title


SUPERTECH

[Crist Rigott]

Well, the new wires are soldered on the CRT and sensor safe silicone has been added. Tomorrow I'll assemble the base to the bulb.

I used Dremel Cut-Off wheels by hand to start scratching the glass away. Then I switched to a #11 hobby blade and scraped the glass away. Then I used the hobby knife to scrape the wire clean and then tinned it.

I used some 30awg magnet wire and cleaned off the enamel. I then formed a very small coil of 2 turns. Yup, I'm using the coil method to attach the new wires to the stubs. A little flux and the wire was positioned on the stud and then soldered. A very nice shaped blob of solder told me I had it licked!

I then cleaned the joints with acetone to clean off the flux. A final rinse of alcohol and on went the sensor safe silicone.

[Electronic M]

Nice work. The coil method for the new wire is what I do too.

[Crist Rigott]

Originally Posted by Electronic M

Nice work. The coil method for the new wire is what I do too.

Thank you.

[Crist Rigott]

I put the base back on before I went to bed last night. I used the same sensor safe silicone. I then soldered the wires to the pins. Cleaned up the pins and we are ready to go.

I hooked the CRT back up to the TV and success!

[Crist Rigott]

I added a 10 ohm 25W resistor to the filament string. The filament string is for 115vac and my wall outlets provide 124vac. I thought that the 124vac would be a bit too much for the filament string, hence the resistor. The filament string is now at 117vac using my wall outlet. I used such a big resistor because I had one on hand and also I like to way oversize these things.

[dieseljeep]

It looks like clearly defined scan lines now.
Are you running the chassis with the original B+ configuration, with just the 25DN6 upgrade?
Great job on the CRT lead wires. Those CRT's don't grow on trees!

[bandersen]

Glad you got the CRT focus sorted out and nice work! One thought - you might want to add a thermistor to give the tubes a soft start. Something like a CL-90 has a 120 ohms cold and around 3 ohms hot.

[Crist Rigott]

Originally Posted by dieseljeep

It looks like clearly defined scan lines now.
Are you running the chassis with the original B+ configuration, with just the 25DN6 upgrade?
Great job on the CRT lead wires. Those CRT's don't grow on trees!

Not quite. Originally I had a 10 ohm 50W resistor (R69) in place of the 5 ohm 5W resistor that came with the kit. I used a 1N4007 instead of the selenium rectifier so I had to go up in resistance from the 5 ohms. Using my iso transformer and variac the 10 ohms gave me about 125 to 128V for the 130V bus (B+). Then I remembered that I'll be powering the TV using the wall outlets of 124vac. I had to go up to 15 ohms to get about 132V B+ voltage.

Thanks.