Another local Hoffman! COLOR!

[Yamamaya42]

OK...
It was NOT a bad 3A3A :O

http://suzaku.live-evil.org/0717221006a.jpg

had a burn out in the heater wire FOR it,,,,

crispy carbon!

http://suzaku.live-evil.org/0717221025.jpg

after the repair

[Electronic M]

Yikes. Hopefully that arcing and high current didn't hurt the rect of worse the fly.

[Yamamaya42]

Originally Posted by Electronic M

Yikes. Hopefully that arcing and high current didn't hurt the rect of worse the fly.

The Fly is OK, the way i found it was, I used a handful of 20KV 5mA HV High Voltage Rectifiers i had, doubled up on them so they would not fry.
but quickly found that when NOT hooked in circuit i had 25k HV, but they would burn up as soon as I tried to wire them into the normal way.

that is how i found 1he 5m to ground short on the heater winding for the rect tube and went to look for the problem.

[Tom9589]

When I looked at the two pictures of the chassis out of the cabinet, I noticed that there were two transformer cans with a piece of black tape over the top adjustment hole. Any idea why they were covered? Was it a way of the manufacturer to discourage "diddlers" from adjusting these cores?

[old_tv_nut]

Originally Posted by Tom9589

When I looked at the two pictures of the chassis out of the cabinet, I noticed that there were two transformer cans with a piece of black tape over the top adjustment hole. Any idea why they were covered? Was it a way of the manufacturer to discourage "diddlers" from adjusting these cores?

Curious. Can't think of a reason offhand. Possible that someone who worked on it did that?

[Yamamaya42]

Originally Posted by Tom9589

When I looked at the two pictures of the chassis out of the cabinet, I noticed that there were two transformer cans with a piece of black tape over the top adjustment hole. Any idea why they were covered? Was it a way of the manufacturer to discourage "diddlers" from adjusting these cores?

no idea why it's like that

Good news is, the HV rect is OK!
bad news is, my patchwork did not hold.
the HV blasted through / around the heat shrink tubing and found a path to grd and arced again, I guess i should not have clipped it down

now time for more drastic measures.

http://suzaku.live-evil.org/0717221306.jpg

huge piece of tubing filled with silicone
this will take many hours to cure
and If it's dry enough to put pack together late tonight, I will slop more on it.

hope to be ready to power it again mon night.

[old_tv_nut]

What circuit are the taped cans in?

For relatively low frequency circuits where the stray capacitance is not significant, it would be possible to include a capacitor inside the coil assembly and automatically pre-tune it during the assembly manufacture, before installing on the printed circuit.

Motorola's coil plant made some pre-tuned assemblies, but I always thought they still had to be adjusted after installation in the chassis. I used eight pretuned coils (IIRC) in our redesign of the CBS video film player (EVR), at frequencies around 900 KHz and 1.8 MHz, [linear-phase chroma pilot and chroma subcarrier filters] but they definitely had to be touched up in the final product. This was due to the differences in strays between the winding machine and the final product. It would have been possible to tune samples in the final product and then have the winding machine duplicate the tuning, but it was not worth it because the printed circuit might be changed at some time (material or layout) and change the strays.

[Yamamaya42]

using this stuff
https://webaps.ellsworth.com/edl/Act...05&language=en

[Yamamaya42]

I am really hoping this CRT is going to work, otherwise things will really suck pretty fast T_T

[Electronic M]

Once you have a good CRT change the bad HV wire properly. When that insulation kludge fails on you again a few weeks or months down the road you'll wish you had replaced the wire.

[dieseljeep]

Originally Posted by Electronic M

Once you have a good CRT change the bad HV wire properly. When that insulation kludge fails on you again a few weeks or months down the road you'll wish you had replaced the wire.

When the high voltage rectifier winding arced through, I used to cut out the wire and used an EDI solid-tube which was a solid-state replacement for a 3A3/3DB3 or a 3AT2, depending on the set. It was especially important on a Zenith that used resistance wire for the winding.
RCA's seldom needed it because the flyback was replaced before.

[Yamamaya42]

Originally Posted by dieseljeep

When the high voltage rectifier winding arced through, I used to cut out the wire and used an EDI solid-tube which was a solid-state replacement for a 3A3/3DB3 or a 3AT2, depending on the set. It was especially important on a Zenith that used resistance wire for the winding.
RCA's seldom needed it because the flyback was replaced before.

thought about that, but when I tried the Philips ECG ECG508 / R-3A3 45KV Silicon Rectifier in my CTC-16XL, it self destructed in 90 seconds for some reason.

bit worried about trying one again.

[old_coot88]

Originally Posted by Yamamaya42

...I tried the Philips ECG ECG508 / R-3A3 45KV Silicon Rectifier in my CTC-16XL, it self destructed in 90 seconds for some reason.

Are those actually silicon? I always suspected they were a selenium stack, and never trusted them.

[Yamamaya42]

Originally Posted by old_coot88

Are those actually silicon? I always suspected they were a selenium stack, and never trusted them.

shango066 also tried one in a roindie, and it fried in 20 min.

so I tend not to trust them.

if anything SS, perhaps this or something like it.
http://hvstuff.com/40kv-1a-high-volt...fier-tesla-ham

[dieseljeep]

Originally Posted by old_coot88

Are those actually silicon? I always suspected they were a selenium stack, and never trusted them.

I never had one fail, so I don't know if they had a string of silicons or selenium stack. If I knew they were selenium, I never would have used them, knowing that the focus rectifiers were.
I used the EDI brand, not the ECG.