Pilot TV-37 comments...

[cbenham]

During the restoration of a Pilot TV-37 for a friend, he asked about the idea of
adding a filament transformer for the CRT to protect it from inrush current via the series heater string. In asking around about this idea, various bits of information surfaced: The heater strings of some sets are wired differently [to address the inrush problem?]; In some sets to which a transformer has been added, the CRT still appears to light brightly momentarily then settle down to a 'normal' level. In the set I've been working on the heater wiring matches the SAMS schematic. With the mod described below, the heater now seems to light normally without an initial surge.
It consists of a small 6.3 [email protected] A transformer mounted on the rear of the HV enclosure with some power resistors wired to replace the 10.5 ohm CRT heater in the string and another in series with the transformer and the CRT heater. In place of the CRT heater, I wired a 10 ohm in series with a 1 ohm, both 10 watt resistors, and in series with the CRT heater a 1 ohm 10 watt resistor. The line voltage here at home [and where my friend lives] is high, in the range of 123 volts. Now, across the CRT heater, I measure 6.32 volts and across the 11 ohm combination, 6.94 volts. The 11 ohm combination is dissapating slightly less than 4.4 watts and does run warm.
Pic of transformer, etc. attached...

[David Roper]

Attached to what?

[batterymaker]

I remember seeing an article about adding a transformer as well--it was either in Radio Age or ARC, probably around the mid-to-late '80s.

[kx250rider]

If you want to be even safer, just make a habit of bringing it up on a Variac. I do that on many of my old sets (mainly for those with original filter caps), but it certainly stops the uneven cold string-filament problem.

Charles

[bgadow]

I went the transformer route on mine.(already running a P1 crt) I thought it worked pretty well. You have to be just a little creative to make it fit nice on that chassis-the filament transformer I used is oversized, because I was too cheap to by a smaller one when I already had the bigger one.

I'd thought about doing this on my VT-71 but I may just stick with a variac. Line voltage has really crept up around here so it wouldn't hurt.

[cbenham]

Originally Posted by David Roper

Attached to what?

Sorry for the inconvenience...

I guess I had too much turkey and egg nog, because when I finally woke up, I saw I had posted this thread to the Early Color Forum instead of this one.

If you look over there you will see the pic attached to the original post.

When I realized what I had done, I looked to see if there was a way to delete my post to the color forum and repost it in the B&W one, but nothing jumped out at me saying, 'here is how to do that'. I also tried to post the attachment to the post in the B&W forum but got a reply saying the image was already posted.

[edison64]

That article was in Radio Age, I have several copies, I will go digging and scan it