Videokarma.org TV - Video - Vintage Television & Radio Forums

Videokarma.org TV - Video - Vintage Television & Radio Forums (http://www.videokarma.org/index.php)
-   Early B&W and Projection TV (http://www.videokarma.org/forumdisplay.php?f=19)
-   -   1950 Motorola update (http://www.videokarma.org/showthread.php?t=246480)

suede 11-13-2009 06:12 PM

1950 Motorola update
 
So i finally got my chassis out of my cabinet. Its surprisingly clean, looks good. I did notice a busted 25l6 gt tube, so i replaced it. Plugged it in and.. nothing. All tubes light up, including the back of the crt, but no snow, no light, no nothing on the face of the crt. No idea of where this newbie should go from here.

[img=http://img297.imageshack.us/img297/2529/cars016.th.jpg]

http://img697.imageshack.us/img697/2714/cars017.th.jpg

DaveWM 11-13-2009 06:57 PM

have you worked on any tube gear before?

grimer 11-13-2009 07:24 PM

---

jeyurkon 11-13-2009 08:37 PM

Nice oil lamp!

John

Charlie 11-13-2009 08:45 PM

That's right... without that speaker socket plugged in, you're only going to get tube filaments... nothing else.

If you try powering up something from 1950 without first changing some caps, you could get a loud blow... so stand back! :D

suede 11-14-2009 02:47 AM

Quote:

Originally Posted by grimer (Post 2959858)
Did you have the speaker plugged in? As the field coil is part of the power supply

Damn.. didnt know that.

Sorry, im just beginning to learn, sorry for the simplistic questions. but we all have to start from somewheres.

Thanks for the help.

bandersen 11-14-2009 03:09 AM

Cool set :thmbsp:

No such thing as a stupid question :no: - stupid is not asking :yes:

Sometimes they used the speaker field coil as a filter choke in the power supply. Makes sense really - why not make it do double duty?

Also means if you replace a field coil speaker in a radio or TV with a PM (permanent magnet) one, you'll need to splice in a choke or resistor to take it's place.

And like Charlie said - change those caps! Unlike tubes, they don't ago so well.


All times are GMT -5. The time now is 02:37 AM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2026, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.