1950 Motorola update - Videokarma.org TV - Video

suede · #1 11-13-2009, 06:12 PM

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]

DaveWM · #2 11-13-2009, 06:57 PM

have you worked on any tube gear before?

grimer · #3 11-13-2009, 07:24 PM

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jeyurkon · #4 11-13-2009, 08:37 PM

Nice oil lamp!

John

Charlie · #5 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!

suede · #6 11-14-2009, 02:47 AM

Quote:

Originally Posted by grimer

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 · #7 11-14-2009, 03:09 AM

Cool set

No such thing as a stupid question

- stupid is not asking

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.