Rock Ola 1478 amp question

br549autosales · by **br549autosales** » Thu Apr 17, 2014 5:05 am

Began working on another jukebox that belongs to a man whose pinball machine I repaired. It is a Rock Ola 1478 and the amp looks to be in poor condition. I have never worked on a juke that has tubes, but it looks to me that most of the ones on this one are bad. When the carousel is turning to select a record, one of the tubes is arcing/lighting up and I hear static from the speakers. This is the only one that I see lighting up out of all of them. The first two pics I am pointing to the one tube that is arcing and the other pic is a component that also has a red glow towards the bottom and is getting pretty hot when the carousel is turning and selecting. The last 2 pics are mainly just to note the condition of the other tubes.

Thanks,

David

MattTech · by **MattTech** » Thu Apr 17, 2014 6:00 am

That chassis looks badly in need of restoration, of course.
But, what is the question?

br549autosales · by **br549autosales** » Thu Apr 17, 2014 6:29 am

Mainly, what would cause the tube I am pointing to to arc/flash and what would cause the other component I'm pointing to, to get hot? I probably just need to send the amp to Bill Bickers to have him rebuild it.

Rob-NYC · by **Rob-NYC** » Thu Apr 17, 2014 8:49 am

David, the first tube you pointed to has gone to air (lost vacuum). It is now arcing --remove it, it can short and kill the output transformer.--

The white cylinder is a power resistor. They do often run quite hot.

Do Not continue to run this amp before it is rebuilt, doing so can destroy the power transformer and/or output trans.

You can find a schematic here:

http://www.verntisdale.com/Rockolaschem.htm

This same person also sells capacitor kits.

Rob/NYC