Re: Flyback Troubleshooting help

  Hold on... Hold on!! :-)

I had the monitor isolated (aka floating) from cabinet ground and PCB so
no isolation was okay. Albeit slightly shock prone, but I was careful.

On 1/17/2011 12:17 PM, John Robertson wrote:
> Jess Askey wrote:
>> Hi Everyone...
>>
>> My Amplifone raster saga continues, I now have two deflection boards
>> and an original deflection coil (thanks John!) but nothing is working
>> yet. Im probably going to go into a little too much info here, but I
>> figure more is *more*. :-)
>>
>> First Important Note: Im running this deflection PBC off the Atari
>> switching power supply which puts out 145VDC for the monitor. Oddly,
>> this is fed directly in where the 125VAC goes, which if you do the
>> analysis, is just fine... it is actually a little easier on the
>> monitor power regulator (120V) since it only has to regulate down
>> from 145VDC rather than 170VDC. The reason this is important is that
>> the switcher shuts down in an overloaded condition (saving me fuses
>> and more) any time I power up the monitor. When I first was
>> troubleshooting this monitor I had a few times where I doubted that
>> the deflection PCB was the problem so I put it on the regular 120VAC
>> line... well, that proved one important thing twice (yes, I was
>> stubborn enough to learn this the hard way twice). I shorted the HOT
>> and the power regulator. So, lets just say that Im pretty sure that
>> using the Atari switching power supply is working well as a
>> troubleshooting method.
> ...
>
> Let me get this straight - you hooked the monitor chassis DIRECTLY to
> the mains - 120VAC?
>
> No ISOLATION transformer?
>
> Small wonder you blew the transistors. You will also have blown diodes
> on the input bridge - I hope you checked them too...
>
> You must always use an isolation transformer when checking raster
> monitors - I even do so with the ones having the built-in switching
> supplies just to keep in the habit...
>
> Now back to troubleshooting the flyback. I'm going to dig out my
> schematic and ponder.
>
> John :-#)#
> --
> John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
> Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
> www.flippers.com
> "Old pinballers never die, they just flip out"

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Received on Mon Jan 17 14:30:30 2011