Rodger Boots wrote:
> Something similar to that works great for checking fluorescent
> ballasts in games. Take a 60-100 watt bulb and connect it in place of
> the fluorescent bulb (so you have the power going to the ballast in
> series with the test bulb). The test bulb should light at less than
> full brightness. No light can mean an open ballast, bright light
> means shorted ballast.
>
> Fun fact, the fluorescent bulbs in games run with 400 mA of current
> through them. Small bulbs (5/8" like used in Eight Ball Deluxe
> pinball) are around 250 (should have been 125) mA. In an emergency a
> ballast may be replaced with a 75 watt bulb (for 1 to 1.5" diameter
> bulbs less than 25" long) or a 40 watt bulb for the 5/8" diameter
> bulbs. Anything over about 24" uses an autotransformer ballast and
> can't be operated with the substitute. The light bulb, not being
> inductive, doesn't start the fluorescent as easily, but will work.
>
> (And now you know what I fiddled around with as a teenager!)
>
>
> John Robertson wrote:
>
>> Testing the Vector monitors with the yoke unplugged is like running
>> an audio amp with the speakers unplugged. No load means little if any
>> risk to the output devices if there is no input.
>>
>> If you have a scope you can hook it up across the yoke lines to see
>> the results, if not, use a 15 watt 115VAC light bulb...the bulb will
>> glow brighter (if no input to the monitor) if one of the output
>> transistors is shorted. The bulb will not pass much current (whats
>> 15/115V = X/60V? about 7 watts or 100MA - please check my math, but
>> it is pretty low current!) - need my ohm's wheel to figure that out..
>>
>> I've used the light bulb test on my servicing of jukebox audio amps
>> over the years (25) and no damage to output transistors, you can
>> check that the amp is set up correctly and the lamp gives an instant
>> indication of problems...with no smoke!
>>
>> John :-#)#
>
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Received on Sat Jul 6 23:26:40 2002
This archive was generated by hypermail 2.1.8 : Fri Aug 01 2003 - 00:34:04 EDT