Re: Tempest - WG6100 Deflection board issues

From: John Robertson <pinball_at_telus.net>
Date: Sun Sep 21 2008 - 23:41:38 EDT

Colin Davies wrote:
> Hi Guys,
>
> I've isolated the fault to either the yoke or the deflection pcb
> itself (I've not got a yoke or spare deflection handy to try
> substituting in a hurry) ... The chassis was quite happy to run
> without the HV unit powered up, so its safe to test (imho) without
> doing any damage.
>
> The -27v rail is fluctuating between -27v and 0v on the scope. (very
> odd !!) the +27V is fine... I can clip the scope on xy mode onto the
> yoke feedback resistors, and see the same fault that was on the monitor.

Get an LV2000 kit to replace the original regulator section, your
monitor wil be much more reliable AND you will probably fix this problem
at the same time. I install the LV2000 kit in every W.G. Colour XY that
comes through our shop. Reduces call-backs!
>
> Has anyone seen a shorted yoke on one of these before ? I'm hoping
> that its just something shorting out/breaking down on the deflection
> pcb - maybe someone has installed a capacitor the wrong way round or
> something ? It's certainly been worked on before.
>
As you found out the yoke was not your problem. You CAN run XY (or
raster) monitors with the yoke unplugged as a test. However NEVER
attempt to run these monitors with any transistors unplugged -
particularly the output transistors! That can or will destroy other
transistors or resistors.

Have you resoldered ALL the Molex pins on the board that everything
plugs into? Very common for one or more pins to have a cracked solder
trace so it is intermittent.

John :-#)#
> I'm reasonably certain that the chassis transistors are ok, as I
> swapped the plugs round, to swap the pairs for the regulator and one
> of the deflection pairs.
>
> As a further note... Q100 and Q101 had been replaced with standard
> 7824 / 7924 voltage regulators, they look like they have just been
> dropped in with no further modifications to the circuit... surely
> this is not good practice ?? I thought this might be the problem,
> soI dropped in some transistors to replace - a mpsa06 and an BD238
> with the legs swapped over (not got a mpsa56 to hand).
>
> I'll get these, just need a little more time to investigate.
>
> Cheers, Colin
>
>
> I plugged in the monitor for the first time ( this was aquired a
> few months ago and it had a known fault) and getting a display...
> BUT something is breaking down in the chassis, and its sucking
> some of the vectors up into the middle of the screen !! (Looks
> fine on the XY scope !!)
>
> I'm thinking I have a HV board fault... I can hear what sounds
> like HV tracking (not the deflection chatter) - I took this
> picture....
>
> http://www.jammaplus.co.uk/forum/uploads/ColinD/2008-09-20_203630_tp4.jpg
>
> I cant leave it on for long as the phosphor will burn... I think
> I'll try another HV unit... and if not.. start trouble shooting
> the deflection with the brighness turned down too when testing !!
>
> Any ideas please ?
>
>
>

-- 
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 Sun Sep 21 23:41:43 2008

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