Re: Starwars and Amplifone Issue

pj pj wrote:
>
>
> ----- Original Message -----
> From: David Fish <dfish_1@comcast.net>
> Date: Thursday, March 25, 2010 2:36 am
> Subject: RE: VECTOR: Starwars and Amplifone Issue
> To: vectorlist@vectorlist.org
>
> > Just for fun, try unplugging the degaussing coil.
> >
> >
> >
> > Dave
> >
> >
> >
> > From: owner-vectorlist@vectorlist.org
> > [mailto:owner-vectorlist@vectorlist.org] On Behalf Of PJ
> > Sent: Thursday, March 25, 2010 2:44 AM
> > To: vectorlist@vectorlist.org
> > Subject: Re: VECTOR: Starwars and Amplifone Issue
> >
> >
> >
> >
> >
> > ----- Original Message -----
> >
> > From: Chris Loggans <mailto:cloggans@yahoo.com>
> >
> > To: pj1@shaw.ca
> >
> > Sent: Wednesday, March 24, 2010 3:55 PM
> >
> > Subject: Re: VECTOR: Starwars and Amplifone Issue
> >
> >
> >
> >
> > PJ,
> >
> >
> >
> > I have seen this problem before.
> > I know you have stated that the
> > output looks correct on the scope, but I would try replacing Q7
> > and Q8 in
> > the Bipolar output section of the AVG board (page 14B in the
> > schematics).
> >
> >
> >
> > Thanks,
> >
> > -Chris
> >
> >
> >
> > I replaced these transistors, as well as replacing the two 0.1uF
> > caps by the
> > MPSu57s on the deflection board to no avail. I even tried
> > to bridge the
> > current sense resistors with ceramic capacitors to see if it
> > made any
> > difference with no luck.
> >
> >
> >
> > So just to recap, the work done on the game to date:
> >
> > -replaced all the 1N914 diodes and transistors on the deflection
> > board,except for the four 6A main rectifiers, the video output
> > transistors, and
> > zener CR5.
> >
> > -replaced all electrolytic capacitors on the deflection board
> > and HV board,
> > including the 4700uF power supply filter caps.
> >
> > -replaced the BU406D, the regulators, diodes, 50ohm resistors,
> > and HV
> > transformer. The high voltage setup procedure completed.
> >
> > -removed all brown jumpers on the deflection and HV boards.
> >
> > -replaced the pots on the deflection board
> >
> > -replaced the fuses on the deflection board
> >
> > -repaired the fuse block and wiring on the power transformer block.
> >
> > -recapped the ARII and added sense mods.
> >
> > -added additional heavy leads between grounds on ARII, logic
> > boards and
> > deflection board.
> >
> > -replaced both 15v regulators and filter capacitors on the AVG
> >
> > -replaced Q7 and Q8 on the AVG.
> >
> >
> >
> > and still no luck...
> >
> >
>
> Did that last night by removing the three toed posistor ...no joy.
>
>
> I did solve the video brightness problem however. I re-jigged the
> video amps with the resistor values from the WG's circuit, and alas,
> the brightness is all good. Fireballs, the green scaled text, and the
> sheild level changes still can slightly defocus the beam, but they
> don't grow so overly bright as to preclude any ability to clip the
> transistors into full saturation.
>
> Now if I could only solve the deflection issue: Here's more
> information after throwing a couple of hours at the thing.
>
> I left it going for about 45 minutes while I probed with a scope.
> After some time warming up, I noticed that the issue isn't as obvious
> as when its cold. I also noticed that the higher the levels are setup
> off the AVG, the more square the characters become. On that, I ran
> the self test when I was setting up the cutoffs and drives after
> "WG"izing the video amps, and on the Linear/binary and linear scaling
> test, the edges of the shrinking square become slightly jagged at
> about 3/4" to the tune of about say 1/32", and progressively more
> jagged when the square is less than 3/16" to the tune of about 1/8".
> When it becomes nearly a dot, the jagged edges are larger than the dot
> itself.
>
> Since I likely have a high frequency response issue in the deflection
> system, it could be I'm chasing something that isn't in the AVG. I
> also noticed that there is a lot of old heatsink compound between the
> heatsink and the deflection pcb substrate. Could this have become
> conductive?
>
What is your girlfriend saying? Live with it? (ducking)

I suggest stepping back for a little while and let it percolate for a
while in your mind. I don't think the grease is conductive, in any case
you do have an insulator between the transistor and the heat sink, don't
you?

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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