Re: RE: Starwars and Amplifone Issue

----- 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?
  

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Received on Thu Mar 25 14:19:08 2010