Re: bad bottlecap transistors causing squiggly vectors?

From: Mark Shostak <shostakmark_at_gmail.com>
Date: Thu Jul 29 2010 - 11:48:38 EDT

Uh, kind of obvious, but you could put the original TO-3 transistors back
in, and see if the problem goes away. If you're like many of us, the parts
are still on the bench...

However, IMHO it's unlikely that it's the transistors causing the issue,
assuming you replaced them with the original devices and not subs.

Also, rule of thumb in push-pull is to replace _both_ outputs at the same
time, and also to replace both drivers when replacing the outputs. This rule
primarily pertains to repairs after a failure and not to, "it ain't broke,
but I'm fixing it anyway" type activity.

-Mark

On Thu, Jul 29, 2010 at 10:37 AM, Pat Danis <patdanis@verizon.net> wrote:

> I too had noticed that some of my WG 6100s were not as sharp after
> replacing all the transistors and doing a complete rebuild of all the
> components. The lines were a little wavy and not completely straight. I
> suspected that perhaps the bottlecap trannies might be an issue but don't
> have the smarts necessary to make a determination if it was the transistors
> or something else I might have replaced during the rebuild. I am going to
> track my findings in some 6100 rebuilds I will be doing in the next few
> weeks to see if there is a correlation to the transistors I am using. I
> have 2 different sources for the present time.
>
> I will see if there is any visible difference between original, and the 2
> sets of replacements transistors after a rebuild. My month of August is
> pretty booked up right now but I need to get some 6100s done so I will
> attempt to get this info posted. I'll even take video if possible. No
> guarantees.
>
> Pat Danis
>
>
> PJ wrote:
>
> I was looking over Darren Finck's post regarding issues with a G05-802
> having amongst a number of things, squiggly vectors. This tweaks my memory
> of the issues I had with an Amplifone that had a bad case of twisted
> distorted vectors on certain objects (see my starwars posts from last
> spring). I also had a similar issue on a G05 with original transistors that
> I figured were getting tired, and once replaced, the issue went away.
>
> The Amplifone in question had new transistor pairs on both channels. Since
> the original transistor pairs were long replaced prior to my involvement
> with whatever transistor the previous owner had on hand (literally), I
> replaced them with the correct parts, and from evidently, the same batch
> that I used in the G05.
>
> What I ended up with was when the drive from the game board was normal, and
> the gains on the deflection were set higher to fill the screen, the vectors
> were distorted, like the start and stop rates were bad. Tweaking the drive
> from the game board to a high level, and dropping the gains on the
> deflection board made the effect less evident.
>
> I'm wondering if the 2N3716s and 2N3792s have changed or the
> specifications aren't what they once were. Anyone else seen this?
>
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Received on Thu Jul 29 11:49:03 2010

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