message repost

messages on the list are limited to 40k, so this message just bounced.
i'll put the schematic up on the spies web page --al

From: Anders Knudsen <Anders_Knudsen@btc.adaptec.com>
Subject: Re: WG failures
In-Reply-To: <2.2.16.19970903151924.29c74da0@pop3.concentric.net>
Mime-Version: 1.0
Content-Type: multipart/mixed; boundary="=====================_873426376==_"

--=====================_873426376==_
Content-Type: text/plain; charset="us-ascii"

At 03:23 PM 9/3/97 PDT, Zonn wrote:
>
>3) The best so far. Run the deflection and HV off a beefed up regulator. I
>removed all the low voltage components (Those uprotected zener diodes and
>Q100/Q101 stuff). I then used a LM317/LM337 regulator pair using the WG's
>low voltage power transistors as current boosts.
>
>This gives very stable noise free vectors. But there is a trade off between
>supply voltage and HV disappation though. Higher voltages going to the
>deflection allows for a faster slew rate, higher voltages going to the HV
>supply allows for shorter HV life.
>

This is exactly what I did a while ago. I removed all the parts to the LV
supply, *except* the large 4700uF filter caps, the diode bridge, and the
power output transistors. i.e., removed: Q100, Q101, R100, R101, R102,
R103, D104, D105, ZD100, ZD101, C102, C103. Note that ZD100 and ZD101 are
mislabled on the P314 as R104 and R105.
I then designed a regulated supply using LM317 and LM337 plus support
components, using small pots to allow for some adjustability. I think I can
range from around +/- 22 to +/- 30. A gif of the schematic is enclosed.

I created a small PCB layout, about 2" x 1.125", so it would fit right over
the spot where the old components were removed. The output from the
regulators is just under the new PCB, so I positioned the through holes
right over the top of holes in the P314 PCB. That allows for the new PCB to
be "piggy-backed" using cliped off diode leads, or some other stiff wire to
hold it in place. The input to the regulators is wired to the new PCB with
some small shielded wires. See enclosed gif of the deflection PCB for
reference.

As a test for this retrofit, I installed one of these new LV PCBs into a
Star Wars (equiped with a WG6100 of course) that a friend of mine has
standing in a theatre in Louisville, CO. It has been running there since
January, and the monitor has not failed yet.
Also enclosed is a gif of the new LV PCB installed on the P314.
I thought about doing a mass production run of the new PCBs. This could
still be easily done, since I have had the gerber files ready to go since
September last year!
Thoughts???
-Anders.
Received on Thu Sep 4 13:54:25 1997