Fitting a Wells Gardner WG6100 Focus Block to an Amplifone HV

By Dezbaz 21 October 2012


Perform at your own risk

Monitors can reach up to 25,000 Volts. Do you know how to discharge this voltage? Please read and find out One of many on the net


Finally assembled one on the NEW Proto boards today

Note: The following applies if fitting a WG6100 Focus Assy

ie One of these

I fitted a new type focus block, from a new WG6100 flyback. The WG has 1 extra HV wire, so had to figure out what was what, as this has never been documented before as far as I know. At first I hooked it up this way (Wrong way in pic immediately below)

There was not enough focus (Which is the problem I had before with the old orig. Amplifone focus block)

I looked at the diagram

You see that resistor, I recently calculated it must be about 20Meg ohms or more, because it can't be measured on my digital ohmmeter (Max 20M scale), and in order to obtain an average of 6000V on the focus pin (when in the centre), and 600V on the Brightness pin, it must be 20 Meg or more.

So if you connect it like in the 2nd picture above, you're losing 1000's of volts at the focus pin, hence not enough focus.

Remember this info applies ONLY if fitting a WG6100 Focus Assy to An amplifone HV and Amplifone Flyback

So, I noticed on the WG6100 focus assy there is 2 wires to the top of the block

So I tapped into that idea, my thinking was if the WG gets the full 19.5KV, without the 20M resistor, and we are using a WG focus block, then we should be able to feed full 19.5KV into there too. So I did (Correct way here)
1. Capped off the white wire

2. I had to split apart the red wires on the WG Focus block and put it back how it was when I got it (See first pic)

Then shrunk down the glue lined heatshrink


* * * IMPORTANT * * *

If using a WG6100 Focus Block, Replace R19 with 100Kohm, 0.5W (Prev was 68K)

If you don't fit a 100K  resistor, you won't be able to get the over-volt pot to cut off at step #7 below (see "Adjusting the HV power supply" chart below)

Set the pots to the middle, fitted the new HV board

Turned the machine on

And it worked, some fine tuning was needed, but the good news is, the focus is fully adjustable past where it needs to be, so the focus is SHARP


Now to set up the HV Board properly

Back to Amplifone site

Back to old Amplifone Site

Contact the Author of this mod: dezbaz [at]


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