Re[2]: TECH: dead Amplifone

-----Original Message-----
From: Dave Langley <robotron@ntlworld.com>
To: vectorlist@synthcom.com
Date: Tue, 12 Nov 2002 14:38:44 +0000
Subject: Re: VECTOR: TECH: dead Amplifone

>
> At 02:08 pm 12 11 02, you wrote:
> >Hi,
> >
> >After 9 years of loyal service I've lost my HV board :( The person playing
> >the game said the image lost focus then the screen went blank- the infamous
> >'red is dead' problem?
> >
> >I don't have an HV ringer and don't know anyone in the UK that has so before
> >I send $200 to WinTron I'm having a quick look at the circuit and would
> >appreciate any help, this is what I've already tested:
> >
> >The BU406D runs hot after being powered up for a few seconds but tests ok
> >using the method in the Amplifone FAQ- it shouldn't run that hot that
> >quickly should it?....but I thought it would almost certainly be toast if
> >the HVT went.
> >
> >I'm reading a junction drop of 1.64v on the 1500v rectifier CR3 (is this
> >normal?)
> >
> >The zero ohm jumpers (on both PCBs) and R12 are ok
> >
> >The over voltage trip LED is NOT lit.
>
> Karl,
>
> When I was in the same position, Paul Swan advised me to do the following
> to rule out the HVT:
>
> 1. Completely remove the RED HVT from the PCB.
> 2. Get a 100W 240v (ie normal household) light bulb and fit it across the
> input of the HVT. Now we have a dummy load.
> 3. power up the HV board. The bulb should glow, and you should have approx
> 48v Peak to peak 20Khz going across the bulb if you scope it. You can also
> check the regulators are giving you +/- 24v.
>
> On my HV board the RED HVT was indeed dead and it took the regs with it,
> but the BU406D was OK. Since they are cheap it might be worth replacing
> the regs anyway. When I'd done all this I fitted my new Wintron and the
> game come on first time (in 12 years!) :o)
>
> As a separate issue, My Amplifone has a pin cushioning problem. My SW
> looks like it's running a WG, but it's an Amplifone. Any Ideas whats
> causing this? The only thoughts I'd had was to replace the entire X
> deflection channel to see if that cures it, or to try my deflection PCB in
> another game at some point to confirm that it is the cause.
>
>
are you sure it's a starwars tube?

i thought the pincushion was corrected by a specially designed yoke on the amplifone, not by electronics?

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Received on Tue Nov 12 10:50:50 2002