Re: 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.

Dave Langley
www.robotron-2084.co.uk

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Received on Tue Nov 12 06:46:24 2002