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Sounds like it. But you can still test the resistance of the +5V supply to 0V to see if you no longer (hopefully) have a short circuit. Thanks for that info Mark, where should I put the meter to test this? Across any +5V and 0V connections. So across the solder pads of ZD2, or as I wrote in an earl...

I attempted to de-solder a leg of the zener diode ZD2. While I was heating the solder and applying light upward pressure on the diode it broke in half. Given how easily it came apart I think it was pretty much already broken. Charlie Sounds like it. Alas, it does make it hard to test the diode to s...

If I remove the nut and bolt from the TIP2955 and lift it upwards so it's completely clear of the heatsink and put the meter on the heatsink and the tab of the TIP2955 there is still a connection. Good that at least you know that it is not the insulation for the TIP2955 that is the cause. Bad news ...

Mark

The picture I posted was only meant to show the insulated "washers" (not many suitable pictures thrown up by a quick search).

Mark

BTW Tony, having been distracted by a Dave post, I forgot to say: thank you for posting these great photos

Mark

Okay, first a warning. The zener diode (ZD2) that is being talked about is designed to reduce the risk of damage to the chips if the +5V line suffers from an over-voltage problem. If that happens, it will go short circuit and the +5V rail will drop to around +1V. So with your meter on voltage, see w...

'Test the left hand pin of the 7805 regulator with the red meter lead / probe. If the fuse (FS1, 3.15A) is intact and the electrolytic smoothing capacitor is connected and at least partly working, the resistance should start low and go upwards in value. Resistance should be >500 ohms.' I've replace...

Welcome Inaki



Mark

Dave wrote:I will "pinch" a copy of your good photos for the site,

You know Dave, if you keep going around "pinching" people, one day you may well get you yourself in trouble

Mark