On Mar 3, 2016, at 9:21 AM, tony duell <a...@p850ug1.demon.co.uk> wrote:
>>> The original resistor (as mentioned in the Subject: line) was one of those >>> safety fusible >>> resistors. AFAIK none of the ones that Farnell stock are. >> >> Oops, I missed that part of the subject line. It'll be fusible for a >> reason, so should be replaced with the same type. Moreover, if it's >> gone, there's probably something else wrong too, so maybe Adrian needs a >> pair ;-) > > I know rather more about this than Adrian has said, so I might as well > let on. It's from a VT100 power supply board, it's in the chopper circuit. > The chopper transistor has failed short-circuit B-C and open B-E and this > took out the resistor (as far as I can tell). > > Knowing how chopper circuits behave (or don't!) I agree this must be replaced > by a fusible resistor. Otherwise next time the chopper fails it might be > spectacular Speaking from complete ignorance, could it be a normal resistor and a fast-acting fuse in series? Aussuming the correct fusible resistor is not easy to locate and that there is room to hang a fuse holder off of the circuit board there?
