You Bar-steward

[CraigGa]

I don't know what the policy on swearing here is so I moderated myself.

After over 40 years working in electronics and telecoms I know a thing or two about Sods (Murphy's) law but this takes the biscuit.

I'm working on my 40+ year old Burman Pro 502, someone in my other thread said that I should rewire the bias supply to make it failsafe. This morning I did just that, powered it up without power tubes and checked to voltage and it was good, then I put in a new pair of KT77's, turned it on and nothing, checked the main's fuse and it was blown so I tried another and still apparently nothing.

Eventually I figured out what happened, on the very instance that I turned the amp on with new valves and a new bias circuit, the pilot light blew and the filament must have shorted the heater supply taking out the mains fuse.
The 2nd time I tried, I turned it off after the pilot failed to light fearing something bad had happened. That bulb has never been changed since 1979 and it waited until now to go out in a blaze of glory!

Now that's Sod's law.

Craig

[martin manning]

So nothing but a new fuse and pilot lamp to sort it out? That bulb had nearly 40 years in, I guess it was tired.

[CraigGa]

So nothing but a new fuse and pilot lamp to sort it out? That bulb had nearly 40 years in, I guess it was tired.

Yes it was a simple fix but a major panic.

Craig

[pdf64]

The value of a light bulb limiter is beyond rubies in such a scenario. After a suitable work area and the necessary screwdrivers and a functional multimeter, it’s the most important asset I possess for these activities. And I muddled along without one for decades

[CraigGa]

Of course you are right pdf, in fact I've just finished building one!

Craig