"If it ain't broke"

[ppppenguin]

Sometimes it's a judgement call. For example I've just overhauled 15 monochrome monitors. They are about 40 years old. Mentioned in another thread. There's one electrolytic I've replaced on all of them because I've seen it fail in other examples of this monitor and it clearly leads a fairly hard life. 25p and a few minutes of time I rate as good insurance against having to pull a monitor out of service at an inconvenient moment. The old part was axial, the new one radial and I really don't care. It's neatly fitted and that's sufficient.

But I've left all the others alone. I've judged that it's too much expense and hassle to do a complete re-cap, especially when most are the generally reliable blue Mullard/Philips type.

[Murphyv310]

Hi.
What did we do for many years without an ESR meter? We used the scope to look at the ripple and then decided to replace the capacitor, visual is useful too and feel, a cap that is getting warm could be failing and due for replacement, Bulging and leaky caps its obvious they are shot. Good ESR meters were expensive many years ago and the penny pinching accountants would often block requests for new test equipment.

[catch29]

SUCCESS!. I now have two working Heathkit MA-12's thanks to your input. I replaced the resistors and smaller cap's and left the biggies that measured ok. I had an initial problem which I tracked down to a duff EL84 which I replaced with one from a Clarville Tenor 57 which I fixed a while back. I am 'soak' testing the MA's running a pair of modified Kef Concerto's via an MP3 player and headphone pre-amp, they power the Concerto's surprisingly easy! That's when 12 watts WAS 12 watts RMS!!. Now I need to find a good stereo pre-amp. I'm a happy bunny [attachment=21343]