"This Grampian 562A PA amplifier came through the workshop recently from a gentleman named "Toddy" from Scunthorpe, UK. Along with this, he also had a beautiful, un-touched, mint condition Leak TL25 PA amplifier with all the original valves (tubes).....including a nice pair of Mullard EL37's! Toddy explained that both these amplifiers had been rescued from a skip. He plays guitar, so he knows a bit about guitar amplifiers, but as these were antique he contacted me via this web-site to have them checked out. The Leak, not surprisingly worked absolutely perfect and required nothing doing whatsoever.
The Grampian wasn't quite so lucky. Yes, it did work, but at a very rough 10 watts or so.
So, Toddy left it with me and after a few hours work changing all the dead/dried out capacitors (though all the main electrolytic's were
fine) and a change of the low ECC82 phase splitter, finally a new pair of 6L6's saw it come up to original spec at 21.42 watts (it is a 20 watt amplifier).
The output of this amplifier had only the 100 volt-line wired. (I have now wired the facilities for the 8 and 16 ohms tapings too.) This tells me that it almost certainly spent its life in a factory of sorts; supplying back-ground music and (or) paging facilities through many 100 volt-line speakers. My guess is that it would have been switched on some 14 hours a day for........well a very long time? It is of no wonder that the pair of 6L6's had virtually no emission!!
After replacing the broken Bulgin socket, pilot lamp bulb and a general clean-up/service I think she is ready to go on EBay now!
By the way, I forgot.....One of the potentiometers has writing on the back of it. It says "22W and a date of 18/3/60". I assume the 22W means tested at 22 watts (which is about right), and of course the other means 18th March 1960. Nice stuff !!!!