AaronL writes:
On Wed, 8 Aug 2012 09:47:24 -0500, "Steve"
wrote:

"Scott Lurndal" wrote in message
m...

Bill writes:

I recall a tube tester at my local drug store, but I am a little young
to remember the big picture.

I worked TV repair in the late 50's. My recollections:

People tried to save money fixing their own TV sets by using those
drug store tube testers. Trouble was those tube testers often said a
good tube was bad thus wasting the money the customer was trying to
save by not calling a TV repairman.

Was "Tube Changing" frowned upon back then
(mid-late 60's?)?

Tube changing (that is trying a new tube in place of a suspected bad
tube in a working TV) was the quickest and most reliable way to see
if that was the problem. There were specific tubes that did specific
things so you didn't have to change out the whole TV's tube set. For
example if the vertical hold wasn't locking there were just a few
tubes that could cause that and you tried only them.

A good repairman would, given the schematics

We didn't carry schematics for all TV models in the shop.

Hmm. A number of sets that I worked on in the 70's had the
schematics glued to the inside of the case.



(although I will admit to using the swap technique to fix a mainframe
once in Brussels).

Yes we swapped boards in mainframes at GE in the 60s also. Like tubes
swapping out was a quick method of troubleshooting.

In this case it was past midnight, testing a completely new firmware and OS
on a working customer mainframe and the FE had gone home hours ago. Given the failure
was in a Load Index Register instruction, which was handled by the Fetch
module, I tried to swap the two (20"x30") fetch cards with the on-site spares
kit. The new OS still faulted. Tried the two Execute Module cards. Still faulted.
Eventually got around to swapping out the MCW (Memory Controller Write) card which
fixed the problem. All night, alone in the datacenter of one of Belgiums larger
banks. Probably wouldn't happen nowadays.