On Mon, 30 Jun 2003 23:35:21 -0400, Philip Nasadowski
wrote:

In article kWPLa.60138$Fy6.17091@sccrnsc03,
"Don Lanway" wrote:

They have their place, like everything... it's my impression that they
handle spikes, overloads and heat better than silicon rectifiers... but I
could be wrong.

Beats me. We use them at work on MG set elevators (the few MGs we still
build, VVVF pretty much dominates traction elevators, at least at the
sub 350 fpm end). I don't know why, but we do. They were popular in TV
sets and other electronics in the 50's, and much hated because they're
smelly when they blow

Spikes and overloads? I don't know, though even by the early 60's, Si
technology was really getting into high power - the 1963 vintage Budd
built Silverliner electric commuter cars for the PRR used 3 bridges with
a six pack in each leg, 570V on each bridge, though the one fed by the
'A' winding had a pair of ignitrons (think really big 2050s in front
acting as 'voltage vales'. This was feeding 4 150hp motors at up to
1500 or so volts. Not bad...

Today's semiconductors are tough. I melted a sample surface mount
mosfet off it's heat sink while stress testing it, and the darn thing
STILL works. Litterally melted the solder and off it slid...

Anyway, Se types work great at low voltages and high currents, IIRC, and
ye, they take abuse. There weren't any other good rectifier diodes in
the 50's when DC motors styarted popping up in jukeboxes anyway.

Hey, while I'm thinking of it, when did AMI switch from a DC motor for
the gripper to an AC type that spun in one direction only?

Some of the 1950's jukes I have seen the AC motor used. J,K and
continental. Have also seen these with DC motors too. Whether these
were factory fitted - or swapped round by techs over the many many
years since new from later models - I don't know. What exact year I
don't know either.

As most of these models were made in overseas countries under licence
as well - and used locally produced motors in some cases which may
have been AC or DC - it makes the issue more unclear still as these
parts find their way swapped into US made ones during the life of the
machine as well .

Rowe went to full AC motor usage in mechanisms starting with the JAL -
200 - and has used them ever since.