Ferroresonant transformers and 3278

Mike Ross tmfdmike at gmail.com
Mon Dec 21 20:33:47 CST 2015

I recently blew up a 3278... it worked ok for a few hours then started
blowing fuses.

I haven't done any troubleshooting yet but checking the manuals on
Bitsavers tells me my US 3278s have ferroresonant transformers
specified as 120V 60Hz only. This can be expected to cause problems
with 120V 50Hz here in NZ from my knowledge of how ferroresonant
transformers work; I'll get excessive magnetic currents - overheating
- all kinds of nasties. I can wind the voltage down a bit and run them
at 90-100V but that doesn't help much.

1. Does anyone in a 50Hz country have any dead/spare 3278s and/or
transformers for them? The IBM part number for the 50Hz 220V are
8715343 or 4119686.

2. I have other equipment where this will be an issue and not so
easily solved. Does anyone have any experience in or recommendations
for frequency conversion equipment? My System/3s for instance all use
60Hz ferroresonants operating off 208V 3-phase - now voltage can
probably be retapped or easily converted but I still need to make a
lot of 60Hz to run them...



'No greater love hath a man than he lay down his life for his brother.
Not for millions, not for glory, not for fame.
For one person, in the dark, where no one will ever know or see.'

More information about the cctalk mailing list