Ferroresonant transformers and 3278

Mike Ross tmfdmike at gmail.com
Thu Dec 31 01:45:27 CST 2015

Thanks for the thought... my main concern is the System/3s and Henk
Stegeman - who has forgotten more than most of us will ever know about
S/3! - says that 60Hz S/3 on 50Hz power is a no-go. Different voltage,
fine - transformer can be restrapped. Different frequency... trouble!

And then there are rotary machines of course. I bet you half my disks
drives need the right frequency or a spindle pulley change.. and even
then *they* probably have ferroresonants in their power...


On Thu, Dec 31, 2015 at 6:37 PM, William Donzelli <wdonzelli at gmail.com> wrote:
> I bet you (or Mike, actually) could get it to work by trial and error,
> swapping in caps. The transformers (generally) are apparently pretty
> forgiving - being off in frequency just results in lost efficiency,
> maybe 10-15 percent lost at most. Not flames, anyway.
> --
> Will
> On Thu, Dec 31, 2015 at 12:30 AM, Guy Sotomayor <ggs at shiresoft.com> wrote:
>> On 12/30/15 9:29 PM, William Donzelli wrote:
>>> Of course! Find the exception that proves the rule!
>> ;-)  However, it would've been nice if it were only necessary to change
>> the capacitor!
>> TTFN - Guy
>>> --
>>> Will
>>> On Thu, Dec 31, 2015 at 12:23 AM, Guy Sotomayor <ggs at shiresoft.com> wrote:
>>>> On 12/30/15 9:06 PM, William Donzelli wrote:
>>>>> Sorry about digging up a slightly stale thread...
>>>>>> 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.
>>>>> ...but straight from the horses mouth, most IBM ferroresonant
>>>>> transformers will work at 50 or 60 Hz. The capacitor may need to be
>>>>> swapped, depending on the equipment.
>>>>> I was hanging around some IBM old timers this evening, including the
>>>>> Big Horse at Endicott.
>>>> I just looked up the FE manual for the 3278 and it shows 5 different part
>>>> numbers for the
>>>> ferroresonant transformer (depending upon region) and only a single part
>>>> number for the
>>>> capacitor.
>>>> TTFN - Guy


'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.'

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