Ferroresonant transformers and 3278

[Mike Ross]

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...

Mike

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
>>
>>



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