Powering European Computers with 60Hz

[fargo]

I have a number of old European computers from Olivetti and Amstrad. They are rated 220v 50Hz. I can provide them the required voltage using transformers, but the AC frequency will always be 60Hz. Is there any danger in running these devices with higher AC frequency?

 

[pbirkel@gmail.com]

From: https://americas.hammondpowersolutions.com/en/resources/faq/definition/what-does-5060-hertz-mean

Transformers that are designed to specifically run at 60 Hz can’t be run at 50 Hz or in some cases only with significant derating. Magnetic flux is proportional to frequency so a 50 Hz transformer has a core 20% larger to handle 20% more magnetic flux than a 60 Hz unit. A 50 Hz transformer will simply run cooler at 60 Hz given the proper voltage is applied.

 

[Timo W.]

People do that all time. The voltage matters, not the frequency. It's all rectified, smoothed and turned into DC anyway. There are very few computers that use the line frequency as a clock signal (e.g. the Amiga 2000), but even that is not much of an issue.

 

[modem7]

Technical information at [here].

 

[stepleton]

Some computers (unlikely to include the ones you're dealing with) have tape transport and disk drive spindle motors that are synchronous AC motors: many 8" floppy drives are this way. Using a different line frequency can cause the magnetic media to move past the head(s) at unusual speeds.

I've overcome this issue in one instance with the help of an 50 Hz AC->DC PSU->DC/60 Hz AC inverter.

 

[Chuck(G)]

Years ago, I picked up a NIB 8" drive, configured for 220/50Hz. I ran the motor on 60Hz and computed the size of motor pulley to get to 360 RPM at the disk. Found one in the scrap box of one of the surplus dealers. The linear PSU in my drive box had dual primary windings for either 240V or 120V operation. Since the drive wasn't presenting much of a load, I powered the whole assembly from 120V/60Hz, but left the primaries in series. The motor ran off the high end of the series (transformer acting as autotransformer). I used the drive for almost 10 years before shelving it for a better one.
Just pointing out that there's more than one way to skin a cat.

 

[Alsilisk]

Its also worth noting that some high end machines (IBM really liked it) use ferroresonant transformers with a capacitor winding as a first stage of the power supply, these do depend on line frequency and if powered with the wrong frequency it could very possibly damage your later stage circuitry. Check for this!

This video explains this type of supply excellently:

 

[Chuck(G)]

Assuming that you have the correct input voltage, changing between 50 and 60 Hz mostly involves adjusting the value of the tank capacitor. If you've ever scoped the output of a ferroresonant transformer, the distortion in the waveform is incredible.

 

[Timo W.]

Its also worth noting that some high end machines (IBM really liked it) use ferroresonant transformers [...] Check for this!

His question was about home computers from Olivetti and Amstrad.

Even if you are right, that's simply not relevant for his question. If you own such a machine, you have way more problems to solve than just line frequency, like having a breaker that can handle 30+ amps.

 

[mbliss11]

I have several European computers too (CPC 6128, BBC Micro and Elk, Acorn Archimedes, Spectrum +2) and I have gotten by simply replacing their power bricks with US ones that output same DC voltages. The BBC micro has a jumper in the power supply you can add and that puts it in 120 operation just need to change out cable. The only thing I have on a step up transformer is my archimedes and honestly have been considering doing a psu mod on that as it only requires 5v dc.

I think you’ll have more issues trying to run a pal monitor on 60hz. Go RGB when possible and look for PVMs that can handle multi region sources if you are trying to go crt route.