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I have 3 European retro computers that I'm trying to run on North American power through a step-up transformer. So, I am using 220V/60Hz instead of the European standard of 220V/50Hz.

  1. BBC Master works 100%
  2. Commodore C128D works 100%
  3. Atari 1040ST fails to boot

Obviously, my question mainly concerns the Atari. I am getting 5V and 12V from the PSU, but no video or any other indications of "life". This Atari was reported to be working by the prior owner (in Europe). Does anyone know definitively whether a European ST can/should work on 60Hz power? Any additional advice/warnings about the other machines using 60Hz is also welcome.

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    Unless the C128D differs from the C64 in this respect it won't work 100% because the CIAs' TOD frequency is 60 Hz instead 50Hz. Not that much software actually used the TOD (time-of-day) clocks though.
    – user722
    Commented Aug 24, 2018 at 17:23
  • What does "fails to boot" for the Atari mean? Does the computer access the disk and try to boot? What monitor are you using? A European ST should basically work on 60Hz mains, it might be having problems producing a stable picture, but should generally work.
    – tofro
    Commented Aug 24, 2018 at 20:06
  • @tofro Black screen on SM124. No disk activity.
    – Brian H
    Commented Aug 24, 2018 at 21:19
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    Then I'm pretty sure that problem is not 50/60Hz-related.
    – tofro
    Commented Aug 25, 2018 at 9:15

4 Answers 4

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A working power supply and a completely black screen hints to a memory problem in the lower banks or an MMU contact problem (which is way more likely with the computer traveling that far). The ST sees no memory at all and won't even display a (white) picture.

I would first carefully remove the MMU from its PLCC socket and thoroughly but carefully clean the contacts with a cotton bud and some iso-alcohol - These sockets are known to corrode over time and create bad contacts.

If that doesn't help and you have a socketed GLUE chip, do the same thing to it.

Still no luck? Remove and re-seat all other socketed chips. If that doesn't help, you need to pull out the oscilloscope.

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    Good advice. After pulling all socketed chips and cleaning with contact cleaner I now have a pure white video output, key click audio, and disk activity, but no desktop. Farthest I got with any disk is a crash with 2 bombs. I have tested the drive on another machine, so I know the drive and floppy disk are all good. So, memory problem?
    – Brian H
    Commented Aug 25, 2018 at 21:50
  • Once you see a white screen, you're one step farther down the road to a working computer (the bombs are actually a good sign). White screen and still no boot can have two reasons: On a plain 1040 ST, it could well be the computer has no ROM-TOS installed and wants to load the OS from disk, then what you're seeing is entirely normal (ST tries to read the OS from disk but fails). Check you have a ROM TOS, and if not, prepare a TOS boot disk. In case you have a ROM TOS, I would (again) check the ROMs, remove them, give them another thorough cleaning and firmly re-insert.
    – tofro
    Commented Aug 25, 2018 at 22:36
  • If that doesn't help, you need to continue with the GLUE.
    – tofro
    Commented Aug 25, 2018 at 22:37
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So, I am using 220V/60Hz instead of the European standard of 220V/50Hz.

Which should be fine for most. Especially the ones with switching PS.

Further 220V is fine, as they are old machines from back when continental voltage was 220 (and Brits still used 240).

My question mainly concerns the Atari. I am getting 5V and 12V from the PSU, but no video or any other indications of "life".

It definitely should. Is the power LED coming up? I assume you're using an Atari screen? SM124 or alike.

I did find an STFM PS drawing, but be aware, that Atari did use many different PS over the years. Some of them where even switchable for 110V and 220V

Any additional advice/warnings about the other machines using 60Hz is also welcome.

Not really more warnings. The main concern is voltage. I'd only be careful with classic transformer based and linear regulated machines of high power consumption - but that's more the mini world, than anything late 80s.

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    Power LED comes on for both the ST and the SM124 monitor I'm testing with. No video or floppy activity.
    – Brian H
    Commented Aug 24, 2018 at 18:22
  • "220V is fine, as they are old machines from back when continental volatge was 220" -- even new machines designed for 230V should work on a 220V supply, as the official range is 230V +/- 10%, so PSUs must be designed to cope with 217V minimum (and, in practice, I believe a large proportion of European mains supply is still actually only delivering 220V, just as a lot of the UK is still supplied with 240V).
    – Jules
    Commented Aug 25, 2018 at 9:48
  • @Jules We all know that tolerances always add to the wrong side, don't they? Sure, using tolerances (or redefning them first, waiting some years and then lifting voltage) was the part of the switch that made it doable. All under the assumption, that household devices are replaced anyway every few years. 230V is mandatory since 1987, with a tolerance of 207-242V. Since 2009 it's 207-253. It's also important to remind that household voltage is not set at the station but at the last regulating transformer - and changeint them is a gradual process, not somuch depending on country as company.
    – Raffzahn
    Commented Aug 25, 2018 at 11:01
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If you checked output power of the power supply to be ok, then it is a problem of computer electronics.

This Atari was reported to be working by the prior owner

Do you think anyone would admit that? Problem may also happen during transportation.

Anyway you need to find someone to take a closer look onto the boards and troubleshoot them. At first take a very close look at the boards and connectors - ensuring connectors are seated well, there're no cut or unconnected wires, and no cold solder spots on the PCB. Use magnifier for inspection.

Update: it was quite uneasy to find power supply unit circuit/photo as most manuals just show "power in" (show main board, but not power supply). This pic shows switched power supply, if it is the right one that frequency does not matter much, and can not be the cause of failure.

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  • I have done the visual inspection and checked for any hot ICs when powered. Nothing seems amiss thus far. Any ideas for common IC failures on 1040ST?
    – Brian H
    Commented Aug 24, 2018 at 18:24
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well I would use oscilloscope and look if:

  1. clock is running
  2. data and address buss is alive

that can rule out CPU and MEMORY side problems. If working measure the modulator input/output if it produces signal. If yes the problem is either in cables or in the monitor itself. Otherwise you might have problem with graphics ICs. However take in mind I am not familiar with ATARI so I do not know its internal architecture.

What 60Hz over 50Hz means?

For linear transformers power supplies it means the inductance is usually higher than designed which could lead to over voltage. And also the inefficiency can be higher (more heating of the transformer) But most of the electronics have a voltage regulator unit so the output should be fine the problem is the regulator itself can heat quite a bit more than usually so check/upgrade heatsinks so they do not damage plastic casing nearby.

Also some electronics use the frequency as timing. This was true for any TV in my region back in the day. If your monitor is the same that might by the problem as the video signal is out of sync with monitor. In such case the screen is either unstable (blinking scrolling skewing) or video signal is ignored by the monitor completely.

If the case you can try to use some kind of AC/AC converter. I think there was few APC/UPS power protection units that produces 50Hz 220V output from any input to protect electronics from bad power supply.

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    Using a transformer at higher-than-specified frequency may lead to higher inductive "losses" which deliver some energy back to the mains on each cycle rather than generating heat; the consequence of such losses is possible output sagging under load. Using a 60Hz transformer at 50Hz, however, may increase--possibly by an order of magnitude or more--saturation losses which do get converted into heat.
    – supercat
    Commented Oct 10 at 23:00

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