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Lorne
January 10th, 2009, 04:02 PM
I just obtained an Altos 8000-1 from Australia.
It works on 220 V, 50 Hz.
And of course, I need it to work on 120 V, 60 Hz.

I've opened up the case and I think the power supply (transformer) might work on both voltages (although not via a switch).

I've attached a copy of the power supply schematic diagram, and a photo of the power supply wiring connections.

1162

1163

I think what I need to do is remove the connector that is between pins 2 and 3, and then take one of the white wires that is presently connected to pin 1 and connect it to pin 2.

Am I on the right track?

I'm no elecrician, so I want to make sure I've interpreted the schematic correctly before I screw it all up (which would be the usual course of events).

Is there anyone out there who can confirm my thinking, or point me in the right direction, if I've got it all wrong?

Thanks in advance.

DimensionDude
January 10th, 2009, 05:27 PM
The markings on the transformer and the schematic are telling us this:

Line in *always* on pins 1 and 4

Link pins 2 and 3 for 230v operation.

Link pins 1,2 and separately 3,4 for 115v operation. Remove link from 2,3.


I will confirm this tomorrow (Sunday) by checking a few industrial dual-voltage control transformers where I work. The vast majority of dual-voltage transformers work in this manner.

Kent

Lorne
January 10th, 2009, 06:08 PM
Kent:

Thank you very much!
I'm glad I asked for assistance.
I now see what you were reading in the schematic.
The same jumper I see on the actual transformer for the 220V setup, is shown in two different locations on the diagram for the 120V setup.

The jumper for the 220V looks like steel or aluminum.
It should be OK to use copper shouldn't it?
And something like the same gauge as house wiring to a power receptacle?

Thanks again.

patscc
January 10th, 2009, 06:12 PM
The idea is to get the series connected windings into a parallel configuration.
I can't tell from the schematic, the numbers are too small for me to make out.
The winding resistance in parallel should be double of the series configuration.

patscc

channelmaniac
January 10th, 2009, 06:57 PM
White on 1 & 3, Black on 2 & 4.

Cut the jumper between 2 & 3

You want to put those windings in parallel.

RJ

patscc
January 10th, 2009, 07:23 PM
Could the schematic be reposted larger, please ?
patscc

Lorne
January 10th, 2009, 07:41 PM
Could the schematic be reposted larger, please ?
patscc

I cropped it - hopefully this is more readable.
1164

Question: If 1 & 2 and 3 & 4 are connected together, it doesn't matter if the line voltage goes to 1 or 2, or 3 or 4 does it?

patscc
January 10th, 2009, 07:56 PM
Much better, thanks. I agree, it looks like 1 & 2 , 3 & 4.

Lorne said...doesn't matter if the line voltage goes to 1 or 2, or 3 or 4 does it?
No, since 1 & 2 are connected together (or will be ), anything going to 1 will go to 2 as well.
If possible, I'd disconnect the power supply from the rest of the computer, just in case, this way you can double-check the voltages.

patscc

Chuck(G)
January 10th, 2009, 07:57 PM
That black wire on 3 goes to a fan, right?

If so, then:

Leave the white wires where they are.
Leave the black wires were they are.
Remove the jumper between 2 and 3
Connect 1 and 2
Connect 3 and 4


So, at the conclusion, you'll have:
Terminal 1: both white wires and a jumper to terminal 2
Terminal 2: A jumper to terminal 1.
Terminal 3: A black wire and a jumper to terminal 4
Terminal 4: A black wire and a jumper to terminal 3


I've got a couple of open-frame PSUs that have the same markings.

Lorne
January 10th, 2009, 08:08 PM
That black wire on 3 goes to a fan, right?

Probably, but I really have no idea where the wires go ! I had a tough enough time taking it apart to even see the transformer. These things are built tough. It's a pain in the butt to get into them. I want to get it back together asap, before I forget where everything goes.

I've got it now - I know what I've got to solder.
Thanks for your help guys - it's much appreciated.

Lorne
January 10th, 2009, 08:39 PM
That black wire on 3 goes to a fan, right?

If so, then:


Your "If so, then" comment, made me go get flashlight, a mirror and a magnifying glass, and check to be sure.
And yes, I'm happy to reply that it does go to a fan.

Thanks again.

modem7
January 10th, 2009, 08:55 PM
And yes, I'm happy to reply that it does go to a fan.
You will have a 240 Vac fan running at 115 Vac. Maybe in that situation, the fan will not blow enough air to do the job it's meant to do. Probably prudent to replace the fan with a 115 Vac version.

tezza
January 10th, 2009, 09:15 PM
If possible, I'd disconnect the power supply from the rest of the computer, just in case, this way you can double-check the voltages.

patscc

Yes, I was going to suggest this myself. Better to be safe than sorry.

Tez

Chuck(G)
January 10th, 2009, 09:21 PM
The black wire going to the fan is connected to 2-3 when running at 220vac; the other wire is connected to 1. Since, on 220vac operation 2-3 represents the center tap of two series-connected primaries, a 120vac fan is used (you can check the nameplate on the fan, but I'm certain).

No fan replacement needed. This was a nice "trick" that was used in the days before SMPSUs. After that, manufacturers started using DC fans. The 5150 PSU is a notable exception--AC fan attached to the SMPSU.

That came as a surprise when we ordered a bunch of 5150s to send overseas (before the 5150 had made its debut on the Continent). The IBM sales office swore that the US systems couldn't be used on 220 vac--and they were right. But it wasn't because the SMPSU couldn't be jumpered for 220 volts--it was the fan! We bought them anyway and swapped the fans in the PSUs. They worked fine, as far as I know, even with the red "warranty" stickers broken.

modem7
January 10th, 2009, 10:19 PM
No fan replacement needed.
Yes, I should have looked at the photo carefully.

Lorne
January 11th, 2009, 06:43 AM
I removed the one jumper, and added the other two.
It worked fine (and the fan blows loads of air too).

Thanks guys - I'm going to add some of you to my elec troubleshooting Rolodex !

Lorne
January 11th, 2009, 06:58 AM
PS: the fan is a Whisper model WR2H1, 115 V, 50-60 Hz, 7W
(even though the Altos nameplate lists the computer voltage as 220)

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Thanks again,

Lorne.

Lorne
January 11th, 2009, 08:45 AM
Follow up question:

I just noticed the following inside the Altos:
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1172

I've got the disk drives spinning and the fan working, but will the other pieces work correctly? IE: did changing the voltage at the transformer allow everything to work as 115 V, or do I now have a parts machine? (And one that I can't even use all the parts from).

Chuck(G)
January 11th, 2009, 09:27 AM
Follow up question:
I've got the disk drives spinning and the fan working, but will the other pieces work correctly? IE: did changing the voltage at the transformer allow everything to work as 115 V, or do I now have a parts machine? (And one that I can't even use all the parts from).

I was going to ask about disk drives.

Short answer: No, the drives won't work, even if they do spin. Not only is the voltage wrong on the drive motors, but the pulley-and-belt setup is spec-ed for 50 Hz. Even if you put 240vac 60Hz power on these motors, the floppy would spin at the wrong speed.

The simplest thing is to replace the drives. The next simplest thing is to replace the drive motors and the drive pulley. The least simple thing is to run the motors off of 240vac (via a step-up transformer) and replace the drive pulley.

tezza
January 11th, 2009, 11:11 AM
For my donated American IBM-PC (115v) I bought an inexpensive step-down transformer so I could run it off the 240v mains.

Is there such a thing as a step-up transformer which will boost 115v to 240v? If so, the simplist thing might be to just leave things as they are and buy one of those?

Tez

frozenfire75i
January 11th, 2009, 11:13 AM
Just hook it up to were your dryer/stove oven hooks up at run taps off that? I don't know if the over seas set up will take two hot 120v wires one neutral and one ground? For a total of 4 wires maybe it has three two hots and one netural.

On 2nd thought maybe that won't work I don't know! But if you do try be careful 220 hurts a bit, and makes bigger boom then 120 ;-)

patscc
January 11th, 2009, 11:23 AM
frozenfire75i said...three two hots and one netural.
Sounds like you're thinking of 2 or 3-phase current. The schematic does not support this, nor do the markings on the x-former.

patscc

Chuck(G)
January 11th, 2009, 01:48 PM
For my donated American IBM-PC (115v) I bought an inexpensive step-down transformer so I could run it off the 240v mains.

Is there such a thing as a step-up transformer which will boost 115v to 240v? If so, the simplist thing might be to just leave things as they are and buy one of those?


You can take any step-down transformer and run it backwards as a step-up transformer. I used to power the final off of my rig using a reversed "pole pig" as the plate transformer. For that matter, you might be able to feed only one side of the main power transformer and use it to develop 240v (with a corresponding loss in power rating).

But that's not the issue here. It's 60Hz vs. 50Hz.

The motors on an ac-powered 8" drive are synchronous with the power line frequency. Instead of resulting in a spindle speed of 360 RPM, you'll get 60/50 of that, or 432 RPM.

You could machine down the (crowned) drive pulley or substitute a timing pulley that would result in the right speed.

Or you can simply swap the drives out.

Lorne
January 11th, 2009, 02:50 PM
I've actually got another Altos (115 V version) that I can't get to work. I'm thinking I could switch the drives from that one to the Aussie one, but I'd really rather get the 115 V one working, as it's a multi-user machine.
I have all the schematics for the Altos - my problem is that I can't read the damn things well enough to figure out where the problem might be.

Are there any volunteers out there, who can read a schematic and point me in the right direction?
(It'd definitly be worth a few pints, on me).

patscc
January 11th, 2009, 04:21 PM
If you google "50 60 hz voltage converters", you'll see a wide range of stuff that converts 60 Hz into 50 Hz & vice versa. The new stuff tends to be pricey, but sometimes you can dig something up as surplus.
Unless you're running something that has an AC motor (like the 8" drives mentioned by Chuck(G)) , or something that derives timing from mains (like some older alarm clocks), it doesn't really matter if you run it via a simple transformer.
patscc

BG101
January 12th, 2009, 01:26 PM
Another way is to get hold of a British or European power inverter - these are not expensive here but the postage might set you back a few $$. Preferably British as these should supply 240v rather than 220v. This will give you the desired 50Hz supply.

You'll need a beefy 12v power supply to feed it from though, but this can be built or sourced locally.







BG

Lorne
January 14th, 2009, 10:27 AM
My sincere thanks go to Chuck(G) and patscc, who both replied to this post.

These two replied to my request for help, and walked me through repairing my Altos 8200, via email.

They are brilliant !
They read the schematics (which I couldn't) and they provided great, clear instructions to troubleshoot the problem, and then what to do to fix it.

If these two were brain surgeons, you could do brain surgery on someone via email !

The Altos was saved from the scrap heap or being parted out, because of Chuck(G) and patscc.

Many thanks guys.

Lorne.

patscc
January 14th, 2009, 11:27 AM
*blush*
Thanks.
patscc

Chuck(G)
January 14th, 2009, 12:12 PM
Our pleasure, Lorne!

Now, who's got a couple of 8" drives to sell Lorne--or who wants to swap some 120v 60Hz drives for some 220v 50Hz units?

That would get him on his way toward getting both systems working.

Thanks!