Olivetti PCS 286 Power Supply Problem

Olivetti / Pcs 286
May 22, 2014 at 11:44:03
Specs: Windows or DOS, ?
Hi all.

I have an old Olivetti PCS 286 and when I plug it, then I turn it on and then, the fuse "explodes".

How can I solve the problem?

(You have a lot of pictures here in my Dropbox: https://www.dropbox.com/sh/j5dmnory...

Thank you and bye.


See More: Olivetti PCS 286 Power Supply Problem

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#1
May 22, 2014 at 12:43:46
When you say the fuse "explodes" you are describing what happens with a dead short, not an overload.

Most 286's use a simple on/off switch on the case. Check the wiring to make sure it isn't frayed or touching the case.

It could also mean the p/s is toast.


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#2
May 22, 2014 at 12:49:40
Here you are what the fuse does:

www.youtube.com/watch?v=6td73je7hg4

No, I think is the power suplly problem.

Bye.


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#3
May 22, 2014 at 15:54:12
You mean the fuse in the power supply, right?

If it has a 115/230 voltage switch make sure it's in the correct position. DON'T GUESS and only change it with the power cord disconnected.

If it uses the standard AT style P8 and P9 power connections, try a different PSU--if you can find one.

If it has the P8 and P9 connectors could they be switched? It's not all that difficult to force them on wrong. They should be attached so the black ground wires on each are next to each other. If they are switched you'll get a direct short on the output side that might blow the fuse. If it doesn't it'll melt the solder of the connector pins (personal experience).


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Related Solutions

#4
May 23, 2014 at 10:33:06
You mean the fuse in the power supply, right? Yes.

If it has a 115/230 voltage switch make sure it's in the correct position. DON'T GUESS and only change it with the power cord disconnected. Well, in this power supply if you want 115v, you put a 115v 2,5 A ; and if you want 240v, you put a 240v 1,5 A. So I put a 240 v, 1,5 A fuse.

If it uses the standard AT style P8 and P9 power connections, try a different PSU--if you can find one. This power supply ins't standard.

So what can I do?


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#5
May 23, 2014 at 14:30:01
The fuse can't 'know' or determine what the voltage input is. There's usually a red switch on the back near the power cord connection that you slide to choose the voltage. If that switch isn't there then likely the input voltage can't be changed or you'd have to open up the PSU to do it. I asked about the switch in case someone had messed with it without your knowledge

Here's some info about the P8 and P9 power connectors that most motherboards of that era used:

http://www.computerhope.com/jargon/...

I remember some older proprietary power supplies having that same wiring configuration but it being molded into a single connection.

Even if the olivetti PSU doesn't have a standard connection it should put out the same voltages as a standard one. If you can't repair or replace the power supply you should be able to splice its connector onto a different, working power supply. You'd just need to make sure you route the voltages to the correct pin.

Your dropbox link goes to a 404 error. Are you sure it's correct?


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#6
May 23, 2014 at 15:18:52
Nope, it wasn't, here it is: https://www.dropbox.com/sh/j5dmnory...


There is not any switch in the power supply.

I'll post a photo of the motherboard power connector so you can determine.


Sorry for bad english, but I'm Spanish.


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#7
May 24, 2014 at 23:24:05
Did you post the picture of the connector yet? If so which one is it? There's quite a few photos there where I can't make out the details. The only one that really counts would be the connector.

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#8
May 26, 2014 at 10:21:57
Sorry, here is a photo of the conector:

https://www.dropbox.com/s/870qmfewq...

and

https://www.dropbox.com/s/lqoaumyx5...

You can watch more photos of the connector in my dropbox link: https://www.dropbox.com/sh/j5dmnory...

Thanks and Bye.


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#9
May 26, 2014 at 23:54:47
That's a weird one all right. If you were to splice that connector onto a working power supply you'd need to know the voltages supplied by each wire. Sometimes there will be a color code label on the power supply identifying which wire carries what voltage. If there's not one there wouldn't be any way to know how to connect them. Your only option then would be to find a shop that hopefully could repair it or try to find an exact replacement power supply.

You say you've got 240 voltage where you're at since you're using a 1.5 amp fuse. What the history of that computer? Is it one you were previously using there or is it one you recently picked up? If it was previously used in an area with 115 volts at the wall socket then that's the problem. Look at the original fuse (if you still have it). It should be marked with an amperage rating.

Do you have any of the original manuals that might answer the above questions?


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#10
May 26, 2014 at 23:57:47
That's a weird one all right. If you were to splice that connector onto a working power supply you'd need to know the voltages supplied by each wire. Sometimes there will be a color code label on the power supply identifying which wire carries what voltage. If there's not one there wouldn't be any way to know how to connect them. Your only option then would be to find a shop that hopefully could repair it or try to find an exact replacement for it..

You say you've got 240 voltage where you're at since you're using a 1.5 amp fuse. What the history of that computer? Is it one you were previously using there or is it one you recently picked up? If it was previously used in an area with 115 volts at the wall socket then that's the problem. Look at the original fuse (if you still have it). It should be marked with an amperage rating.

Do you have any of the original manuals that might answer the above questions?

message edited by DAVEINCAPS


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#11
May 27, 2014 at 06:36:34
There ins't any label on the PSU that indicates the voltage. Before creating this post, I tried all the electronics repair shops in my city, and they always said No.

I picked it up some months ago, the first 5 min worked well apparently, because I didn't have the video cable, bit after those minutes, the fuse exploded.

Yes, the original fuse is for 250V 1A.

No.

Bye.


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#12
May 27, 2014 at 20:55:11
You say it worked OK the first 5 minutes but you didn't have a video cable. Does that mean you never saw anything on the screen? Maybe heard fans and drives spinning and LEDs flashing and assumed it was working? Those functions don't necessarily mean the computer is working.

The 250 volt rating of the original fuse doesn't mean it's meant for 250 volts. Fuses blow because of excess amperage not voltage. The 250 volts mean it's rated for usage up to 250 volts.

I don't know what country you live in. Are you sure you have 240 volts at the wall sockets? I'm still not completely convinced that's not a problem.

I found this old thread here:

http://www.computing.net/answers/do...

You might send him a private message and see if he still has the machine and wants to get rid of it or maybe you can talk him into making some voltage measurements at the connector.

Other than that you may just need to set it aside and wait for one to show up on ebay. Or if this is an all-or-nothing thing right now you could put a larger fuse in--2 amp or 2.5 amp--and see what happens.


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#13
May 28, 2014 at 06:58:46
Well, I heard the PSU fan, but I remember that I didn't heard the HDD spinning and I didn't saw the flasing led of the Floppy drive.

Yep, I know.

I live in Spain, we have 220 Volts. In the Olivetti says between 220V - 240V.

Well, I saw the profile of the guy and his last "online" was a month ago. I will ask him If I cannot repair the original PSU for the voltage meassurement.

This is the last, last option, put a higher ampered fuse.

Bye.


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#14
May 28, 2014 at 11:55:42
OK, it sounds like the PC is configured for your 220 voltage so that shouldn't be the reason.

Does the fuse blow when you plug in the power cord or when you turn on the PC? If it's when you plug the cord in the problem may be near the power cord plug-in. If it's after you turn on the PC it could be anywhere in the PSU box.

Hopefully the other poster will still have the unit and can help out.

message edited by DAVEINCAPS


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#15
May 28, 2014 at 14:34:27
Hello!

As you ca see in the video : www.youtube.com/watch?v=6td73je7hg4
The fuse explodes when I turn on the PSU, not when I plug the cord.

I'll send him a PM.

Thanks and bye.


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#16
May 29, 2014 at 16:14:28
They way that fuse pops it is not the symptom of a little surge and a case of the fuse being a bit under-rated. You have something far more severe such as a short circuit somewhere.

The only thing increasing the fuse rating "might" do for you is cause a similar pop where the fault happens to be. Not quite the way to diagnose it though LOL.

Always pop back and let us know the outcome - thanks


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#17
May 30, 2014 at 09:49:35
Well, DAVIDINCAPS, do you have any idea?

Bye.


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#18
May 30, 2014 at 10:11:49
As DAVINCAPS said "it could be anywhere in the PSU box". Unless you are into power electronics and have access to components they are not usually considered to be repairable. Fortunately replacements are not too expensive.

Always pop back and let us know the outcome - thanks


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#19
May 30, 2014 at 17:55:32
If you google 'olivetti' there are official sites but I don't think it's the same olivetti that built that computer. None I saw listed support for it. When those businesses change hands they often hang onto the name because it's recognized. You can email them though and ask if they have any information or even parts leftover from that model.

Sams photofacts or Sams computerfacts might have some information but I didn't find anything associated with that specific model. If the power supply has a separate model number you might do a search based on that.

Other than that I can't think of anything beyond what I've already mentioned--find someone with a working PCS and see if they'll take some voltage measurements so you can splice the old connector onto a regular AT type power supply or find a used PCS you can use for parts or a power supply by itself.

message edited by DAVEINCAPS


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#20
May 31, 2014 at 02:26:52
I'll e-mail them.

The PSU box has some numbers, but I didn't find anything on google.

So, I ca consider this computer dead?


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#21
May 31, 2014 at 07:32:22
"So, I can consider this computer dead?"

Looks like it unless you can replace or repair the PSU.

Always pop back and let us know the outcome - thanks


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#22
May 31, 2014 at 17:44:25
I'd set it on the shelf and wait for something to show up on ebay or maybe you can get a few bucks for it as a non-working vintage PC.

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#23
July 5, 2014 at 08:10:35
Hello all

After reading a little bit and make some electronics recall I started reparing my Olivetti PCS 286 PSU. The good news it: It's done !!!
Mine PSU explodes the fuse: It's problem was located in the bridge rectifier (it was short circuited), the power transistor was also short circuited and also replaced the PSU driver (FD1) and also the optocopler: that one with a number 3 above it. One advise NEVER replace the fuse with a higher one or you will melt the board tracks. Please note that the primary transistor is a BU508AF (equivalent one)

I have some photos to send it needed. Please write to: pstmg (at) y a h o o dot c o m

Regards
Paulo


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#24
July 5, 2014 at 08:17:29
I would like to see the photos, but I don't know your e-mail.

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#25
July 5, 2014 at 10:20:40
enon97

Assuming you are referring to response #23 then the email address has been disguised on there at the end of the response. This is almost certainly to stop the spammers engines from finding it but possible for a human to deduce if you work it out.

Always pop back and let us know the outcome - thanks


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#26
July 5, 2014 at 10:33:45
Already solved. Thank you.

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