I blew my rare AX 990 accidentally

By landlord

Resident (35)

09-07-2018, 02:30

I accidentally plugged my MSX AX 990 into 220V while it was set to 110V. I heard a really loud pop.

When I've done this in the past it usually sets the fuse off and a simple replacement would fix the problem.

In this case however, the fuse did not trigger, and the transformer blew out.

I would like to get a replacement but there is nothing written on the transformer.

How can I figure out what rating the transformer is?

On the sticker on the bottom of the computer it says: 110/127/220/240V ~ 50/60 Hz 16W

Any help would be really appreciated. This is an extremely rare computer

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By fernando.collazo.5682

Champion (257)

09-07-2018, 06:34

Oh my God!
I hope you could fix It soon...
Good luck

By gdx

Enlighted (6443)

09-07-2018, 09:26

Tell us how many ouputs the transformer has, then take PCB pictures and components behind the outputs of the transformer (regulators and chips).

I do not think you will find an equivalent transformer but, you can ask a professional to change the copper coils when you find the output values.

By landlord

Resident (35)

09-07-2018, 14:27

I took pictures of the transformer and the PCB.

MSX AX990 PCB

Please let me know if you need close ups of something specific.

The blue wire from the transformer connects to the upper two pins on the 4-pin connection in the picture.

Good news is I did not burn the motherboard. I took apart my AX 660 which is practically the same computer and used the transformer on the AX 990 and it worked fine. So I am certain the problem is only with the transformer. Just need to sort out replacement or a fix.

EDIT: Based on the video below, I could probably fix this transformer by replacing the blown output fuse inside the transformer?

https://youtu.be/6ePclpV1_kw?t=31m18s

By Jipe

Paragon (1625)

09-07-2018, 14:27

you can read the secondary voltages on the transformer of the AX-660 with a multimeter

By ali6x944

Master (198)

10-07-2018, 10:05

first don't worry or panic it happens to the best of us...
second I want you to test the continuity of the primary side because most faults of that nature burn the primary of the transformer, also do what Jipe had suggested and test the secondary voltages on the transformer of the AX-660 .
finding the replacement is rather simple and cheap from Ebay or digikey or jemaco.

By gdx

Enlighted (6443)

10-07-2018, 10:15

Yes, the transformer seems standard. If the output voltages are twice the same you will easily find a replacement.
You will just have to find a transformer of 25~30VA. If the output voltages are different, it will be more complicated.

By gdx

Enlighted (6443)

10-07-2018, 12:52

Looking closely at the PCB, I see a 3-pin connector that appears to be for the transformer input and another 4-pin connector that appears to be for the transformer output. 3 pins for the entry seems logical for 2 x 110V since there is a voltage selector. By cons, on one of your photos I see a transformer with a connector with two pins only.

By Jipe

Paragon (1625)

10-07-2018, 13:01

the connectors of the transformer taken in picture do not correspond with the connectors of the mother card !!

By Colemu

Hero (544)

10-07-2018, 13:14

I did the same with my Japanese Playstation and X68000 XVI

I'm usually very careful, but must have had a couple of Brain Farts!

Hope you get it sorted

By landlord

Resident (35)

11-07-2018, 01:03

gdx wrote:

Jipe wrote:

the connectors of the transformer taken in picture do not correspond with the connectors of the mother card !!

Yes, it's weird. As mentioned in my previous post the blue wire with 2 pins was connected to the 4 pin connector using the upper 2 pins. On the AX 660 the same connector on the board has 2 pins not 4. Not sure what the intention was for having a 4 pin connector on the AX 990.

Anyways, I will try figuring out how to test the outputs from the AX 660 transformer and report back. Appreciate all the help