Bridgeport Interact 1 mark 2 MTI-1 transformer

08 Jan 2022 19:08 #231153 by cybermaus
Hi all

I have a Bridgeport Interact 1 mark 2 with KTK spindle drive, and I got it working with quite some repairs.
So now it is fully working. However, the transformer on the MTI-1 board also got damaged, I am currently running it with 3 separate jury rigged transformers. Because the original it is a small but 415V in and 16V+18V+18V triple out transformer, so rather custom. (Model OEP M1818/6)

So here my question:
Among all you retrofitters, is there anyone who has a MTI-1 board tossed aside. Even if broken/burned, as I only need the transformer?
(actually, I may be interested in more spare parts, but this is the one I need)

Many Thanks

BTW: as stated, I did quite some troubleshooting and repairs:
- replaced burned RIFA capacitors on KTK drive
- replaced shorted Fako capacitor on TNC-155 controller PSU
- replaced burned RIFA capacitors on MTI-1 drive
- replaced shorted SCR/Thyristor on MTI-1 board
- replaced fused relais

So if anyone needs some help on the (original) electronics of this thing, try asking me, I am slowly building some understanding, though here is always more to learn. Also, I have a pretty complete set of schematics.

The following user(s) said Thank You: andypugh, tommylight

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19 Jan 2022 13:56 #232435 by andypugh
Have you considered winding your own transformer?
For your application it seems that it might be fairly easy to take something like a 415 -> 230V transformer and then remove the secondary to replace it with your 3 x low voltage secondaries. That way you don't need to worry so much about properly encapsulating and insulating the primary.

There might be some good info online, I found this with a quick google.

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19 Jan 2022 13:59 #232436 by andypugh
Here is an example of what I have in mind, as a commercial product:

Which leads me to wonder how hard it would be to simply _ignore_ the existing secondary on a toroid and add your own three. As long as the existing secondary is left open-circuit it should be invisible.

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19 Jan 2022 14:16 - 19 Jan 2022 14:17 #232437 by cybermaus
thanks, yes it would be an option. But here is the thing: For it to fit on the PCB, it needs to be the exact pin-out and size. (a EI42 core with EI38 pinout)

And to make it external, mounted elsewhere in the cabinet like above self made toroid, well, then I can easily pick up a pair of small R-core/chassis/toroid transformers from ebay. (a pair of them, so get both voltages) 

Not very clean, but they would be very small, so I could make it work.
Last edit: 19 Jan 2022 14:17 by cybermaus.

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24 Jan 2022 17:41 #232987 by cybermaus
Some followup:

ACE Transformers and Coils in the Netherlands will build me a drop in made to order PCB transformer. I mention their name, but to be honest, I am not even sure they want too much of this sort of one-off business.

Price is of course way higher then mass produced transformers, but is kinda what I had originally expected/hoped.

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02 May 2023 11:18 - 16 May 2023 15:05 #270474 by cybermaus
Small addendum. This CNC milling machine is now for sale.

So 2 years ago my trader brother bought this machine non-functional from a Technical University. and as mentioned above, I have I spend several weekends private time figuring out the electrics, and got it all fixed up and working as original. I used it since then, but the space is needed for other stuff, and I do not have the space at home. As such, I have a private emotional interest in this otherwise professional auction.

Bridgeport INTERACT 1 MK-2 Milling machine

As evident by the still present bed-scrape patterns, the university probably did not run a lot of hours on it.
Also likely for the last 10 or so years it sat still, as someone tried to repair the Heidenhain TNC155, and then wired it back incorrectly, in such a way it could not have run again.
(see attached repair log, it's all properly fixed now, with branded components sourced from DigiKey)

Also, if anyone ever needs some technical documentation, contact me,
Mind you, I do not frequent this forum often).
Last edit: 16 May 2023 15:05 by cybermaus.

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