[sdiy] MKS-70 Switch internal transformer from US 117 to UK 240

random variate randomvariate at hotmail.co.uk
Thu Sep 16 23:55:53 CEST 2010

Hi Richard, appreciate your looking in to this.

Am I right in taking your note to mean that I would need to change the mains input filter board too?

I asked on Gearslutz and heard from one chap that the tech that worked on his mks-70 just resoldered the transformer.


On 16 Sep 2010, at 22:47, Richard Atkinson <rga24 at cantab.net> wrote:

> I just had a look inside my USA MKS-80. The power supply transformer has two taps, one for 100V (Japan voltage) and another for 117V (USA). It's clearly a 117V/100V device with no alternative wiring for 220V/240V. So there is no possibility of rewiring the USA MKS-80 transformer for 240V operation. It would have to be replaced with another transformer.
> The MKS-70 service manual on the other hand seems to indicate that there are 100V, 117V, 220V and 240V taps on the MKS-70 transformer. (page 33 out of 44)
> Apart from that, the mains input filters are different between 100/117V, 220V and 240V, and there are different power connectors between 100/117/220V and 240V.
> On Sep 15 2010, random variate wrote:
>> Thanks Richard
>> Indeed it's C9, but I'd like to standardise as I use power distributers with built in conditioners which are all c13/14, so I'd like to standardise. I have C9s but the conditioners do clean things up a bit and of course there's surge protection.
>> I confess to being a newb with transformer tech so could you help a bit further with regards to what to look for re: parallel/serial below.
>> Once I'm happy with the mks job I'm going to rewire my US polysix too 
>> Thanks all for replies, very much appreciated
>> Tim
>> On 15 Sep 2010, at 14:22, Richard Atkinson <rga24 at cantab.net> wrote:
>>> If it's like the MKS-80 and the JX-10 I have here, the MKS-70 will use an IEC C9/C10 connector in both its US and UK incarnations. If you can find a UK C9 lead you should be able to use it with your MKS-70 once you have rewired the transformer.
>>> Check the transformer very carefully when you do the rewiring job. Many multi-voltage transformers have two sets of primary coils, which are run in parallel for 110V and in series for 220V/240V.
>>> On Sep 15 2010, random variate wrote:
>>>> Hi there everyone, newb here
>>>> I'd like to get rid of my step up transformer wart on my US model MKS-70 and have checked the internal transformer:
>>>> Currently soldered on 117v point and 0v point
>>>> There are 220v and 240v winding points
>>>> The power filter board has a 250v rated glass fuse
>>>> 1. So, is the switch as simple as de/resoldering from the 117v point to either the 220v point or 240v point
>>>> 2. Would anyone suggest using the 220 rather than 240v point?
>>>> 3. I'd also like to swap out the 2 pin US square power socket for a Euro 3 pin IEC 'kettle' socket - there's no grounding though? Should I just leave the grounding or would you suggest a chassis pin?
>>>> Advance thanks
>>>> Tim
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