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Mastech HY3003D-2 can switch to 110 from 220?

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xkip:
Hello, I'm planing to move to Canada. So, reviewing my hardware if it can works or can be converted to 110v.
In general user manual for this power supply (that fits to all models) there is a switch on the back that supposed to switch between 110V & 200V modes.
But in my case this hole is actually covered by sticky label that states this is 220V only. While inside the device there is a paper label 110/220. It is true that there is no switch.
I've seen couple schematics, but none of them includes this switch... Does any body have proper schematics for it?
I feel like it depends from coil layout... If it have 2 separate primary coils and they are chained in serial to work in 220V I hope I can rework this a little bit to go parallel instead (this is probably what actually switch supposed to do). Am I somehow close to the solution or this device might have different coil voltage for different markets and conversion is not possible in my case?

tooki:
See the little front-panel switch circuit board? It's got two red wires coming in from the mains, and orange-green-orange-green going out to the transformer. As you said, for 230V (as configured) the two primary windings are in series; for 120V* you put them in parallel. (You'd need to test the exact color coding, since it's possible that one primary winding is orange and the other is green — or that each winding is orange on one end and green on the other.) Quite possibly, that's exactly what the unused connector footprint on the switch PCB does. (Either that, or the second connector is for the input voltage switch, and when that's not used, jumpers are installed. My HY3005 clone is like that.)

*It's not 110V and hasn't been for nearly 100 years!

ArthurDent:
I believe tooki is correct except in some parts of the world it is actually 110VAC, not 120VAC. ;)  I 'think' if you unplug the connector with the green/orange wires and check how the runs on the underside of the board connect the pins for the connectors that aren't there, you may find that one of the two blank connector locations is wired like the drawing I've included. If there was a connector in the correct one of the two blank positions you could just move the green/orange connector to the other position to change from series (220) to parallel (110) instead of having a switch on the back. This would connect the two green wires together to one side of the line and the two orange wires together to the other side of the line. You can probably check the board wiring from the topside with small probes on a DMM. The small difference between 110 and 120 shouldn't matter either plus you're probably going from a 50 hertz world to a 60 hertz world that will reduce the no load (excitation) current for the transformer as well. If you can find another 4-pin connector to solder in the correct position (or move the existing one) you will be able to make this voltage change without cutting and modifying any wiring which would keep it neater.

One word of warning: if the two primary windings are placed in parallel out of phase, this will blow a fuse.  If you put a 100 watt incandescent bulb in series with the transformer primary the first time you try it after making the change in the primary wiring and the bulb doesn't glow brightly, and the supply works, it is wired correctly.

tooki:

--- Quote from: ArthurDent on August 25, 2018, 11:52:01 am ---I believe tooki is correct except in some parts of the world it is actually 110VAC, not 120VAC. ;)
[…]
One word of warning: if the two primary windings are placed in parallel out of phase, this will blow a fuse.  If you put a 100 watt incandescent bulb in series with the transformer primary the first time you try it after making the change in the primary wiring and the bulb doesn't glow brightly, and the supply works, it is wired correctly.

--- End quote ---
Except the OP isn't moving to "some part" of the world, they expressly said "Canada", which is 120V. ;)

Good call on the phase, though!

ArthurDent:
"Except the OP isn't moving to "some part" of the world, they expressly said "Canada", which is 120V."

You misunderstood what I meant. I live in this 120VAC/60 hertz world and understand that.  Check the labels shown in the first post which read '110V/220V' and the frequency listed on the back of the supply read '50Hz'. The point was that there are 110VAC countries even today and the supply was labeled for those areas.  :)

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