Sumo Polaris voltage conversion?

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JayMX
JayMX Posts: 435
in Electronics
So a friend of mine picked up a Sumo Polaris (Model 310) this weekend. The power cord on the amp is a standard parallel blade, but the back panel shows the input voltage as 220. Does anyone here have experience with these old amps?

I will get some photos of the interior when I have it in my possession. All he sent me was a shot of the backside for now:
41iyk4mvt4v9.jpeg

I did through research online find a photo of a similar unit that someone had installed an IEC on the back panel but the label read 220 (like my buddy's) so I assume they were able to run it off 110... here’s a screenshot:
pr9a8d1hl5b4.jpeg

I'm just not sure what it would take to convert from 220 to 110... maybe just simple rewiring to different taps on the transformer? Maybe a whole different transformer....? Please if anyone has experience chime in.

Any thoughts? Thanks!
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (3x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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  • mhardy6647
    mhardy6647 Posts: 33,037
    edited June 2019
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    Depends on the power transformer. If it has dual taps on the primaries, should be trivial to convert. The fuse would need to be replaced, too (from 3A to 6A).

    The other way to do it is an outboard step-up transformer (120 to 240 VAC) -- the only problem is that this amp will require a big, beefy step-up transformer, which wouldn't be cheap! 6A @ 120VAC means that a minimum capacity of ca. 750 watts (more accurately, 750 VA) would be required. Even higher capacity would be better, of course :)

    EDIT corrected my gaffe on down vs. up! :p

    I see cheap ones on Amazon (via a quick googlin') -- I'd be wary of such, FWIW. Sort of like hifi audio, mostly, one gets what one pays for B)
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  • JayMX
    JayMX Posts: 435
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    Thanks @mhardy6647 🤘🏻
    I’d rather not do a step up transformer, if at all possible... dunno if it would be worthwhile and like you said, it would have to be relatively large... 😬

    The amp finally found its way to my garage. Had a minute tonight to pop the lid and see its innards. I tried as best I could to map out how it’s currently wired, don't think I drew up the switch correctly now that I look at my sketch... pretty sure it’s a single pole double throw. That said, I can not find anything online using the numbers printed on the side of the transformer as a reference to determine mfg or what the wire colors are...

    The only thing I’m thinking I could do at this point is pull the transformer completely out of the chassis (so I have no chance of damaging the amplifier circuitry,) then blind test the taps and see what comes out the secondary side... any other suggestions, speculations?

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    swkdh7lsopsa.jpeg
    Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
    Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (3x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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  • JayMX
    JayMX Posts: 435
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    Just to close the loop here. I figured, “what the heck” and I just plugged er in. No speakers or input attached. Breaker didn’t pop, so I whipped out the meter, measured the secondary side of the xformer and found 56vdc right where it should be 60 according to the schematic. So I did another what the heck, powered down, hooked a pair of sacrificial speakers up and my phone to the input, flipped the switch and out came beautiful, clear sound. I think the dude that said it was set up for 220 was on crack. It works perfectly. Mystery solved.
    Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
    Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (3x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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  • Clipdat
    Clipdat Posts: 12,599
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    Great news!
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