Deltalab Effectron power supply query

[pvision]

I've seen quite a few Effectrons but not seen (or maybe not noticed) this before. As they arrive they're setup for 110 Volt but have four solder pads to change voltage. Normally the pads are linked L-K and K-J for 110V and you change this to K-K for 220V. So far so good

This Effectron II ADM 1024 (one of dozens of similar versions of the Effectron) has a second set of solder pads (marked 100 / 200) beside the main PSU cap that appear to link one end of the rectifier bridge to the positive of the main cap (I think this link is marked I on the schematic)

I can't quite get my head round this - any suggestions?

Quick explanation of the PSU: it has two sets of secondaries, two rectifier bridges, three 7812s and a 7805. The #2 secondary feeds a 7812, the positive output of which is tied to ground so giving a -12V supply. The secondaries don't have centre taps and #2 secondary is electrically isolated from #1

When the primary is wired appropriately the transformer doesn't care whether the supply is 110V from a US socket or 220V from a UK one so why change anything?

Is this 100/200 link a red herring, unrelated to voltage switching?

One thing to notice is that the schematic shows voltage inputs of 100, 200, 110 & 220 Volts at the power input which suggests (to me, at least) that the link is voltage-related

I don't have a specific schematic for this model but have attached a diagram for another Effectron

Thanks!

 

[opacheco]

pvision,

O have a pair of units like this too!....do you have the complete schematics in order to check this you noted about the ac voltage psu?(and get a copy of them too!)

Thanks
opacheco

 

[JohnRoberts]

100V was a mains voltage in parts of Japan... I don't think I encountered any 200V mains.

JR

 

[radardoug]

I think its a red herring. Just series the primaries, and bring it up on a variac while watching the voltages.

 

[pvision]

I think its a red herring. Just series the primaries, and bring it up on a variac while watching the voltages.

My usual method is to measure the secondary voltage with the unit powered up on 110V then change the wiring or solder pads for 220V  operation and power it up again at 110V. If the secondary voltage halves (or very close to) then all is good

Schematocs for these are hard to find and every version of them seems to be different. I'll see what I can dig out and upload them

Nick Froome

 

[houtson]

Hi @pvision - did you get to the bottom of the the 100 /200V link - is it needed to covert 110V to 240V?

I've got same ADM 1024 and looking to change voltage. I've soldered the middle jumper to put the primaries in series but I don't get the 100 / 200V link.

The best schematics that I've found for the ADM 1024 are at Stec Records - Software but they didn't help me understand that additional link.

cheers Paul

 

[JohnRoberts]

Back then low volume manufacturers commonly used dual primary transformers. For the 230V market the two primaries were connected in series, for 115V market the two primaries are wired in parallel. The winding polarity matters.

JR

 

[houtson]

HI @JohnRoberts - I get the primaries in series rather than parallel, the concern was there is another jumper on the rectifier side of the transformer unusually marked (as 100 / 200V as per picture in the first post).

I pushed on an just made the change on the primary side of the transformer and ignored the 100 / 200V jumper - all seems to be fine, no magic smoke and basic operation all confirmed ok.

Cheers, Paul

 

[Khron]

That kinda sounds like the kind of voltage doubler one might see on some older / cheaper desktop computer power supplies.

https://slidetodoc.com/presentation_image_h2/4bfcd06d15b2c7be37eda8af38c9aef1/image-19.jpg