help with mains conversion on original dbx 160vu

[beatnik]

i have an original dbx 160vu

it's 110V version and i want to use with 220

i see the transformer has multiple primaries with jumpers on pcb to change the configuration

right now is wired as follows

- black + brown --> AC
- red + orange --> AC
- yellow --> DISCONNECTED

i tried to figure it out by myself and i think i should use this configuration

- brown --> AC
- black + red TIED TOGETHER
- orange --> AC
- yellow --> DISCONNECTED

however, i'm not 100% sure and i prefer hearing your opinion first. i don't want to damage the original transformer, or even myself!

i attached a drawing of the psu section

 

[radardoug]

No wire colors shown on the drawing, pity.
You need to make sure you get the phasing of the transformer right. So you need to identify the start and finish of each winding.
Currently the starts are wired together, and the ends are wired together. So by disconnecting  the wires you can then use an ohmeter to identify the separate windings.
Then you need to wire it as follows:
              Mains input phase to Start 1
                End 1 to Start 2
              End 2 to mains input neutral.
It is not possible to tell if you have the color codes coreect until you identify each winding.

 

[beatnik]

seem that will do the trick

what exactly should i be looking for on the multimeter?

thanks

 

[sahib]

Remove the wires from the PCB.

Put your multimeter onto ohm setting and check the windings.

If you have an analogue multimeter the needle will  move if the colours  belong to the same winding.

If  the multimeter is digital it depends on your multimeter but generally it shows 1.

However, following the colour code order;

Black
Brown
Red
Orange

I would estimate the following;

Black/Red are one winding and Brown/Orange the other.

This gives you two options.

Black - AC
Brown and Red tied together
Orange - AC

or

Brown - AC
Black and  Orange tied together
Red - AC

 

[beatnik]

hi, i am measuring the transformer. i read the following

black/red 111 ohm
orange/yellow 19 ohm
yellow/brown 81 ohm
orange/brown 100 ohm

how to interpret those values? i would really like to learn the concept

 

[sodderboy]

I wouldn't sweat the yellow.  It might be a tap for 100V Japan or something else altogether.  I first thought it could be a shield, as the schemo shows the possibility, but not if it has any continuity with windings.  It does not show on the schematic, whereas the two coils you need to connect in series do show.

You can use the molex connector to help you.  The two wires to the flat end are your "start" wires, the two on the pointed end are the "end" wires.  I would make sure that there is NO continuity between BLK-ORN and BLK-BRN.  Same with NO continuity between RED/ORN and RED/BRN.  This will verify that there are two isolated coils.  If this is the case then you will connect, as Sahib wrote

BLK-AC
RED-BRN
ORN-AC
YEL-No Connection

Sometimes NO continuity is more important.
Mike

 

[beatnik]

I wouldn't sweat the yellow.  It might be a tap for 100V Japan or something else altogether. 

it is very possible

alright, i will rewire the transformer that way. thanks guys, i learned some tips

one last question, should i change fuse rating? right now has 1A 250V

 

[sodderboy]

Please pause, think, calculate on paper, and post YOUR answer.
And get compressing.
Mike

 

[David Kulka]

For 220V it should be jumpered as below. You don't change the transformer wiring, just the jumpers.

 

[beatnik]

actually i had to invert black and brown, otherwise i couldn't jumper in that way

right now the order is orange-yellow-red-brown-black. can you confirm just in case?

i am still waiting to power it up because i want to add an iec inlet first. trying to find a metal shop that can do the cutout cause the panel is too thick for the tools i have