step-up transformer instructions?

[kill_surf_city]

I have step up transformers that I need to install on my Eros 2 so it will work with my cartridge. Are there any detailed instructions for installing these? I'm kind of lost. They're the 1990E SUTs. Any help would be greatly appreciated. My knowledge of electronics begins and ends with the instructions provided, so I may need a bit more detail in going about this. Thanks!

 

[Paul Birkeland]

You'll have to let me know what you need beyond this:
https://forum.bottlehead.com/index.php?topic=11097.0

 

[kill_surf_city]

You'll have to let me know what you need beyond this:
https://forum.bottlehead.com/index.php?topic=11097.0

Okay great. Thanks Paul!

 

[kill_surf_city]

You'll have to let me know what you need beyond this:
https://forum.bottlehead.com/index.php?topic=11097.0

1.  Pop the resistors out of each RCA jack that go to pin 9 on each EF86 (leave them attached to the socket, just pop out the end sitting in the solder cup of the RCA jack).
2.  Remove the 47K loading resistor on each RCA jack.
3.  Reconnect them at terminals 2 and 17.

so the resistor that's connected to A9 would be connected to A9 on one side and then terminal 2 on the other. Then the 47k resistor that I removed from RI is attached to terminals 1U and 2U?

It's hard to tell from the photos, but which terminals are the pink and yellow SUT wires connected to? I see the black wire is connected to 3U. Orange and white are twisted together and attached to the right input tab and then the grey and red wires are twisted and connected to the solder cup. Do I have that correct? If so I think i just need to know which terminals the pink and yellow are soldered to.

 

[Paul Birkeland]

Which wires go where in terms of the orange, white, grey, and red depends on whether your wiring for 1:10 or 1:20.

The pink and yellow wires are the output of the SUT.  These connect to the same terminals that the 47K resistors occupy, and it looks like I grounded pink.  The black wire also connects to ground (not 3U).

 

[kill_surf_city]

Which wires go where in terms of the orange, white, grey, and red depends on whether your wiring for 1:10 or 1:20.

The pink and yellow wires are the output of the SUT.  These connect to the same terminals that the 47K resistors occupy, and it looks like I grounded pink.  The black wire also connects to ground (not 3U).

What’s the difference between 1:10 and 1:20. I’m wiring for my Dynavector XX2 Mkii.

 

[kill_surf_city]

The black wire also connects to ground (not 3U).

From the image it looks like the black wire is connected to terminal 3, just above where pink is connected. Isn't that 3U? What I'm seeing is yellow to 1 pink to 2 and then black to 3.

 

[Paul Birkeland]

I would send it to terminal 1 instead.  When I put those in, I mistakenly read that as a can ground, but it's an electrostatic shield and it should go to audio ground.

For that cartridge, I would go with the 1:20 configuration, which is consistent with the photo you're looking at, not the two below it. 

 

[kill_surf_city]

I would send it to terminal 1 instead.  When I put those in, I mistakenly read that as a can ground, but it's an electrostatic shield and it should go to audio ground.

For that cartridge, I would go with the 1:20 configuration, which is consistent with the photo you're looking at, not the two below it.

Okay great. So the connection would go yellow to terminal 1, pink to 2, and then the black to 1 as well?

 

[Paul Birkeland]

Yes.

 

[kill_surf_city]

Yes.

Great thanks a lot Paul. I’ll give this a go tomorrow.

 

[kill_surf_city]

Yes.

Ive completed one side but it's not letting me post replies with attachments for some reason. What testing should I do before finishing and turning it on?

 

[Paul Birkeland]

Just fire it up and test it out.

 

[kill_surf_city]

Just fire it up and test it out.

All done. All the LEDs are still lighting up. Should i retest voltages for different values or should they be the same as in the instructions?

 

[kill_surf_city]

voltages are all within range just as before.

 

[kill_surf_city]

Just fire it up and test it out.

Ok, fired up, voltages all within range. Only problem seems to be a very low hum in both channels. It goes away when the volume is turned all the way down on my amp. Any suggestions?

 

[Paul Birkeland]

If you don't have your turntable hooked up, you could get some hum from the open input.  Otherwise you may need to experiment a little bit with where the Eros sits to minimize magnetic hum pickup.  I haven't experienced this issue with the Sowter step-up transformers, but definitely with some others in the past.