Recapping Falcon PSU - My rectifier is different

[derkom]

I'm in the process of recapping a Falcon PSU with exxos' kit (hoping to tame a ~300 mV ripple on the +12V rail) and after replacing all the caps, I've noticed that my rectifier doesn't look anything like the one in the photo on exxos' PSU page, and also there's a resistor missing from right next to it (R4). (I imagine it's simply not supposed to be there, and this is just a slightly different revision of the PSU. I am also missing R18 in the upper right.)

IMG_20180919_122549.jpg (412.05 KiB) Viewed 5510 times

I am reasonably comfortable with electronics, but not nearly the level of a lot of you guys, so I figured I'd better ask here before continuing. Does anyone recognise this revision of the Falcon PSU, and am I good to continue here and replace the rectifier with the new one from exxos' kit?

Thanks!

[kodak80]

The bridge rectifier is the original square one and is correct. The one Exxos supplies is slightly different but has 4 legs so you need to make sure you align the positive and negative legs:



R4 and R18 was missing from my Falcon PSU and they look the same. Recap worked fine.

[derkom]

The bridge rectifier is the original square one and is correct. The one Exxos supplies is slightly different but has 4 legs so you need to make sure you align the positive and negative legs:

R4 and R18 was missing from my Falcon PSU and they look the same. Recap worked fine.

Yep, no worries on the legs. Thanks for filling me on the other details. I shall continue the project.

[derkom]

Oh silly me. If I'd just looked at the beginning of the Falcon section on the PSU page, I would have seen a picture that matches mine. Good job, me.

[exxos]

The differences on the resistor are 110V vs 240V configs.. some better images in this section.

https://www.exxosforum.co.uk/forum/viewforum.php?f=59

[derkom]

...and it's done.

+12V ripple before...

MZK8UfN.jpg (37.97 KiB) Viewed 5489 times

...and after...

IMG_20180919_145713.jpg (37.37 KiB) Viewed 5488 times

50 mV/div in both cases.

[exxos]

[Atarian Computing]

...and it's done.

50 mV/div in both cases.

Cool, so from 250mVpp to 100mVpp? What kind of load are you running here?

[derkom]

Cool, so from 250mVpp to 100mVpp? What kind of load are you running here?

Both times just using the load resistors supplied by exxos. "5V uses 2.2R (loads 5V rail with 2.2amps) and 12V uses 10R (loads 12V rail with 1.2amps)"