juniorhifikit

Power Transformer-series/parallel 110v/220v question
« on: October 25, 2006, 07:09:30 AM »
Question about series/parallel power transformer circuit.  I've seen this on a lot of my gear, and did this on my SSL clones, but it's been a while since I wrapped my head around it.  This is the circuit from a Hafler amp power supply:
Insert image:

My question is, do I need to keep R124 and R125 (which are there for the 110v mode) and ADD R126 to get 220v;  or do I remove them and use ONLY R126; or do I jumper across (short) R124 & R125 for the 220?  It seems like with NOTHING at the R124 & R125 position, there's no circuit.  Any insite would be greatly appreciated!
[/img]


Harpo

Re: Power Transformer-series/parallel 110v/220v question
« Reply #1 on: October 25, 2006, 08:08:52 AM »
Quote from: "juniorhifikit"
My question is, do I need to keep R124 and R125 (which are there for the 110v mode) and ADD R126 to get 220v;  or do I remove them and use ONLY R126; or do I jumper across (short) R124 & R125 for the 220?  It seems like with NOTHING at the R124 & R125 position, there's no circuit.  Any insite would be greatly appreciated!


For 220v mode leave out R124 and R125 and add R126. Those (R)esistors for usual are zero ohms (jumpers). The 'circuit behind' is the power transformer with dual primaries (J9-1/J9-2 for 1st.winding and J9-3/J9-4 for 2nd winding).  R126 put these transformer windings in series (joining J9-2 + J9-3) for 220v.
For 110v mode leave out R126 and add R124+R125 to set the 2 primary windings in parallel.

Hope I could help
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.  -Douglas Adams

juniorhifikit

Power Transformer-series/parallel 110v/220v question
« Reply #2 on: October 25, 2006, 01:41:15 PM »
Perfect - Thanks!

I love this forum! :grin:


 

Related Topics

  Subject / Started by Replies Last post
8 Replies
2396 Views
Last post July 15, 2011, 08:56:36 PM
by Rob Flinn
3 Replies
512 Views
Last post September 01, 2018, 09:54:21 PM
by Script
38 Replies
2123 Views
Last post October 28, 2018, 11:37:23 PM
by JohnRoberts
5 Replies
442 Views
Last post May 29, 2019, 02:32:15 PM
by Michael Tibes