help with power suply

alo
maybe i`m stupid,but i realy can`t get my jlm power suply to work.
got a new p/t 230v on primary and dual sec with12v each sec.
connected sec in series to get 24v, and got about 29v(seems ok).
connected the ct to the ov on the board and the two other leads each to the 24v on the board.
measuread 31vdc on the 48v connection.
measuread 23vdc on the +/- connection
moving the trimmers to get the correct voltages doesn`t do a thing.the voltages stay the same.
semms some of you builded a jlm 99v, so if you could help i`d be very glad.
best regards.
pedro

alo
man,this sure it`s a tough one:not a single reply.
i read all the post`s about these `questions and tried everything i know but no luck at all.
you see:my computer as a prob. that i can`t send email`s,otherwise i`d email joe malone to help me out.
best regards
pedro

do yo have a lint to the schematic?
thanks!
cj

assuming that all bridge/smoothing components are ok(need to check that..) i'd say that something was loading the 48v supply..? as for the 23v, you mentioned measuring from + to - ? is this a +12 0 -12 supply? you should reference your negative lead to 0V. are your measurements with the supply free running or powering something?

pedro,
none of this sounds right ??

your power transformer is 230 volts in
2 x 12 volts ac out .... ????

why ?

What did you want to run this JLMx project at ?
24 volts single ended or do you want a dual power rail ?
This trafo can only give you 12-0-12 or ... 0-24
a dual rail of 12 volts is just not right.
If you are in a hurry and want to get this tested then 4 x 9v batts can be set up to give 18-0-18.

make sense so far ??

hi
think i did not explained myself right.
p/t in=230vac
p/t out=2*12vac.
so:if sec in series,i get 24vac.
from reading posts about how to connect the p/t to the power suply, here is what i have done:
ct not connected.
one 24vac to the power suply.
second 24vac lead to the 0v on the power suply.
guess what: it worked fine.
48vdc out of power suply.
+34vdc and -34vdc to the 99v opamps.
by the way kev:building a dual 99v jlm pre.

excellent

you have one of Joe's early power supply boards.
I have not see one of these but I think I can guess how it is making two rails from one 24 v ac input.

... so all is well then.
let us know how it sounds as many have probably not gone for the +/-34 volts.

be careful and check before you experiment with other gain blocks.

.. oh .. and say thanks to Joe.
... thanks Joe :green:

? how can you get -V if you don't reference the CT to gnd?

HI Guys. Thanks for helping Pedro out with this.

A link to the schematic for the JLM power supply to see how it works can be found here
http://www.jlmaudio.com/JLM Power Supply.htm

Joe