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Old 27th January 2013, 11:15 AM   #11
Mooly is offline Mooly  United Kingdom
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On here

To add a photo, files or non standard files.

First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.

Then click "Manage attachements". Maximise the new Window so that you can see all the text.

Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"

The pictures should now be attached and when you submit your post they will appear.

Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.


If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that."
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Old 27th January 2013, 11:20 AM   #12
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See here a picture and the schedule

Note that all is the same exept the 15000uF is 22000uF and voltage is 25VAC
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Old 27th January 2013, 11:21 AM   #13
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WOW !!!! Far too much. You should be expecting a few 10s of Ohms.

What have you connected to X3 and X4 ?

Last edited by KatieandDad; 27th January 2013 at 11:23 AM.
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Old 27th January 2013, 11:24 AM   #14
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Checked all the caps... all in good position. What could be the problem?
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Old 27th January 2013, 11:26 AM   #15
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If you have left X3 and X4 open circuit, then it wont work.
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Old 27th January 2013, 11:28 AM   #16
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How do you mean? The resistor is not enough?
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Old 27th January 2013, 11:28 AM   #17
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There is definitely something screwy there!! Have you measured the resistance of the transformer secondaries when disconnected from the board?

I wonder if the transformer has a built in fuse. if it does, with the amount of capacitance you have on the PS you may have blown it (it may just go very high resistance, could even possibly be a polyswitch). You may need a soft start circuit.

Tony.
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Old 27th January 2013, 11:29 AM   #18
Mooly is offline Mooly  United Kingdom
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Think about it... be logical

Switch on and you have 25 volts AC applied to the rectifiers. Yes ? I can't explain your meg ohm reading other than to say that either the meter is faulty or that there is some DC voltage confusing the reading or that you are trying to measure through some insulation or varnish etc. 25 volts applied to the diodes is proof enough that the tranny output is OK.

The 33 volts climbs slowly. If there were a short or a real low resistance path somewhere then a huge current should be flowing and something should be getting hot. Is it ? Are any diodes getting hot during this time ?

Could the diodes be fake ?
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Old 27th January 2013, 11:38 AM   #19
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Hi Wintermute and Mooly,

The resistance on the secondary's is "zero" Ohm. I get a perfect 25VAC out of both secondarys.

I do use a softstart(see picture from before) and even a DC trap to cancell out toroid "Hum". To be sure that the softstart or DC trap weren't defective, I have also measured without those circuits.....

Fake diode's? I got them from Per-Anders himself... so I don't think so.... Nothing gets "hot" only a bit warm but nothing serious....
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Old 27th January 2013, 11:47 AM   #20
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I'll ask again - What have you got connected to X3 and X4 on the schematic ?

If they are open circuit, then you will get the symptoms that you are experiencing.

I can see on your photo that X3 and X4 are open circuit.

Last edited by KatieandDad; 27th January 2013 at 11:52 AM.
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