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Old 16th November 2012, 10:26 PM   #8501
studeb is offline studeb  United States
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my understanding is that the source has the "triangle pointing to N" tied to it, so it looks to be correct.
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Old 17th November 2012, 05:54 AM   #8502
vgeorge is offline vgeorge  Greece
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Looks OK Doug.
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Old 17th November 2012, 11:28 AM   #8503
Doug R is offline Doug R  United States
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Thanks guys.
Doug
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Old 18th November 2012, 07:37 PM   #8504
Doug R is offline Doug R  United States
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Default Well I'm off to bad start

Hi Guys,
As usual, once I touch anything solid state, I screw it up.

What I did:

1. Made one piece of Salas LV shunt from the pdf version (and shown below) for moving magnet 38 V in/28 V out

2. Made one raw supply with 18-0-18 Xfr and a dropping resistor to give 40 V loaded with about 120 mA load (333 ohm resistor)

3. Didn't think to check the unloaded voltage of the raw supply.

4. Hooked up the raw supply to the regulator with a 500 ohm load on output of
regulator (28 V/0.06 A = 0.056 Amp)

5. Got no voltage at output, so checked V/in
Yikes! 55 volts.

6. Checked transistors while still connected on board.
Did a diode check with my DMM Found:

Q1 IRF9540 G to S = OL G to D = OL
Q2 BF245A G to D = continuity G to S = continuity (obviously)
Q3 BC546B B to C = OK B to E = continuity
Q4 IRF9540 G to S = OL G to D = OL
Q5 2SK170 G to D = continuity G to S = Continuity (obviously)
Q6 BC546B B to C = OK B to E = OK
Q7 BC546B B to C = OK B to E = OK

OK, so was I supposed to have V/in 38 V unloaded?

Which three leggy things do I need to replace?

How can I avoid doing this again?
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File Type: jpg Salas LV Shunt.jpg (57.7 KB, 106 views)
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Old 18th November 2012, 07:43 PM   #8505
Salas is online now Salas  Greece
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Did you connect the 4 wire output right to your dummy load? Do a check.
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Old 18th November 2012, 08:09 PM   #8506
Doug R is offline Doug R  United States
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Yes I did Salas.
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Old 18th November 2012, 08:12 PM   #8507
Doug R is offline Doug R  United States
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Also, the LEDs did not light up right away when I turned it on, but they flickered on and off while I tried to read some voltages.
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Old 18th November 2012, 08:13 PM   #8508
Salas is online now Salas  Greece
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Had any Leds glowing during the test? All BJT semis are 65Vceo so I doubt you killed any. Do you have an up side and underside shot so we may help? Should be some wrong connection its possible.
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Old 18th November 2012, 08:14 PM   #8509
Salas is online now Salas  Greece
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Cross posted. Seems there is life in there by the flickers. Retrace the routing bit by bit.
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Old 18th November 2012, 08:15 PM   #8510
Doug R is offline Doug R  United States
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Will do Salas.
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