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my power supply does not give any output!

Posted by: arunsoman on
i am here by attaching my circuit , is their any problem with the circuit?

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Heatcon Schematic_9 25W_tny277PN.pdf 31.28 KB

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Submitted by VCastrellon on 11/10/2008
Disconnect the external bias voltage (D9 cathode and C13+) from U1 BP/M pin. Leave only C4 connected to BP/M pin. Start your power supply again. If you power supply is now running, you need to adjust your bias voltage as described at http://www.powerint.com/sites/default/files/product-docs/tny274-280.pdf page 8-9 let me know if this fix your problem
Submitted by arunsoman on 11/12/2008
i switched on the supply, i gven i/p ac 47 volts,then i got drain to source 103 volts,the result i got here.. At output: +12V output i got 39volt +5v output i got 0.00volt -5V output i got -18volt apart from these ,the clamping section resistor 100K 2W getting more heat and transformer noise is comming ,instead SB180 i am using UF4007 is their any problem?or please suggest other diode
Submitted by VCastrellon on 11/12/2008
Your schematic looks OK. Please follow the procedure to try to fix your power supply. the outputs should be un-loades. YOU MUST USE AN ISOLATED TRANSFORMER AT THE INPUT. Input voltage: start from 0 volts, connect your oscilloscope probe to DRAIN Node. Then increase your Input voltage gradually until you see the drain node starts to switch. When this happens do not increase the input voltage anymore. Measure your output voltages. You say you have voltage at +12V and -5V outputs. Measure +5Vout. If you do not have any voltage measure with the oscilloscope the waveform voltages at pin 10 and pin 9 of the transformer (When measure voltages at secondary side, connect your oscilloscope probe ground lead to output return). You must see a square waveform in phase with the DRAIN waveform. in the event you had voltage at pin 9, this waveform is going to be rectified and filtered by D10 and C11. and then the DC voltage will go though L3 to the output. So if you have a square waveform voltage at pin 9 of the transformer but you do not have 5V output, then your path is open somewhere between pin 9 and the output connector. Please let me know if this is the case. In the event you do not have voltage square waveform at pin 9, let me know to continue troubleshooting. Thank you
Submitted by arunsoman on 11/15/2008
the path opened in the 5V track ,after correction i got all the supply outputs In +12V output i got 11.47 Volt without load with load 10.5V In +5V = 4.9 with and without load in -5V= -5.55 volt with and without load Sir current also less in the 12V output