Felicitus Posted April 19, 2010 Report Share Posted April 19, 2010 (edited) Hi, I've bought the MF kit from Mike's Elektronikseite and went for "happy soldering" this afternoon. However, when I wanted to test the circuit (details are on http://www.ucapps.de/mbhp_mf.html ), I noticed that the voltage regulator (LM317) became pretty hot, so I immediately disconnected the power (15V DC) to look for mistakes, but I didn't find any except that the trimmpot (P1) was at 0 (but I'm not very good in debugging electronics, so I might have missed something). After that, I checked the voltage at C4, but it is at 0.87V constant, no matter what I put in with the trimmpot (P1). Could it be that the voltage regulator was damaged when the P1 was at 0? And if yes, how can I test if it is really damaged? Oh, and I noticed that on the build page, the image http://www.ucapps.de/mbhp/mbhp_mf_2.jpg shows diode and resistor swapped around in place. Is that a mistake or does it just look wrong? Thanks, Timo Edited April 19, 2010 by Felicitus Quote Link to comment Share on other sites More sharing options...
TK. Posted April 19, 2010 Report Share Posted April 19, 2010 Hi Timo, Oh, and I noticed that on the build page, the image http://www.ucapps.de...p/mbhp_mf_2.jpg shows diode and resistor swapped around in place. Is that a mistake or does it just look wrong? The orientation of the diode is important and it's correct on this picture (and other pictures that are located on the MBHP_MF page) The orientation of the resistor doesn't matter. However, does this mean that you soldered the diode the wrong way? Thats very likely the reason why the voltage at C4 is so low, and why LM317 gets a short. Probably the circuit will work (no damages) if the diode pins are swapped. Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
Felicitus Posted April 19, 2010 Author Report Share Posted April 19, 2010 (edited) Hi Thorsten, thank you for your response. Actually on http://www.ucapps.de/mbhp/mbhp_mf_2.jpg it looks like as if the upper one is the resistor and the lower one is the diode, that's why I am confused. However, I did build the circuit as given in the schematic, where the lower one is the resistor and the upper one is the diode. Now as you mention it, I'm not sure if the orientation is correct. As far as I remember I've placed the diode so that the bar on the diode is upwards - I will try to turn it around and see if it gets better. One mistake I've already corrected was that I swapped the two diode types around, but I did correct that already. Another question: For testing, I only power the circuit with 15V DC and no connections to the master board. Could this be the reason why it fails? Thanks, Timo Edited April 19, 2010 by Felicitus Quote Link to comment Share on other sites More sharing options...
TK. Posted April 19, 2010 Report Share Posted April 19, 2010 Actually on http://www.ucapps.de...p/mbhp_mf_2.jpg it looks like as if the upper one is the resistor and the lower one is the diode, that's why I am confused. Ok, probably the blue color of the resistor confused you. Another question: For testing, I only power the circuit with 15V DC and no connections to the master board. Could this be the reason why it fails? No, thats fine and shouldn't cause any negative effect. Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
Felicitus Posted April 19, 2010 Author Report Share Posted April 19, 2010 Thank you for your answers, I really hope it's only the swapped-around diode. It is hard to see what orientation the diode is on the photos :( Have a nice evening! Timo Quote Link to comment Share on other sites More sharing options...
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