Hi Dear, Just look at #2173 Salas's message. My calculation using the excel file gives approx 0,3 watt P(R101), I=160 mA and R=11,8 ohm. Wattage rating of resistor is R*I*I.
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Wow! Talking a busy built. I hope that the regs payed back in performance?
Thanks for good wishing, same 2U2.
Get some smoke ... smell good!
I have built a SSLV1.1 BiB which is used for my M3 headphone amp.
I used a 15V x 2 xfomer and intended to set an output of 34V @ 340ma.
For details, please refer to the attached excel file.
When testing the reg, I used a dummy load of 147ohm (100 + 47). A DMM was connected to the dummy load and was used for measuring the output voltage. Another DMM was connected to R301 to measure the current. While I was turning the pot R305 and got 17V output, I noticed that the current shown in another DMM was more than 1A! I switch off the power immediately.
Then, I switched on the power again and found only the D302~D304 lit. But no more readings from the two DMM: only 0V and 0A.
I am sure that the Q301 was well cooked. See pic.
Action will be taken:
replace the Q301 IRF9610;
Questions:
is there any wrong calculation made that causes the current across R301 greater than 1A?
BTW, Salas can you help me to simulate the stability of the BiB reg, I used 2SK30A instead of 2sk117? Also, I have plenty 2sk372 GR at hand.
I have built a SSLV1.1 BiB which is used for my M3 headphone amp.
I used a 15V x 2 xfomer and intended to set an output of 34V @ 340ma.
For details, please refer to the attached excel file.
When testing the reg, I used a dummy load of 147ohm (100 + 47). A DMM was connected to the dummy load and was used for measuring the output voltage. Another DMM was connected to R301 to measure the current. While I was turning the pot R305 and got 17V output, I noticed that the current shown in another DMM was more than 1A! I switch off the power immediately.
Then, I switched on the power again and found only the D302~D304 lit. But no more readings from the two DMM: only 0V and 0A.
I am sure that the Q301 was well cooked. See pic.
Action will be taken:
replace the Q301 IRF9610;
Questions:
is there any wrong calculation made that causes the current across R301 greater than 1A?
BTW, Salas can you help me to simulate the stability of the BiB reg, I used 2SK30A instead of 2sk117? Also, I have plenty 2sk372 GR at hand.
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I would not be suspicious of calculations and oscillations before I was sure that the 9610 got enough sinking. You are asking it to dissipate 14W ultimately in a short. Maybe Rset is small. I see 3 greens when you allowed for red. Look at its drop early. Maybe a more capable one like the 9530 if its not the Rset. Though slower enough.
Yeah, to be conservative, I may replace the 2 ohms R301 by a 4 ohm resistor. If the current is too low, I can parallel it by another 4 ohm. BTW, I have a spare 9610 sitting around.
Forget to mention these measurements:
1. I desoldered the original Q301 and the first 2 pins of on the left give a reading of 26.7 Ohm. My LCR meter said that the desoldered Q301 is damaged.
2. The first 2pins of the on board Q306 also give more or less ohms.
3. The newly replaced (soldered) Q301 give 6xx ohms.
Maybe, I have to replace the Q306 and check if it also get cooked.
BTW, last time, I connected an ammeter in parallel to R301 to measure the current.
I doubt that it killed the mosfets by drawing too much current across them.
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Check all main semis since there was a bad start then, better safe than sorry.