Platon, ok - try the following:-
1. Connect the cathode of D17 to 0V
2. D15 should go OFF
3. If it does not go OFF, measure the voltage at the drain of Q3 with D17 still shorted to 0V
4. The voltage should be near to V+. If it is near to 0V, then it is likely that Q3 is faulty.
5. If the drain voltage is near V+ with D17 shorted, then U1 is probably faulty.
I suggest you just replace Q3 and U1
(Your gate voltage is a bit low - either your meter is loading it, or you have some gate leakage which is a sure sign it is faulty)
1. Connect the cathode of D17 to 0V
2. D15 should go OFF
3. If it does not go OFF, measure the voltage at the drain of Q3 with D17 still shorted to 0V
4. The voltage should be near to V+. If it is near to 0V, then it is likely that Q3 is faulty.
5. If the drain voltage is near V+ with D17 shorted, then U1 is probably faulty.
I suggest you just replace Q3 and U1
(Your gate voltage is a bit low - either your meter is loading it, or you have some gate leakage which is a sure sign it is faulty)
U1-PDTA144ET
Q3-2N7002
Replace transistors...and test your recommendations.
And,other transistors are ok ..??
U2-PDTC144ET
U3-PDTA115ET
Q3-2N7002
Replace transistors...and test your recommendations.
And,other transistors are ok ..??
U2-PDTC144ET
U3-PDTA115ET
C2 can be any plastic film.
MKS or MKT
The D4 & D5 rectifier requires the electrolytic to be oriented that way.
D17 (a Zener) is not turned on when 3.6Vdc is present.
Q3 @ 1.7Vdc gate seems a bit low to turn on the FET.
MKS or MKT
The D4 & D5 rectifier requires the electrolytic to be oriented that way.
D17 (a Zener) is not turned on when 3.6Vdc is present.
Q3 @ 1.7Vdc gate seems a bit low to turn on the FET.
AndrewT-I know ... it just does not work as it should.
http://www.diyaudio.com/forums/solid-state/236522-sx-amp-nx-amp-170.html#post4590093
http://www.diyaudio.com/forums/solid-state/236522-sx-amp-nx-amp-170.html#post4590093
D17 acts primarily to ensure the max voltage across the gate of th the mosfet is 4.7 V. This is to ensure that the turn off time is reasonably short. The2N7002 will be on well below 4.7 Volts.
Did you do the specific tests I proposed in post#1701, Platon? You have to isolate where the problem is from.
U1 was changed to 47k to reduce the dissipation. This is not the root cause of your problem.
Either the issue is coming before the 2N7002, it's with the 2N7002, or its U1 or any combination of the above. Please do the specific tests in post #1701
Did you do the specific tests I proposed in post#1701, Platon? You have to isolate where the problem is from.
U1 was changed to 47k to reduce the dissipation. This is not the root cause of your problem.
Either the issue is coming before the 2N7002, it's with the 2N7002, or its U1 or any combination of the above. Please do the specific tests in post #1701
Last edited:
hello, i am a beginner in the diy world ,i never built an discrete amplifier, chips -yes and i was about to buy these pcb from ebay.
But it looks like these amplifiers(100Wx2 Ovation nx) are not so easy to be done, 171 pages of tweaking and questions prove that. My question would be if i should start with the 60-100watts hi fi power amplifier from sound.westhost.com rod elliott or to give the 100Wx2 Ovation nx a try?
thanks guys
But it looks like these amplifiers(100Wx2 Ovation nx) are not so easy to be done, 171 pages of tweaking and questions prove that. My question would be if i should start with the 60-100watts hi fi power amplifier from sound.westhost.com rod elliott or to give the 100Wx2 Ovation nx a try?
thanks guys
Yes its easy and you will be very happy to solder smd parts.Its an excellent amplifier to build also you will get excellent support from Bonsai and others.Happy Build.Before you build please read the documented pdf file.You will get all your answers there.
Ok thanks for the quick answer, so you think that I should give it a try even I never built an discrete one? Elliott amp looks much easy to be done, less components and so...
http://www.diyaudio.com/forums/solid-state/236522-sx-amp-nx-amp-170.html#post4590093 look picture.Drain 2,4V
Platon, It seems to me that Q3 is not working. If you replaced it and still have this problem, look for something on the board. I would remove Q3 and then measure again at the drian and come back with what you are seeing.
Don't replace it. Take it out, and then see if D15 stays on
Before replacing it, come back and let me know what happens after you have removed it.
Before replacing it, come back and let me know what happens after you have removed it.
