That is where I would focus. What is the value of that R1, and what
is the voltage on the Drain of that Q2?
Ok :
I have the board in front of me, in such a way that I can read the inscriptions on it. I see Q2, that is in the left side, between the trimmers and two 1000μf caps.
I can see the square face of Q2, in front of me. The legs of Q2 have inscriptions, "D", "S" and "D", from left to right.
D-G = 9.5/9.6 volts
D-S = 8.6 volts
S-G = 1,00 volts
R1 (Near Q2) = 1;00 volts
R1 = 101,34 ohm
Or, D-Ground = 9.6volts ; S-Ground = 8.6volts
S to Ground, of course, 0 Volts.
Last edited:
I am struck by the idea that with R1 = 100 ohms and the voltage of 3
out of 4 are at 1.7 or 1.8 volts that the error is there.
The current should be lower, certainly less than 10 mA, which makes
the one with 1.0 volts the more correct one.
By any chance did you reverse the stuffing Q1/Q2? If so, you could be
operating the Q1's at a non optimal bias current.
out of 4 are at 1.7 or 1.8 volts that the error is there.
The current should be lower, certainly less than 10 mA, which makes
the one with 1.0 volts the more correct one.
By any chance did you reverse the stuffing Q1/Q2? If so, you could be
operating the Q1's at a non optimal bias current.
I must have a defective Q2... otherwise there is a mistery here. I don't remember how the jfets matching are organised, but I may have to buy a new set. Do I have to replace them all? It's a litle bit tricky, because the soldering pads on this board are very litle... but it is feasible.
You may laugh, but I even changed the 100 ohm resistor.
You may laugh, but I even changed the 100 ohm resistor.
Last edited:
As it should be, but the voltages are high. 1.7 V through 100 ohms
is 17 mA, way out of line for a device whose maximum is about 12 mA.
with that resistor value.
We do want to be sure that it's really 100 ohms, and not 1K which
looks remarkably like it.
Q1's are matched at Idss figures of 6 or 7 mA, and mated to the
degenerated Q2's for a current figure slightly lower. Your numbers
for voltage across the 100 ohm resistors should be less than 1 volt.
Perhaps we should send you another set.
Nelson,
I am sure that resistor is really 100 ohms.
I took it out, measured and it is. Then, I measured another one and it is 100 ohm too. I soldered it. In the bag from Mouser it is writen 100 ohm! My multimeter has a new battery! So yes, I'd like that someone send me another set. Where can I buy it or pay it? Thank you, this is taking to much of your precious time. For me it's ok, these things happen.
I am sure that resistor is really 100 ohms.
I took it out, measured and it is. Then, I measured another one and it is 100 ohm too. I soldered it. In the bag from Mouser it is writen 100 ohm! My multimeter has a new battery! So yes, I'd like that someone send me another set. Where can I buy it or pay it? Thank you, this is taking to much of your precious time. For me it's ok, these things happen.
email me your mailing address and I will send you a set.
If you don't have my email, you can find it on the bottom of the page
at FIRST WATT
I have got my Korg Christmas present.....the special "Toshiba only" version
But I never say no to a glas of Montrachet
I am not a fan of alcohol, I hate most, I am alergic.
I hate the effect of it in my head and in my body and it gives me headaches.
I feel dumb, it doesn' suit me. Normally, one or two glasses puts me in a bad shape, it ruins my day, I mean it.
But if I have a botle of Montrachet in my table I feel very inteligent and can drink it all, slowly, no problemo.
