Newark sent me wrong ones,once for preamp. I check them now, either read the colors or useing a meter.
Package sticker was right just wrong ones in the bag.
It happens. But I learned somthing I won't forget.
Package sticker was right just wrong ones in the bag.
It happens. But I learned somthing I won't forget.
I measured R17 its supposed to be 56.2k
My multimeter set to 200k i measured 55.7
R1 measured at around 4.75k
R2 around 1.5k
R13 around 681
R19 around 1k
I continued to measure all resistors on the amp board, they seem to match with documentation. Im shopping for a variac, any suggestions on which one to get are welcome.
I double checked my observation from yesterday to make sure im not crazy (my mother never had me checked 😉 ). I cheated and powered up the amp for 10 seconds...
It does draw 6.5 Amps. The voltage drop over the source resistors was 0.92volts and climbing.
Ok, first priority is finding a variac! 😎
I am looking at this as a learning experience.. hang in there with me.
My multimeter set to 200k i measured 55.7
R1 measured at around 4.75k
R2 around 1.5k
R13 around 681
R19 around 1k
I continued to measure all resistors on the amp board, they seem to match with documentation. Im shopping for a variac, any suggestions on which one to get are welcome.
I double checked my observation from yesterday to make sure im not crazy (my mother never had me checked 😉 ). I cheated and powered up the amp for 10 seconds...
It does draw 6.5 Amps. The voltage drop over the source resistors was 0.92volts and climbing.
Ok, first priority is finding a variac! 😎
I am looking at this as a learning experience.. hang in there with me.
"I am looking at this as a learning experience.. hang in there with me. "
best way to look at it if you ask me!
"Im shopping for a variac, any suggestions on which one to get are welcome."
i would look for something that is adjustable 0-130Vac and at least capable of 10 amps.
do you understand why the variac? i mean why its helpful in this situation?
"I measured R17 its supposed to be 56.2k
My multimeter set to 200k i measured 55.7
R1 measured at around 4.75k
R2 around 1.5k
R13 around 681
R19 around 1k"
i don't know what meter you are using so it leads me to this question.....
on the 200k setting did it give you a K for the others but not for R17?
if R17 is 55.7 ohm thats the trouble its jacking up the bias way high!
at .92v dropped on the resistor that leaves 44.8 volts (in a perfect situation) across each fet with .92A going through them. P=IxE gives you 41 watts trying to be disapated! Each fet!
thats 492W total.
thats not to far off from what i have for 1.2's
what are the color bands on R17
best way to look at it if you ask me!
"Im shopping for a variac, any suggestions on which one to get are welcome."
i would look for something that is adjustable 0-130Vac and at least capable of 10 amps.
do you understand why the variac? i mean why its helpful in this situation?
"I measured R17 its supposed to be 56.2k
My multimeter set to 200k i measured 55.7
R1 measured at around 4.75k
R2 around 1.5k
R13 around 681
R19 around 1k"
i don't know what meter you are using so it leads me to this question.....
on the 200k setting did it give you a K for the others but not for R17?
if R17 is 55.7 ohm thats the trouble its jacking up the bias way high!
at .92v dropped on the resistor that leaves 44.8 volts (in a perfect situation) across each fet with .92A going through them. P=IxE gives you 41 watts trying to be disapated! Each fet!
thats 492W total.
thats not to far off from what i have for 1.2's
what are the color bands on R17
The color bands on R17 are green, blue, red, red, brown
The multi meter is set to 200k, which i think means that is the maximum value it can measure. If i drop it down to 20k or lower it gives me a value of 1which is an outside value. Im pretty sure R17 has the right value..
Could i have messed up the gain or current boards?
I think a variac allows you to start with a lower voltage, correct?
The voltage drop over the source resistors is pretty close to the current draw the meter indicated...
Hmmm. What a fascinating puzzle. 😛
The multi meter is set to 200k, which i think means that is the maximum value it can measure. If i drop it down to 20k or lower it gives me a value of 1which is an outside value. Im pretty sure R17 has the right value..
Could i have messed up the gain or current boards?
I think a variac allows you to start with a lower voltage, correct?
The voltage drop over the source resistors is pretty close to the current draw the meter indicated...
Hmmm. What a fascinating puzzle. 😛
you are right. green=5 blue=6 red=2 red=2 0's brown tolerance.
and you know i was wrong.
if the value is lower it is going to make the mpsa conduct more lowering the bias.
im going to have to think a bit.
I think a variac allows you to start with a lower voltage, correct?
yes. giving you a variable power source.
yes. giving you a variable power source.
ok after some thinking..... mesure the voltage drop across both mpsa's. across the collector and emiter.
and also the voltage drop across the 1.5 ohm of the top mpsa.
if your mpsa is bad it will mess with the bias.
i would wait to do this until you have a variac unless you have lots of extra parts.
and also the voltage drop across the 1.5 ohm of the top mpsa.
if your mpsa is bad it will mess with the bias.
i would wait to do this until you have a variac unless you have lots of extra parts.
Sakellogg,
I will find a variac and do the test you mentioned.
I'm patient and optimistic. There is current running through the system! That is the start of success to me. I would be more disappointed if it was completely dead.
Thanks again for your help.
I will find a variac and do the test you mentioned.
I'm patient and optimistic. There is current running through the system! That is the start of success to me. I would be more disappointed if it was completely dead.
Thanks again for your help.
This dialoge is very useful to me!I face the same problem .In search for a variac....Wait for findings...Keep on trying...
When I first checked my amp for a few seconds I measured normal dc ofset(20mV).Then ,disaster! dc at speaker terminals,blown 1ohm resistors on constant current pcb .After turning of I checked everything .Found several irfp 240 fried.I finished the second channel with extreme acuracy in respect to follow instructions.I turned it on using light bulbs for protection.the bulbs indicated false. I guess variac is a choice in order to take measurements.
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Yes, it look like Karajak is using the exact same boards.
Karajak, what enclosure are you using? It seems very nice and spacious.
Karajak, what enclosure are you using? It seems very nice and spacious.
Crap, I didn't see your second post. It is the same boards.how long before you had dc on your speaker posts?
And don't get bummed out you both will get it.
And by the end you will know how it works.
And don't get bummed out you both will get it.
And by the end you will know how it works.
I am using the same KK boards .It was about 20 seconds when dc apeard at spkr terminals. The case is based on FISHER heatshinks.I bought them a few years ago.EXPENSIVE! I could afford them back then.
Its my first project with these boards.Previous attempts with finiss boards were an absolut sucess story.I am deeply dissapointed.
Its my first project with these boards.Previous attempts with finiss boards were an absolut sucess story.I am deeply dissapointed.
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don't blame the boards. there is no problem with them. i have aleph2 with the same boards myself. and there was never any problems.
Misunderstanding! I do not blame the boards.I followed pcb instructions and each component was measured before mounted.Iam dissapointed because i canot figure out what is wrong...
Karajak, we will figure it out, no worries. My wife and I are planning a vacation to Greece, I am certain by that time you will have your aleph2's working by then. Just hang in there with me!
I ordered a variac, hopefully it will be here before the weekend, maybe later.
I ordered a variac, hopefully it will be here before the weekend, maybe later.
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