|11th February 2003, 08:22 AM||#1|
Join Date: Dec 2002
Location: East of Munich, Germany
Aleph 5 wonīt play
Hello Aleph builder club!
I have trouble bringing my just finished aleph 5 to live.
When connected to power I can meassure almost no bias current. Additionally I have full positive rail voltage at the output!
Thank god I didnīt connect a speaker.
Something must have gone completely wrong here!
Could zeners with too lower power rating be the reason? I used the smallest types (500 mW I guess) and empoly KRISTIJANīs A5 boards. All Fets were tested before soldering.
Any help /opinion is greatly appreciated. Thanks in advance!
|11th February 2003, 09:48 AM||#5|
diyAudio Moderator Emeritus
Join Date: Jan 2003
I would start measuring the voltages as listed in the original schematic: 4-5V across R11, 9V across the Z5, 4-5V across Q5.
Maybe you can give us some more details.
/Hugo - Knows how it feels when things don't work
|11th February 2003, 10:52 AM||#6|
Join Date: Feb 2003
My first post.
My experience told me that if I encountered problems such as yours, what I need was just a refreshing moment. I would get out or continue on the next day, and would find out that it was just a simple silly mistake.
Based on the experience, I expected you to have answered your own question. But may be the situation is diferent! Then you may need to give exact data for others to assist you solve the problem. You said you measured + rail on the output? Did you mean a "shortage" between Drain and Source of the signal MOSFET? Or else?
|11th February 2003, 06:19 PM||#8|
Join Date: Aug 2001
Sit back and relax, then go to work
First of all check the orientations of Q1 to Q5. Take a look on PSU to A5 PCB wire connection, then check the voltage ratings on all transistors.
Aleph 5 works fine - there must be your error why doesn't work
After this test send us more information.
Music is a part of my life, DIY is my life.
|11th February 2003, 06:36 PM||#9|
Join Date: Mar 2002
The power rating of the zener diode could be even 500 mW, and this is
not the reason that your amplifier did not worked from the beginning.
It is 99 % probably an human error during construction,
and not part defect.
Also, there can be a numerous reasons why it comes to the point that
amplifier refuses to work.
When soldering any mosfet tranzistor, you should do that with the soldering iron
grounded, just in any case to avoid static electricity that can damage the
Also, do not heat the transistors and diodes more than required.
You should check for the correct diode orientation, and check the all
resistors and diodes with the Multimeter.
In some cases some colors can look like very similar and it is very
difficult to tell which one it is, especially on the metal-film types.
Check that the all transistors are electricaly isolated from their
Also, if you have any higher voltage at the output (like very high offset),
you should desolder all the transistors and then check each one separately
for their proper operation.
Before another power up, check the power supply for the right voltages.
Before any first power up try to check everything several times,
no matter how long it would take and how that is boring, at the end it can
save you a lot's of your time and nervs.
|12th February 2003, 09:53 AM||#10|
Join Date: Dec 2002
Location: Vienna, Austria
Reason: reverse positioned zenerdiode in the diff. current source.
Leads to no current in diff pair -> no current in output devices
-> maximum positive voltage on output!
Turn this zener!
'Jazz is not dead, it just smells funny' F.Zappa
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