Aleph mini one channel not working

yoke · 8th March 2008, 05:08 PM

Aleph mini one channel not working

Hi
I have put together two channels of Aleph Mini, couple months ago. ( based on Brians GB PCB and curcuit )

But some how I manage to destroy one channel. I believe that, during the operation under voltage, PCB have touched aluminum bar under it, and now I have 18V (power supply voltage) on the output.

I was hoping that, only, fault would be destroyed output mosfets but they are fine, they still work (I have check them by procedure described in here http://www.bcae1.com/ampfail.htm ). But I replace them any way (for some other reason)

So does any one have any idea what could be wrong in the circuit that would produce power supply voltage on the output?
Since I have no experience in fixing power amps ;-) and have no equipment for that, except one multimetar ;-)

thanks

sandstorm33 · 8th March 2008, 06:08 PM

If all mosfets are "good" including front end devices I would check Q4 and C2 and C3.

yoke · 8th March 2008, 06:55 PM

Hi sandstorm33...thanks for replay
I haven't check front end mosfets, I’m hoping that I will not need to desolder them since it will be very difficult to solder them back in the place...

will see if any one else have some other idea, what could be wrong...
have to see if I have some spear ZTX450...

yoke · 9th March 2008, 09:42 AM

I have replace bouth ZTX450 and I still have +18V on the output...

yoke · 9th March 2008, 10:53 AM

o.k.
I have found one folt,broken resistor...R27 (0.5 5W )

http://diyamps.com/aleph/docs/miniAleph-sch.pdf

could it be it ?
I mean if I replace only this one resistor, everithing should work, or should I try to find if there's something else broken.
what should I check that could be relate with broken R27 ?

sandstorm33 · 9th March 2008, 11:14 AM

Quote:

Originally posted by yoke
o.k.
I have found one folt,broken resistor...R27 (0.5 5W )

http://diyamps.com/aleph/docs/miniAleph-sch.pdf

could it be it ?
I mean if I replace only this one resistor, everithing should work, or should I try to find if there's something else broken.
what should I check that could be relate with broken R27 ?

R27 broken (or burnt) would cause the output to see+18volts . If you checked the OUTPUT MOSFETS and thet are good than you should be OK after replacing R27.

yoke · 9th March 2008, 11:14 AM

I have replace R27 and now everything works...well I didn't conect input or speakers but multimeter at the output says 0.022V...;-)

Thanks sandstorm33

sandstorm33 · 9th March 2008, 12:15 PM

Quote:

Originally posted by yoke
I have replace R27 and now everything works...well I didn't conect input or speakers but multimeter at the output says 0.022V...;-)

Thanks sandstorm33

Cant get much better than that!!!!

8th March 2008, 05:08 PM	#1
yoke diyAudio Member Join Date: Jan 2004 Location: Split	Aleph mini one channel not working Aleph mini one channel not working Hi I have put together two channels of Aleph Mini, couple months ago. ( based on Brians GB PCB and curcuit ) But some how I manage to destroy one channel. I believe that, during the operation under voltage, PCB have touched aluminum bar under it, and now I have 18V (power supply voltage) on the output. I was hoping that, only, fault would be destroyed output mosfets but they are fine, they still work (I have check them by procedure described in here http://www.bcae1.com/ampfail.htm ). But I replace them any way (for some other reason) So does any one have any idea what could be wrong in the circuit that would produce power supply voltage on the output? Since I have no experience in fixing power amps ;-) and have no equipment for that, except one multimetar ;-) thanks

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Mini Aleph Board & Aleph 2 Parts List	gpsmithii	Pass Labs	3	16th January 2010 04:58 AM
New K-12g only one channel working	audioblast	Tubes / Valves	9	14th May 2007 02:13 PM
Pass Aleph-3 one channel not working?	meaw	Pass Labs	5	26th January 2004 06:21 AM
Zen4..only one channel working..	frankv	Pass Labs	10	2nd December 2002 03:08 PM
First channel of Alpeh 4 is working, however...	Edwin Dorre	Pass Labs	14	11th June 2002 10:22 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

8th March 2008, 06:08 PM	#2
sandstorm33 diyAudio Member Join Date: Sep 2006	If all mosfets are "good" including front end devices I would check Q4 and C2 and C3.

8th March 2008, 06:55 PM	#3
yoke diyAudio Member Join Date: Jan 2004 Location: Split	Hi sandstorm33...thanks for replay I haven't check front end mosfets, I’m hoping that I will not need to desolder them since it will be very difficult to solder them back in the place... will see if any one else have some other idea, what could be wrong... have to see if I have some spear ZTX450...

9th March 2008, 09:42 AM	#4
yoke diyAudio Member Join Date: Jan 2004 Location: Split	I have replace bouth ZTX450 and I still have +18V on the output...

9th March 2008, 10:53 AM	#5
yoke diyAudio Member Join Date: Jan 2004 Location: Split	o.k. I have found one folt,broken resistor...R27 (0.5 5W ) http://diyamps.com/aleph/docs/miniAleph-sch.pdf could it be it ? I mean if I replace only this one resistor, everithing should work, or should I try to find if there's something else broken. what should I check that could be relate with broken R27 ?

9th March 2008, 11:14 AM	#7
yoke diyAudio Member Join Date: Jan 2004 Location: Split	I have replace R27 and now everything works...well I didn't conect input or speakers but multimeter at the output says 0.022V...;-) Thanks sandstorm33

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)