aleph 2 problem

karajak · 3rd January 2011, 07:38 PM

i finished my aleph 2 cnstruction and i tested forgeting to connect the led diode. almost emediately the mains fuse was melted. i checked the circuit and after connecting the led i changed all irfp 240 of the constand current side.i found at least 2 short circuited and 2 power resistors(1om)destroyd.
i turned then the amp on and as a result after 30 sec of normal operation (dc ofset 40mvolt)the220 om resistors next to the irfps started burnig and i stop any eford in doing anything else.
question:all theese happened because i didnt connect the led ?what do i do now?

Nelson Pass · 3rd January 2011, 08:37 PM

The LED should not have had anything to do with it.

Most of the time this happens there is a wiring or component
value error. Time to start looking for it, and also think about
how you can limit the supply power for next time you fire
it up.

karajak · 4th January 2011, 01:28 PM

thanks nelson for the reply. it is a relief for me to know that led is not the cause of the problems.i will start checking everything starting from wiring.

eyoung · 4th January 2011, 08:41 PM

get a variac and a mains cable with 100w light bulb on hot lead there are numerous threads with powering up for the first time safely and limiting damage ...

Peace,
Elwood

karajak · 5th January 2011, 03:07 PM

thanks! this is what i shoud have done from the biginning! after a few total succes progects i forgot the basics.....

karajak · 12th January 2011, 01:12 PM

i checked everything seems ok. i didnot mention that psu voltage is 53 volts(plus minus).its higher than the 45 mentioned in the schematics.do i need to replace any parts value due this voltage diference?

h_a · 12th January 2011, 03:24 PM

You have almost 20% higher dissipation than stock that you need to cope with (you could reduce bias a bit) otherwise not a big topic.

Or you could burn 1 or 2 V's by building a CRC supply.

Have fun, Hannes

3rd January 2011, 07:38 PM	#1
karajak diyAudio Member Join Date: Jan 2008 Location: ATHENS	aleph 2 problem i finished my aleph 2 cnstruction and i tested forgeting to connect the led diode. almost emediately the mains fuse was melted. i checked the circuit and after connecting the led i changed all irfp 240 of the constand current side.i found at least 2 short circuited and 2 power resistors(1om)destroyd. i turned then the amp on and as a result after 30 sec of normal operation (dc ofset 40mvolt)the220 om resistors next to the irfps started burnig and i stop any eford in doing anything else. question:all theese happened because i didnt connect the led ?what do i do now?

4th January 2011, 08:41 PM	#4
eyoung diyAudio Member Join Date: Aug 2007 Location: Sunny SC,USA 15 min south of Charlotte NC	get a variac and a mains cable with 100w light bulb on hot lead there are numerous threads with powering up for the first time safely and limiting damage ... Peace, Elwood __________________ "when you open your mind to the imposible, soon you will find the truth...."

12th January 2011, 03:24 PM	#7
h_a diyAudio Member Join Date: Sep 2006 Location: Graz, Austria	You have almost 20% higher dissipation than stock that you need to cope with (you could reduce bias a bit) otherwise not a big topic. Or you could burn 1 or 2 V's by building a CRC supply. Have fun, Hannes __________________ fresh matched IRFP240/IRFP9240 fets \|\| AlephJ/JX-kits F5 transistor kits \|\| Burning Amp BA-1/2/3 transistor kits

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3rd January 2011, 08:37 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	The LED should not have had anything to do with it. Most of the time this happens there is a wiring or component value error. Time to start looking for it, and also think about how you can limit the supply power for next time you fire it up.

4th January 2011, 01:28 PM	#3
karajak diyAudio Member Join Date: Jan 2008 Location: ATHENS	thanks nelson for the reply. it is a relief for me to know that led is not the cause of the problems.i will start checking everything starting from wiring.

5th January 2011, 03:07 PM	#5
karajak diyAudio Member Join Date: Jan 2008 Location: ATHENS	thanks! this is what i shoud have done from the biginning! after a few total succes progects i forgot the basics.....

12th January 2011, 01:12 PM	#6
karajak diyAudio Member Join Date: Jan 2008 Location: ATHENS	i checked everything seems ok. i didnot mention that psu voltage is 53 volts(plus minus).its higher than the 45 mentioned in the schematics.do i need to replace any parts value due this voltage diference?

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