Hi all,
I just finished 6 3886 PCB's from chipamp.com.
a few days ago I started connecting things up. when 3 PCB's where mounted and connected i decided to test these.
connected mains and nothing happened (this is good i thought)
when measuring the DC on output I have 7 mV on one channel, but 24 Volts (!) on the other two plus really hot chips (they started smelling, no smoke)
I disconnected everithing, checked the connections and resistor values, everithing seems to be OK.
could these be faulty chips? is there any way to find out what could be wrong?
I also checked the power supply's but this is all fine..
I did a search and found a few threads describing this, but could not find much help in there..
many thanks for your help..
I just finished 6 3886 PCB's from chipamp.com.
a few days ago I started connecting things up. when 3 PCB's where mounted and connected i decided to test these.
connected mains and nothing happened (this is good i thought)
when measuring the DC on output I have 7 mV on one channel, but 24 Volts (!) on the other two plus really hot chips (they started smelling, no smoke)
I disconnected everithing, checked the connections and resistor values, everithing seems to be OK.
could these be faulty chips? is there any way to find out what could be wrong?
I also checked the power supply's but this is all fine..
I did a search and found a few threads describing this, but could not find much help in there..
many thanks for your help..
I would suspect a couple of things right off the bat:
1) Are the chips isolated from gnd either by using the TF package LM3886 or by using an isolator on the T package?
2) Look for a solder bridge/short on your PCB.
I hope you find you trouble. I would suspect the hot melted chip is dead... But you may have gotten lucky.
1) Are the chips isolated from gnd either by using the TF package LM3886 or by using an isolator on the T package?
2) Look for a solder bridge/short on your PCB.
I hope you find you trouble. I would suspect the hot melted chip is dead... But you may have gotten lucky.
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