Hi, I have been trying to find the bug in a Truepath kit with no success. Hopefully, somebody here with knowledge of these amps will be able to help.
First, there is no signal connected to the inputs and there is no load at the outputs. 75 ohms test resistors are connected at VPP and VNN. A 100 Watt light bulb is at the main 110v input for safety as suggested in the assembly manual.
When I switch the amp on, the light bulb goes on for about 3 seconds and then goes off. Amp unmutes and everything seems normal until mute LED starts to flash repeatedly at 1 second intervals and mains transformer starts making a humming sound.
V5 is stable at 4.95 volts and I5 goes from 43 mA to 48 mA repeatedly. VN10 is stable at 10.1 volts and In10 goes from 50 mA to 175 mA repeatedly also.
75 ohms test resistors stay cool and Mosfets also.
I just hope that this is simple to someone around here since debugging is not my strong suit.
Thanks.
First, there is no signal connected to the inputs and there is no load at the outputs. 75 ohms test resistors are connected at VPP and VNN. A 100 Watt light bulb is at the main 110v input for safety as suggested in the assembly manual.
When I switch the amp on, the light bulb goes on for about 3 seconds and then goes off. Amp unmutes and everything seems normal until mute LED starts to flash repeatedly at 1 second intervals and mains transformer starts making a humming sound.
V5 is stable at 4.95 volts and I5 goes from 43 mA to 48 mA repeatedly. VN10 is stable at 10.1 volts and In10 goes from 50 mA to 175 mA repeatedly also.
75 ohms test resistors stay cool and Mosfets also.
I just hope that this is simple to someone around here since debugging is not my strong suit.
Thanks.
Check output filter capacitors for shorts.
1 second intervals are probably an over current event.
I don't know if this amp has IC or IC plus mosfets.
Check mosfets if fitted and if not that then IC has probably blown.
1 second intervals are probably an over current event.
I don't know if this amp has IC or IC plus mosfets.
Check mosfets if fitted and if not that then IC has probably blown.
After verifying, no shorts on output caps. If this was the problem would the mosfets get warm? Mosfets stay cool as the test resistors also. This amp is based on the tripath TA3020 chip. I happen to have another amp exactly the same and working perfectly. I tried the TA3020 chip from that amp wich I know is working and the result is the same. So, the chip is ok also.
Ok, problem solved! Both V5 and VN10 power supplys where fed by the same transformer with 12VAC and 18VAC outputs with a common ground. Obviously, sharing the same ground does not work because after feeding both supplys with their own transformer everything is working perfectly. So today is music listening on my now triamplified setup 🙂
Thank you Nigel for your support!
Thank you Nigel for your support!
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