My parents found the time to completely clear out their house during the current crisis and threatened to throw all of my old amplifiers, from back in the day, away.
I could not allow this and have taken possession of every bit of crap... I mean audio equipment I had bought as a kid and young adult.
Some of has gone straight in the bin, (Longmill EQ anyone? 😀) and some is worth saving.
I don’t know how I blew this one up, but it was gone good and proper.
The primary side caps were literally blown and the thing doesn’t even power up enough to draw any current from my current limited PSU.
There is a little spark from the caps charging but nothing else when the remote is connected.
There is 12v on the PSU FETs but no oscillation, I suspect a dead 494 but it’s a surface mount component and I don't have a hot air soldering station or any chipquik...
Could there be something simple that I may have missed to check first?
I could not allow this and have taken possession of every bit of crap... I mean audio equipment I had bought as a kid and young adult.
Some of has gone straight in the bin, (Longmill EQ anyone? 😀) and some is worth saving.
I don’t know how I blew this one up, but it was gone good and proper.
The primary side caps were literally blown and the thing doesn’t even power up enough to draw any current from my current limited PSU.
There is a little spark from the caps charging but nothing else when the remote is connected.
There is 12v on the PSU FETs but no oscillation, I suspect a dead 494 but it’s a surface mount component and I don't have a hot air soldering station or any chipquik...
Could there be something simple that I may have missed to check first?
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The first thing to do is to look at the voltage on all terminals of the 494 to see if the problem is input to the IC. Copy and paste the following if you post the voltages. I'd avoid using hot air to solder ICs. I don't understand what 'fit' means.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
I'm sorry, I tapped that out on my phone and the autocorrect seems to have had a field day.😱
Pin 1: 0
Pin 2: 0
Pin 3: +3.00
Pin 4: +3.00
Pin 5: +2.18
Pin 6: +2.18
Pin 7: +2.18
Pin 8: 0
Pin 9: 0
Pin 10: +0.38
Pin 11: +0.08
Pin 12: +0.08
Pin 13: +0.41
Pin 14: +0.96
Pin 15: 0
Pin 16:+3.00
Negative lead referenced to B- remote power OFF
Pin 1: 0
Pin 2: 0
Pin 3: +2.64
Pin 4: +2.64
Pin 5: +1.83
Pin 6: +1.83
Pin 7: +1.83
Pin 8: 0
Pin 9: 0
Pin 10: +0.33
Pin 11: +0.09
Pin 12: +0.07
Pin 13: +0.47
Pin 14: +0.65
Pin 15: 0
Pin 16:+2.64
Negative lead referenced to B- remote power ON
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It happens that there is a working A1275 on the driver board from that Lanzar optidrive I failed to fix, I'll install it and power her up. 🙂