Folks:
An update. I removed the R channel V+ and two ground wires from the PS pcb so the L channel, R channel and PS could all be separately tested. The PS board was tested first:
0R measured across the two V+ inputs (at the pcb).
0R measured across the two V- inputs (again, at the pcb).
0.L (infinite) measured across inputs V- and V+.
0.L (infinite) measured across outputs V+ and ground.
I then connected the two switch legs together, installed the Meanwell supply and tried to measure across a V+ and ground at the output. Within 2-3 seconds, the 1000 uF cap blew. The photo below shows the cap after it released its smoke. The Meanwell's LED stayed dim, blinking rapidly, the entire time.
There are no stray wires. If there was a problem at the power inlet (i.e., I had stupidly mixed a V- and V+), the readings before I powered up the Meanwell would have been different. What the $#&*?
Insights appreciated.
Regards,
Scott
An update. I removed the R channel V+ and two ground wires from the PS pcb so the L channel, R channel and PS could all be separately tested. The PS board was tested first:
0R measured across the two V+ inputs (at the pcb).
0R measured across the two V- inputs (again, at the pcb).
0.L (infinite) measured across inputs V- and V+.
0.L (infinite) measured across outputs V+ and ground.
I then connected the two switch legs together, installed the Meanwell supply and tried to measure across a V+ and ground at the output. Within 2-3 seconds, the 1000 uF cap blew. The photo below shows the cap after it released its smoke. The Meanwell's LED stayed dim, blinking rapidly, the entire time.
There are no stray wires. If there was a problem at the power inlet (i.e., I had stupidly mixed a V- and V+), the readings before I powered up the Meanwell would have been different. What the $#&*?
Insights appreciated.
Regards,
Scott
Attachments
I am adiabatically putting mine together now. PS board is wired. Given the experiences I did measure the polarity of the meanwell with a voltmeter to be sure.
Couple of things to report:
-The grey and purple wires length provided have been measured with a micrometer. follow instructions.
-check the crimping connections. The silver coated wire 1mm^2 is slippery as it is and even with my impeccable crimping credentials and tools
I could not solidly crimp the white into the blue terminal to the switch which is made for a 1.5mm wire. I ended up removing the blue ring, soldering and heat shrinking and it looks real good now.
Oh and the two spades coming out of the meanwell connectors seem to be real gnds so I will prob heat shrink them to avoid surprises.
Couple of things to report:
-The grey and purple wires length provided have been measured with a micrometer. follow instructions.
-check the crimping connections. The silver coated wire 1mm^2 is slippery as it is and even with my impeccable crimping credentials and tools
I could not solidly crimp the white into the blue terminal to the switch which is made for a 1.5mm wire. I ended up removing the blue ring, soldering and heat shrinking and it looks real good now.Oh and the two spades coming out of the meanwell connectors seem to be real gnds so I will prob heat shrink them to avoid surprises.
Last edited:
Hi Scott, dont´t worry, I´m always around to do those things too ; ), just saw the PSU Filter LED blinking, took it off immediately after 2 seconds or so, checked and got the mistake and changed polarities.
But no filtercap blown..
maybe I should change it nevertheless..
best
st
Pass DIY Addict
Joined 2000
Paid Member
Scott, this was going to be my third suggestion to you. I wasn't sure when I hit this stage, so I connect the power inlet plug to the power supply and actually measured before soldering. Sometimes I don't even trust myself to read docs and spec sheets properly
Glad that you found the problem. With my very first amp, an a40 that I built about 20 years ago, I mixed up P-ch and N-ch devices for the push-pull topology. Blew lots of stuff up that night!
Glad that you found the problem. With my very first amp, an a40 that I built about 20 years ago, I mixed up P-ch and N-ch devices for the push-pull topology. Blew lots of stuff up that night!
After a week of daytime playing i finally bolted the top plate on. 
Listening to this amp i would echo all the other comments from before
Spacious - lots of room but not artificially so. No one has shown up behind me yet
Dead quiet
Stable - after setting the bias at the first hour it has not significantly drifted
Is 10W all one really needs?
Listening to this amp i would echo all the other comments from before
Spacious - lots of room but not artificially so. No one has shown up behind me yet
Dead quiet
Stable - after setting the bias at the first hour it has not significantly drifted
Is 10W all one really needs?
I did in fact try this combo in my honored photo-taking/testing phase of 6L6's Vfet— MC cart/SP10MKII --> Salas's UFSP --> Salas's DCG3 --> Vfet --> OSMCs ....the combo was lovely—got PLENTY loud...