It's alive!!!
Apologies for the terrible quality -- in my excitement, I accidentally took a video rather than a picture (this is a screenshot). I started by desoldering the trimmer I thought was bad, but upon removing it and measuring it out of circuit I realized it was actually fine. Still not 100% sure what happened there; I tested it so many times that I doubt it was bad probe contact. I did have to bend the leads a bit so it would fit and I think the wiper may not have been making contact with the solder, since it was barely long enough to reach through the PCB. I re-mounted both trimmers in the opposite direction, so now they will be adjusted from the top, which is fine since I removed the PCB covers.
Once that was done, I re-mounted the boards and connected everything but the outputs. Threw it on the DBT with two 150w bulbs and flipped the switch -- there was a flash of light as the caps charged (I had completely drained them before working on it) but after that the bulb went dark. The best part: all three relays activated, and no smoke! I was beginning to wonder if my re-wiring of the soft start circuit was the culprit, so this was a big relief. @merlynski unfortunately the alligator clips for my 1k resistors were delayed by FedEx and I was too impatient to wait, so I went straight ahead and connected the outputs. Again, all three relays latched in the expected order, with only a faint light from the two 150w bulbs. Left it on the DBT for about 10 minutes and no smoke or increase in current draw. Had to stop because it's getting late, but I'm going to be setting bias and offset tomorrow and hooking it up to my sacrificial speakers (disembodied $20 full-range drivers from Parts Express) to see if it'll actually make music. @merlynski thanks a million for all the help, I've learned a ton and had a great time working on this thing.
Apologies for the terrible quality -- in my excitement, I accidentally took a video rather than a picture (this is a screenshot). I started by desoldering the trimmer I thought was bad, but upon removing it and measuring it out of circuit I realized it was actually fine. Still not 100% sure what happened there; I tested it so many times that I doubt it was bad probe contact. I did have to bend the leads a bit so it would fit and I think the wiper may not have been making contact with the solder, since it was barely long enough to reach through the PCB. I re-mounted both trimmers in the opposite direction, so now they will be adjusted from the top, which is fine since I removed the PCB covers.
Once that was done, I re-mounted the boards and connected everything but the outputs. Threw it on the DBT with two 150w bulbs and flipped the switch -- there was a flash of light as the caps charged (I had completely drained them before working on it) but after that the bulb went dark. The best part: all three relays activated, and no smoke! I was beginning to wonder if my re-wiring of the soft start circuit was the culprit, so this was a big relief. @merlynski unfortunately the alligator clips for my 1k resistors were delayed by FedEx and I was too impatient to wait, so I went straight ahead and connected the outputs. Again, all three relays latched in the expected order, with only a faint light from the two 150w bulbs. Left it on the DBT for about 10 minutes and no smoke or increase in current draw. Had to stop because it's getting late, but I'm going to be setting bias and offset tomorrow and hooking it up to my sacrificial speakers (disembodied $20 full-range drivers from Parts Express) to see if it'll actually make music. @merlynski thanks a million for all the help, I've learned a ton and had a great time working on this thing.
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