Sorry, I don’t think I’m understanding the instructions. I took the meter and put black probe on ground at power supply board and the red probe on the v+ of the output vfet board and those were the readings I got.
I built it 2 years ago so I don’t remember the solder brand, maybe Kester? I think my temp on the iron was pretty high.
I built it 2 years ago so I don’t remember the solder brand, maybe Kester? I think my temp on the iron was pretty high.
Re-check meter settings. DC volts. Can't measure over 36.
With power off you should be able to measure continuity between all the "G" connections on both output boards and they should all read zero ohms. Then you can measure DC voltage (with power on) between any "G" and each V+ on those OS boards.
With power off you should be able to measure continuity between all the "G" connections on both output boards and they should all read zero ohms. Then you can measure DC voltage (with power on) between any "G" and each V+ on those OS boards.
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As long as you can flow solder to be shiny liquid and it stays pretty shiny after it dries. No-lead solder or too low temps can yield cold joints and those look iffy.
Sorry everyone, I’m nursing a bad flu while I try to pass the time on my 5th day homebound 🙂
I meant to write 35.3v and 33.5v. Do you see any poor soldering, is that what you mean? There’s continuity between all grounds.
I‘m perplexed on why both sides measure close to the same but one side is generating heat to the touch and the other is not? They are both biased to 14v.
Thanks again for the help.
I meant to write 35.3v and 33.5v. Do you see any poor soldering, is that what you mean? There’s continuity between all grounds.
I‘m perplexed on why both sides measure close to the same but one side is generating heat to the touch and the other is not? They are both biased to 14v.
Thanks again for the help.
14V on the case of either IR output device (Q2)? Both transistors on that side are cool? Any voltage across R1 and R2 on that side?
Thanks for responding. Yes, 14v on the case of Q2 on both channels. Voltage across R1 and R2 is .1 on the cool (right) channel and 1.3 on the (hot) left channel.
Dunno. If nothing's heating on that OS, it's probably okay to leave on. I'd use the layout diagram in the PDF (for the OS) and measure all the node voltages, comparing those on the apparently good channel to this one. Then report back. Zen or others may see something else right away.
pictures are showing very bad soldering job in several places, especially on PSU section, but logically to expect similar job done on amp pcbs itself; expect because we can't see underside on pcbs
best approach - dismantle channel from heatsink, resolder everything
there is some crucial point on circuit without contact, most likely
post pictures of channel pcb copper side
anyhow, it would be best to re-work soldering job on entire amp
best approach - dismantle channel from heatsink, resolder everything
there is some crucial point on circuit without contact, most likely
post pictures of channel pcb copper side
anyhow, it would be best to re-work soldering job on entire amp
I figured Pa did the OS board, but there does seem to be reason for dismantle. I've done that with mine several times and am about to do it again, unfortunately. (Added DC-DC regulator seems to be misbehaving.)
Pa did with boards what was necessary to ensure specific VFet being exactly biased
as far as I remember, that was placing output parts, source resistors, opto and few surrounding resistors
rest was to Greedy Assembler
see pics here, especially those in post #8: https://www.diyaudio.com/community/...-pt-2-n-channel-assembly-by-mighty-zm.385977/
Coulda sworn my OS was fully assembled and tested in my kit, but it's been awhile. If this one was soldered by OP, that's a flag.
There are probably many good soldering tutorials on this site, but here's a quick vid. To (finally) address fumes I recently added this instead of an expensive fan and foam filter, FWIW.
There are probably many good soldering tutorials on this site, but here's a quick vid. To (finally) address fumes I recently added this instead of an expensive fan and foam filter, FWIW.
Thanks everyone for the insight and help. I’ll resolder everything and check connections. It‘s definitely a mistake on my part. I received the kit from the lottery pick so everything came together and the OS boards were already assembled. When I built it a few years ago everything worked fine and played well; I did something that messed it up or bad soldering degraded with age. I‘ll spend time this week going through it. Thanks again for the help.
Might as well address that buggered power connector at the same time. The inside connector was tedious to solder, I well remember. Hopefully that part doesn't need anything.
Hope your flu is better and quickly subsides.
Hope your flu is better and quickly subsides.
Also looks like some of those wires have broken wires where they are stressed at the connection point. Those will need to be cut back and stripped again, so the cable is at pull song.
Hello Ya'll been off for a over a year. I left the N VFET on the bench and never installed it in the case. I cleaned the clutter from the bench and picked the project back up. Barring any issues, I should have the N up in a week, or so. I'm waiting on some hardware. Also, have the P channel to do. After I get a listen to those, they will be shipped to a friend. He always wanted to listen to some of Papa's designs, so I'm going to send him both amps and the 4 MJ FE to check out. I told him I would do it if he builds an external linear supply for them. I'll let him keep the one he likes for Christmas. He has a ton of VFETs, so I shall have him send me one back too! lol Both of them have Mod shop cases and should be good looking.
One gripe is the T bracket, I would have liked to mount it in the middle of the sink, for better dissipation, but the way they were drilled didn't allow it. I suppose I could have redrilled, but that kinda defeats the point of a kit. I also ran into the sink and T both not flat as others have said.
Other niggles, I would have liked a bit larger dia screw for the T, or another hole in the middle. The output board holes could have been just a smidgen larger, so you could go to the next size screw to fasten the FETs to the T bracket. This can be solved by switching from metric to standard and going with a 6x32 which is just about perfect. It also allows for larger nuts to be used and help with contact on the bottom of the board. I know you can't torque those anyway, but I like the larger size for stability and grip/contact area.
The thought was to leave a lot of room in the front, for a possible supply, but that won't fly with the TUBA sitting tight in the rear. Yes MJ, I will have a TUBA in each version. 🙂
Finally got the bug back, I thought it had gone, but alas, it was hibernating.
Pics when I start getting it in the case.
One gripe is the T bracket, I would have liked to mount it in the middle of the sink, for better dissipation, but the way they were drilled didn't allow it. I suppose I could have redrilled, but that kinda defeats the point of a kit. I also ran into the sink and T both not flat as others have said.
Other niggles, I would have liked a bit larger dia screw for the T, or another hole in the middle. The output board holes could have been just a smidgen larger, so you could go to the next size screw to fasten the FETs to the T bracket. This can be solved by switching from metric to standard and going with a 6x32 which is just about perfect. It also allows for larger nuts to be used and help with contact on the bottom of the board. I know you can't torque those anyway, but I like the larger size for stability and grip/contact area.
The thought was to leave a lot of room in the front, for a possible supply, but that won't fly with the TUBA sitting tight in the rear. Yes MJ, I will have a TUBA in each version. 🙂
Finally got the bug back, I thought it had gone, but alas, it was hibernating.
Pics when I start getting it in the case.
you have it all covered here:
Very cool, didn't see that. I was deciding how I might deal with some of it, or not. The umbilical connector is a big deal as I wouldn't want that thing getting pulled out while the amp is running. I'll probably get it going and test it, then decide on upgrades/corrections. I can then order what I want and not have to wait on it with the amp sitting there like a paper weight.