Since my jfets are matched and I opted to include C1 for now, but dont have a distortion analyzer - no need to jumper anything with RV1 removed, right?
Just leave RV1 out? This trimpot doesnt have anything resembling a stopper to find the middle and my meter isnt getting a read on it attached to the board
Just leave RV1 out? This trimpot doesnt have anything resembling a stopper to find the middle and my meter isnt getting a read on it attached to the board
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It’s a 25-turn pot, yes? Turn one direction until it clicks, and then twist the other way 12.5 turns. This works better than you’d expect.
Its one of these: https://www.mouser.com/ProductDetail/858-67WR200LFTB
No clicks, stoppers or anything ( on either ). Theyre still in, but I have no idea if they are centered, and will probably grab a bourns equivalent while Mousering.
The amp is up and running, but I somehow missed the memo on being a blaspheous heretic ( literally the first time ever ) and cant get the offset to 0, only -100 to -150mv. Ordering up the recommended parts, and all the goodies for Norwood and Moutain View while at it.
Iron Pre is up next
Also.....HAPPY THANKSGIVING Y'ALL!!!!!! And thank you for the help 🙂
No clicks, stoppers or anything ( on either ). Theyre still in, but I have no idea if they are centered, and will probably grab a bourns equivalent while Mousering.
The amp is up and running, but I somehow missed the memo on being a blaspheous heretic ( literally the first time ever ) and cant get the offset to 0, only -100 to -150mv. Ordering up the recommended parts, and all the goodies for Norwood and Moutain View while at it.
Iron Pre is up next
Also.....HAPPY THANKSGIVING Y'ALL!!!!!! And thank you for the help 🙂
The Bookshelf-3WCs do not disappoint, paying mind to placement. Wayne's 2018 preamp into an F4 is more than enough oomph to drive them to irresponsible levels in a large room. Fairly certain I'll do a pair of the Faital 3wc-10s next, perhaps in the spring.
Primary speakers prior to that were a pair of Canton CT-1000s from the mis 80's that I refurbished 15 years ago. Rebuilding their dried out crossovers was my first DIY audio project. Being a healthy ( accurate ) 93db efficient, they made it possible to enjoy all these glorious amplifiers 🙂.
Ony thing the Canton's do better than the 3WCs is bass extension, predictably. They go lllooowwwwwwww. Everything else about the Troels 3WCs is better.
Primary speakers prior to that were a pair of Canton CT-1000s from the mis 80's that I refurbished 15 years ago. Rebuilding their dried out crossovers was my first DIY audio project. Being a healthy ( accurate ) 93db efficient, they made it possible to enjoy all these glorious amplifiers 🙂.
Ony thing the Canton's do better than the 3WCs is bass extension, predictably. They go lllooowwwwwwww. Everything else about the Troels 3WCs is better.
Redundant power supply parts gone. Boards cleaned with isopropyl. Heretical blasphemy complete. Ishikawa RV1 removed. It lives. Warming up for final adjustment 🙂
Will leave it Ishikawa'd for a while, to get used to it. Parts for Mountain View are all here, so thats up next. Norwood when the backordered HA9P5002-5Z gets here in perhaps January or Feburary '24.
![IMG_0922[1].JPG](https://www.diyaudio.com/community/attachments/img_0922-1-jpg.1238878/ "IMG_0922[1].JPG")
Will leave it Ishikawa'd for a while, to get used to it. Parts for Mountain View are all here, so thats up next. Norwood when the backordered HA9P5002-5Z gets here in perhaps January or Feburary '24.
Hello Fellow DIYers
For 5 days my M2X sounded amazing. Checked the offset repeatedly, after long periods of time ( in its final home ), as is customary - and all was well. It was very stable. Then on the 5th day disaster struck and my transformer failed. One of the secondaries dropped, leaving the negative side of the power supply dead. +12Vdc presented at the outpus of both channels, across my speakers. This one definitely goes in the "bad luck" bucket, as I and many other have used many of these particular transformers for years without issue. This particular one sat on a shelf unused since June 2013, as I was going to build a second F4 but ended up going a different direction so didnt need it until now. Suffice it to say, a refund is not in the cards. A new one is already on the way.
Now I'm left to assessing what, other than a couple of my woofers ( mid and tweets seem fine ), was cooked in the process. Slightly concerned about the woofer coils, and perhaps other crossover parts. A little out of my wheelhouse in determing what 12Vdc could do to those.
Heatsinks were still warm when I discovered what had happened. They cooled as I was metering my way through the amp. So it was likely in that state for less than an hour. More likely < 30 minutes.
Im guessing the IRF240/9240s are toast, but not sure what else on the boads I should aim to replace while ordering up parts. On that note, I'm all out of IRF outputs. Going to use 240/9140s from the DIYA store to replenish as I assume the 9140 are an acceptable substitue.
Sharing my misfortune here so all may benefit from whatever troubleshooting steps come next...lemonade from lemons.
For 5 days my M2X sounded amazing. Checked the offset repeatedly, after long periods of time ( in its final home ), as is customary - and all was well. It was very stable. Then on the 5th day disaster struck and my transformer failed. One of the secondaries dropped, leaving the negative side of the power supply dead. +12Vdc presented at the outpus of both channels, across my speakers. This one definitely goes in the "bad luck" bucket, as I and many other have used many of these particular transformers for years without issue. This particular one sat on a shelf unused since June 2013, as I was going to build a second F4 but ended up going a different direction so didnt need it until now. Suffice it to say, a refund is not in the cards. A new one is already on the way.
Now I'm left to assessing what, other than a couple of my woofers ( mid and tweets seem fine ), was cooked in the process. Slightly concerned about the woofer coils, and perhaps other crossover parts. A little out of my wheelhouse in determing what 12Vdc could do to those.
Heatsinks were still warm when I discovered what had happened. They cooled as I was metering my way through the amp. So it was likely in that state for less than an hour. More likely < 30 minutes.
Im guessing the IRF240/9240s are toast, but not sure what else on the boads I should aim to replace while ordering up parts. On that note, I'm all out of IRF outputs. Going to use 240/9140s from the DIYA store to replenish as I assume the 9140 are an acceptable substitue.
Sharing my misfortune here so all may benefit from whatever troubleshooting steps come next...lemonade from lemons.
Will do. Havent had time to get further til this weekend. I was thinking that they were basically passing the 12 rectified volts from the wall, open - but my understanding of the circuit is not comprehensive ( admittedly )....really only how to build it. I know their voltage rating is higher but not how to interpret that through the circuit, within the context of what happened.
I havent used DC prophlyactics in any of my amps to date but am wondering if maybe now would be a good time to start?
🙂
I havent used DC prophlyactics in any of my amps to date but am wondering if maybe now would be a good time to start?
🙂
I'm attempting to track what you're saying as I'm a bit confused.
If'n you're saying the -25VDC leg turned off at the transformer (i.e. the secondary stopped conducting) then not sure what harm was caused other than at the speaker. As 6L6 pointed out, fix the psu, power up in a controlled manner, start assessing damage.
If'n you're saying the -25VDC leg turned off at the transformer (i.e. the secondary stopped conducting) then not sure what harm was caused other than at the speaker. As 6L6 pointed out, fix the psu, power up in a controlled manner, start assessing damage.
Yes, one of the secondaries stopped conducting ( erratically ). On finding this I immediately disconnected everything, including the amp boards from the PS filter cap bank.
Starting at the PS cap bank, where the amp boards are were connected: it measured good on the positive side, 0 on the negative side ( both sides of the board )
I then disconnected the power supply cap board/bank ( whetever is best to call it ) from the rectifiers and measured AC in and DC out at the rectifier blocks.
One of the secondaries, and the block to which it was attached, measured fine: 20AC input, 26 DC output.
The other secondary/rectifier block: .250 AC volts, millivolts DC out.
I know what its like to be on the other side of this conversation trying to coax information out of a less knowledgeable person, so appreciate the help and patience.
Thanks guys.
Starting at the PS cap bank, where the amp boards are were connected: it measured good on the positive side, 0 on the negative side ( both sides of the board )
I then disconnected the power supply cap board/bank ( whetever is best to call it ) from the rectifiers and measured AC in and DC out at the rectifier blocks.
One of the secondaries, and the block to which it was attached, measured fine: 20AC input, 26 DC output.
The other secondary/rectifier block: .250 AC volts, millivolts DC out.
I know what its like to be on the other side of this conversation trying to coax information out of a less knowledgeable person, so appreciate the help and patience.
Thanks guys.
I call it the filter board as the function is to smooth out (or filter) the output of the rectifiers.
Yup, I'd try replacing the transformer, test the PSU with no signal boards. Then test one signal board at a time then both.
delecoy,
Since the AC goes into the PS board and then out to the transformer primaries, did you check the connections to be sure that the AC was getting to both transformer primaries? And then follow through to the transformer secondaries without the rectifiers connected. Might as well be as thorough as possible.
Since the AC goes into the PS board and then out to the transformer primaries, did you check the connections to be sure that the AC was getting to both transformer primaries? And then follow through to the transformer secondaries without the rectifiers connected. Might as well be as thorough as possible.
Hi Ben,
Yes, that was actually the last step before ordering another transformer. I checked all the terminations on the transformer itself, disconnected then reconnected the primaries to the board, then swapped where the primares were connected ( to try to rule out a fault in the board itself ). AC measurements at the secondaries ( without rectifiers attached ) between steps confirmed the same secondary stayed dead the whole time....damndest thing ever. Even more so since none of that had been touched since it was complete, 5 days prior, only having been opened to check offset ( maybe 5 times ).
It was just a bad transformer :|
New one gets here Monday.
On a positive note, I love how the M2x sounds. I think I even prefer it to the F4 ( gasp! ). Excited to get this all resolved then try Mountain View and Norwood next.
Cody
Yes, that was actually the last step before ordering another transformer. I checked all the terminations on the transformer itself, disconnected then reconnected the primaries to the board, then swapped where the primares were connected ( to try to rule out a fault in the board itself ). AC measurements at the secondaries ( without rectifiers attached ) between steps confirmed the same secondary stayed dead the whole time....damndest thing ever. Even more so since none of that had been touched since it was complete, 5 days prior, only having been opened to check offset ( maybe 5 times ).
It was just a bad transformer :|
New one gets here Monday.
On a positive note, I love how the M2x sounds. I think I even prefer it to the F4 ( gasp! ). Excited to get this all resolved then try Mountain View and Norwood next.
Cody
That is really unfortunate and bad luck. Transformers are simple devices and to have one work for a while and then fail - a bad connection between the windings and leads? What are the resistances of the transformer primary and secondary windings?
Measuring across the primary leads, red to black, gives 1.6 ohms for both primaries.
My cheap auto-ranging multimeter was struggling to figure out the secondaries, measuring across blue to green. One side ranged 0 - 0.2 ohms, the other was all over the place.
Working on setting up a bench power supply to test the boards before the new trafo gets here.
My cheap auto-ranging multimeter was struggling to figure out the secondaries, measuring across blue to green. One side ranged 0 - 0.2 ohms, the other was all over the place.
Working on setting up a bench power supply to test the boards before the new trafo gets here.
This might seem bit strange but if ypou can find some 16 ohm power resistors, they're really useful to check the output of the power supply under load - for the F amp, this is usually about 1.5A so the 16R will getpretty hort but with added lengths of wires, can dump them in bowls of water, heatsinks, etc abnd also pair them up for amplifier loads (ie 8R) - a cheap, useful bit of kit