After a few months working fine, I've had a suspicious crackle and pop in one channel and then it stopped altogether - and it looks like it's blown the woofer in my vintage Celestions as well 🙁
I'm now measuring -20v dc on the speaker output that side.
Nothing appears to have burnt on the amp board, I'll start dismantling to investigate, but does that amount of DC point to anything in particular being the fault?
I'm now measuring -20v dc on the speaker output that side.
Nothing appears to have burnt on the amp board, I'll start dismantling to investigate, but does that amount of DC point to anything in particular being the fault?
Hello toolkit,
I would check my railvoltages (output of PSU) first. Are there still circa +-24 V DC getting to the M2X-board
of the faulty channel?
Then I would measure the voltage over the bias resistors (R13 / R14).
No source at input, no speakers at output!
Perhaps some others can give additional advice?
Greets
Dirk
I would check my railvoltages (output of PSU) first. Are there still circa +-24 V DC getting to the M2X-board
of the faulty channel?
Then I would measure the voltage over the bias resistors (R13 / R14).
No source at input, no speakers at output!
Perhaps some others can give additional advice?
Greets
Dirk
Rails look OK, +-24.9v
Good board: R13 and R14 0.62V
Broken channel both 0.7V
Now I have had a torch in there, the PCB around the IRFP9240 looks a bit scorched - but that could be the initial soldering.
Good board: R13 and R14 0.62V
Broken channel both 0.7V
Now I have had a torch in there, the PCB around the IRFP9240 looks a bit scorched - but that could be the initial soldering.
It seems to be burnt, yes.
And there is a very little amount of goop, just a dot in the middle of the surface, so heat transfer is weak.
I recommend Keratherm 86/82, or goop on the whole surface of the FET. But Keratherm is in my opinion better.
And there is a very little amount of goop, just a dot in the middle of the surface, so heat transfer is weak.
I recommend Keratherm 86/82, or goop on the whole surface of the FET. But Keratherm is in my opinion better.
I like the Keratherm too. Use split lock washer and large flat washer for mounting, torqued to .9 N-M (I use a Garant T-handle). Otherwise device could loosen over time with thermal cycling.
🙂 🙂
You just saved me another 30 minutes of searching! Were your ears burning or something?
I am filling my own stocking so-to-speak, and this is one of the things I desperately wanted. I just couldn't find the link to the name that I had copied / pasted from somewhere...
Thanks!
Best Stocking Stuffer Ever!
Added to cart...
I just ordered some Cedarburg boards from JLCPCB. I'm now on Mouser attempting to fill out the BOM (minus the AD797, which I already have). The diodes are no longer available. Is this a suitable substitute? https://www.mouser.com/ProductDetail/onsemi-Fairchild/1N3595TR?qs=VnWRSnLxLU2UlMjzvclIqA== It seems to have most of the proper specs; I'm just concerned that the 8pF of capacitance may not meet the "low capacitance" called for in the BOM. The obsolete part was 3pF.
I ordered 20 boards, so I'll have a few to share with the community once I've built and tested a pair.
Thanks
I ordered 20 boards, so I'll have a few to share with the community once I've built and tested a pair.
Thanks
DigiKey has >75K pieces of BAS34 in stock. Buy 200 and hoard them forever. OBTW "octopart.com" found them; it's Best Practice to use octopart.com early and often.
An acceptable substitute is BAS45A which Mouser has 8K pieces in stock. Reverse leakage is the same (1nA) and capacitance is slightly higher (4pF).
An acceptable substitute is BAS45A which Mouser has 8K pieces in stock. Reverse leakage is the same (1nA) and capacitance is slightly higher (4pF).
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Thanks, Mark. I could have/should have checked. Was looking to only pay one shipping charge on a relatively small order. I'll get 100 and throw in enough + spares when I distribute the extra boards.
I am a total newbie with no experience at all as far as building amps, is there any particular information in this thread as to what other materials I need after I buy the circuit board? For sure, I will need a case, but which one? Is there any other materials needed to build this amp? ALso is there a detailed instruction from start to finish? Apologies for the novice questions. Thank You
For a total newbie - as you wrote - I recommend to read the whole thread, there is a lot of information, it's impossible to pick out something because nobody knows what you know.
And even after reading this thread - you should consider to start with something easier. Buy a full kit, f.e. the ACA, build it with success and collect experience in soldering, mounting, completing, measuring. There is also no mains voltage with all the danger for unexperienced first-builder.
I know, it wasn't exactly the answer you expected, but I think it's the better way. Others may have another opinion.
And even after reading this thread - you should consider to start with something easier. Buy a full kit, f.e. the ACA, build it with success and collect experience in soldering, mounting, completing, measuring. There is also no mains voltage with all the danger for unexperienced first-builder.
I know, it wasn't exactly the answer you expected, but I think it's the better way. Others may have another opinion.
Hi.
Above comment is on point.
I started with a Noir headphone amp / preamp, which can later server as pre-amp for your M2x. The PCB is sold with the front plate and back plate of the futur chassis (which you can buy from Modushop) so it gives a good practice on everything while being cheaper, easier, low risk in term of voltage / associated risks.
I then went to M2x in which you have to be much more careful with the power supply (dealing with 220/240v), have to plan a bit of 2d or 3D to have the front panel / rear panel drilled according to the stuff you need and so on.
Ps: or the ACA (power amp) and ACP+ (preamp and headphone) are there exactly for the purpose of starting from scratch
@Boac
This post by @ItsAllInMyHead will help you.
https://www.diyaudio.com/community/threads/a-noobs-first-first-watt-m2x.338175/post-5902398
This post by @ItsAllInMyHead will help you.
https://www.diyaudio.com/community/threads/a-noobs-first-first-watt-m2x.338175/post-5902398
If any of you local to the USA have a pair of blank Milpitas daughter boards please contact me. If not, I’ll try the swap meet or add to my order from JLPCB.
Thank you!
Anand.
Thank you!
Anand.
For those that may be interested, even though 968-HA9P5002-5Z for Norwood has shown out of stock for a long time I placed an order anyways and they are due to arrive today.
Mouser shipped without showing replenished inventory.
Mouser shipped without showing replenished inventory.