Thank you, Anand! It’s been in the making inside my head for a while. Hoping for a good result 
Now to continue PSU work and back plate. Just found a solution that will make all 12 caps fit, so no capacitance is lost
Now to continue PSU work and back plate. Just found a solution that will make all 12 caps fit, so no capacitance is lost
Got one of these:
https://www.amazon.com/gp/product/B01LVW4SLP/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
So far no issues....
These (babysitters) are certainly useful once the amp is flawless. But I’d triple-check everything is good before using such a jig (and not use it to cool down something that overheats because something might be not proper. )
Good point. I did run it once without any additional cooling and it worked fine for 2 or 3 hours.
I think the issue might be that I installed the MOSFETs at the end of the heatsink, so heat dissipation is not optimal.
Other than that, I have checked and could not find anything abnormal.
DC offset is pretty stable for a DC coupled circuit, as is the bias moving a few milivolts up or down.
I don’t get it. The temps you posted should pose no problems, unless real life values are higher than what you measured, I always push it further than that, with the only reward being better sound, and increased risk of imminent meltdown. I agree with Myleftear in that you should not stop searching for the problem. Pics would be good if you choose that approach and need advise/tips from the forum.
Hunch? I would say it is rather a JFET/gain stage issue than an output MOSFET related problem.
Regards,
Andy
Hunch? I would say it is rather a JFET/gain stage issue than an output MOSFET related problem.
Regards,
Andy
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I hear you. Now the the question is how accurate are those temperature measurements?
I use one of these multimeters to measure:
https://www.amazon.com/Multimeter-A...er&qid=1631486700&sprefix=klei,aps,193&sr=8-2
I use one of these multimeters to measure:
https://www.amazon.com/Multimeter-A...er&qid=1631486700&sprefix=klei,aps,193&sr=8-2
Following on the theory you mention that it might be the frontend, do you have any suggestions on how to go about it to prove it or discard it?
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I would trust that meter to measure temps. Just be sure you are getting good contact. If you can reach the middle mosfet pin without too much trouble, that will give the best temp reading. Be careful not to short pins, that will blow things up for sure.
I haven’t built the J myself. Work is in progress with the J Zen, but this nevertheless means I am not extremely familiar with this particular circuit - hands on at least.
But to solicit relevant help/advice, I would recommend you do the following:
1: Post pics of the PCB on the problem channel.
2: Confirm that a) All resistors were measured before installing, b) All solder joints look good, and c) all flux residue is cleaned off, and d) confirm your source for the JFETs used.
This will be a good start, and there are plenty of people active in this thread that will jump to help you once pics and relevant info is in place.
Regards,
Andy
Q re transformer leads
I am about to wire up the first mono block in my Aleph J build. I am using Avel Lindberg 250VA transformers. The leads on the transformers are tinned. (See attachment.) My plan is to use crimp connectors (circular and snap on) on the leads. However, I have a vague recollection that one should not tin the wires when using crimp connectors. Is my recollection correct? If so, should I remove the tin before crimping?
Thank you for any assistance anyone can provide.
Jazzzman
I am about to wire up the first mono block in my Aleph J build. I am using Avel Lindberg 250VA transformers. The leads on the transformers are tinned. (See attachment.) My plan is to use crimp connectors (circular and snap on) on the leads. However, I have a vague recollection that one should not tin the wires when using crimp connectors. Is my recollection correct? If so, should I remove the tin before crimping?
Thank you for any assistance anyone can provide.
Jazzzman
Attachments
I'm often using needle-end wire crimp connectors ...... but I'm crimping them gently then soldering
everyone is having own way ..... my is to always solder
everyone is having own way ..... my is to always solder
Do what Zen Mod says for a secure connection. If you do want to crimp, just cut off the tinned ends of the wire to get to bare copper before crimping with a proper crimping tool.
I tried your method but M3 stands seems too thin to me for donuts weight...
Attachments
I put a washer right under the spacer to stabilize, and also I put in a third spacer per side - in the middle point (see pic). I expect it to carry a dual mono with 2x300, 12 porn caps and 4 x 2.5 pound inductors. They seem not to hold, or tested?
Unless you are using this? Google bilderesultat
Jokes aside: ZM’s approach is probably far more stable. A bolt and towered nuts to achieve desired height. Gonna try my way, and if it fails, Mightys way. I had many spacers on hand, so…
Btw your build progress looks fantastic!
Unless you are using this? Google bilderesultat
Jokes aside: ZM’s approach is probably far more stable. A bolt and towered nuts to achieve desired height. Gonna try my way, and if it fails, Mightys way. I had many spacers on hand, so…
Btw your build progress looks fantastic!
Attachments
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