Good to know, @joaoranito, that your Aleph J is holding fine with the new jfets!
I'm also enjoying my Aleph J (the ZM modification at the moment) so much.
And I have the diyStore boards waiting for jfet replacement too.
I'm also enjoying my Aleph J (the ZM modification at the moment) so much.
And I have the diyStore boards waiting for jfet replacement too.
I'm interested too! I was planning to build an F4 after this (I have some good preamps that can swing enough volts for a buffer) but the Aleph J sounds so good direct from my DAC that I am hesitating... 🙂
Hi guys (any gals?), I'm seeing ~5-7C difference on a couple IRFP140 packages. Two are hitting 59-60C while the rest are at 53-55C. I'm about to take apart and re-apply thermal paste, as I suspect I was too skimpy on it. Both are on the one side, so it seems possible that was the first amp board I assembled. I became more comfortable and liberal with the paste on the 2nd board assembly
Or... do we expect this sort of delta between units?
Or... do we expect this sort of delta between units?
Is this what you mean?
Right Side
Q6 59C R17 .410
Q5 52C R16 .380
Q8 60C R19 .399
Q7 52C R18 .390
Left Side
Q6 53C R17 .373
Q5 55C R16 .389
Q8 53C R19 .375
Q7 55C R18 .393
During the build I did notice a couple of the .47ohm resistors were out by the high side of their 10% tolerance. But I tossed them in anyhow. At this point I'm wishing I had made note of where they were placed. I'm fairly certain they ended up the R20-R23 parallel network.
Right Side
Q6 59C R17 .410
Q5 52C R16 .380
Q8 60C R19 .399
Q7 52C R18 .390
Left Side
Q6 53C R17 .373
Q5 55C R16 .389
Q8 53C R19 .375
Q7 55C R18 .393
During the build I did notice a couple of the .47ohm resistors were out by the high side of their 10% tolerance. But I tossed them in anyhow. At this point I'm wishing I had made note of where they were placed. I'm fairly certain they ended up the R20-R23 parallel network.
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well, re-goop those you want, and it'll be handy to torque them all with torque-thingie, 0.9Nm
if not, try to be same gentle on all of them
Pa spoiled me, insisting, so I realized that having torque thingies for both M3 and M4 is very good for my OCD
if not, try to be same gentle on all of them
Pa spoiled me, insisting, so I realized that having torque thingies for both M3 and M4 is very good for my OCD
currents - you're in 8%, which is better than 10% of resistors
so, chill - think just of goop and temperatures and torque
so, chill - think just of goop and temperatures and torque
Pa sez - M3 - 0.9Nm
Ok, he wrote in Yank measures, so I converted to adequate for my tool
Peppe - use that for Fiat and Moto Guzzi, not for mosfets
The mounting torque limit of many of our favourite parts (IRFP240, IRFP150, IRFP9240, etc)
is quoted as 1.1 N.m on the datasheets, so 0.9 seems like a good value to use.
is quoted as 1.1 N.m on the datasheets, so 0.9 seems like a good value to use.
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with mica&goop and AluOxide pads, I would dare and use more than 0.9
with soft pads (keratherm) everything above is showing more squeeze in area of mosfet hole, less squeeze in pin area
OCD is easiest to beat with proper tool
with soft pads (keratherm) everything above is showing more squeeze in area of mosfet hole, less squeeze in pin area
OCD is easiest to beat with proper tool
IRFPs are specced at 1-1.1Nm torque I think. I plan to buy a mini torgue wrench. One that can do lower than 1Nm.
Regards,
Andy
Regards,
Andy
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Momentskrutrekker Micro Click MC2 0,4-2Nm PROXXON | Elektroimportøren AS
Something like that. Expensive little bugger.
Something like that. Expensive little bugger.
I’ve always taken into account the thermal expansion of metals when torquing dissimilar metals…aluminum generally speaking expands twice that of steel…so yes it makes perfect sense to use very slight pressure when sucking down transistors. The key is getting all the same pressure in any case.
Peppe - use that for Fiat and Moto Guzzi, not for mosfets
Ok, please suggest a wrench!
I'm going to use mica+goop, so 1.?
0.9
can't suggest a wrench, I was lucky - bought first one new for 1/4 of regular price, recalibrated it from 1.2 to 0.9
bought second one SH for 15E, recalibrated it from 1.5 to 1.2
now I have first for M3, second for M4
M4- handy to think less while dealing with pucks
can't suggest a wrench, I was lucky - bought first one new for 1/4 of regular price, recalibrated it from 1.2 to 0.9
bought second one SH for 15E, recalibrated it from 1.5 to 1.2
now I have first for M3, second for M4
M4- handy to think less while dealing with pucks