Gentlemen,
up to now just one member has sent a pm to show interest in a pair on Cinemags. I think we would need at least 10 pcs in order to get a significat discount. I would be really happy if we could reach that number
Have a nice evening
Ernst
Sorry, already ordered and paid for mine a month ago. Sad thing is I might even be in the same production batch if you do get a group together.
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Here is the picture
it's hard imagining anything else than problem with thermal interface , amp not having any gain (besides xformer) , so no possibility of oscillation
IRFP either wasn't tight enough , or there was a burr somewhere , needing time to dig through isolation
what thermal interface you're using ?
IRFP I'm sending are genuine parts , got from vendor with whom I'm working for more than 20 years , so there is no doubt about that issue as possible culprit
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Here is the picture
as I wrote in post #1 :
put mosfets on/under the pcb , in exact arrangement with mounting hardware as can be seen in posts #2 and #3 , just bellow this one ; to remind you , exact arrangement is :
heatsink-Keratherm-mosfet-pcb-big washer-smaller washer if needed-springie washer as absolutely necessary part-bolt
tighten with brain , not force , but not skimp on necessary force ; my solution is to always use stainless steel washers and especially Allen bolt , because nowadays that's only way to have certainly mechanically proper part ........ usual steel bolts are more often utter drek than not
from your picture I see that you didn't put big washer ; pcb will sag in time if there is just small washer - as in your case - and pressure on mosfet will decline
depending on thermal interface you used , pressure is more or less important for proper thermal transfer , but is always important
ZM I know where pin 1 was on the CineMags ( I have already cut the 4 corner pins), but I dont know where pin 2 etc go on the PCB. I.e how the trafo should be oriented. On my picture pin 1 is under the C in 4HPC. So my question is actually if the orientation is correct as shown in my picture
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Cinemag CMOQ orientation on pcb
xformer pic :
red dot Pin 1
black dot Pin 2
Pin 1 and Pin 2 are closer together than rest of pins
cut corner pins marked with green arrows
pcb pic - black circle and arrow - Pin 2
edit: link to this post included in post #1
xformer pic :
red dot Pin 1
black dot Pin 2
Pin 1 and Pin 2 are closer together than rest of pins
cut corner pins marked with green arrows
pcb pic - black circle and arrow - Pin 2
edit: link to this post included in post #1
Attachments
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Thanks a lot ZM, BK & Ben I see my orientation is correct.
I have plowed through the tread 3-4 times over the last couple of months, still didnt remember #62
Now next step is to dissassemble my M2 so I can reuse powersupply and box for Sissy. Need another box and supply so I can compare M2 and Sissy at a later date.
I have plowed through the tread 3-4 times over the last couple of months, still didnt remember #62
Now next step is to dissassemble my M2 so I can reuse powersupply and box for Sissy. Need another box and supply so I can compare M2 and Sissy at a later date.
Thanks a lot ZM, BK & Ben I see my orientation is correct.
I have plowed through the tread 3-4 times over the last couple of months, still didnt remember #62
Now next step is to dissassemble my M2 so I can reuse powersupply and box for Sissy. Need another box and supply so I can compare M2 and Sissy at a later date.
I believe pretty much everything is covered in post#1
though , if you cant find it , just ask
I have no problems repeating what's needed ....... better that way than to leave out that gray smoke
yeah , resistor along opto - named Rs as for Rshunt
used in B. M25 , not in Sissy
27 or 39 ..... you have good chance that 27 is enough ..... just later I realized that some JFet triplets are asking for more than 27R
blame on me ........ and (as usually) I'll blame Pa , he didn't taught me well enough
used in B. M25 , not in Sissy
27 or 39 ..... you have good chance that 27 is enough ..... just later I realized that some JFet triplets are asking for more than 27R
blame on me ........ and (as usually) I'll blame Pa , he didn't taught me well enough
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