Babelfish M25, SissySIT - general building tips and tricks

Beautiful work as always Juntuin!

Thank you very much! :)

well , be sure what's alive , what's not - before powering up

if you're monitoring across R in CRC (cap bank) , initial current jerk is normal (filling that second C) , and it's short ..... long enough to scare you for a moment

:)

I don't understand those huge reading differences across resistors, what could cause those? Well, I'll do some work and try it again.
 
Correction; Only R19 is now showing strange readings.. 31,2k on working amp, 100ohm on non-functional amp. And yes, they are same size resistors, took them off and measured to be sure :D

Edit; and Q4 all legs shows shorted in multimeter on non-functional amp. Just to be clear, IQ was set to zero at first powering attempt. Took Q4 off and it's definitely broken. Now R19 makes some sense. Can I try 9240 instead?
 
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well , wasn't behind you when you powered it , so I really can't say what was wrong

sole thing I can say-that I never stumbled on bad brand new IRFP mosfet , never .....

yes, you can use 9240 instead , and you most probably will not hear any sound difference between 9240 and 9140

I didn't meant to be rude, just tired :D two identical channels, other one works and other won't work.

Something chanced along 9240. Now it stays stable couple on mV's about 10-15sec, then starts to climb slowly, but with increasing speed as volts go up.
 
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Official Court Jester
Joined 2003
Paid Member
is it oriented OK ?

regarding part quality , I took care to buy so called "double gauge" , which means no nowadays thin-back regs ; and I know these are imported from reputable vendor ( range of Digikey, Mouser , Conrad , TME)

just in case , 7805 with name looking at you , pins down ; left pin is IN , mid pin is GND , right pin is OUT
 
It was oriented as silkscreen marked, so pretty sure yes :) is it possible that I have broke it myself somehow? I haven't actually never got my hands on new unused broken component since I also buy only from Mouser and Digikey. This time I hope that it is the case, voltage regs are those rare parts that I can buy locally!

So I checked it like 10 times visually and DMM, there was about 25v input and 0v output, so soldered it off and getting new regulator at monday.
 
Official Court Jester
Joined 2003
Paid Member
well , I didn't made them by my self , so I can't vouch for zillion % for anything

but , as most parts which are in kit and as for regular things I'm buying for everyday's work , I'm buying same things from few local vendors at least last 20 years

never had faulty 78xx or 79xx , but there is always first time for everything :(

though , all you need to ruin it is one slip with probe or tweezers, sometimes even unnoticed

can't tell that I didn't made exactly that , more than once

just recently , while assembling previous SissySIT , I killed one BD critter ....
 
Official Court Jester
Joined 2003
Paid Member
just checked few things on web - these are certainly made by ST Electronics , so I resume reputable company

anyway , that's irrelevant now - what I meant to wrote is - while troubleshooting , it's probably wise to solder/mount 3A15sloblo fuses in both rails ; once when you are on safe ground , remove them out