Hi all, just removed all the PS fets from my Continuum and found one shorted fet, these were new not so long ago as I rebuilt this amp from scratch almost 
it was working OK then started sapping power..
..so now with all fets removed I have a short from drain to source, any ideas what this could be? all outputs check out fine and gate to drain on PS seams fine too..
Mark.
it was working OK then started sapping power....so now with all fets removed I have a short from drain to source, any ideas what this could be? all outputs check out fine and gate to drain on PS seams fine too..
Mark.
I did try this for a little while but to no avail, I can go back and have another try!
Most SS amps have snubbers or Zobels < RC networks> across the fets have you checked the caps in these for shorts. They are usually film type caps but I have seen film caps short out.
Look for a large power resistor and some caps near the transformer on each side just atop the fets and in between the transformer and the fets. The resistors run kind of hot when the amps is working.....hope this helps some...
Look for a large power resistor and some caps near the transformer on each side just atop the fets and in between the transformer and the fets. The resistors run kind of hot when the amps is working.....hope this helps some...
Hi Cecil, hope all is well! how are you eyes now?
but year, there is 2 large resistors that do get a little hot and a round/flat cap next to each one..
I definitely have an intermittent short somewhere, just put 2 fets back in and it idles OK until you lift the board up at the PS end then it start pulling amps
how does one test for shorted caps? what resistance should they read?
Mark.
but year, there is 2 large resistors that do get a little hot and a round/flat cap next to each one..
I definitely have an intermittent short somewhere, just put 2 fets back in and it idles OK until you lift the board up at the PS end then it start pulling amps
how does one test for shorted caps? what resistance should they read?
Mark.
Hi Cecil, hope all is well! how are you eyes now?
but year, there is 2 large resistors that do get a little hot and a round/flat cap next to each one..
I definitely have an intermittent short somewhere, just put 2 fets back in and it idles OK until you lift the board up at the PS end then it start pulling amps
how does one test for shorted caps? what resistance should they read?
Mark.
Hi Marko, nice to hear from you old friend. My left is was botched and is not worth very much currently. Right eye is fine now. cataracts a true sign of getting old I guess
. Still trying to find a qualified doctor to restore my left eyes vision via re-constructive surgery and Lens replacement. Cross your fingers for me, eh?Lifting the PC board and having the short appear is bothersome to me. Not having the amp here in front of me i can only guess at this one. But your on to something and I can only suggest that you search diligently to find out why this short occurs. It's definitely not right. I have seen SS toroids short out, so please check carefully under the board where all the bare wires connect and run to the toroid I have seen issues in this area. Some kapton tape and some minor movement of the toroid windings usually will clear anything you find here up.
Film caps should not read anywhere near low ohms on a resistance scale of a voltmeter. If they due pull one end to make sure but IMO any low ohm reading on a film caps is a bad thing.
Let me know what you find, eh?....C
it has four inductors.. one of them does have a little blackening on it
what are they used for?
OK, disconnected the inductors and still have problems.. with just 2 good fets installed (one on either side of caps) the amp starts to draw about .5amp and steadily rises to over 6amps before I pull power, one side seams a lot hotter than the other?
one other thing I have noticed is when just remote and earth are connected one of the thermal switches gets very hot (occasionally, not always), not sure if this is anything to do with me bypassing this (remember I had previous issues?).
damn this amp has been nothing but trouble from the offset
one other thing I have noticed is when just remote and earth are connected one of the thermal switches gets very hot (occasionally, not always), not sure if this is anything to do with me bypassing this (remember I had previous issues?).
damn this amp has been nothing but trouble from the offset
this is giving me lot of headache right now, been through the PS checking solder connections and it's now pulling 16 amps straight away and the fet on the right gets too hot to touch instantly, the one on the left is fine I have replaced A1562 again just in case and also the silver/round component just under it. all resistors appear to be fine on both sides of cap bank.
it's strange how at 1st the amp was just pulling 0.3amp (which steadily climbed and climbed to over 8amp), and since going over all solder connections it now just rockets up to 16 amp straight away
I have replaced A1562 again just in case and also the silver/round component just under it. all resistors appear to be fine on both sides of cap bank.it's strange how at 1st the amp was just pulling 0.3amp (which steadily climbed and climbed to over 8amp), and since going over all solder connections it now just rockets up to 16 amp straight away
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