All amplifiers from the past age have been of blameless type so nothing interesting about them. Quasi is even older.
I still have old blameless circuit that can do ppm at high power. But so many years later, people are still building/posting blameless types with inferior THD, even with more complex stages??
But Leach amp came with "new" idea (about TIM), and the circuit type was new (to me) as well.
I'm beginning to think my Slewmaster tester chassis just doesn't want to happen. I've been having negative channel output device failures out of the blue whenever I power them with my 65 Volt supply. I could beat it up all day long with a 40 volt supply with no issues. Up until now I've never found a reason why. No sign of heat or oscillation. It would be just idling away on the bench, then DC protection would trip and an output device would be shorted. Last night on power up I heard a sizzling noise from my supply area. It sounded like a cap spilling it's guts. I powered it down and took a quick look. I didn't see any sign of cap rupture but I need to pull the chassis right apart to see anything. I'm wondering now if one of my monolithic bridges are shorting intermittently. I'm thinking now I should just scrap the supply and start fresh with TO-220 rectifiers instead.😕
Hi OS,
Happy New Year!!
I'd like to ask a favor. You were always good about adding notes on your schematics. Would you please add designations for the wattage of all resistors that are over 1/4W? I'm worried I may have some wrong on the Infidel and looking at the last two IPS you posted I don't see those either.
Thanks, Terry
I powered up a PSU that I had pulled from my Aleph-X a while back. One of the caps was in bad need of reforming. I heard a Fzzzzzzz sound and a big puff of smoke. I was sure a cap had exploded but instead I found the 35A bridge had blown. I was able to reform the cap and replaced the bridge and all is fine. First time I had seen a bridge fail.
The bridge failure would explain some odd occurrences. I've had a couple other amps acting oddly when testing on this same supply. It never clued in to me that it may be the supply itself. I've also had the breaker trip on the outlet once while trying to get Tubesomo running. That was with this same supply just feeding an input board.
The last 2 will work with all 1/4W.
The only drawback is the Infidel rail dependence. 65-75V rails are good for the
specified values - VAS I trimmer can be "tweaked" for 5+ma .
There is method to my madness. Most IPS resistors are 1/4W , even 1/8w would
do.
Just 3 exceptions ... zener dropping resistors , VAS emitter resistors , and
CFA feedback dividers.
ALL VAS's are 5.3ma and differentials are 1.4-1.6ma - fully standardized.
I'm swapping symasui/wolverine/and spooky with <1mv OPS bias change.
PS - I'm laying out the "BSIPS" IPS now ....
true "junkbox" parts = <.003% thd20
OS
Yep , china bakelite bridge will smoke right up. My old 25A metal case bridges
have survived exploding caps , shorts , and other mishaps.
Don't trust the ratings on (some of) the new parts. New mouser red LED's =
supposed 20ma ... B$ ! Good thing I design IPS led's to only run at <2ma !
Blew a red @ 10ma while "fiddling". 😱
OS
Led voltages seem to be rising as well. I've given up buying LEDs from Mouser. My last batch of "standard" red LEDs had a 5 volt dropping resistor in them. I'm really tired of getting 1 watt resistors in a 1/4 watt package too. You would think these would be options they would list in their search engine. Newark does.
Sorry to hear of this issue !! I don't think it's the amps.
I've run all my IPS/OPS combo's for several days/nights at 76V. Your issue does
have me suspicious of the "new" bridges. 😱
I did run the "big" supply by itself before I hooked slew's to it. My 4X 8200u's
(S. korea caps) seem to be fine with the trafo/bridges.
As I am not yet "hammering" a full 5 pair OPS yet , who knows ?
OS
I've actually never loaded these down yet on a 65V supply. I was listening to music and burning them up with a 4 ohm resistor bank at 40 volts without a hickup. As soon as I stepped up to the big supply they've been self destructing just idling. I've never gotten them warm enough to properly set idle current yet. I've got a couple steel can 3 phase bridges around I could try but I think I'm just going to bite the bullet and start from scratch. Those caps are too big to risk having one grenade on me.
Any recommendations on TO-220 diodes? Are MUR860s a good choice?
That batch of red's you gave me have no resistor , if they did - I would not of blown 3.
I blew 2 on spook by not hooking the ground up and one seeing how bright
I could get my arduino fault indicator to go. 😱
If the voltages were rising on the spooks , my currents would be all over the place
(CCS's). But ... these LED's can not handle much current.
I am suspicious of all these new components and whatever china meth city
they come from. 🙁 I'll test , blow a few up .... see what consistancy is in a
batch - not like old parts.
OS
I still prefer Newark's search engine where you can select the forward voltage. I don't have the time to download and decode a part number on a datasheet for simple components. Their prices are slightly higher but much fewer surprises later.
IDP30E60 Infineon Technologies | Mouser
Infineon ....
Precision to-220 diodes made in Dresden,Germany or Kalum , Malaysia .
Not "meth city" china diodes. 😀
OS
Who and where is Very important.
ON semi =
All the chips and caps are made in USA/Canada.
The output devices are actually made in old Sanyo factories in
japan,china,vietnam, and malaysia (they bought sanyo discrete).
My red LED's are Kingbright (child labor) ... slave kids mixing the pots
of epoxy so I can have pretty LED's. 🙁
Oops ... that might be slightly political. - but still wrong !
OS
I've always liked On Semi/Motorla's devices Now they are dropping TO-92s from their lineup. They farmed the manufacturing of them out and their suppliers aren't producing TO92 any more. Not everything has been made in their own plants.