I was thinking... what kind of speakers do you drive? I believe you have high efficiency jobbies?
I've been driving 90db/watt speakers.
nope
as it seems, culprit is in 5V6 (ZD2-ZD3) zeners
as I said few times - I invested some serious time to devise small caps arrangement (anti-oscillation measures) to ensure compatibility with all 3 iterations and there is no chance of amp being unstable
was banging my head in recent time trying to determine scenario of SIT iteration misbehaving, when I know through what I put my own (serious clipping, overcurrent protection engaging) and 'nuttin bad
conclusion - with border-line SIT Ugs values, upper 5V6 zener (ZD2) is evidently going in conduction, establishing current path though C12, so Q1 going Berserk, and then inevitably smoking R24 and at least well heated Q2
anyhow, will post set of files, just for giggles, with cleaned up notes and - especially - protecting zener values changed to 8V2
it would be wise including another zener, just for SIT option (logically named ZDSIT), just in case of ookup as derekr made - missed R52 ........... but I already know what is happening when too much choices are left to Greedy Boyz Hordes - headache to Poor ZM .........
it would be much clever/less headache - that I devised 3 different amps/pcbs of this (triple) one
as it seems, culprit is in 5V6 (ZD2-ZD3) zeners
as I said few times - I invested some serious time to devise small caps arrangement (anti-oscillation measures) to ensure compatibility with all 3 iterations and there is no chance of amp being unstable
was banging my head in recent time trying to determine scenario of SIT iteration misbehaving, when I know through what I put my own (serious clipping, overcurrent protection engaging) and 'nuttin bad
conclusion - with border-line SIT Ugs values, upper 5V6 zener (ZD2) is evidently going in conduction, establishing current path though C12, so Q1 going Berserk, and then inevitably smoking R24 and at least well heated Q2
anyhow, will post set of files, just for giggles, with cleaned up notes and - especially - protecting zener values changed to 8V2
it would be wise including another zener, just for SIT option (logically named ZDSIT), just in case of ookup as derekr made - missed R52 ........... but I already know what is happening when too much choices are left to Greedy Boyz Hordes - headache to Poor ZM .........
it would be much clever/less headache - that I devised 3 different amps/pcbs of this (triple) one
^ Thanks. Your attention and effort is very much appreciated.
Your analysis of the damage sure makes sense... it is the damage we saw.
Looking at the schematic... is that ZD3 instead of ZD2? The 5V6 zeners are ZD3 and ZD4.
ZD2 is marked as 22V and just below Q3.
How do we know what a "bordeline" SIT Ugs value is?
I have six spares of them babies and I believe RT has more. For sure, mine were matched... the one in use was a matched pair, the other six are a pair and a quad, matched, quad just in case you ever come out with the Badabing Super Duper Bang SIT. It'd be nice to know if they are "borderline" before we power them up... ooops!
BTW, Seeing smoke out of your amp is part of the agreement. Once, sure.... what worried me a lot was seeing it twice. I was ready to repurpose it to an SET. Except, I like the sound of the SIT.
Thank you very much... you gave a very nice birthday gift today.
Your analysis of the damage sure makes sense... it is the damage we saw.
Looking at the schematic... is that ZD3 instead of ZD2? The 5V6 zeners are ZD3 and ZD4.
ZD2 is marked as 22V and just below Q3.
How do we know what a "bordeline" SIT Ugs value is?
I have six spares of them babies and I believe RT has more. For sure, mine were matched... the one in use was a matched pair, the other six are a pair and a quad, matched, quad just in case you ever come out with the Badabing Super Duper Bang SIT. It'd be nice to know if they are "borderline" before we power them up... ooops!
BTW, Seeing smoke out of your amp is part of the agreement. Once, sure.... what worried me a lot was seeing it twice. I was ready to repurpose it to an SET. Except, I like the sound of the SIT.
Thank you very much... you gave a very nice birthday gift today.
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yes, ZD3 and ZD4 in your case
as I said, will post comprehensive set of files, covering both iterations of pcbs
as soon I came back from Ma's, today is second Jesus Birthday Party (Orthodox Xmas), and tradition is to mingle in The Nest
it is just (or "just") happenstance that with initially established value for protection zeners, there is some as that
entire idea of implemented biasing circuit is that there is no critical value or inadequate value of SIT Ugs
I believe with this change, it'll be
Beginning to wire power supply and have a few questions. First, I planned on using the zenmod approved method of running wires from transformers underneath the slotted shelf thing.
The wires are not long enough to make it to switch/fuse fixture. This is deluxe 5U box and ac/fuse thing is what comes with the completion kit, shurter by looks.
Is 16 gauge milspec wire, silver plate multi strand with Teflon insulation sufficient for "transformer" extensions? I've never heard of special transformer lead wire but didn't know if special stuff needed. I've shortened some transformer leads, but made the connections with pieces of what I cut off. That will not serve here obviously!
Russellc
The wires are not long enough to make it to switch/fuse fixture. This is deluxe 5U box and ac/fuse thing is what comes with the completion kit, shurter by looks.
Is 16 gauge milspec wire, silver plate multi strand with Teflon insulation sufficient for "transformer" extensions? I've never heard of special transformer lead wire but didn't know if special stuff needed. I've shortened some transformer leads, but made the connections with pieces of what I cut off. That will not serve here obviously!
Russellc
Attachments
Another thing just hit me. Previous dual mono were mono blocks, so each had there own IEC/fuse fixture and power cord. My F5 was dual mono,
but I carried the through including two power cords. Not so this time, just one IEC fixture. I suppose I just double up on the hookups to the IEC/fuse fixture?
but I carried the through including two power cords. Not so this time, just one IEC fixture. I suppose I just double up on the hookups to the IEC/fuse fixture?
when going dual mono (in one case, logically) - IEC and mains switch are common, then everything else is separate, especially important to mention separate mains fuse(s) for each Donut
"s" in parentheses at fuse(s):
if regs in your neck of wood are calling for one fuse per circuit, go with that
if regs in your neck of wood are calling for fuse per leg ( so fuse in phase and fuse in Neutral) go with that
of course, no one prevents you of going overkill, installing separate IEC and switch for each channel
"s" in parentheses at fuse(s):
if regs in your neck of wood are calling for one fuse per circuit, go with that
if regs in your neck of wood are calling for fuse per leg ( so fuse in phase and fuse in Neutral) go with that
of course, no one prevents you of going overkill, installing separate IEC and switch for each channel
same logic as you (ideally) have one fuse per circuit in your house
I mean - it is ever hardly ideal in our houses, especially if built in Yore and with fishy regulatory or application of same, but when building your own amp, no reason to cheat
in short - fuse will (hopefully) do prescribed duty only if dimensioned properly
if you dimension fuse to live through power-up sequence of 2 parallel Donuts, even with obligatory soft start circuit, how you can expect it to have appropriate value to react in case of trouble with just one Donut?
it's hardly to expect having trouble with both Donuts in same time
I mean - it is ever hardly ideal in our houses, especially if built in Yore and with fishy regulatory or application of same, but when building your own amp, no reason to cheat
in short - fuse will (hopefully) do prescribed duty only if dimensioned properly
if you dimension fuse to live through power-up sequence of 2 parallel Donuts, even with obligatory soft start circuit, how you can expect it to have appropriate value to react in case of trouble with just one Donut?
it's hardly to expect having trouble with both Donuts in same time
In the Orthodox church, Epiphany is like the Catholic Christmas? Or more like Three Kings' Day?
When do you exchange gifts? The Anglo Saxon Christmas or the Western Continental King's Day?
My late, much missed mom, had an epiphany many years ago.... me. ;-)
So, you gave us all a gift! Thanks. I'll call you Caspar... Oh Wise Man.
Yes, Christmas, regardless of day, is all over... mingle in the nest. The whole family gets together... making pilgrimages, so to speak. It's very nice, I love seeing the family. I just stay out of the Soap Operas, watch out how much I drink, my wife tells reminds me not to tell many jokes, we see the young one growing up, etc...
A belated Merry Christmas to you.
OK... back to the subject.
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