Well, now i just need to triple check my order, place the order, and wait for parts....
I do hope I'm not upsetting Mr Pass with my 'repairs' of this amplifier.
But my goals are pure, to repair the previous 'damage' and make it look more like it did originally, and get it performing as close to new as possible.
I do hope I'm not upsetting Mr Pass with my 'repairs' of this amplifier.
But my goals are pure, to repair the previous 'damage' and make it look more like it did originally, and get it performing as close to new as possible.
Attachments
I would love Mr Pass to comment on this post 😀
As i sit here awaiting my parts (tomorrow i hope).
I have a pondering question.....
IF the 'buzzing' transformer IS due to 'dc on the mains',
would not a 1:1 mains isolation transformer be a far better and safer 'cure' than the 'two caps four diode' methods seen around..
I am Not at all comfortable with the idea of diodes and caps directly in the mains path...
I know it would be more expensive, but dammit, i'd rather spend the money and know it wont kill someone...........
As i sit here awaiting my parts (tomorrow i hope).
I have a pondering question.....
IF the 'buzzing' transformer IS due to 'dc on the mains',
would not a 1:1 mains isolation transformer be a far better and safer 'cure' than the 'two caps four diode' methods seen around..
I am Not at all comfortable with the idea of diodes and caps directly in the mains path...
I know it would be more expensive, but dammit, i'd rather spend the money and know it wont kill someone...........
twocapsanddiodes will not kill anyone , if you pack them wisely ;
use your imagination
isolation xformer will kill DC ( but also humming in the process) , you can also have some nice benefits of making balanced/symmetric mains feed , but be sure to use EI xformer type , because they're less sensitive to DC in primary .
in any case - you need to find culprit of buzz of your toroid ; killing DC is easiest and cheapest way to do it ; probably best and most effective way to have a fun is to build both DC (caps&diodes type) blocker and isolation/symmetrizing xformer in one common case , connected in series .
that way you can kill both possible hum and noises from mains
conclusion is - DC blocker with caps and diodes is completely legit way of doing it - you just need to take normal precautions in housing it .
use your imagination
isolation xformer will kill DC ( but also humming in the process
) , you can also have some nice benefits of making balanced/symmetric mains feed , but be sure to use EI xformer type , because they're less sensitive to DC in primary .in any case - you need to find culprit of buzz of your toroid ; killing DC is easiest and cheapest way to do it ; probably best and most effective way to have a fun is to build both DC (caps&diodes type) blocker and isolation/symmetrizing xformer in one common case , connected in series .
that way you can kill both possible hum and noises from mains
conclusion is - DC blocker with caps and diodes is completely legit way of doing it - you just need to take normal precautions in housing it .
Hmmmmmmm, what i might do then, is build a quick and dirty cap/diode blocker, just as a test.
if that works, then ill go for a xformer + ??? solution.
Im aware that iso trans may very well buzz, which is why id be looking for vacumm impregnated or 'baked' versions. and as a seperate device, i can rubber mount it, and stick it in a solid noise insulated case..
would i have to go the full 800w for this to match the x150's 800w max draw ?
Begs the question though...
If 300w+ toriods are known for being vunerable to 'mains dc', and its so 'easy' to throw a few $$ of parts at it can cure it.
Why do some makers not do it from factory ?
I say 'some', because im seeing some that do actually use the cap/diode built into there amps......
Oh, and does anyone have any diagrams of their prefered method for mains filtering and blocking ??
Thanks to all...................
if that works, then ill go for a xformer + ??? solution.
Im aware that iso trans may very well buzz, which is why id be looking for vacumm impregnated or 'baked' versions. and as a seperate device, i can rubber mount it, and stick it in a solid noise insulated case..
would i have to go the full 800w for this to match the x150's 800w max draw ?
Begs the question though...
If 300w+ toriods are known for being vunerable to 'mains dc', and its so 'easy' to throw a few $$ of parts at it can cure it.
Why do some makers not do it from factory ?
I say 'some', because im seeing some that do actually use the cap/diode built into there amps......
Oh, and does anyone have any diagrams of their prefered method for mains filtering and blocking ??
Thanks to all...................
isolation xformer principle
you need power at least 2 times of your max load power - meaning ~1,2KW , even if I have some doubts that you'll use 600W for your amp
but - that's your last concern in this stage ; it's more like icing on the cake , and it is really a question did your system will like it or not
you need power at least 2 times of your max load power - meaning ~1,2KW , even if I have some doubts that you'll use 600W for your amp
but - that's your last concern in this stage ; it's more like icing on the cake , and it is really a question did your system will like it or not
Attachments
Ta kindy ZM.
Weeeeeeeeeeeeeeeeeeeeeeeee
my parts arrived today
Weeeeeeeeeeeeeeeeeeeeeeeee
already been at those pesky little buggers 😀
tell ya what, the caps I chose have a bit more weight to them, feel more solid..
pics will come in due course, so just hold on 😉
it's actually going faster and easier than i thought it would.
should have it ready for cleaning and reassembly by tomorrow ??
see how i feel. If i get all the parts swapped out tonight, I'll be mega happy..
boy it looks sooooooooo much better already..
Weeeeeeeeeeeeeeeeeeeeeeeee
my parts arrived today
Weeeeeeeeeeeeeeeeeeeeeeeee
already been at those pesky little buggers 😀
tell ya what, the caps I chose have a bit more weight to them, feel more solid..
pics will come in due course, so just hold on 😉
it's actually going faster and easier than i thought it would.
should have it ready for cleaning and reassembly by tomorrow ??
see how i feel. If i get all the parts swapped out tonight, I'll be mega happy..
boy it looks sooooooooo much better already..
As a rule transformer noise with Plitrons/Powertronics is due to dirty AC,
but it's not as though I've never seen a transformer go noisy.
Diodes and caps are OK as long as you do your wiring carefully. In addition
to that and the isolation transformer you can try a couple of thermistors
in series with the AC line. Two CL60 from GE Sensing would probably tell
the tale.
😎
Many thanks Mr Pass.
It's still on the bench, but going back together.
Daym it looks so much better now.
I hope to make you proud 😉
Hope to have it running and reset on the weekend.
Then I can get back to the buzz.
I notice the main board already has a pair of CL60's in the primarys.
So I'm assuming that a second pair would be beneficial ?
Thanks all....
It's still on the bench, but going back together.
Daym it looks so much better now.
I hope to make you proud 😉
Hope to have it running and reset on the weekend.
Then I can get back to the buzz.
I notice the main board already has a pair of CL60's in the primarys.
So I'm assuming that a second pair would be beneficial ?
Thanks all....
Dayum, what a big booty amplifier.
After all this time i still gets the hots from minimal front end power amps.
IT LIVES !!!!!!!!!!
Yes, it lives .............
got it together and just powered it up to make sure it works..
will do the adjustments over the next few days.
decided to unbolt and check the transformer washers.
ewwwwwwwwww.
previous IDIOT had done the bolt up that tight, theres a HOLE from the windings in the top rubber washer...
didnt short out, still the 'wrapping' insulating it, but come on people.
the bolt is to stop the transformer from moving. not to crush it...
so i cut some new washers out of 4mm thick rubber, and installed those either side before bolting the whole lot back in.
transformer still buzzes. doh.
that'll be next weeks project, try a 'dc blocker'...
mains voltage of 244 vac (wow, never seen it that high here before, ever).
filter caps measure 40.7 vdc.
other bias and offsets are basically as previously stated, due to presetting the trimmers while swapping them out.
Oh, and someone somewhere, decided to replace the fuse.
spossed to be 2.5 amp. this brainiac stuck in an 8 amp fuse........
other than that. nothing to report.....
im tired, and work just sacked 4 other staff today, not me thank ffff.
so i need a rest, and a serious drink before i do more.
but home stretch here i come 😀 Yayyyyyyyyyyyyyyyyyyyyyyyyy...
Yes, it lives .............
got it together and just powered it up to make sure it works..
will do the adjustments over the next few days.
decided to unbolt and check the transformer washers.
ewwwwwwwwww.
previous IDIOT had done the bolt up that tight, theres a HOLE from the windings in the top rubber washer...
didnt short out, still the 'wrapping' insulating it, but come on people.
the bolt is to stop the transformer from moving. not to crush it...
so i cut some new washers out of 4mm thick rubber, and installed those either side before bolting the whole lot back in.
transformer still buzzes. doh.
that'll be next weeks project, try a 'dc blocker'...
mains voltage of 244 vac (wow, never seen it that high here before, ever).
filter caps measure 40.7 vdc.
other bias and offsets are basically as previously stated, due to presetting the trimmers while swapping them out.
Oh, and someone somewhere, decided to replace the fuse.
spossed to be 2.5 amp. this brainiac stuck in an 8 amp fuse........
other than that. nothing to report.....
im tired, and work just sacked 4 other staff today, not me thank ffff.
so i need a rest, and a serious drink before i do more.
but home stretch here i come 😀 Yayyyyyyyyyyyyyyyyyyyyyyyyy...
Attachments
clean is good 😉
if i remember right, you were going to try and work out what bias i should be running based on filter cap voltages (40.7vdc).
well, the starting point before i do the temperature based final setting at any rate...
i should be ok with the info here.
but feel free to add whatever you think is needed 😉
ta 😀
if i remember right, you were going to try and work out what bias i should be running based on filter cap voltages (40.7vdc).
well, the starting point before i do the temperature based final setting at any rate...
i should be ok with the info here.
but feel free to add whatever you think is needed 😉
ta 😀
Who cares what the rail voltage is.
Minimum bias setting is 100mA per output device, 47mV across one source resistor, 94mV at the TPs between two.
Anything more is what your hand can take during the summer in south Oz.
Minimum bias setting is 100mA per output device, 47mV across one source resistor, 94mV at the TPs between two.
Anything more is what your hand can take during the summer in south Oz.
go for 94mV at 2 pin headers
we need to check is that thing wired for 240V or something else
considering that xformer is declared as 2x27Vac , 2x 40Vdc seems too high
we need to check is that thing wired for 240V or something else
considering that xformer is declared as 2x27Vac , 2x 40Vdc seems too high
yup - white bridge wire is in 240 position
still don't get how you're getting 40Vdc per leg ....
still don't get how you're getting 40Vdc per leg ....
nope
see picture
wrong colors are parked left
brown and blue must be parked left
then - from bottom - black , orange , red , violet
see picture
wrong colors are parked left
brown and blue must be parked left
then - from bottom - black , orange , red , violet
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