I'll let you know later what's proper reading
however , MOhm means xformer kaput .........
just in case - confirm that there is connection between pin 3 and GND , same as between pins 5 and 1
regarding working channel , and measurement on pin 7 - you're certainly doing something wrong ; recheck trice what' you're measuring ..... put probe on + side of C2 , if you're not sure in pin numbers
logically thinking - there is no chance that xformer is damaged by rest of circuit (while input JFets are OK) , even if complete output stage is gone in flames and smoke ....... C2 is pretty good shield for that
but , if you did some mishap with probes , tiny spark is enough to fry fragile wires in xformer ......
however , MOhm means xformer kaput .........
just in case - confirm that there is connection between pin 3 and GND , same as between pins 5 and 1
regarding working channel , and measurement on pin 7 - you're certainly doing something wrong ; recheck trice what' you're measuring ..... put probe on + side of C2 , if you're not sure in pin numbers
logically thinking - there is no chance that xformer is damaged by rest of circuit (while input JFets are OK) , even if complete output stage is gone in flames and smoke ....... C2 is pretty good shield for that
but , if you did some mishap with probes , tiny spark is enough to fry fragile wires in xformer ......
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The transformer is from a board that blew in a spectacular manner, I thought it would be ok so reused it and the capacitors (which all measured fine), all the rest of the components are new.
Maybe it got damaged when I removed it from the old board?
I'll do the rest of the checks when I get a chance later tonight or tomorrow.....
Maybe it got damaged when I removed it from the old board?
I'll do the rest of the checks when I get a chance later tonight or tomorrow.....
full primary (pin 1 to pin 3) 44R
full secondary (pin 5 to pin 7) 235R
so :
pin 1 to GND : 44R
pin 7 to GND : 279R
give or take 5% (due to differences in multimeters and production )
another test - solder (any ) cap from 4.7uF to 22uF between pins 1 and 7 and you must get sound (unity gain )
that's another way to conclude that xformer (or traces for it ) is Dodo
full secondary (pin 5 to pin 7) 235R
so :
pin 1 to GND : 44R
pin 7 to GND : 279R
give or take 5% (due to differences in multimeters and production )
another test - solder (any ) cap from 4.7uF to 22uF between pins 1 and 7 and you must get sound (unity gain )
that's another way to conclude that xformer (or traces for it ) is Dodo
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OK , I have idea what you're talking about , but you need to use ( and think ) term "between" , not "at"
if there is no connection between pins 5 and 1 , pcb is faulty
so , check again :
- pin 1 to pin 3 ( in other words , between pin 1 and pin 3)
-pin 5 to pin7 ( in other words , between pin 5 and pin 7)
write here and we'll know finally ......
if there is no connection between pins 5 and 1 , pcb is faulty
so , check again :
- pin 1 to pin 3 ( in other words , between pin 1 and pin 3)
-pin 5 to pin7 ( in other words , between pin 5 and pin 7)
write here and we'll know finally ......
got one on order, thanks......
I require some assistance to pinpoint an M2 amplifier hum on both channels (tea bag version)
It presents as a louder than normal hum that can be described as earth loop hum
Speakers are 104db and other amps even the tube amp is quieter
Apart from an earth ground loop - as I am very certain that its wired perfectly as a star earth configuration as I was tutored by - wdecho and Tea Bag by PM
Also tried a bus style earth with no improvement
The amp hums plugged in on any power point and even when connected to a regulated power filter - a Thor PS10 - this can be set to supply 220 V or 240 V
And if you are still reading this the hum is constant on both settings
The toroidal transformer used is an audio quality spec from Germany
The power supply has oversized capacitors on Tea Bags boards
Also swapped out the fast acting bridge rectifiers for sealed type and mounted them on their own heat sinks
What should I look at as an alternative possible cause for this hum ? Could it be
1) Power supply cable (internal ) is NOT shielded ( have plans to swap over soon )
2) Faulty capacitor / s or Resistors
3) Unfiltered IEC power socket
4) Problem with PCB mounted transformers
5) Other unusual earth wire issues
6) Should I use shielded cable on all internal hookup wiring ( note RCA wire is shielded now )
7) Faulty CL60 ? On power side
8) Anything else
Thanks in advance
It presents as a louder than normal hum that can be described as earth loop hum
Speakers are 104db and other amps even the tube amp is quieter
Apart from an earth ground loop - as I am very certain that its wired perfectly as a star earth configuration as I was tutored by - wdecho and Tea Bag by PM
Also tried a bus style earth with no improvement
The amp hums plugged in on any power point and even when connected to a regulated power filter - a Thor PS10 - this can be set to supply 220 V or 240 V
And if you are still reading this the hum is constant on both settings
The toroidal transformer used is an audio quality spec from Germany
The power supply has oversized capacitors on Tea Bags boards
Also swapped out the fast acting bridge rectifiers for sealed type and mounted them on their own heat sinks
What should I look at as an alternative possible cause for this hum ? Could it be
1) Power supply cable (internal ) is NOT shielded ( have plans to swap over soon )
2) Faulty capacitor / s or Resistors
3) Unfiltered IEC power socket
4) Problem with PCB mounted transformers
5) Other unusual earth wire issues
6) Should I use shielded cable on all internal hookup wiring ( note RCA wire is shielded now )
7) Faulty CL60 ? On power side
8) Anything else
Thanks in advance
Attachments
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Bolshoe Spasibo for that Zen Mod - Will change this tomorrow and post results
@ Wdecho - They were supplied by Tea Bag as part of the kit
I should post a real photo of current setup
Attachments
I agree exactly with this. That is the way mine is wired.
I dont know also if you shorted inputs and see if that tells us if it's picking up problems upstream.
edit: note above, I do not supply any Input JFETs. Just transformer, boards, and output mosfets.
Are they Toshiba or LSK? The reason I ask is as most know buying Toshiba is very risky nowadays being there are so many fakes being sold. There are still reputable sellers but they are rare. I know you have been fighting this hum for a number of days. Finding hum can be very frustrating.
Ahh sorry
The Toshiba matched JFets were supplied by a fellow in Israel ( purchased 2 sets just in case I need a spare set )
Also I had the boards populated by a professional electronics technician so I'm sure all is well with solder joints
