Just beginning the examination after failure of one channel in my Aleph J/M@ 1/2 and 1/2 monoblocks.
Listening along when suddenly BRAAAP! and one channel goes dead. Definite smell of burned electronics in the air. Oddly, examination shows nothing on the Aleph J board burnt or crispy.
Replaced blown fuse after removing from system and hooking up to variac. Slow power up, both leds lit up but around 70-80 volts the transformer began physically humming power down.
Closer examination shows NO fried parts, smoke residue, roasted outputs, tanned resistors, nothing. As experiment, flipped power supply switch over to M2 side, still on variac and begin turning up voltage. At around same place (70 - 80 ) volts, again transformer began humming and small poof of smoke with same smell came up, but between power supply and Aleph J side of amp.
Power down, close examination, nothing. Since it occurs on both sides, Aleph J or M2 I assumed power supply at fault. Unbolt PS board from amp floor to examine back side, and nothing! No fried spots, nothing.
Looking and thinking, the only thing in the "neighborhood" of smoke was the CL-60 from power supply to chassis ground. Doesnt look cooked, but they are already black in color to begin with.
If it was the CL-60 I'm thinking the Transformer failed and CL-60 doing its job?
First step, disconnect secondart leads from rectifier blocks and repower slowly with variac, see if it still hums. (the transformer itself). If yes, problem (well, one of them) will be obvious.
Then if good, remove cap bank and add rectifiers back. If rectifiers failed, (I doubt it but who knows) replace, otherwise reconnect cap bank and test, again I doubt it, nothing swollen or funky looking.
If all checks out, which I dont think it will I will reinstall Aleph J board back in the other monoblock, which started out as Aleph J to make sure all is right with it, and order another transformer.
Sound like reasonable forensic exam? Oh, I did check out the switch which determines which amp board gets the power. All seems as normal with it.
My first First Watt clone failure.
Russellc
Listening along when suddenly BRAAAP! and one channel goes dead. Definite smell of burned electronics in the air. Oddly, examination shows nothing on the Aleph J board burnt or crispy.
Replaced blown fuse after removing from system and hooking up to variac. Slow power up, both leds lit up but around 70-80 volts the transformer began physically humming power down.
Closer examination shows NO fried parts, smoke residue, roasted outputs, tanned resistors, nothing. As experiment, flipped power supply switch over to M2 side, still on variac and begin turning up voltage. At around same place (70 - 80 ) volts, again transformer began humming and small poof of smoke with same smell came up, but between power supply and Aleph J side of amp.
Power down, close examination, nothing. Since it occurs on both sides, Aleph J or M2 I assumed power supply at fault. Unbolt PS board from amp floor to examine back side, and nothing! No fried spots, nothing.
Looking and thinking, the only thing in the "neighborhood" of smoke was the CL-60 from power supply to chassis ground. Doesnt look cooked, but they are already black in color to begin with.
If it was the CL-60 I'm thinking the Transformer failed and CL-60 doing its job?
First step, disconnect secondart leads from rectifier blocks and repower slowly with variac, see if it still hums. (the transformer itself). If yes, problem (well, one of them) will be obvious.
Then if good, remove cap bank and add rectifiers back. If rectifiers failed, (I doubt it but who knows) replace, otherwise reconnect cap bank and test, again I doubt it, nothing swollen or funky looking.
If all checks out, which I dont think it will I will reinstall Aleph J board back in the other monoblock, which started out as Aleph J to make sure all is right with it, and order another transformer.
Sound like reasonable forensic exam? Oh, I did check out the switch which determines which amp board gets the power. All seems as normal with it.
My first First Watt clone failure.
Russellc
I had ookups in past - blown diode in diode bridge, usual metal brick thingie
reason - original maker of FW clone forgot to put either split washer under nut , or to use locknut
due to thermal cycling, diode bridge was loose, so way to go south fully opened
so, secured bolt is a must, while thermal goo under the bridge is optional
not saying that's the case for you, but one of possible thingies
reason - original maker of FW clone forgot to put either split washer under nut , or to use locknut
due to thermal cycling, diode bridge was loose, so way to go south fully opened
so, secured bolt is a must, while thermal goo under the bridge is optional
not saying that's the case for you, but one of possible thingies
Rectifiers hooked up, but leads from them to cap board disconnected. turn up variac and there is 18.1 volts DC coming of the rectifiers. All seems well, but no real load on anything.
Disconnecting the amp boards switch, add cap board back and measure voltage coming from cap board...this should begin to get interesting...if amp problem shows with either M2 or AlephJ hooked to power supply, I'm thinking problem will be there. Caps are not swollen, hope it isnt them, built this back when Panasonic's discontinued line of caps were still available.
Ok, hook up cap board with amp boards disconnected...
Russellc
Disconnecting the amp boards switch, add cap board back and measure voltage coming from cap board...this should begin to get interesting...if amp problem shows with either M2 or AlephJ hooked to power supply, I'm thinking problem will be there. Caps are not swollen, hope it isnt them, built this back when Panasonic's discontinued line of caps were still available.
Ok, hook up cap board with amp boards disconnected...
Russellc
diode test/beeeeeep! us usually good enough to test caps for shorts
just wait some time, beep is there as long caps are charging and being under beep! R value ( usually 30 to 50 Ohms)
if cap is OK, you'll see infinite value
if there is short, you'll need to pull/desolder caps in parallel, to see which one is toasted
just wait some time, beep is there as long caps are charging and being under beep! R value ( usually 30 to 50 Ohms)
if cap is OK, you'll see infinite value
if there is short, you'll need to pull/desolder caps in parallel, to see which one is toasted
Not as interesting as I thought, cap board hooked up, power supply lights up with 23.8 volts DC on outputs. Only thing that looked funny was one rectifier block's connectors may have been loose, should probably solder directly, but this has made testing a little easier.
Don't know if such a connection coming loose would have caused that but it's the only "funny" looking item I've seen in the amp.
I'm going to have to stare at this a while and decide if I want to reconnect amp boards
and retry or mount Aleph J board in other mono block.
SOMETHING smoked, what all would cause the CL-60 to smoke? (if it was that...)
I think I will reconnect the M2 side and give it a whirl. If I damage that board in the process, I have another pair of M2 boards stuffed and ready to go, just blank Aleph J boards and matched set of Toshiba Jfets for it.
Russellc
Don't know if such a connection coming loose would have caused that but it's the only "funny" looking item I've seen in the amp.
I'm going to have to stare at this a while and decide if I want to reconnect amp boards
and retry or mount Aleph J board in other mono block.
SOMETHING smoked, what all would cause the CL-60 to smoke? (if it was that...)
I think I will reconnect the M2 side and give it a whirl. If I damage that board in the process, I have another pair of M2 boards stuffed and ready to go, just blank Aleph J boards and matched set of Toshiba Jfets for it.
Russellc
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double thread ?
Missed the part about double thread, thought I was typing in same one, but I am doing multiple things at once.
Russellc
M2 side hooked up bias around .64, set the off set to 0. All seems "normal" so I guess I will try the Aleph J side. Oh well, something smoked, I am beginning to be more certain it was the connection on the rectifier block that caused this, maybe it got nudged when the 1/2 and 1/2 mono block conversion went down?
Now to try Aleph J side then back to system for check. should CL-60 be replaced as caution?
Russellc
Now to try Aleph J side then back to system for check. should CL-60 be replaced as caution?
Russellc
Aleph J also with normal operation. All I can come up with is the rectifier connection, not going to try to replicate that failure mode. With nothing else found so far, I am for now attributing this problem to to connection to the rectifier, I dont understand if that could have caused the transformer to hum like a mad bear and smoke to come off of the CL-60 (I think) and blow fuse, but that's how it is, September 26th, 2020. this is Walter Cronkite signing off.....until this rears its ugly head again anyway.
Russellc
Russellc
I will measure a new one and compare. Going to try amp in system now. In mean time BA3 Amp playing very well along with Iron Pre!
Russellc
Is there a kind of loop that should not be there so when rectifier connection was bad a kind of unbalance in PSU caused that current flow through CL-60 to chassis?
Maybe check if CL-60 is a bit hot now when everything seems ok?
I think no current should flow though it in normal operation so voltage across it should be zero?
Maybe check if CL-60 is a bit hot now when everything seems ok?
I think no current should flow though it in normal operation so voltage across it should be zero?
I’ve had a similar occurrence, where a loose connection (or improper connection, can’t remember) sent current through the CL60 groundbreaker. It sent out some smoke, but continued working after I discovered issue. The one indicator was that the CL60 became very brittle, and I was able to easily snap material off of it. (Yes, I replaced it).
Thank you Meper and codyt. When I first had built the M2, one day after moving it to different system it made some odd burping noises like a Harley Davidson pulled up in drive.
I also had funny bias readings. Turned out a wire from amp board to power supply was in the PCB through hole, but not soldered. Solder made it work fine!
Different power supply problem but similar noise. I think I will replace CL-60 just for safe measure. In fact, based on Zenmod's comment I will replace rectifier blocks.
Russellc
I also had funny bias readings. Turned out a wire from amp board to power supply was in the PCB through hole, but not soldered. Solder made it work fine!
Different power supply problem but similar noise. I think I will replace CL-60 just for safe measure. In fact, based on Zenmod's comment I will replace rectifier blocks.
Russellc
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And not so much. After playing beautifully all this time, same thing again, same smell. Think I shut down before fuse blew, maybe we will see. Pretty darn sure it's something with power supply. I'll have to dig around for some rectifiers and order some if none. Time to start replacing some PS parts.
Russellc
Russellc
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