You could disconnect the amp boards and test PSU alone and load then with power resistors. Also when using variac use an A-meter on primary side so you can check if primary current match with secondary current in load resistors?
Too lazy to read every post - apologies
1) Have you tried running your amp from a lab power supply just to be sure no damage was done to the amp?
2) What transformers were used in your build?
3) Any weird loose connections or poorly crimper connectors etc?
4) Do all solder joints look good?
5) Always be careful tightening a transformer down (not too tight), you don't want to do damage to the insulated windings
I have worked on a transformer failure task at work - cause was due to operating the transformer at elevated temperatures, causing crack growth on the insulated windings which eventually led to shorted windings.
Your transformer could possibly be damaged.
I will go back and read more.
1) Have you tried running your amp from a lab power supply just to be sure no damage was done to the amp?
2) What transformers were used in your build?
3) Any weird loose connections or poorly crimper connectors etc?
4) Do all solder joints look good?
5) Always be careful tightening a transformer down (not too tight), you don't want to do damage to the insulated windings
I have worked on a transformer failure task at work - cause was due to operating the transformer at elevated temperatures, causing crack growth on the insulated windings which eventually led to shorted windings.
Your transformer could possibly be damaged.
I will go back and read more.
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My first gut instinct is you have some damaged transformer windings that are shorting out when the transformer reaches a certain temperature.
I am inclined to agree. I thought connections at first, due to the "works fine now but not later" nature of problem. After running fine some while, it did it again.
I was watching close, definitely the CL-60 that smoked.
Since I am in the middle of a few builds, I'm inclined to
Reassemble the Aleph J in it's original case (problem is in other amp, originally M2). That would clear amp board.
Russellc
I was watching close, definitely the CL-60 that smoked.
Since I am in the middle of a few builds, I'm inclined to
Reassemble the Aleph J in it's original case (problem is in other amp, originally M2). That would clear amp board.
Russellc
1 no, I don't have a lab power supply...that needs to be remedied.
2 Antek 500 VA 18+18
3 yes, rectifiers using connectors, thought I made sure of tightness, replacements will be soldered.
4 solder joints appear good, but I am removing power supply board for better examination of its under side and associated wiring..
5 yes, snug but not over right.
I have ordered a pair of the Avel-lindberg transformers you pointed out in the M2x thread.
Russellc
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Aleph J board removed. Other amp, (originally my Aleph J) removed M2 board. Getting ready to put Aleph J back together for test.
Cleaned up all power supply board solder points, rewiring power supply without switch.
Have some different trans on the way, adding new bridge rectifiers to order for other projects
Problem amp has power supply removed, transformer and 3502 bridges as well. Nothing looks hot or cooked. Still suspecting dead bridge or problem with transformer.
I would normally assume, due to being "fixed" once that it would be connection problem, but transformer is likely problem.
Russellc
Cleaned up all power supply board solder points, rewiring power supply without switch.
Have some different trans on the way, adding new bridge rectifiers to order for other projects
Problem amp has power supply removed, transformer and 3502 bridges as well. Nothing looks hot or cooked. Still suspecting dead bridge or problem with transformer.
I would normally assume, due to being "fixed" once that it would be connection problem, but transformer is likely problem.
Russellc
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Aleph J back to single chassis format (not in "problem amp, the other original aleph J chassis) turned on via variac, reset bias and offset and its been cooking for a while. Just put back in system.😕
My thoughts are this will work fine and problem is with other chassis power supply. I dont have replacement rectifiers on hand and will need to order some, already have transformers coming, they were for another amp but I can test with them for now.
Russellc
My thoughts are this will work fine and problem is with other chassis power supply. I dont have replacement rectifiers on hand and will need to order some, already have transformers coming, they were for another amp but I can test with them for now.
Russellc
I absolutely love these bridge rectifiers
http://www.digikey.com/product-detail/en/ixys/VBO52-08NO7/VBO52-08NO7-ND/1653182
Tough as nails built like a tank, with a low forward voltage drop.
You would just need to fit ring connectors.
They are bigger than normal bridges so you would also need to be sure you have space.
http://www.digikey.com/product-detail/en/ixys/VBO52-08NO7/VBO52-08NO7-ND/1653182
Tough as nails built like a tank, with a low forward voltage drop.
You would just need to fit ring connectors.
They are bigger than normal bridges so you would also need to be sure you have space.
These will be added to order. If this turns out to be rectifiers, no more 3502 for me, these will be new go to.
minimum 10 pieces
Russellc
minimum 10 pieces
Russellc
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The reassembled AlephJ has been working flawlessly for a couple days now. Always refreshing to hear this amp, really a nice piece.
This narrows at least to point I am certain it is power supply. The caps look fine, board looks fine (speaking of "problem" amp) although I have empty teabag power supply boards but don't really suspect board problem.
Fairly certain we have rectifier possibly failing, or bad transformer that like pico thought, goes bad once certain temp is met. I could see a transformer doing that but I don't know if a bridge would intermittently fail, or simply work or not work when going bad.
Waiting for parts.
Russellc
This narrows at least to point I am certain it is power supply. The caps look fine, board looks fine (speaking of "problem" amp) although I have empty teabag power supply boards but don't really suspect board problem.
Fairly certain we have rectifier possibly failing, or bad transformer that like pico thought, goes bad once certain temp is met. I could see a transformer doing that but I don't know if a bridge would intermittently fail, or simply work or not work when going bad.
Waiting for parts.
Russellc
most likely Donut, but you already know that exclusion game only can result in finding a culprit
Yup. Transformers on way. Rectifiers are screwed tightly to the perforated inner base...maybe not sinking rectifier heat away?
Now, which part to try first, rectifier or transformer. Think I will trade out transformer first. Is such a failure in rectifier block measurable?
Russellc
Now, which part to try first, rectifier or transformer. Think I will trade out transformer first. Is such a failure in rectifier block measurable?
Russellc