I woke up this morning at 6am and couldn't resist the urge to try to figure this out. So much for my zen time.
You are lucky! I should have left well enough alone, as mine was working perfectly as well. I had no idea that a simple change like this would fry my amp, and I am not equipped with the knowledge or tools to fix it.
$800 for an "experiment" and 2 days worth of "triode sound". At least I know what a SET sounds like now...
Honestly, I can't remember the last time I felt this angry and disappointed.
Sounds simple except that I have no idea what I am doing. I know how to test B+ and cathode voltages at R17/R27. That's the extent of my knowledge. I will not put my hands in a live amp.
Which tubes should be installed when I test? Just the rectifier?
If something went this wrong, I feel like it will just do more damage to power it up again without having a clue... I've got $350 worth of OPTs in it.
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There is a thread somewhere on here on checking out newly built SSE boards, which, at that time, were still designated Simple SE.
Look for that thread, and follow the check out instructions. The member who posted it was Ty Bower or something similar.
You will start with taking simple resistance checks, no tubes installed, and no power applied, so no danger to the operator.
Look for that thread, and follow the check out instructions. The member who posted it was Ty Bower or something similar.
You will start with taking simple resistance checks, no tubes installed, and no power applied, so no danger to the operator.
The Ty Bower post that I found only explains how to test B+ and cathode voltages, as far as I recall. That's the post I used to do my initial check out.
Resistance checks require me to remove the resistors - so here I am faced with removing all the resistors from my board because I tried UL mode?
I'm sorry, but there is nothing simple about this situation. I appreciate your time and effort to help me, but I am too angry and not nearly knowledgeable enough to figure this out. I also have no solder right now so I can't take it all apart and put it back together.
The problem with making a project that any idiot can build is that most idiots won't know how to fix it.
Resistance checks require me to remove the resistors - so here I am faced with removing all the resistors from my board because I tried UL mode?
I'm sorry, but there is nothing simple about this situation. I appreciate your time and effort to help me, but I am too angry and not nearly knowledgeable enough to figure this out. I also have no solder right now so I can't take it all apart and put it back together.
The problem with making a project that any idiot can build is that most idiots won't know how to fix it.
What I would really like to try to understand is; what is the electrical difference between triode and UL modes that would/could lead to dramatic failure? Does UL mode put more load/current through certain components? Would UL mode make my OPTs run warm? If one of my power tubes went bad, how would I test it? Have I fried one or both of my OPTs? How would I test them?
Checking all resistances seems futile to me when the amp ran perfectly in triode mode, but that just shows my complete lack of knowledge...
Checking all resistances seems futile to me when the amp ran perfectly in triode mode, but that just shows my complete lack of knowledge...
I looked at the pictures of your board and everything seems to be installed correctly.
The amp was still making music from both channels when the event occurred? If so all of the major components are still alive.
Smoke comes from burnt parts, most often resistors. The smell is like burnt plastic, much like that from touching a plastic kitchen utensil to the glowing stove coils. It usually leaves telltale evidence of what fried.
Steam and stink comes from an electrolytic capacitor that built up too much heat, creating pressure, and eventually breaching the pressure vent (in all modern caps to reduce explosions). The smell is like wet cardboard burning. There can be minimal evidence of the capacitor venting if the vent is on the bottom. Modern caps have vents on both ends. The lines scribed across the top of your caps are the top vent. Examine them carefully with a magnifying glass to see if one has split. C12 or C22 would be the most likely candidates.
My first thought was that this is a runaway tube event. It is not uncommon for a brand new tube to exhibit runaway, especially those sourced from Ebay, since they may be tubes that didn't pass QC in the factory.
I bought a dozen "6L6GC's" on Ebay over 10 years ago for $3 each. They were the exact same Chinese tubes that I had been getting from AES for $7 each......except that the AES tubes all worked, and 4 out of 12 of the Ebay tubes were bad, or went into runaway within a week or two.
A runaway tube will slowly draw more and more current eventually getting red hot and possibly sparking out. As it's current draw increases if forces more and more current through the cathode resistor, and possibly blowing the resistor and / or the cathode bypass cap. A loose screw on your cathode resistor connectors could also cause a blown cathode bypass cap since a poor connection could force all of the current through the capacitor.
Carefully examine both output tubes, especially the one connected to the OPT that got hotter. Look at the painted lettering (if there is any). Is it more discolored than the other output tube? Is there discoloring around the plastic part of the base. Do any of the internal parts look burnt, or warped due to heat, compared to the other tube?
If no clues are found here, we will have to do some simple electrical tests. Some pictures of the board, and how you have the OPT jumpers connected may be helpful.
The amp was still making music from both channels when the event occurred? If so all of the major components are still alive.
Smoke comes from burnt parts, most often resistors. The smell is like burnt plastic, much like that from touching a plastic kitchen utensil to the glowing stove coils. It usually leaves telltale evidence of what fried.
Steam and stink comes from an electrolytic capacitor that built up too much heat, creating pressure, and eventually breaching the pressure vent (in all modern caps to reduce explosions). The smell is like wet cardboard burning. There can be minimal evidence of the capacitor venting if the vent is on the bottom. Modern caps have vents on both ends. The lines scribed across the top of your caps are the top vent. Examine them carefully with a magnifying glass to see if one has split. C12 or C22 would be the most likely candidates.
My first thought was that this is a runaway tube event. It is not uncommon for a brand new tube to exhibit runaway, especially those sourced from Ebay, since they may be tubes that didn't pass QC in the factory.
I bought a dozen "6L6GC's" on Ebay over 10 years ago for $3 each. They were the exact same Chinese tubes that I had been getting from AES for $7 each......except that the AES tubes all worked, and 4 out of 12 of the Ebay tubes were bad, or went into runaway within a week or two.
A runaway tube will slowly draw more and more current eventually getting red hot and possibly sparking out. As it's current draw increases if forces more and more current through the cathode resistor, and possibly blowing the resistor and / or the cathode bypass cap. A loose screw on your cathode resistor connectors could also cause a blown cathode bypass cap since a poor connection could force all of the current through the capacitor.
Carefully examine both output tubes, especially the one connected to the OPT that got hotter. Look at the painted lettering (if there is any). Is it more discolored than the other output tube? Is there discoloring around the plastic part of the base. Do any of the internal parts look burnt, or warped due to heat, compared to the other tube?
If no clues are found here, we will have to do some simple electrical tests. Some pictures of the board, and how you have the OPT jumpers connected may be helpful.
Generally not. Some voltages change a little, but we are talking 5% or less.
The OPT will produce very little heat on it's own. Usually they would need to run for several hours to feel even slightly warm. The nearby tubes however RADIATE a lot of heat as InfraRed radiation which will make their surroundings warm, especially things that are painted black.
If the amp was still playing, even with distortion on one channel, the OPT's are likely fine. They are pretty hard to kill in a "normal" amp like the SSE.
I'm pretty sure that the change to UL did not cause your failure. A measurement of the cathode resistors and capacitors is the first thing I would do if a careful visual inspection does not turn up the source of the smoke / stink. Something made the smoke, it will do it again if not found.
Thank you for your assistance, George.
I can't recall if both channels were making music when the event occurred, because I was too focused on hitting the switch and pulling the power cable out. I know I could still hear music for sure.
I removed the board earlier and inspected all the top-side components and found no sign of heat anywhere. All the resistors look like they did when I installed them. No browning on any of them. All solder connections look shiny and solid. I've looked closely at the caps and other components on the bottom side and it also looks fine to my untrained eye. No signs of capacitor leakage. Cathode resistors also look immaculate.
The output tubes are Electro-Harmonix (Russia) EL34-EH that were previously used in my EL34 P-P amp. They were a set of 4 and I burned one out in that amp so pulled the remaining three and installed 4 new Mullard re-issue EL34s. So these EL34-EH tubes have some hours on them. Enough that one of their brothers burned out. Close inspection shows no obvious signs as you have described. Neither tube was glowing red when the event occurred. I feel like I would have noticed that, but again I was in "kill it fast" mode.
Attached pic is how I have it wired now, which is precisely as it was wired when it worked fine for hours in triode mode. When I switched to UL, I removed the blue jumpers and installed the (purple, now taped off) UL taps exactly as shown in your wiring diagrams. That was the only change I made.
I should note that the only sign of heat that I can find in the whole works is the aforementioned star ground point. As you can see, I have that point connected to: 1) the top plate (via one of the OPT bolts), 2) ground connector of each speaker output, 3) ground connector of one RCA input connector. The charring on that ground point was there before this event occured (due to my screw up with the alligator clip) but I can't say for sure that it isn't worse now.
I can't recall if both channels were making music when the event occurred, because I was too focused on hitting the switch and pulling the power cable out. I know I could still hear music for sure.
I removed the board earlier and inspected all the top-side components and found no sign of heat anywhere. All the resistors look like they did when I installed them. No browning on any of them. All solder connections look shiny and solid. I've looked closely at the caps and other components on the bottom side and it also looks fine to my untrained eye. No signs of capacitor leakage. Cathode resistors also look immaculate.
The output tubes are Electro-Harmonix (Russia) EL34-EH that were previously used in my EL34 P-P amp. They were a set of 4 and I burned one out in that amp so pulled the remaining three and installed 4 new Mullard re-issue EL34s. So these EL34-EH tubes have some hours on them. Enough that one of their brothers burned out. Close inspection shows no obvious signs as you have described. Neither tube was glowing red when the event occurred. I feel like I would have noticed that, but again I was in "kill it fast" mode.
Attached pic is how I have it wired now, which is precisely as it was wired when it worked fine for hours in triode mode. When I switched to UL, I removed the blue jumpers and installed the (purple, now taped off) UL taps exactly as shown in your wiring diagrams. That was the only change I made.
I should note that the only sign of heat that I can find in the whole works is the aforementioned star ground point. As you can see, I have that point connected to: 1) the top plate (via one of the OPT bolts), 2) ground connector of each speaker output, 3) ground connector of one RCA input connector. The charring on that ground point was there before this event occured (due to my screw up with the alligator clip) but I can't say for sure that it isn't worse now.
Attachments
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I can easily remove the cathode resistors and measure them. Which capacitors specifically should I measure and do I need to remove them from the board to do so? I do have a capacitance meter.
I am tempted to power it up with the rectifier installed and its belly exposed to see where the smoke comes from but my gut tells me that's a terrible idea.
EDIT: removed and measured cathode resistors - 667 ohms and 663 ohms
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I just asked my daughter to explain the noise that she heard. I specifically asked if the noise seemed to come from the speakers/music or from the amp itself - like was it an electrical shock/zap sound or what?
She said it came from the speakers, that the music sounded glitchy and weird, and just bad/wrong. Sort of like when you drag the needle across a record, but not exactly.
When I entered the room, it sounded normal, but again I cannot say with any certainty that both channels were working.
So if it was a tube that fried, why the smoke and where did it likely come from?
In hindsight, I should have grabbed my infrared thermometer gun and flipped the amp over quickly to try to find what was so damned hot... In my mind I was imagining finding the obviously charred, failed component.
She said it came from the speakers, that the music sounded glitchy and weird, and just bad/wrong. Sort of like when you drag the needle across a record, but not exactly.
When I entered the room, it sounded normal, but again I cannot say with any certainty that both channels were working.
So if it was a tube that fried, why the smoke and where did it likely come from?
In hindsight, I should have grabbed my infrared thermometer gun and flipped the amp over quickly to try to find what was so damned hot... In my mind I was imagining finding the obviously charred, failed component.
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Ooh, I know that feeling.
You're probably right. But now that you know your cathode resistors measure ok, you might want to literally sniff around and see if you can catch a whiff of what "poofed". That includes all of the transformers. I've never burned up a Hammond power transformer, but I've used enough of their 200-series to know they run a bit too hot for my taste.
Hammond transformers are known to run hot. I have a Hammond built Allied transformer in one of my SSE's and you can't touch it after it's been on for several hours, but I am running it well in excess of it's ratings. Another one of my SSE's has a 274BX in it and it gets rather warm, but you can touch it. I was looking at my wiring and comparing it to yours, and it was different. Then I realized that my transformer has a 1999 date on it, 21 years old.
Is this a new transformer that was never used before? If so it could have an internal short that would make it overheat, and eventually fry. It is rare, but does happen, and if that is the problem, it will occur in the first few hours of operation. If the transformer was previously used and never overheated, then this is likely not the case unless it was dropped or subject to physical abuse.
If smoke came from the transformer, there should still be a residual burnt smell at the base of the transformer where the leads come out. Unfortunately you might have to remove it from the chassis to tell. Another possibility, that happened to me years ago, is that one of the wires from the transformer was cut by the sharp edge on the chassis where the wires pass through. I did not use a grommet and the metal chassis eventually cut into the wire enough for some fireworks. It made a black spot and blew the fuse, but that was all.
The easiest way to "smoke test" the transformer is to disconnect and tape up the red wires from the board and pull out all the tubes. This will remove all load from the transformer. Plug the amp in and turn it on. The transformer should not get hot, smoke, or blow a fuse. Use the smallest fuse that you have. If it remains cool or slightly warm after an hour or so of continuous no load operation, it is OK. If bad stuff happens, it is fried internally.
A short in any of the big caps will result in a blown fuse, rectifier tube, or a vented cap. They are probably not the issue. The caps most likely to cause trouble in an SSE are the cathode bypass caps C12 and C22. They are easy to test without removing them from the amp. You will need to remove the jumpers from the T1-SEC and T3-SEC terminals. Connect one wire from your cap meter to the cathode resistor wire close to the cap, and the other wire to the right most screw terminal on the connector where you just removed the jumper.....it goes to the cap.
A tube that went into runaway usually causes the cathode bypass cap to vent spraying a stinky steam. There is usually a sticky goo left behind, but I don't see evidence of that.
I have fried a couple over the years. It was usually due to severe overloading or water intrusion. My TSE got wet in a hurricane. After it was all dried out it worked fine for several months, then just blew a fuse. A bigger fuse made it work again for a week or two, so in went an even bigger fuse......It played for about an hour then started smoking, but kept on playing. When things got real stinky, I shut it down and swapped the transformer. Autopsy revealed that it was all rusty on the inside.
C12 and C22 measure around 1330uF-1350uF.
I'll have to take a look at the power transformer next, I guess.
Also note: I did install grommets in the all the holes for tranny wires.
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George, I am running the smoke test that you described above. It has been about 15 minutes so far and no smoke, not popped fuse, etc. The transformer is running at about 90F, compared to the OPTs which are room temperature at about 80F. I will wait the full hour and report back.
Note: Wondering if the current inrush limiter is getting enough current to heat it up and allow it to function...
Note: Wondering if the current inrush limiter is getting enough current to heat it up and allow it to function...
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OK so the OPTs had been warmed by the sun before. They are down to 76F now since I closed the blinds - which is about room temperature. I only mention this as a baseline temp for comparison.
The power tranny is running at 99.5F after an hour of zero load. No smoke, no stink.
What's your verdict, George?
The power tranny is running at 99.5F after an hour of zero load. No smoke, no stink.
What's your verdict, George?
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