As soon as you get to the first click, the pot is then at the end of its travel in that direction.
More clicks just mean that you are still at the same end of the travel in that direction.
Instead of having a stop, there are clicks. The same thing happens in both directions.
The pot does not click while the wiper is moving, only when it stops at the end of its travel.
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Rooting for you brother!
In my psyche I would need to know what happened to start with on the build. I think you figured that out with the unterminated resistor. At that point I would probably start over with a new board and components that I knew were OK instead of potentially missing something and finding yourself back at square one. But I do appreciate your tenacity! Just trying to prevent the double feature.
In my psyche I would need to know what happened to start with on the build. I think you figured that out with the unterminated resistor. At that point I would probably start over with a new board and components that I knew were OK instead of potentially missing something and finding yourself back at square one. But I do appreciate your tenacity! Just trying to prevent the double feature.
Maybe this is a limited series on Netflix: 10 episodes, 1 season with option to extend to 2nd season.
I removed all the parts from the circuit board, but as this was the third time for the mosfets see photo for damage done. I assume this means the board is toast?
I'm waiting to be alerted that boards are back in stock [supposedly this month] so I may be down for awhile.
I removed all the parts from the circuit board, but as this was the third time for the mosfets see photo for damage done. I assume this means the board is toast?
I'm waiting to be alerted that boards are back in stock [supposedly this month] so I may be down for awhile.
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That board will still work. Just check that the center pin has continuity with speaker out/other mosfet center pin after you solder it in. Or you could jumper between center pin and "Out" with wire.
But is it a good idea to use? I don't know. A lot of current flows through there. Also, I think what you need is the least amount of potential problem variables. If you know what I mean.
Also, when removing mosfets it's better to cut the pins and then desolder them one by one if you are not going to use the mosfets again, if you didn't do that. It helps avoid situations like this.
But is it a good idea to use? I don't know. A lot of current flows through there. Also, I think what you need is the least amount of potential problem variables. If you know what I mean.
Also, when removing mosfets it's better to cut the pins and then desolder them one by one if you are not going to use the mosfets again, if you didn't do that. It helps avoid situations like this.
But don’t get discouraged Chiptech.
Early on in my DIY days if done the following:
- blown up a pair of expensive speakers (this lesson taught me what DC offset is).
- had the power cable to tripath amp catch on fire in my lap.
- Installed the power supply to a phono amp with the polarity reverses (what’s that bubbling sound? Oh, it’s the capacitors).
Early on in my DIY days if done the following:
- blown up a pair of expensive speakers (this lesson taught me what DC offset is).
- had the power cable to tripath amp catch on fire in my lap.
- Installed the power supply to a phono amp with the polarity reverses (what’s that bubbling sound? Oh, it’s the capacitors).
Chip:
Get a new board and parts. Use dale resistors for the small ones if you can, install them so we can read the code when you take a pic of the boards. Test your jfets to make sure them are good after you take them out. Get new mosfets. Use Keratherm sil pads or Mica and grease to install them.
Take good pics of both sides of the boards and show us before you fire it up. Install one channel at a time so if there is a problem you will only damage one channel.
Have some sacrificial speakers ready (I use an old guitar speaker) for when you are ready to connect it to speakers.
You'll be alright. It's worth it.
Get a new board and parts. Use dale resistors for the small ones if you can, install them so we can read the code when you take a pic of the boards. Test your jfets to make sure them are good after you take them out. Get new mosfets. Use Keratherm sil pads or Mica and grease to install them.
Take good pics of both sides of the boards and show us before you fire it up. Install one channel at a time so if there is a problem you will only damage one channel.
Have some sacrificial speakers ready (I use an old guitar speaker) for when you are ready to connect it to speakers.
You'll be alright. It's worth it.
And just so you understand what likely happened (someone like Dennis or Jim can probably explain this better but her I go):
The F5 is a push pull amp. The n and p mosfets work with each other, against each other to create a sort of equilibrium. Imagine two fire hoses spraying against each other.
The gate of the mosfet is the valve on those hoses. Each mosfets valve is turned on and controlled by the gate.
There is a resistor on the gate that establishes the connection. On one mosfet this connection was missing. In essence, the valve that controls the mosfet could not open.
Since the other mosfet has nothing holding it back it and nothing to push against it went wild and overheated and burned up the source resistor.
At least that’s the likely scenario.
The F5 is a push pull amp. The n and p mosfets work with each other, against each other to create a sort of equilibrium. Imagine two fire hoses spraying against each other.
The gate of the mosfet is the valve on those hoses. Each mosfets valve is turned on and controlled by the gate.
There is a resistor on the gate that establishes the connection. On one mosfet this connection was missing. In essence, the valve that controls the mosfet could not open.
Since the other mosfet has nothing holding it back it and nothing to push against it went wild and overheated and burned up the source resistor.
At least that’s the likely scenario.
Hey Eric, I installed these pads yesterday using Chemtronics CW7250 grease and took heatsink temp readings every 15 minutes from startup. This is what I found when comparing to the Bergquist - the result was the opposite of what I expected. I wonder why heat transfer would be slower at startup?
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Cool stuff! 
No pun intended.
It's a guess and only a guess, but it could simply be the time that it takes for the actual pad / insulator to reach its equilibrium and transfer heat from the output device to the heatsink. Root cause / explanation could potentially be the characteristics of the insulator itself and/or the contact between the output device and the Aavid insulator and to the heatsink. Did you use thermal paste between both the output device and the insulator along with between the insulator and the heatsink? I don't know the thermal characteristics of a thin layer of paste, but in some applications, if it's too thick or too thin it can affect thermals.
It would be very interesting (not that I'm suggesting that you take the additional time) to see the output device temps overlaid on that graph.
Thanks for sharing!
No pun intended.It's a guess and only a guess, but it could simply be the time that it takes for the actual pad / insulator to reach its equilibrium and transfer heat from the output device to the heatsink. Root cause / explanation could potentially be the characteristics of the insulator itself and/or the contact between the output device and the Aavid insulator and to the heatsink. Did you use thermal paste between both the output device and the insulator along with between the insulator and the heatsink? I don't know the thermal characteristics of a thin layer of paste, but in some applications, if it's too thick or too thin it can affect thermals.
It would be very interesting (not that I'm suggesting that you take the additional time) to see the output device temps overlaid on that graph.
Thanks for sharing!
Cool stuff!
It's a guess and only a guess, but it could simply be the time that it takes for the actual pad / insulator to reach its equilibrium and transfer heat from the output device to the heatsink. Root cause / explanation could potentially be the characteristics of the insulator itself and/or the contact between the output device and the Aavid insulator and to the heatsink. Did you use thermal paste between both the output device and the insulator along with between the insulator and the heatsink? I don't know the thermal characteristics of a thin layer of paste, but in some applications, if it's too thick or too thin it can affect thermals.
It would be very interesting (not that I'm suggesting that you take the additional time) to see the output device temps overlaid on that graph.
Thanks for sharing!
Yes a thin layer of paste on both sides of the insulator. I may just re-do the test and check the MOSFET temps.
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This is a curious result, Mark. When I did my original comparison of thermal interface materials, I didn't bother with interim time period measurements. I just waited for a full hour and took my readings.
Like ItsAllInMyHead, I'm wondering if this is a function of the thickness of the materials and the time required to heat them up before they begin passing the heat along. Dunno? The Aavid ceramic pads from Mouser are thick - something like 2mm. You can get cheaper ones from China on ebay, these seem to be 1mm thick. I never compared the two thicknesses.
I'm now a big fan of the ceramics because they don't puncture like the soft silpads do, plus they are re-mountable if you need to take things apart for trouble shooting.
Thanks for sharing your results, Mark. Interesting indeed!
Like ItsAllInMyHead, I'm wondering if this is a function of the thickness of the materials and the time required to heat them up before they begin passing the heat along. Dunno? The Aavid ceramic pads from Mouser are thick - something like 2mm. You can get cheaper ones from China on ebay, these seem to be 1mm thick. I never compared the two thicknesses.
I'm now a big fan of the ceramics because they don't puncture like the soft silpads do, plus they are re-mountable if you need to take things apart for trouble shooting.
Thanks for sharing your results, Mark. Interesting indeed!
Yes, so thick I had to loosen the lower mounting screws on the boards or they would have bent them at the corners. Perhaps more heat is going out the top? I don't know.
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I've also run into the challenge of having to rebend the mosfet legs while rebuilding a project or two and substituting the thicker pads.
I still haven't settled on the "ideal" length for a PCB standoff. Some time ago, I purchased a bunch of 5mm ones and now these are a bit too short. Long time ago, I purchased some that are 15mm or so and these are way too long.
Maybe something like 8-10mm?
I still haven't settled on the "ideal" length for a PCB standoff. Some time ago, I purchased a bunch of 5mm ones and now these are a bit too short. Long time ago, I purchased some that are 15mm or so and these are way too long.
Maybe something like 8-10mm?