Hi Andy,
If R18 burns out it’s not because of oscillation but because of a bad or intermittent connection on your main pass BJT transistor. If you forget to connect the transistor Flying lead (or have a loose connection), the only path for the current is through R18. I burned one out when I once forgot to connect the flying leads Molex. Did you crimp the Molex connector properly? Try soldering the wires permanently to see if the problem goes away.
I have only 1 more set of SSRs gen 1 saved for my own next project. We can work something out if you really need another one.
If R18 burns out it’s not because of oscillation but because of a bad or intermittent connection on your main pass BJT transistor. If you forget to connect the transistor Flying lead (or have a loose connection), the only path for the current is through R18. I burned one out when I once forgot to connect the flying leads Molex. Did you crimp the Molex connector properly? Try soldering the wires permanently to see if the problem goes away.
I have only 1 more set of SSRs gen 1 saved for my own next project. We can work something out if you really need another one.
I have already bypassed the Molex connectors on my SLBs (because I hate them so much!
) and soldered the wires directly to the pcb.btw, I think it is R15 which blows if you don't have the transistor flying leads connected - at least, that's what happened the first time I fired up an SLB.
Thanks, X.
Andy
Hi Andy,
When you have a loose connection on the BJT the current passes through both R15 and R18, and either may burn out. Have you verified that you don’t have a cold solder joint on the board somewhere? The PCB has a large ground plane and being 2oz copper and 2mm thick FRP, requires at least a 60w iron and big fat chisel tip to fully liquify the solder. Cold solder joint might cause intermittent connection leading to random melt downs. That’s about all I can think might be the problem as no one else seems to be having these issues. What value are you using for R18?
This is a bit OT and belongs in the SLB thread - perhaps we should take it up over there?
The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB
When you have a loose connection on the BJT the current passes through both R15 and R18, and either may burn out. Have you verified that you don’t have a cold solder joint on the board somewhere? The PCB has a large ground plane and being 2oz copper and 2mm thick FRP, requires at least a 60w iron and big fat chisel tip to fully liquify the solder. Cold solder joint might cause intermittent connection leading to random melt downs. That’s about all I can think might be the problem as no one else seems to be having these issues. What value are you using for R18?
This is a bit OT and belongs in the SLB thread - perhaps we should take it up over there?
The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB
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I guess I am going to need to make more of these. Currently sold out.
Let’s start an interest list to see how many people are interested in another round. This time it will be rev2 with some upgrades.
Can handle up to 150v so good for 350w amp. The ground on power supply is optically isolated from amp negative, use with bridged amps possible. Also has remote instant shutoff with a small external low capacitance PSU board to do the turning off when powering down. This will stop the speaker thump as disconnects in 100ms.
These will go for $47ea. Fully built and tested. I need at least 100 to go to production.
Free shipping in the US.
GB interest list... please add your name.
Name / number of units / Country
Let’s start an interest list to see how many people are interested in another round. This time it will be rev2 with some upgrades.
Can handle up to 150v so good for 350w amp. The ground on power supply is optically isolated from amp negative, use with bridged amps possible. Also has remote instant shutoff with a small external low capacitance PSU board to do the turning off when powering down. This will stop the speaker thump as disconnects in 100ms.
These will go for $47ea. Fully built and tested. I need at least 100 to go to production.
Free shipping in the US.
GB interest list... please add your name.
Name / number of units / Country
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Hi X,
I've just fired up my 'problematic' AN 4R board - after increasing C4 in the attached AN 4R schematic from 15pF to 22pF (Hugh's suggestion, to stop the 4R cct from oscillating).
And it worked!
I also then found that my suspect SSR board is working fine! Yay! So I don't need another SSR board!
Andy
Attachments
Hi X. Can I just confirm my understanding that your new version will handle speaker protection with an amp running B+ of 150V?
If so, that makes them usable with my 6C33C SE-OTL amp with B+ at 140V - always been a little nervous of the consequences of a valve failure...
Yes, the MOSFETs are rated to 150v and so is the onboard voltage regulator.
Here is the part from Infineon - good for 150v, 80A, and 10.5mOhm Rdson.
https://www.mouser.com/ProductDetai...zNvH0CV6YSeQt6chqXZC6ZrmDvglxrL3HiHg4yREonQ==
Here is the part from Infineon - good for 150v, 80A, and 10.5mOhm Rdson.
https://www.mouser.com/ProductDetai...zNvH0CV6YSeQt6chqXZC6ZrmDvglxrL3HiHg4yREonQ==
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