Hi all
I got an almost completed B1 from a friend with too many projects. He used high quality components, original JFets and the soldering looks fine. However, it distorts like mad. I have no clue to why really, but I am beginning to suspect that the circuit may have been connected with the wrong polarity from the power supply (19,5 volts). That could damage the large polar caps. Could that result in distortion? No visible damage to anything. I do not have an osciloscope, but the voltage in the circuit seems right.
I got an almost completed B1 from a friend with too many projects. He used high quality components, original JFets and the soldering looks fine. However, it distorts like mad. I have no clue to why really, but I am beginning to suspect that the circuit may have been connected with the wrong polarity from the power supply (19,5 volts). That could damage the large polar caps. Could that result in distortion? No visible damage to anything. I do not have an osciloscope, but the voltage in the circuit seems right.
you need two pairs, not one quartet
say that pair matched in 1mA is OK, matched in 0.5mA is even better
pics
DiyAudio store get in stock LSK170 B grade quarted matched with Idss+-0.1mA
Linear Systems Matched JFETs – diyAudio Store
PassDiy shop have jfet's with the board PassDiy
So ... I finally finished my build and put it in a nice shiny box, powered it up and it is power cycling! I read back through this thread and another person had a similar issue and he switched power supplies and that resolved it. I purchased a Meanwell GS15B-5P1J for mine, 18V @ 830mA. This is the one cycling! I grabbed a 12V 2A wall wart I had laying in the basement and it works without cycling. WTF is causing this? Does anyone have a known good 18V supply they can recommend?
Don't ask me.
Obviously one can tolerate the load and the other one cannot.
Maybe the first one was faulty from the beginning?
Obviously one can tolerate the load and the other one cannot.
Maybe the first one was faulty from the beginning?
What size caps are you using on the initial RC filter? I know some switchers have issue with the initial charge due to some protection circuitry. Not sure if the initial in rush could be triggering it?
Thanks! 😀
codyt said:
10kuF ... that is the only thing that makes sense but the Meanwell datasheet only mentioned zener protection?
What PSU are you using on your B1?
That's it! I powered it with the 12V for a few minutes, then swapped out supplies and the 18V is powering it fine now that the caps are charged.
Now I just need to know what 18V supply to order that works! 😎
Nice! I’ve used a Triad and a Meanwell in the past. Triad was WSU240 and Meanwell was SGA12U24. Both are 24v, but I recall using a random 19v Walmart-special switched in the past as well.
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I also saw this on the data sheet from the one you have now. Not sure if that is what’s happening or not.
“ Protection type : Hiccup mode, recovers automatically after fault condition is removed”
“ Protection type : Hiccup mode, recovers automatically after fault condition is removed”
Build it!
Hi,
I am revisiting this post ~10 years after building my B1. I just wanted to encourage those thinking about building it to do it. It is quite a simple build and generally will not require troubleshooting. For fun I did my B1 in a point to point manner (no pcb) and put it in a simple enclosure.
My build is still working great with an 18v external laptop power supply after 10 years. I use it regularly in the garage coupled to a diy amp and mainly use a bluetooth receiver for input.
a few pics
Cheers
Hi,
I am revisiting this post ~10 years after building my B1. I just wanted to encourage those thinking about building it to do it. It is quite a simple build and generally will not require troubleshooting. For fun I did my B1 in a point to point manner (no pcb) and put it in a simple enclosure.
My build is still working great with an 18v external laptop power supply after 10 years. I use it regularly in the garage coupled to a diy amp and mainly use a bluetooth receiver for input.
a few pics
Cheers
Attachments
Have you tried placing some resistance between the offending power supply and your PCB?
