V 1.1 build problem.
Just fired up a mosfet BiB +/- boards, and I am not able to adjust voltage on either board. One is at ~ -13 V, and the other ~ +20 volts. Checked the trim pots (5K) and they are fine. Using 2 red LEDs, and 1K8 R203/103 with the zener position jumpered. Test load is 75R 5W, with sense wires hooked up.
BOM says Q104 is BC550 and Q204 is BC560, but the schematic appears to be confusing me? Clearly I have made the same mistake on both boards. Ideas?
Just fired up a mosfet BiB +/- boards, and I am not able to adjust voltage on either board. One is at ~ -13 V, and the other ~ +20 volts. Checked the trim pots (5K) and they are fine. Using 2 red LEDs, and 1K8 R203/103 with the zener position jumpered. Test load is 75R 5W, with sense wires hooked up.
BOM says Q104 is BC550 and Q204 is BC560, but the schematic appears to be confusing me? Clearly I have made the same mistake on both boards. Ideas?
Sorry...
Merlin, I am on dial up here, with an iffy connection to boot... No way am I going to try and post any picks from here. Looks cool though!
I ahve double checked thta the trim pots are not backwards, they are definitely correct. Everything seems like it should be fine, just weird that there is no voltage adjust???
Merlin, I am on dial up here, with an iffy connection to boot... No way am I going to try and post any picks from here. Looks cool though!
I ahve double checked thta the trim pots are not backwards, they are definitely correct. Everything seems like it should be fine, just weird that there is no voltage adjust???
So...
Use R003? Is it OK to run briefly (with good sinking) at no load for voltage adjust, with sense wires hooked up of course?
Very small dummy loads. Use in the hundreds of Ohm.
Use R003? Is it OK to run briefly (with good sinking) at no load for voltage adjust, with sense wires hooked up of course?
Do you have big sinks so to run briefly without a dummy? In that case all the CCS current is going to burn across the shunt Mosfet too, times output voltage. It must be shorted between F0 & S0, F+, S+ for positive, F0 & S0, F-, S- for negative. But before you try such dangerous stuff, do you have enough DC voltage after rectification? Also is the CCS working? How much voltage drop across the 5R6s?
Yes...
~1.0 V across R1. Big sinks, .125" angle stock 1.5"x1.5"x4", should not be a problem-I understand all the current will have to be dissapated. I can only run it briefly to get the voltage close, and test, then I can hook it up to my real load. I understand the sense wires must be hooked across to the corresponding output.
Thanks Salas!
~1.0 V across R1. Big sinks, .125" angle stock 1.5"x1.5"x4", should not be a problem-I understand all the current will have to be dissapated. I can only run it briefly to get the voltage close, and test, then I can hook it up to my real load. I understand the sense wires must be hooked across to the corresponding output.
Thanks Salas!
What it looks like is the 9610s are high Vgs and the difference from 3xLeds is small. So the CCS current ended up small. Do you have extra 5R6s to run in parallel to the ones installed? That would be the safest. Using the 75R dummies, no changes. I think the regs are simply current starved now for the targets testing. If its a trend with the CCS Mosfets batch, I will have to revise the Rset recommendations to half. But lets see what is it first for sure.
dont run without a load. It'll likely blow the IRF.
I think salas is saying use something akin to 1K 5W.
1K 1W will be fine @ 15V actually.
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