Guru
Joined: 26/07/2007
Location: AustraliaPosts: 1686
| Posted: 10:57am 04 Nov 2017 |
"And, it managed to solicit above another point of info about which I was unaware of. Namely, the location of the little transformer with relation of the secondary capacitor. I always thought it odd to stick it on the side of that little transformer, now it appears there is a good reason for that."
No.
The capacitors next to the tranny are for wave shaping, and as it turns out for you now, they are best placed on the output of your torroid... where you now have them.... sot thats a good thing...... They do not have any direct influence on the VFB, they make a sine wave out of the hash from the torroid.
The 4uf I was referring to is the 4u7 on the rectified side of the little tranny.
I know you wanted to be different, but if you look at my board, it has two decoupling and filtering parts to it.
First it is rectified, then it goes through 7k5 resistor, then it goes through the trimmer, which is 1k8 from ground, and the trimmer is 500r.
It then has 4u7 across the output of the trimmer.... to ground...so stage 1 low pass filtering and decoupling is achieved, then it goes through another resistor, and to the VFB pin as well as another decoupling/filter cap of small capacitance to chop off the HF ripple that may be there.
The only reason I have the bigger 4uf of caps on the control card is for replication simplicity. There are at least 16 of these things running 24/7 across the island... so we are probably in the 30 or more run years now across the range.. probably closer to 40. They run everything and anything, as you will have found with your powerjack unit. Hopefully your new one is ready for prime time too now.
They are incredibly reliable, and cause me no problems ( except for the known battery under-voltage problem mentioned earlier).
So mine are designed to be cookie cutter construction, they all work first time, they all work completely reliably in the field. I had to make it so there was very little chance for variation in construction. You will note your power jack version worked out of the box, so do mine. There are good reasons to use the circuit boards to do as much as you can, with as few interconnects as possible.
I hope that clears up the misunderstanding with the caps. It won't hurt to put a 100n to ground on your VFB pin to catch the HF hash that the 4u7 misses.... and twist your interconnect wires to keep stray induced voltage and noise out of them if your concerned with noise.
........oztules
Village idiot...or... just another hack out of his depth