I had so much shenanigans with those lambdas that I got rid of them and got HP. Its kind of well built, but they also had the "treat the transistor like a vaucuum tube' that IMO makes it very sensitive to certain loads (remote wired transistors on long wires). And the panel meter access is just annoying. Plus the lack of connectors, they have point to point wired chassis elements. HP was so much ahead of the game even 20 years before some lambda units came out.
I like their brick shit house design but its also got flaws in terms of not keeping up with the best build methods. They are sold at bottom dollar for a reason IMO.
This brand started to hurt my feelings... I would not invest that much time in it.
As for the FBT chips, the common ones from the LQ and LD supplies float around sometimes. But I have not seen LL before, its older. It might be possible to replace it with one of the chips from the newer ones, since they likely just changed the analog panels to digital and left the rest of the circuit pretty much alone. But it would require some study.
And my FBT chips usually were a can-8 or can-10 package IIRC, but it should not be a problem to dead bug a different shape in it, the way the supplies are built with inductance, it hardly will matter at all, you are adding inches to miles.
I really got the feeling that the designers were like "lets just replace the vacuum tube with a transistor without considering the specifics". These supplies absolutely HATE inductive loads. Even a little.
The whole "mount the transistor 10 inches away on little wires, make a square foot loop area fdr the feedback loop' thing got old.
Those little harrisons (despite being a single board in a shoddy chassis" were IMO built correctly with people that understood the technology, and have similar noise performance and much higher electrical robustness. The lambdas are not general purpose designs. Harrison was trying to cut cost (its a budget brand), but some how they actually got what I think is the correct electrical layout solution because of it, with the heatsink/transistor/board combo, on the back no less, brilliant thermal design for passive cooling, good loop area for normal operation.
Now, I can't be sure they were not leveraging the "wired" design to be lower noise, that is possible that they got higher performance then HP because of this in that region, but the gains are kind of small in terms of RMS and its a bunch of trouble. And the PSRR of modern stuff is so high, that it hardly matters like it used to. Very low noise vs extremely low noise does not matter, so long its low noise. The circuits are built too different now to care.
Now, if I had your supply (LL series, analog panel meter), maybe I would still keep it around, because it was the entire series of problems that made me change my mind. 7-segment panel meter problems were like the tipping point. If you got rid of them, maybe I would have tolerated the other bits or even modded the units for some quality of life stuff like interconnects for repair reasons. But I am not holding my breath for it being a 'great' lab supply.
Home
Help
Search
Login
Register
