BK Precision 1770 linear power supply instruction and service manuals

[disago]

Hi all,

I just acquired a BK Precision 1770 linear power supply and had some trouble obtaining the Service Manual. I requested it from BK Precision support and they replied the same day with it.

I'm attaching it in case it's useful for anyone else, along with the User Manual and the Datasheet.

Have a great week!

[MathWizard]

Thanks, just looking at the schematic on page 9 of the SM, they have the outputs of 3 op-amps tied directly together, U103/104. How's that allowable, is it a mistake on the schematic ??

Also, I'm just trying to make up some values and get the circuit working, but whats the purpose of Q105 on that page ?? C155 would start at zero volts, and then if Q105 turns on, it would keep it there, so to me that doesn't seem like a soft start type setup. Is it some overvoltage sensing of the +20V Vcc with that zener ??

[Kleinstein]

The amplifiers that are tied together at the outputs are Lm393. This are not OP-amps, but comparators with a open collector ouput.

With some care a few of the comparators can be used for linear operation too, but they are prone to oscillation and the manufacturer / age may matter.