Author Topic: help with the schematic  (Read 218 times)

bretskee

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help with the schematic
« on: March 20, 2020, 08:04:26 PM »
Hi Felix,

as in one of the other posts, I too have stupidly damaged my unit. In diagnosing the issue, I looked at the schematic and am wondering how part of it is intended to work. The section is attached. I understand of course how the mosfets introduce the shunt resistors for uA and nA, but I do not understand the logic of the mA circuit and how the RDSon of its mosfet is not significant in the path. Could you explain the idea behind the bypass mosfets also please. The NMA tag is a mystery as it does not appear anywhere else on the circuit.

A brief explanation would be helpful. Thanks

Felix

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Re: help with the schematic
« Reply #1 on: March 20, 2020, 11:04:42 PM »
Without going into very detailed detail, that circuit is part of the switching and biasing logic.
But to get to the botttom of your problem - you're in need to fix your CR correct? Maybe I can help more with that.

bretskee

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Re: help with the schematic
« Reply #2 on: March 21, 2020, 08:11:15 AM »
OK, i have found my issue with a blown mosfet and repaired it by using one from the uA switching circuit. The rest of your answer is not very helpful.

Felix

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Re: help with the schematic
« Reply #3 on: March 21, 2020, 08:37:28 PM »
Did you buy your CR from LPL or from WELECTRON?