EDC MV105 with Galvanometer HELP - Page 1
Forum section: electronics / testgear

author: menengrone
author_rank: Contributor
timestamp: February 02, 2016, 01:12:20 am
content: Hi guys, many members discuss EDC equipment here, so I have one MV105 with galvonometer that not work, with the schematic of MV106 found here, has galvanometer schematic, but I don't Know if is right, first, the input is grounded.Second, setup instructions says, short circuit on input to calibrate FS in 10V, so everything is grounded, turn the trim-pot and nothing.Someone can help, someone has Galvanometer to share information, schematic, pics, etc.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: February 02, 2016, 10:43:52 am
content: I have a mv105g, the original manual that came with it is for the mv106g also.If you need me to open the cover and take photos or measurements, please let me know.Do you have the full manual, or just parts of it?-Chris

author: PTR_1275
author_rank: Frequent Contributor
timestamp: February 02, 2016, 11:03:30 am
content: To set the galvometer up on mine, I flick the switch to "zero", start on 10v, then progressively go to smaller and smaller ranges making sure the needle is centered.When I then use it, change the switch from "zero" to "use", apply your input, start at 10v and adjust the first decade (1 v knob) until the needle is a little to the right if centre, go back one click, then turn the galvometer down one range and start tweaking with the next decade. Repeat this until you get the reading you wanted.

author: menengrone
author_rank: Contributor
timestamp: February 02, 2016, 12:14:05 pm
content: Thank you PTR_1275,I have the manual of MV106 found here in the Forum, posted by Dave, in fact is some parts of MV106 and some versions of Galvanometer, but MV105G has some differences.If you has original manual with schematics please contact me, I really want one copy.The Galvanometer schematic is wrong, you can see it.I am repairing this instrument because the electr. capacitors are very old and is very bad (tested, had loss of 8% and ESR High), so I changed for new ones.This unit uses reference diode 1N927A I want to change for 1n929A but I not find the procedure of how to extract the parameters wrote in the label near the diode in chassis (current and voltage). That I Know stable temp and adjust current for minimum variation.

author: menengrone
author_rank: Contributor
timestamp: February 11, 2016, 10:48:06 pm
content: Please someone that has EDC instruments with a Galvanometer, please send pictures of PCB, scale and switch of zero adj. please.

author: Vgkid
author_rank: Super Contributor
timestamp: February 12, 2016, 01:20:47 am
content: Have you e-mailed Krohn Hite about a manual. They usually have those for older pieces of gear.Really helpful company.

author: menengrone
author_rank: Contributor
timestamp: February 12, 2016, 03:24:19 am
content: Here in the forum has a manual of MV106 with schematics of galvanometer, schematic on top of topic, but has some errors,negative zener is inverted,the resistors of power supply 2X 110R, in my pcb has 330R(first) and 110R(2.),the amplifier module is 235J in my pcb 225, Who knows how it works.and the +(red) input of reference is grounded.I didn't get enter in site of Krohn-Hite for contact. Timeout all time, in any document related to company.

author: Vgkid
author_rank: Super Contributor
timestamp: February 12, 2016, 05:50:59 am
content: It is the same account for calibration/service/partsservice@krohn-hite.com