Instek GOS-620 Calibration manual? - Page 1
Forum section: electronics / testgear

author: jknightandkarr
author_rank: Contributor
timestamp: January 15, 2020, 07:38:02 am
content: Just finished one of Dave's videos on his $19 Hameg analog ocsilloscope. Been meaning to register but upon looking for a calibration manual for my Instek GOS-620 scope, I have the service manual, but would like anything on calibrating the inside components in case I have to replace something. I know the up and down traces might need adjustment. I uploaded a photo of my display. Is this normal? From what I've seen on YouTube, I think mine needs adjustment.

author: Specmaster
author_rank: Super Contributor
timestamp: January 15, 2020, 08:58:16 am
content: The calibration procedure should be in the service manual, however looking at your photo, that is not your problem but your probe needs adjusting. This video will explain your problem, what it is and how to adjust the probe to get back to a perfect square wave again.

author: jknightandkarr
author_rank: Contributor
timestamp: January 16, 2020, 07:04:25 am
content: Thanks for the video I will watch it. I figured my up and down lines aren't right, but I watch zome videos from people who have the same scope as me, and they all, look fades going up and down, while some scopes have them just as bright as the side to side lines.I will check my manual for calibration info.

author: Specmaster
author_rank: Super Contributor
timestamp: January 17, 2020, 01:09:02 am
content: Just trust me, you do not want to open up the scope and start touching anything, you need specialist equipment to that. Your photo is just perfect apart from it needs the x10 mode adjusted as shown in the video which is either done on the probe or the BNC plug end with a very fine screwdriver. The vertical lines should be almost invisible due to the amount of time the line has to taken to reach from the bottom to the top of the line. This time is very short in comparison to the horizontal which you can see if you play around with the timebase knob. By doing that you will see many short horizontal lines or if you turn the control in the opposite direction, you should be able to it down just part of a horizontal line that occupies all the screen width. What you will notice is that while playing with the timebase like this, the vertical length, i.e. the number squares on the screen it occupies remains the same regardless of the number of horizontal lines you display.Basically the horizontal squares are measurements of time and the vertical ones are a measure of the voltage. Click on this link and it will present you with loads of videos that will take through the basics of how to use a scope and how to calibrate the probe to provide you with a nice neat square wave.https://www.youtube.com/results?search_query=oscilliscope+basics

author: jknightandkarr
author_rank: Contributor
timestamp: January 17, 2020, 10:28:13 am
content: Thanks will check it out. Though I have had it open once to make a small repair that involved one wire popping loose from its connector.

author: Specmaster
author_rank: Super Contributor
timestamp: January 17, 2020, 07:06:56 pm
content: Yeah, thats OK, I was meaning, don't open it up and start twiddling the various calibration pots because you'll screw it so badly if your not careful with the proper tools to do it with.

author: jknightandkarr
author_rank: Contributor
timestamp: January 19, 2020, 01:50:02 am
content: Trust me, i wouldn't mess with anything unless i knew its ideal setting.

author: Specmaster
author_rank: Super Contributor
timestamp: January 19, 2020, 02:04:41 am
content: OK, but to obtain the ideal setting for your particular problem, it can all be done from the front panel, from the outside and the ideal tool for the job is the little special screwdriver that is supplied with each and every probe, some will be very fine gauge steel set in a plastic handle and others will plastic or even ceramic, depending on the make of probe. The good news is that for your scope you only need basic probes with a X1/X10 switch which use a plastic handle with a very thin piece of steel as the blade to avoid as magnetic / capacitive interference as possible when adjusting the square wave on screen.