Kenwood CS-4025 question. [Problem fixed] - Page 1
Forum section: electronics / repair

author: SID6581
author_rank: Newbie
timestamp: May 28, 2017, 05:33:15 pm
content: Because the EEV channel and 2 others.I want to pickup after many years working with electronics again more. Still would fit in the category Novice.Now i buyed 17 years ago a kenwood CS-4025 scope.I placed it on the self and it still works.But my problem is that if you change the Volt/Div setting. i see spikes on the screen. I do not see that on Ch2.Now you would think, dirty contacts. But at first look all contacts seems pretty sealed, i need to look closer.I like to know what others think, just accept the spikes while switching Div/Volts.Or try to look for a place wherer you can sprake soem contact spray in the Ch1 switch ?Last option could be that something else is not 100% on that channel.The scope is not used for many years.Thanks.

author: SID6581
author_rank: Newbie
timestamp: May 29, 2017, 07:15:39 pm
content: I looked better at the scope. decided to not botyher about switching spikes.I discoveryed that with the first test i forgot to select channel 2.So both channels have the same switching spikes.After so many years start to rememb er how the scope workedBut, now a strange problem.I connected the scope calibrate to ch1. and adjusted the setting so i see a square waveform.After that i did set ch2 to the same settings and moved the probe to ch2 and switched it.But the signal on channel 2 is lower then on ch1.After that i have connected my power supply set to 12 volts to the scope.Ch1 i need to set at 5 volt/div. But if i set ch2 the same i need to switch it to 0.5volt / div to get the same result.The scope is defective after a long time of no use ? Or something else did happen.Well i can still use the scope for basic things. but only on channel one for now.It could be possible that ch2 gain need to be adjusted again, and that things then work fine. (VR57)

author: rsjsouza
author_rank: Super Contributor
timestamp: May 30, 2017, 10:41:01 am
content: Quote from: SID6581 on May 29, 2017, 07:15:39 pmI don't have mine here with me now, but check if the magnitude adjustment setting of both channels is set to "cal" - the small potentiometer in the middle of the volts/div rotary dial. Rotate it in the direction of the "cal" arrow (clockwise) until you can feel a lock and then you should have a precise measurement.

author: SID6581
author_rank: Newbie
timestamp: May 30, 2017, 11:13:07 am
content: QuoteThanks, thats the default setting i use.But it still need a different bolt/div setting with the same input compared to ch1I found a better manual with all schematics now. Looking at that.

author: SID6581
author_rank: Newbie
timestamp: May 30, 2017, 12:23:37 pm
content: I found it !Really a beginners trap.The knob of the ch2 volt/div where not placed correct.Not sure how that could happen, mabye in the past with something.I placed that now correct back and the voltage seems the same now as ch1.I compared ch1 with ch2 by putting the same signals in and display them both,It seems close enough to call it ok.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 30, 2017, 12:36:00 pm
content: Good to hear this is fixed. And thank you for reporting back what it was (too many folks ask something only to vanish without any regards for the efforts of others that replied)