Iwatsu SS-5212 display problem - Page 1
Forum section: electronics / repair

author: zulphur
author_rank: Newbie
timestamp: January 17, 2020, 11:03:45 am
content: Hi,I have recently bought my self an Iwatsu SS-5212 Oscilloscope for some tube amplifier testing. Problem is that I can not get the display to work properly. There only is a trace on the left side of the display, it can not be adjusted to the right side. Adjusting in the left part of display is no problem, it goes up/down and left/right. Problem is the same for both channels. I can not find any documentation or instructions for this scope, and I do not have the greatest experience in finding faults and fixing complex devices. I would like fix this scope if possible.Any ideas? Maybe it is even down to me not adjusting scope correctly?Attached is a picture of the display.ThanksAnders

author: coromonadalix
author_rank: Super Contributor
timestamp: January 17, 2020, 11:34:56 am
content: Normally the button position with the red circle (joined photo) should help to center the displayed wave ... you have the red (center) normally locked control, try to see if its doing somethingUse the Cal out pin with the probes to get an stable displayed signal ...Or maybe some capacitors filtering issuesthe best would be : try to find an service manual and an user manual before doing anything ...For the inside adjustements : one trick is when its powered off completly and all power is discharged, take an ohm meter and measure if possible all the trimpots inside called horizontal and vertical position, measure each side of the 3 pins and take note of the values on a paper.BUTThe front panel position button is the one who will center the displayed wave(s)

author: zulphur
author_rank: Newbie
timestamp: January 17, 2020, 01:33:03 pm
content: Thank you for the quick reply. Attached are 3 photos of the results when I operate the position button. First photo button all way counter clockwise, photo 2 button in the middle, and photo 3 button all way clockwise. I have tried the pull function as well, this does not shift trace to right side of display either.Thanks

author: JFJ
author_rank: Regular Contributor
timestamp: January 17, 2020, 03:27:16 pm
content: It looks like there's a problem with your oscilloscope's horizontal amplifier or the timebase signal feeding it. A first step would be to check that the voltages of the scope's various power supply rails are correct.In the absence of an Iwatsu service manual, you may find the "Troubleshooting The Horizontal Section" chapter of this Tektronix guide helpful:https://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: zulphur
author_rank: Newbie
timestamp: January 18, 2020, 08:51:34 am
content: Thank you for the suggestions so farI went ahead and removed what I belive is the board containing the horizontal amplifier. I discovered some questionable repairs to the board (see picture). The repair is in an area with 2 equal circuits with 2x2 2SC995X transistors with heat sink. Could the horisontal amplifier be seperated into 2 amplifiers driving each half (left/right side) of the CRT?I can go ahead and change the components in the “repaired” side, but which ones to start with?/Anders