Anyone used "TV mode" with Instek 6103C scope and some other service questions - Page 1
Forum section: electronics / testgear

author: jjd
author_rank: Contributor
timestamp: April 23, 2025, 12:00:58 am
content: I recently tried to use the scope's TV trigger mode, and in both TV-V and TV-H mode I cannot really see anything close to what's shown in the documentation (meaning blanking and the start of frame/row). When the timescale is fairly long, I see the pattern of H and V blanking, but zooming in to see the start of a frame/line the screen basically washes out. The same results happen if I try to scale channel 1's voltage scale, and just for TV mode. FWIW, using a 10x probe in 10x mode and I've played with adjusting the trace brightness just in case, but that didn't change much just brighter blurry image.One other curious thing I've noticed, is when power on get two notifications... check CRT and check EPROM. The latter gives me a warm fuzzy feeling that maybe something (calibration data?) isn't found so maybe running in default uncalibrated mode? There's a socked SOIC part that I was thinking was firmware, but maybe it's also storing parameters? I haven't pulled the part because I haven't figured out if if that's worth the grab (expecting protected). Anyone know if that's the EPROM? There's a small EPROM in the W78E58-40 micro and there's also a 93LC66 serial EPROM in the schematic. But I don't see a way to interface with either of those parts.While I got the attention, I've also noticed the rotary knobs for the V/DIV and TIME/DIV are a little chaotic and was thinking of trying to hit 'em with a little deoxit, but while I was thinking they are rotary encoders the schematic isn't what I expected but that could produce a similar result, right? Would the cleaning be a bad idea with what I'm seeing in the schematic?Thanks for any suggestions

author: jjd
author_rank: Contributor
timestamp: April 23, 2025, 07:28:05 pm
content: So little update, the initial "TV mode" issue is show in these images... the source (slightly seen in the background) is an Apple II, which if you're not aware has a slightly "odd" video signal in that the signal is both progressive and a little out of NTSC spec so I decided to run a test because maybe the scope can't trigger correctly on this signal.So these are the TV mode issues... both images are ch-1 tv-mode h-sync trigger, you can see there appears to be two scan lines zoomed out, and when zooming in it's tough to make out anything other than the blanking period and then the luma. Zooming in, there is no fine detail to either the blanking, color burst, or luma periods.

author: jjd
author_rank: Contributor
timestamp: April 23, 2025, 07:37:48 pm
content: Decided to grab a different video source as a sanity check and found this from a DVD player's splash screen.This looks much better!!! The blank, color burst, and line luma look as expected!After confirming the scope "should" be able to handle the tv-mode triggers I went back to the Apple II and this time, decided to remove the monitor from the equation in case it's affecting the signal, and things look better:This isn't great, nor as nice as the dvd player capture, but I can be at peace knowing this scope can't do a great job with a Apple II composite video signal.Still need to figure out the EPROM if anyone has thoughts on that, would be great if there's an interface to that SPI EPROM or the ~40 pin mcu.