can a Vector type oscilliscope be used to clean up a vhs video tape - Page 1
Forum section: electronics / beginners

author: dariens007
author_rank: Newbie
timestamp: February 21, 2016, 03:28:14 am
content: howdy, i'll be setting up my lab soon for tinkering with electronics. hehe i think i got that uni-t because he rags on them so bad lol?but anyway i was looking for an oscilliscope...and i saw a vecotor oscilliscope. seems very different from a normal oscilliscope so it probably cannot be used really the same way? was curiousbut anyway..i also remmeber that i have about 50 VHS tapes i need to convert to digital. can a vectorscope be used to clean it up and make it look better?i was trying to figure out it... well if anybody happened to know i had about 16 hours to make the purchase. it's 50 bucks and it looks like there are 2 vectorscope in a rack mount that appear to be working.so...2 for the price of one? seller says it came from a radio stationEDIt: forgot this is the model and serialLeader LBO-5860H Waveform Monitor/LVS-5850B Vectorscope W/ Rack - the first one this is a single buyLeader Electronics LBO-5860A Waveform Monitor and LVS-5850B Vectorscope- the second one this is a single buybut does anybody know if it can be used for that?IF not...would it really be useful as a normal oscilliscope?or...just some help about what i could use it for really...especially cleaning up vhs if that's even possiblei plan on taking electornics apart...tinkering, building some things in the future

author: vk6zgo
author_rank: Super Contributor
timestamp: February 21, 2016, 03:49:57 am
content: Quote from: dariens007 on February 21, 2016, 03:28:14 amThere are Vectorscopes & Vectorscopes.Video Vectorscopes range from the early 520series Tek units,& their modern equivalents, which not only measure colour signal vectors---they also measure differential gain & phase,through smaller ones which are vectorscopes only,to "vector displays" which require an external device to provide the decoded colour signals,There are also audio vector displays which are used for stereo sound signals.(the ones you are looking at may be that type,which are useless for video.)If the tape signals look lousy because your VHS playback device is lousy,there may be adjustments within the device you can do----whether a vectorscope would be useful is doubtful.If you are using the composite output of your VHS device,you may be able to use something like a Colour Stabilising Amplifier to "tweak things up a bit".Component video may give you better results.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 21, 2016, 03:54:03 am
content: A waveform monitor (like your Leader LBO-5860H) was used to examine analog video signals back in the pre-digital era. It is a little bit like a regular oscilloscope except that it has fixed vertical sensitivity and fixed horizontal sweep frequencies and fixed triggering. You can typically use an ordinary general-purpose oscilloscope to view analog video waveforms, but a waveform monitor is essentially useless except for viewing waveforms.And a vectorscope (like your Leader LVS-5850B) is even more specialized to show the PHASE of the 3.57545 MHz color subcarrier with the color-burst as the reference. This is what the displays look like when viewing a typical video scene...While a waveform monitor and vecorscope may help you VIEW problems playing back antique videotapes, they won't do any good to actually CLEAN UP the video.If you want to digitize old VHS cassettes, you will need a decent playback machine and something to digitize the video, and quite probably a time-base corrector (TBC), possibly with dropout compensation (DOC). Some cassette machine have TBC and DOC functionality built in, and digitizing interfaces have some limited TBC functionality (for example the Canopus ADVC-300).

author: N2IXK
author_rank: Frequent Contributor
timestamp: February 21, 2016, 11:32:06 pm
content: Both a vectorscope and waveform monitor are useful for checking video signals, but as others have said, they will do nothing to "clean up" a poor or distorted signal. To do that, you want a timebase corrector (TBC) and/or a processing amplifier (procamp).The TBC is good for stabilizing the signal from a VHS or other consumer grade video source. A procamp can help improve sharpness, white and black clip levels, sync levels, etc. Procamps and TBCs are best adjusted WITH a waveform monitor and vectorscope, along with a standard test signal source.

author: dariens007
author_rank: Newbie
timestamp: February 22, 2016, 10:25:57 am
content: Thanks! So i'll pass on the vector type scope as i wont really benefit from it. I'll have to look up those other 2 things u guys were talking about to help improve the Vhs.Ill just have to buy a real oscilloscope!Thanks aagain

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 22, 2016, 01:58:22 pm
content: Your major challenge will be extracting the signal off the tape with some of reasonable completeness and quality. Because VHS was a rather low-end consumer format, "interchange" was frequently a problem. Slight differences between the recording machine and the playback machine cause problems.And then tape damage causing both time-base errors as well as drop-outs where the tape is creased or crunched or some mechanical defect that prevents perfect contact between the tape and the heads flying around on the drum.Here is a video showing some common VHS playback problems and how a TBC corrects many (but not all) of them...https://youtu.be/tMA5aH_olAQAs @N2IXK mentioned there is also a "proc-amp" (processing amplifier), sort of a "tone control" for video. That was an important tool back in analog video days, but these days, those kinds of controls are nearly trivial and free in the digital domain once you have the video captured.