Videotek TVM-621 vector scope, waveform monitor manual?
 

This is a long shot, but does anyone have a service OR user manual for this product? Videotek was a smaller company and is no longer in business (best I can tell). I've only been able to find a catalog page (attached), but I need to know the calibration procedure.

How do you know that the unit needs a calibration? The vectorscopes I have mostly agree with each other, and I'd say they are all within maybe 2-3% of each other, though mine I guess are a bit more modern.

I assume the way you'd test them is to hook up a known good color bar generator and see if everything looks correct? I'd be curious to see a picture of the unit connected to a color bar generator to show how far it currently is off that would warrant changing the calibration.

The unit's red "uncal" light is illuminated.

Beyond that - there are some buttons I'd like to understand better. Since posting below, I found that ServiceManuals.net has it for $17 as a PDF download. I'll probably just purchase it, the site/business info checks out.

Uncal probably means that you have adjusted settings outside of the internal defaults using one of the knobs. Kind of like how being off of "unity" or having changed the default values on a proc amp. Oscilloscopes do this with a "var" knob that allows you do make fine adjustments and when that is used, they'll often display "Uncal" somewhere on the screen to let you know that you aren't using the default settings.

My guess is if you slowly move the variable gain knob, the uncal light will turn green at a specific spot (to indicate it is set to the default spot), or you might just need to press the button right below it to disable the variable gain maybe.

Either way, first step I think would be to attach it to color bars to see if it is already accurate. However you do calibrate it, you'll need one of those. Popular ones would be any of the tektronix pattern generators that usually start with "TSG" in their part numbers. Since this scope is composite only, you might be Able to get away with this inexpensive TSG200: https://www.ebay.com/itm/365419156344

I have a green AVT-8710 that defaults to color bars when no input is connected. Not sure how accurate it is for calibration purposes, though ...