Quasar VR-1000 - Page 3 - Videokarma.org TV - Video

starbond · #31 10-07-2019, 09:29 AM

Another update. the NTSC generator arrived this weekend. plugged it into the monitor input and oh boy, the colors are pretty bad. Looks like I have a lot of adjusting to do. Any advice?

old_tv_nut · #32 10-07-2019, 10:13 AM

Can your generator be set to a plain red field (or other single color?) Try that and see what you get.

starbond · #33 10-07-2019, 10:56 AM

Quote:

Originally Posted by old_tv_nut

Can your generator be set to a plain red field (or other single color?) Try that and see what you get.

Unfortunately no, I have a raster option but that just outputs a black screen.
The other settings are dots, crossgrid, and NTSC bars color and non-color.

Electronic M · #34 10-07-2019, 12:20 PM

Quote:

Originally Posted by starbond

Unfortunately no, I have a raster option but that just outputs a black screen.
The other settings are dots, crossgrid, and NTSC bars color and non-color.

Got a DVD player with composite and a DVD with an all red screen in it that you can pause on (a season appropriate horror flick might have an all red screen)?

old_tv_nut · #35 10-07-2019, 01:29 PM

Can you put in some regular video and see if you're getting rainbows from left to right? It's hard to tell on those bars, but the chroma frequency may be off. This seems very peculiar though, as I thought the monitor input on most VCR's just went directly to the RF modulator without being processed by the VCR color circuits. So, first you need to figure out exactly what is happening to the signal so you can figure out how to fix it.

starbond · #36 10-07-2019, 04:16 PM

Quote:

Originally Posted by old_tv_nut

Can you put in some regular video and see if you're getting rainbows from left to right? It's hard to tell on those bars, but the chroma frequency may be off. This seems very peculiar though, as I thought the monitor input on most VCR's just went directly to the RF modulator without being processed by the VCR color circuits. So, first you need to figure out exactly what is happening to the signal so you can figure out how to fix it.

On this VTR there is a switch for BW or Color. On playback mode you can switch between the two and if your tape was in color you'd get color picture, otherwise you can watch it in BW. When i switch to color mode on a tape i KNOW should be in color, I also get ranbow banding like this (see image)

This VTR has twin leads for UHF and VHF in, then RCA video.audio outs as well as coax VHF output. The generator is running thu twin lead VHF in, then I have the RCA video out going to the in on my tv.(right side of the previous image). In the schematic, most of the adjustment pots for a Scope are controlled though the VTR in monitor mode with a NTSC picture pattern.

old_tv_nut · #37 10-07-2019, 04:31 PM

OK! Since the instructions say to use an NTSC input and set the VCR to monitor mode, it must actually be doing color processing in that mode.

So, it does appear that the color frwquency is off, and by multiples of horizontal rate. That is a long way to be off, but the circuit may need that range to sync properly to tape playback.

If you want to try a short-cut (no guarantees), I would say try C525, 3.58 MHz oscillator frequency. Try to keep track of how much you turn it so you can turn it back if it doesn't work.

old_tv_nut · #38 10-07-2019, 04:37 PM

If C525 has NO efffect in monitor mode, it may mean that going to monitor mode was only meant to make the oscillator free-run, and there actually is no color processing in monitor mode. In that case, you really do need a frequency counter.

starbond · #39 10-07-2019, 04:51 PM

Quote:

Originally Posted by old_tv_nut

OK! Since the instructions say to use an NTSC input and set the VCR to monitor mode, it must actually be doing color processing in that mode.

So, it does appear that the color frwquency is off, and by multiples of horizontal rate. That is a long way to be off, but the circuit may need that range to sync properly to tape playback.

If you want to try a short-cut (no guarantees), I would say try C525, 3.58 MHz oscillator frequency. Try to keep track of how much you turn it so you can turn it back if it doesn't work.

Thanks I will take a look tonight after work. BTW on the schematic, it says "frequency counter with 1 second gate interval" do you know what this is/how i could use one for this? A quick search on ebay shows many cheap digital freq. counters, but i'm not sure how to use that here.
https://www.ebay.com/itm/DIY-Digital...229348d37cccd5
I'm also attaching another sheet from the schematic, this time the Color RECORD scope measurements, again all through Monitor mode but these may effect something as well. I dont have a scope currently as I've been debating if spending $100+ on a one time use for this one project makes sense.

old_tv_nut · #40 10-07-2019, 05:37 PM

You need a counter that can measure down to 1 Hz resolution like this one:
https://www.ebay.com/itm/0-1-1100MHz...-/121840965555

starbond · #41 10-07-2019, 07:53 PM

Quote:

Originally Posted by old_tv_nut

You need a counter that can measure down to 1 Hz resolution like this one:
https://www.ebay.com/itm/0-1-1100MHz...-/121840965555

Thank you for that link. But how do I use that? What are the connection points? Sorry for dumb questions.

And you were right, adjusting C525 does nothing, so I will have to get a frequency counter

old_tv_nut · #42 10-07-2019, 08:15 PM

Quote:

Originally Posted by starbond

Thank you for that link. But how do I use that? What are the connection points? Sorry for dumb questions.

And you were right, adjusting C525 does nothing, so I will have to get a frequency counter

The connection point on the counter is labeled "RF input" in the photos on ebay.
The connection points on the VCR are listed in the "Connection" column on the sheet you posted. For example, to set the 3.58 Mhz oscillator frequency, you would connect the RF input of the counter to TP503.

starbond · #43 10-07-2019, 09:31 PM

Quote:

Originally Posted by old_tv_nut

The connection point on the counter is labeled "RF input" in the photos on ebay.
The connection points on the VCR are listed in the "Connection" column on the sheet you posted. For example, to set the 3.58 Mhz oscillator frequency, you would connect the RF input of the counter to TP503.

The connector on that chip looks like this:. How do I get that to connect to my board?

old_tv_nut · #44 10-07-2019, 11:29 PM

You may have to get some clips like this:
https://www.digikey.com/product-deta...xoCq2MQAvD_BwE
or this:
https://www.digikey.com/product-deta...hoC6lcQAvD_BwE

starbond · #45 10-11-2019, 09:24 AM

I bought an oscilloscope the other day from CL. Been trying to check the different pot adjustments on the boards, to minor success. Cant seem to get the NTSC signal showing like it should.

BUT I did get the RF cover off over the 3.57mhz crystal. I have a feeling it mightve gone bad. Going to get a new one soon, looks like the old one is in a HC6 style case