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Old 10-07-2019, 04:31 PM
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old_tv_nut old_tv_nut is offline
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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.
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Old 10-07-2019, 04:51 PM
starbond starbond is offline
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Quote:
Originally Posted by old_tv_nut View Post
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.
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File Type: jpg rec-ad.JPG (94.7 KB, 12 views)
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