VCR won't record or playback color

A portable Beta VCR from 1985 works perfectly except there is no color:

  1. Pre-recorded color tapes play back in B&W
  2. Tapes recorded on this VCR play back in B&W on this VCR
  3. Tapes recorded on this VCR play back in B&W on other known good VCRs

Therefore, the VCR can neither record nor playback color signals. What is the most likely cause?

Is it the 3.58 MHz oscillator, the comb filter, the color killer, or lack of a color burst? Or, is it just a defective transistor or IC that contains an internal B&W/color switch?

Thanks

Reply to
VCR Gymnast
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My guess would be the 600kHz3.58MHz conversion circuits. Do u have a schemo for this unit and what kind of test signals are u capable of injecting?

Reply to
Ray L. Volts

VCR Gymnast ha escrito:

Today I fixed a sony vhs with this symptom. e-e pic ok, tapes no colour, as you describe. had to resolder a bit in the y/c section and replaced several 1uF caps and the 4.43 xtal for good measure.

-B.

Reply to
b

"VCR Gymnast" wrote in news:1152157251.328327.300970 @a14g2000cwb.googlegroups.com:

Have you tried cleaning the heads? We had one that went to black and white and cleaning the heads made it come back to color part way.

Puckdropper

--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
Reply to
Puckdropper

Make sure there isn't a color / bw switch somewhere, like on the back panel. Seen it on U-Matics, anyway...

Mark Z.

Reply to
Mark D. Zacharias

I cleaned the heads both manually and with a Scotch cassette cleaner, but no improvement. Video remains B&W.

Reply to
VCR Gymnast

There is no external BW/Color switch. This switch is present inside an IC somewhere in the chroma circuit, which is a separate module in this very small modular VCR. Even though this VCR is a Beta from 1985, it is the smallest VCR ever made.

Reply to
VCR Gymnast

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