Help needed re RF sound in RGB mod Sony KV-F29SF1

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captaineos
Posts: 28
Joined: Mon Aug 06, 2018 2:20 am

Help needed re RF sound in RGB mod Sony KV-F29SF1

Post by captaineos »

Hi everyone
Long time CRT enthusiast and here needing help with RF SOUND post RGB mod.
Sony KV-F29SF1
Australian Model
G3F Chassis
Sony CXA1587S RGB chipset
Work performed:
- Wire up female SCART head with R G B terminated with 75-ohm resistors to ground
- SCART Sync pin to Male RCA jack to plug into Video 1 IN for sync
- SCART sound pins to male RCA jacks for sound on Video 1
- Voltage divider of +5V via 1.5K ohm resistor and 470ohm resistor to ground to make 1.1volts, measured in circuit perfect and switched
- Blanking of 1.1v to pin 44
- R G B to pins 47,46,45 respectively
- Lifted factor 100ohm chip resistors

Turned on, image fantastic, stable, centered, vibrant, joy.

However
When you press the TV/VIDEO button it goes from RF to Video 1,2 and 3.
The sound isn't turned off from RF!
So you get the untuned channel static "chhhhhhhhhhhhhh" noise mixed in with the stereo input.
If you select the RF input; e.g channel 1 then the sound is muted and no untuned static is heard.
If you select Video 1, again RGB image is there looking perfect but you get the static sound and no volume control. E.g volume up or down doesn't lower the static.

Huh?

Any ideas would be great as the only option I see is to ask my friend to run external speakers which isn't ideal.
Jeremy from Canberra, Australia.
KPackratt2k
Posts: 211
Joined: Sun Apr 04, 2021 11:02 pm
Location: Seattle, WA, USA

Re: Help needed re RF sound in RGB mod Sony KV-F29SF1

Post by KPackratt2k »

Do you have any RF devices you can test with (e.g. a VCR or an old game console with an RF adapter) to see if having a device connected to RF would get rid of the problem? It sounds like the microcontroller or audio switching chip on the TV could be having issues with its sound detection circuit. If you're certain that you'll never use RF on this TV, you can lift the pins responsible for pulling sound for RF from the jungle chip or audio switching chip, depending on which chip has pins for the RF audio.

Also, check to make sure the ground for your RGB connector is going to a ground pin. It's possible that you've soldered the ground of your connector to an active pin for RF audio. Check for continuity with a multimeter from the shield of the AV jacks to determine if it's ground or not.
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