RF-Tap Location Types

Before fully understanding what you need to understand ware, there are several locations to tap a VCR for its raw video, audio, control & potentially timecode off the audio channels The Tap List has all relevant data on the physical points located on current VCR's updated as members collectivly contribute more information.

We are tapping into and capturing the tracked full video signal that's a pre-amplified RF signal.

The Signal Range of any usable information across all formats of VHS is approx. 250khz-8mhz, this extends into the 9-10mhz range for Beta tape formats.

Name of signals for tapping is Video Envelope this contains both Y/C Luminance & Chrominance so when looking on a schematic its the RF C line mostly being the current go-to default tap as it has full signal in most cases but more in-depth testing on a per-VCR basis is needed hence test points are your best bet.

Complete signal chain of the VHS VCR (video cassette recorder).

Drum With Magnetic Heads -> Connection Board -> Ribbon Cable -> Board with Control IC Chip -> Internal Signal Tracking -> Tracked RF Output -> Pushdown or Ribbon -> Mainboard or Processing Boards -> Demodulation -> Possibly TBC & DNR systems -> Baseband Composite Playback (1 RCA or S-Video separated)

(Pro/Prosumer decks have control/amplification on an dedicated shielded board)

1. Test Points

Video:

RF Y, RF C, RF Y+C, V RF, PB, PB.FM, V ENV, ENV, ENVELOPE, VIDEO ENVE, VIDEO ENVELOPE

HIFI:

HIFI, A.PB, A-Out, A ENV, HIFI Envolope

Pro Decks: Some have external RF output for duplication use these ports need further testing.

These are all valid points for tap testing and creating amplified or non amplified BNC backports if signal issues occur try an 10uf or 100uf electrolytic cap in-line.

2. Post Control/Head Amplifier

As higher-end units normally have their control and amplification unit on a user-removable board of note the Panasonic K-Deck (FS-200/NV-HS1000/NV-HS950/950B etc) this allows you to either run cables directly from said amp before it sends to the rest of the system with some amplification boards are easier to access allowing for a direct amplified SMA/SMB soldered male ports on the amp its self allowing for a very clean and self-contained setup.

(Note: On the NV-HS950B this works fine for VHS but needs an 10-100uf cap for SVHS)

3. Mainboard & Processing Boards

While audio test points are always findable on the main PCB for HIFI VCR's, higher end units have there demodulation/time base corrector's on separated boards usually alongside a full array of test probe points that can also be better flittered and have higher amplification in some locations but can also cause issues if components are degraded.

4. Direct Head Drum

This method will require either a modified control board or an external amplifier as its the "True Raw" untouched unamplified signal this tapping method is intended for testing and development, as such its easier to do later generation VCRs that expose the solder points with topside control boards allowing for ease of direct solder tap to 50Ohm SMA or DIN 1.0/2.3 connectors to be run off of said points then amplified for direct capture, with multi card CX setups viable as of 2022 this is now an viable R&D segment.

Types of Cable and Connectors And Length!

The only set standard here is 50Ohm cable and connectors.

So for cable, the general recommendation is the common RG316/RG58 & RG178 for smaller needs which is cheap per meter small enough to be routed internally broadly obtainable in bulk or via off-shelf cables so that's the reference this wiki will be using.

Full-BNC is the best for fixed backports with a locking and reliable connector used in everything from 1960's communications gear to current day cine cameras.

Micro-BNC (DIN 1.0/2.3) Is the smallest locking knock safe connector seen on portable equipment. (Reference Part Number: 45K201-400L5)

SMA is a flat external sided, threaded locking connector found in almost all common consumer RF devices such as 4G/Handset radio units.

SMB is the lesser-known but it's a tighter than TS-9 style non-locking connector.

Amplification

While there are few benefits for maintaining the signal level and lowering noise for weak output VCR most benefit is for extended cabling and for CX card users having 6db set to off and digital gain set to 0 on the CX cards for cleaner RF captures & VCRs with a low signal output from a test point.

Listed below are chips that are available for off-shelf part use and premade boards are widely available.

1. Analog Devices Dual Channel OPA AD605 (In-testing)

2. Analog Devices Linear Technology LT1252 Low-Cost Video Amplifier (built for application)

3. Texas Instruments OPA657 (Confirmed on LD players)

4. Texas Instruments OPA690 (Used by the DomesDayDuplicator)

5. Analogue Devices AD8367 An tested amplifier that could be used for future solutions