# Research Notes

## What Is Well Established

- RM-M7G has a 41-page service manual available publicly through ManualsLib.
- RCP-TX7 has an official Sony 28-page operating manual PDF.
- RCP-TX7 has a 22-page service manual locally downloaded as
  [docs/manuals/0a9f4a.pdf](manuals/0a9f4a.pdf).
- RCP-TX7 Volume 2 is probably the schematic/circuit volume and appears mostly
  on paid/manual mirror sites.
- Both devices use Sony's 10-pin remote ecosystem through CCA-7 cables.
- RCP-TX7 uses a data protocol described as RS-232C-compliant/new protocol.
  CCU-TX7 and CCU-D50 material point to 38,400 bps for RCP-TX7-class remotes.
- DXC-D30 material confirms that PC control is possible only with proper Sony
  protocol.
- CCU-D50 command mode matters: `M5A mode` is the RM-M7G/basic-control path and
  `TX7 mode` is the RCP-TX7/detailed-control path.
- The RCP-TX7/CCU-TX7 10-pin remote pinout is now mostly established:
  serial data on pins 4 and 7, serial/data grounds on pins 5 and 6, DC power on
  pins 9 and 10, composite video on pins 2 and 3, and spares on pins 1 and 8.

## What Is Not Yet Confirmed

- Exact Sony command protocol framing, checksums, command table, and session
  behavior.
- Exact RCP-TX7 schematic availability from free public sources.
- Whether the RCP-TX7 22-page service manual contains enough board-level detail
  for the current fault; Volume 2 is still the stronger schematic target.
- Exact CCA-7 wire color to pin mapping; extracted wiring diagrams are too
  degraded to trust without continuity testing.
- Whether all CCA-7 cables are fully straight-through for every pin in every
  system, although related service documentation strongly suggests this cable
  family is the correct interconnect.
- Whether the serial lines are true RS-232 voltage levels on every compatible
  camera/CCU path or merely RS-232C-framed/protocol-compatible.
- Exact differences between RM-M7G and RM-M7GP.
- Exact dimensional/weight discrepancy for RCP-TX7 between operating manual and
  catalog-style references.

## Suggested Next Steps

1. Obtain the RCP-TX7 Volume 2 schematic manual.
2. Obtain a CCU-D50 service manual if CCU-side board repair becomes relevant.
3. Verify the normalized 10-pin pinout against the original PDF page images and
   any physical CCA-7 cable available.
4. Build a continuity-tested cable map with connector orientation photos and
   wire colors.
5. Check whether serial lines are true RS-232 voltage levels or TTL-level serial
   with RS-232-style framing on any particular device.
6. Use a passive serial analyzer or high-impedance oscilloscope probes on a
   known-working camera/remote combination before attempting custom control.
7. Document observed packets, timing, and state transitions in a future
   `docs/protocol/` folder.

## Practical Reverse-Engineering Cautions

- The remote connector carries both power and data, so a wiring mistake can
  damage the remote, camera, or CCU.
- Pin 10 is the positive remote power feed and pin 9 is its return in the
  RCP-TX7/CCU-TX7 pinout. Verify polarity before applying power.
- Bench discovery notes have confirmed pin 9 as ground and pin 10 as power on
  the current cable/panel under test; see [Discovery Notes](discovery-notes.md).
- Pins 2 and 3 are composite video, not serial data.
- Pins 4 and 7 are the serial data pair directions; use high-impedance probing
  before attaching an adapter.
- Sony uses the phrase RS-232C in several documents, but that does not guarantee
  standard DB-9 pinout, command language, or safe direct wiring to a PC serial
  port.
- Some connected cameras disable local controls while RM-M7G/RCP-TX7 is present.
  That can look like a fault if the control handoff behavior is not expected.
- CCU modes matter. CCU-D50 can operate in M5A mode or TX7 mode, and the wrong
  mode can make a good panel appear nonfunctional.

## Sparse Forum Trail

Searches for exact forum-style discussions around `RM-M7G` and `RCP-TX7` found
mostly manual mirrors, reseller listings, and camera/CCU manuals. There does not
appear to be a rich public repair-forum trail for these exact units. The best
available repair information is in the service manuals and related CCU manuals.