# Discovery Notes

This file records hands-on observations separately from manual-derived facts.
Treat these as bench notes: useful and current, but still worth rechecking with
photos, continuity tests, and instrument captures.

## 2026-05-13 - RCP-TX7 10-Pin Power and Cable

Observed on the RCP-TX7 10-pin remote connector/cable during restoration work:

- Pin 9 confirmed as ground / DC return.
- Pin 10 confirmed as power input.
- Cable color for pin 9 / ground: brown.
- Cable color for pin 10 / +12 V power: brown-white.
- Cable colors for pins 1-8 have been continuity-mapped; see the working cable
  map below.
- Yellow and yellow-white conductors are present in the cable but did not map to
  connector pins during continuity testing.
- With power present on pins 9 and 10, the panel shows a green `PANEL ACTIVE`
  light.
- The inside of the 10-pin cable contains 12 wires total.
- Three of those wire groups are twisted pairs.

Immediate implications:

- The bench result agrees with the RCP-TX7 and CCU-TX7 manual pinout for pins 9
  and 10.
- The 12-conductor cable construction suggests not every conductor maps
  one-to-one to the 10 connector pins; shielding/drain, duplicated grounds, or
  paired signal returns may be present.
- The three twisted pairs are likely important candidates for serial data,
  composite video, and/or power/ground pairing, but this should be confirmed by
  continuity testing rather than color or twist assumptions.

### Working Cable Map

This table combines the manual-derived pin purpose with hands-on color mapping.
Rows marked `confirmed` have been checked on the current cable/panel under test.

| Pin | Purpose | Cable color | Status | Notes |
| ---: | --- | --- | --- | --- |
| 1 | Spare / unused | red | confirmed | No function shown in service manual. |
| 2 | VBS / composite video X | black | confirmed | 1.0 Vp-p composite video input to RCP. |
| 3 | VBS / composite video ground | green | confirmed | Video reference/ground. |
| 4 | Serial data, RCP to CCU/camera | orange | confirmed | RS-232C-based data direction. |
| 5 | Serial/data ground | blue | confirmed | One of two serial/data grounds. |
| 6 | Serial/data ground | grey | confirmed | One of two serial/data grounds. |
| 7 | Serial data, CCU/camera to RCP | purple | confirmed | RS-232C-based data direction. |
| 8 | Spare / unused | purple-white | confirmed | No function shown in service manual. |
| 9 | DC return / ground | brown | confirmed | Confirmed as ground on current cable. |
| 10 | +12 V remote power input | brown-white | confirmed | Confirmed as power input on current cable. |

### Unmapped Cable Conductors

The cable contains two additional conductors that did not show continuity to
the 10 connector pins during the current test:

| Conductor color | Current status | Notes |
| --- | --- | --- |
| yellow | unmapped | May be shield/drain-related, spare, broken, or connected only at one end. |
| yellow-white | unmapped | May be shield/drain-related, spare, broken, or connected only at one end. |

Recheck these against connector shells, shield braid/drain, cable strain relief
hardware, and both ends of the cable if accessible.

Suggested next observations to capture:

1. Connector orientation photo showing pin numbering reference.
2. Wire color list, including which colors form each twisted pair.
3. Confirm whether yellow and yellow-white connect to shield, shell, or one end
   only.
4. Resistance between pins 5, 6, and 9 with the cable disconnected.
5. Scope/meter idle voltage on pins 4 and 7 relative to pins 5/6 and pin 9.