Sony RM 95 remote controller hack

Sony RM 95 wired remote controller has two versions:

1. REGULAR, as seen on the picture below. It has no sticker below the HOLD switch (NOR <-> ADJ). As You thought, it cannot be used to edit the EEPROM / RAM locations of various Sony devices (VCR, camcorders etc.). This seems to be the cheaper model (in 2021 it costs 40-50 EUR on ebay.de).

2. ADJUSTMENT remote controller with sticker and Sony lot number printed on it. This costs a much more (100-150 EUR!) and can be used to access the service data (edit the EEPROM etc.).

 

Fortunately I've figured out a solution how to convert a regular RM 95 to an adjustment one. Maybe there are other articles on the Internet regarding this issue, but I was unable to find it. The only reference was the RM 95 service manual and the following site:

https://english.electronica-pt.com/repair-tips?ref=RM95&marca=&sintoma=

The schematic / service manual is available here:

https://www.manualslib.com/manual/545797/Sony-Rm-95.html

But this is a description how to convert a ADJUSTMENT remote controller to a regular one! We need a vice-versa method. On the schematic it clearly seems what is missing: on a regular version R18 is not soldered to the PCB, so I've added a 10k resistor (1206 instead of 0805... :) ).

This modification was not enough to enable the adjustment mode. I have also checked J1 and J2 connections: J2 was present by default, but J1 was missing. Connecting a wire didn't solve the problem: as I thought in advance, it will either break the microcontroller or will cause malfunction. Fortunately option 2 has been realised: no damage was made to the microcontroller, but blocked the entire remote controller. So, J1 is definitively not required. :)

The solution was to short pins on the HOLD switch (as marked on PCB - see the picture below).

This step enabled the adjustment functions after switching the switch to HOLD position. Now I have a fully functional adjustment RM 95; no need for a PC software, interface, anything.