If you are working from a physical board and need to create or verify the Rm1-2316 schematic:
Engineers have successfully reverse-engineered the Rm1-2316 schematic to create replacements using:
One popular DIY solution (posted on EEVblog Forum) replaces the Rm1-2316 with a TI UC3845 plus an external 2.5V shunt regulator (TL431) and two MOSFETs. The schematic remains 90% identical except for the pin mapping. Rm1-2316 Schematic
When you open a service manual and see the Rm1-2316 on page 5, do not panic. Follow these steps:
Step 1 – Identify the Supply Rails
Look for the input voltage (usually labeled "Vcc Unreg" or "+18V_unreg") and all output voltages (+5V, +15V, -15V, +24V). These labels tell you the converter’s goal. If you are working from a physical board
Step 2 – Locate the Transformer
The primary winding connects to the switching MOSFET, which is driven by one of the DRV pins. The secondary windings go to output rectifiers. This confirms the topology (flyback, forward, or push-pull).
Step 3 – Trace the Feedback Path
From an output voltage (e.g., +15V), follow a resistor divider to the LED of an optocoupler. The optocoupler's transistor then connects to Pin 6 (FB). That is your regulation loop. Best substitute search: Compare the pinout against:
Step 4 – Inspect Protection Components
A resistor (0.1-0.5Ω) between the MOSFET source and ground, with a trace leading to Pin 13 (CS), confirms current-mode control. Also look for a diode clamp across the primary (RCD snubber).
Step 5 – Check Soft-Start and Compensation
Find the capacitor on Pin 8 (soft-start) and the series RC network between Pin 5 and Pin 6 or Pin 5 and GND. If these are damaged, the supply will oscillate or fail to start.
Before delving into the schematic, it is vital to understand the board's role.