Replace Amiga CD32/1200 voltage detector with a TC54VC

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Amiga CD32

I often get dead Commodore Amiga CD32 devices on my bench that only give a black screen. In most cases the Voltage Detector / Reset Generator is broken, if that’s the case then machine stays in reset and won’t boot.

The original Ricoh ( RH5VA43A, CBM: 391283-02 ) ( datasheet ) voltage detector is not being manufactured anymore,
so I searched for a replacement part and found the Microchip TC54VC43 ( CMOS ) ( datasheet ), don’t use the TC54VC43  ( CMOS ) ( datasheet ) ( this was the chip I picked to be the replacement part. The VC is a push-pul version instead of open drain. The original RH5VA43A is open drain. )

Use the TC54VN43  ( cmos open drain )

PLEASE NOTE: the TC54VC43 could be problematic on a CD32 when a keyboard is connected  to the CD32.

Anton Gale confirmed and tested this: The TC54VN works without issue (with & without keyboard). R628 is also kept at its original value (10K).

With the VC version one resistor (R628) of the voltage divider has to be changed, but with the VN version no changes have to be made.

TheVN version can be used in an Amiga 1200 as well.

Result after replacement

Picture by: Anton Gale

The pins of the TC54 must be bend a little bit to fit on the pads.

Amiga 1200

Remove old RH5VA43A and replace it with a TC54VN43.
1 pin has to be bend a bit to fit.

Pin compatible

 

 

 

Another alternative: XC61CN4302PR-G ( not tested )

Voltage detector must be CMOS / OpenDrain