The ‘HB-45A’ is a custom IC used on some PCBs manufactured by Seibu like Raiden II/DX and SPI motherboard.It can be considered an evolution of the ‘HB-41’ that we already treated in a past article:
It shares the same 20 pin SIL package embedding most of the analog sound system.Its function is to mix and pre-amplify both music and sound FXs :
Here’s how it look “naked” of its external coating:
Design is almost identical to its predecessor with the presence of two OP-AMPs (a dual and a quad one) although they operate from a single supply (+12V) and not dual (+5V/-5V) like the ‘HB-41’.All other components are ceramic/tantalum capacitors and resistors (surface mounted and printed film ones) which are part of the application circuit of the two OP-AMPs
It took some time to draw schematics not without some difficulty due the presence of some hidden printed film resistors located under the quad OP-AMP:
Schematics were then routed to a PCB which looked pretty good on a 3D preview :
The real thing assembled in all its parts :
For a while I was not able to test this reproduction due the lack of a working PCB (the “decapped” original part was taken from a dead board) until the user ‘opt2not’ from Arcade Projects and KLOV forums kindly volunteered.The test platform was his working Raiden DX PCB.He first removed the original ‘HB-45A’ in a very clean way (he used an Hakko FR-300 desoldering gun)
Installed some female 2.54mm round machined headers:
Lastly the reproduction fitted onto the board:
Then he made recordings of audio of both original custom and reproduction redirecting it to a PC from a HAS supergun using a SPDIF breakout from the SCART connection.
Here ‘s capture using the original HB-45A:
Here’s the one using my reproduction:
Comparing the music and FXs at the beginning and end of the recordings sound identical.No differences in quality can be noticed (the slight background noise is normal when there is silence).
For this successful reproduction project I would like to thank again ‘opt2not’ for his precious testing and all material (pictures and audio captures) he provided me.I recommend you to check out his blog :