Product Review: HomePin 1B1165/2 Replacement CPU Board

Product Images

1B1165/2 Front 1B1165/2 Back

Product Description

This is a very ambitious project, completely reproducing the Zaccaria 2nd generation 1B1165/2 CPU board, with some really nice improvements and upgrades. The 1B1165/2 is compatible with all of Zaccaria's 2nd generation games, and is backward compatible with the 1B1165/1 and 1B1165.

First, and most important of all, it comes with several options to replace the original design's NiCad battery used to maintain power to the CMOS RAM when the game is turned off. HomePin includes a button cell holder and button battery, which can be used, though I cannot recommend any battery installed on a CPU board due to the risk of battery leakage. Fortunately, the HomePin design includes three other options. There is space, and solder pads, for a 5.5V 1F memory backup "supercap" like Mouser part number 555-DB-5R5D105T. This is my preferred solution to the problem, and I highly recommend it, even though it does require some minor soldering skills to install. The third option is a set of jumpers that can be installed so that a ZeroPower M48Z02-70PC1 RAM replacement can be installed in the IC3 position. The forth option is a set of solder pads where a two pin .100" header can be installed for use with a remote battery holder. This works well, though I prefere the supercap option for neatness and convenience.

Another nice upgrade is that IC4 and IC5 are socketed by default. These are the game's RAM, and while they don't fail often, this makes replacing them in the future easy.

The board comes with ROM sockets and jumpers set up for 2 x 2764 EPROMs. Some 2nd generation games used other ROM combinations originally, but all of my "free play" ROM images are in 2 x 2764 format, so you can install them easily in this board.

HomePin's design eliminates the use of the CA3081 transistor arrays used on the original boards, replacing them with seven BC547 transistors. There is no functional difference here, and the individual transistors take up a bit more board real estate than the CA3081, but the stocks of CA3081s are starting to dry up, and the prices on them are going up, so this is a nice upgrade in the future servicability of this board vs. an original.

HomePin has added varistors to the switch matrix which should, at least in theory, help in cases where somebody short circuits +39V solenoid voltage in to the low voltage switch matrix lines. This most commonly happens on games like Farfalla and Magic Castle which stack solenoid voltage (End of Stroke) switches with low voltage switch matrix switches on the flipper mechanisms to activate the "R-E-A-C-T" outlane flippers. I have not tested this feature, but it seems like a good idea.

Another interesting change in terms of future parts availability and servicability is that HomePin has replaced the offset pin headers used for CN10 and CN11 with standard .100" inline pin headers. The original offset pin headers are no longer available.

One thing to note is that this CPU board does not include the Signetics 2650A processor at IC9. HomePin expects the buyer to re-use the 2650A from their original board, or to obtain a replacement on their own. Fortunately, Signetics 2650A processors are available from

Product Testing

HomePin was nice enough to send me a board for evaluation and testing. I took the opportunity to run my own board diagnostics testing ROM in it first, and it passed all of my tests with no problems. This is normally the test ROM I used when repairing boards, and it has been written to excercise each subsystem of the board individually, so as to help locate and diagnose any problems.

Having found no problems with my test ROM, I then installed a set of game ROMs in it (Devil Riders), and ran it on my test bench. This allows easy and convenient testing of the CPU in concert with a power supply, sound board, and driver board, with all of the game's inputs and outputs available. Again, no problems were found and the board ran fine, passing all of the game's self tests.

Last, I installed a set of game ROMs (Faralla) in the board and installed it in one of my games. As expected by this point, since it had already passed all of the tests I would normally do on a repaired board before shipping it back to a customer, the board ran fine in my Farfalla through self tests, operator audits, game settings, and actual game play.

In summary, this is a nicely designed, professionally assembled, and very nice replacement for the original 1B1165/2 CPU board. It is not an inexpensive option, but for a game without a CPU board, or for one that is so damaged that it is not repairable, it may be a lot easier than tracking down an original replacement and then potentially having to have it repaired as well. If you need a 1B1165/2 board, contact HomePin.

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David Gersic [an error occurred while processing this directive]

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Last updated 8 November 2013