Several people asked me about a possible replacement for the Hybrid used on several Taito games as they have boards where these have failed.
So, I drew up a possible circuit, and then Jrok decased one and put the schematic for that up on a forum. Between my version and the real thing, I put together a PCB that will allow two GAL's and a pile of resistors to be used to create a functional replacement.
Original TC0070RGB - connected to socket since many of the legs were broken!
Replacement, installed on a Rainbow Island PCB
As you can see, the replacement is not quite as pretty, but is made from fairly easily available components that you can get on ebay or remove from old parts PCB's - street fighter two bootlegs are usually a good source for GALs. Screen shots from the installed device are shown below.
Colour Test screen
Normal game screen
As a stop press to this, I was sent a Bubble Bobble PCB, which does not use this hybrid, but instead uses three PC040 DAC hybrids. These are also beginning to suffer the same fate, and on this particular PCB all three were dead.
The circuit for the PC040 shows it to be a 6 bit DAC, whereas the TC0070 is only a 5 bit DAC, but checking on the schematics shows that for Bubble Bobble at least, only 5 of the bits are used, with the lowest bit being connected to GND. So I thought it may be possible to use one of these on that PCB as well.
Wired to Bubble Bobble PCB
and it works!
To build one of these yourself, you will need the following :-
1 x PCB (Gerbers here)
3 x transistors C1815
3 x each resistor - values 100 ohm, 1k, 2k, 4k, 8k and 16k
you can get the PCB's from me, priced at £6, or a kit of parts £15 posted in the UK.
n.b. I have used these RGB output PCB's on several of my Taito PCB's, and other people have used them as well, and as yet no-one has reported any problems. I can not guarantee that it will work on your particular PCB, although I have no reason to think that it will not!