merrylander
AK Member
After cutting the cover from an original Yamaha IG02930 pre-driver chip, finding Sanyo’s recommended circuit, and checking the schematic in the CR-1040 service manual that showed what was internal to the IG02930, I was able to come up with the schematic for a replacement.
The IG02930 is basically Sanyo’s circuit with some added components. It was relatively easy to determine resistance values with a meter on the un-covered IG02930. Diodes and transistors were taken from typical devices that would meet the voltages in a CR-1040. Since the internals of all pre-drivers are the same with only different voltage ratings, this replacement will sub for IG02940 and IG02950, in other words it will work in the CR-840 and CR-640.
Although I also did a drawing for a circuit board I was not about to order up a batch until I had proven my circuit. At Radio Shack I found some small circuit boards that had 15 row and 15 columns, just the thing for a 15-pin device. This is shown in the third drawing, not pretty, but effective. This layout took a few tries and is the way it is simply because I found you could not get two component leads through a single hole. I also laid it out so that the three legs of each transistor would bend to the corners of an equilateral triangle and not be crossing each other.
If you choose to construct a pair of these devices I suggest that you mount the components first and just tack them in place with a bit of solder. Next run all the surface wiring and lastly get some Kynar wire run the insulated leads. I strongly suggest that you do not attempt to do it all in one pass or you will need the services of a good Ophthalmologist. Don’t cut any surplus wire from the components until step 2 as this extra lead will form the surface wiring in many cases.
I downloaded the free copy of Eagle but the learning curve looks to need more time than I have spare. One could make a single circuit board large enough to comfortably hold the components of both pre-drivers and simply hook that into the main PC board with ribbon cables. That, or translate the transistors into surface mount equivalents and do a small board.
The IG02930 is basically Sanyo’s circuit with some added components. It was relatively easy to determine resistance values with a meter on the un-covered IG02930. Diodes and transistors were taken from typical devices that would meet the voltages in a CR-1040. Since the internals of all pre-drivers are the same with only different voltage ratings, this replacement will sub for IG02940 and IG02950, in other words it will work in the CR-840 and CR-640.
Although I also did a drawing for a circuit board I was not about to order up a batch until I had proven my circuit. At Radio Shack I found some small circuit boards that had 15 row and 15 columns, just the thing for a 15-pin device. This is shown in the third drawing, not pretty, but effective. This layout took a few tries and is the way it is simply because I found you could not get two component leads through a single hole. I also laid it out so that the three legs of each transistor would bend to the corners of an equilateral triangle and not be crossing each other.
If you choose to construct a pair of these devices I suggest that you mount the components first and just tack them in place with a bit of solder. Next run all the surface wiring and lastly get some Kynar wire run the insulated leads. I strongly suggest that you do not attempt to do it all in one pass or you will need the services of a good Ophthalmologist. Don’t cut any surplus wire from the components until step 2 as this extra lead will form the surface wiring in many cases.
I downloaded the free copy of Eagle but the learning curve looks to need more time than I have spare. One could make a single circuit board large enough to comfortably hold the components of both pre-drivers and simply hook that into the main PC board with ribbon cables. That, or translate the transistors into surface mount equivalents and do a small board.
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