Hello: I'm an electrical engineer in PSE's facility services group and don't have the opportunity much of asking electrical questions. I like to fix things and found mikrocontroller.net with my topic of interest but it isn't in English. I wish I had the English version of that topic that discussed the Toshiba T2295A chip. I don't see rules for postings so kindly let me know if this appropriate for this forum/web site. The T2295A chip drives the tachometer meter on a scooter that is 37 years old. The meter works with, say, 1.25 VDC at it passing 12.5 ma, so the meter's internal resistance is 100 ohms. This is with the meter out of the circuit. Meter works as a voltmeter and is fully functional, though labeled in RPM. Looking back into the PCB and capacitor (driving the meter) I see 200 kohm, but the meter always has 0 VDC in sitsu. Is there discussion on mikrocontroller.net on how it works, expected voltages at the ZIP-9 chip leads, back sheets in English as alldatasheets.com doesn't list it? The PCB schematic comes from mikrocontroller.net. Later: You know, I think I got it working. I saw VCC and IN and they were swapped. Probably all these years by the original equipment manufacturer. Looking at the schematic I got from mikrocontrollers.net in a language I didn't understand, yet seeing those two words/symbols on the drawing helped me just minutes ago. Swapped the yellow with the black wires to the Honda Flush tachometer.
: Edited by User
Good afternoon sir. Did you ever find a datasheet for this T2295A? I have the same problem. The circuit diagram you provided matches the circuit board that I removed from my tachometer, but I am getting no voltage out to the meter. The tachometer functioned correctly for 20 years. Then failed. All the components look and measure okay, so I want to remove the T2295a and pin check it. But I can't fond the datasheet anywhere. Thanks, Martin Canada
No, never got a pinout of the chip. Wiring was actually correct and for some reason the tachometer works in the scooter. Someone told me to replace the largest capacitor but I didn't do that. Did you?
Hi, thanks for the fast reply. I have not replaced any components yet. On the test bench I can measure the pulses entering the chip @ pin 2, but no voltage out on pin 6. But I am very new to circuits and diagrams, so I may be off base. The short of it - I detached the the board from the rest (coil / needle) and when I power the needle portion only, it works. When connected to the board, does not work. I am putting 1 kHz 12 volt pulses in. Those drop across the R1 resistor, so they are about 2 volts at the pin into the IC. I assume that's correct - the resistor is good, and there is nothing else between. After that...nothing out. I can order a chip off eBay for about 5 bucks. I might just swap it out and see if that works. I might try changing that cap too. Parts are cheap. Stay healthy! Thanks for the tip, and BTW, the diagram you posted was really helpful! Martin
You're welcome. I thought it fortunate that I could even find the schematic, somewhere.
Hi, I changed that cap (6.3v / 1000uF). The tach is working again, so I guess that was the problem. Cheap fix. Cap cost $1 at the local electronics supply store. Thank again! Martin
Hey, that is great!. I would have to thank whomever told me about the capacitor replacement. David Babbitt