I have a John Deere CCU unit from a customer that needs repairing. I do know that the two IC units in the pictures are bad as nothing goes in or out in any configuration and one smells the smell of burned.
Let me know if anyone can figure out where or what. I have had no luck.
That part I can see, and I found that there are suppliers out there that can send me some of those part number. But I am not sure if they would be counterfeit or not since I have no datasheet or anything.
That is what I am looking for is datasheet information or a cross for that part.
I tried to locate a good credible website for the stats on this transistor or a data sheet, but unfortunately I found none. The 00S83 seems a good part number though we don’t carry it by the looks of it and since I could not locate any good source for the specs of the part I cannot offer a possible sub for it.
Maybe someone else knows more about it. Best of luck.
The Motorola discrete semiconductor unit (Semiconductor Components Group) became Onsemi in 1999. The micro on the PCB is dated 1997 so I would expect this device (transistor, IC, SCR, TRIAC, etc.) to also be of that vintage.
Pretty much all last century Motorola discrete semiconductors have data sheets online (just tried the most obscure part I remember, MM4002, and found it). I threw out my full shelf of last centuries Motorola’s data sheet books 3 years ago because of this.
Motorola did a lot of private labeling for reasonably small quantities during the last century. If this was private labeled that would certainly explain the lack of data sheet.
I could make guesses that might make the PCB unrepairable by anyone anywhere, but that’s rarely what people want. So unless you say you’re OK with blowing it up permanently, I’m not going to guess.
If I had the PCB in hand and it was worth > $3000.00US to figure it out, I’d do some reverse engineering (Warning that 3 grand might not end with a repaired PCB). Most of that I’d do with and ohmmeter and visual inspection to generate a schematic. Then I’d track down what data sheets and specification sheets I could find for other parts on the PCB. Analyze all the information to create reasonable electrical specs for the mystery component.
Yeah I know you are right on that. Definitely pretty scary to try reverse engineer-guess on this unit. When I try test it as a mosfet all the voltages are extremely low, when I test in a component tester it is listed as two resistors, and when I try test it in circuit as a voltage regulator it does step the voltage down. But with very low current available.
Tough question. It is difficult to tell from the pictures, what type of device that is. Indeed it can be a transistor, SCR or TRIAC. Certainly re-branded. It could be a regulator as well, though. Pins 2 and 3 seem to carry high current according to the trace widths, so likely the pin 1 is the control pin (Gate, Base, ground (e.g. negative LDO), etc.). Usually MOSFETs have Drain in the middle and Source at pin 3 so would argue that the device is a high-side switch (P-type MOSFET or N-type MOSFET with gate bias boostrap).
A bit larger picture (optimally showing the whole board) could perhaps help in solving the mystery. The PCB seems to be designed using auto-placement and -routing, yielding an ugly result, which adds some sour flavor to a reverse-engineering task.
One long term solution is to wait until 2024 and ask schematics from a Deere dealer in Colorado, as due to “Right-to-Repair” legislation, they should then provide that.
I think you might be right about waiting until John Deere finally has to give the option to repair. I have a few modules in my shop that need repair that are John Deere. I do a lot of AG based repairs.
I will attach a photo of the whole circuit, both sides. Just for fun.
I wouldn’t bet a large sum on it, but my small bet would be on a simple old MC7805ACTG or similar. The MC33064 5V supervisor heke identified is monitoring pin 3 of the TO-220, which is where you’d find the output of a typical TO-220 regulator of that variety.
David’s bet is actually pretty good. It looks like the pin 1 of both devices are connected together (on bottom side of the PCB) and are wired over to a large electrolytic, suggesting that it is the raw supply voltage line. The MCU SAB80C517 is a 5V device, thus the 7805 seems likely. There are apparently no other regulating devices on-board, thus these guys must be them then! The MC33064 is probably the MCU brown-out reset circuit.
Edit: Changed reference to David. No idea where I got John… my apologies. Betting on David’s solution, Sounds solid.