Copying a 93c86 chip in circuit

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nitrogrease
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Copying a 93c86 chip in circuit

Postby nitrogrease » Fri Nov 02, 2018 9:41 pm

Hello!

I am trying to copy a 93c86 eeprom chip in circuit. I have wired the SOIC clip according to the diagram on the chip selection screen. I keep getting an Overload protection error. The chip is in a Subaru ecu board. I have seen videos and other forum posts where it was shown to be possible to read and write the chip in circuit on one of these ecu boards. One suggestion was that it might be necessary to short the crystals on the board to make it work. I tried that and still get the Overload protection error. Is there anything else I should try?

Thanks!

ArT
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Re: Copying a 93c86 chip in circuit

Postby ArT » Sat Nov 03, 2018 9:26 am

Hi! Yes you can check few things.

1. Chapter 5 in manual - hope you do not missed it (few tips and tricks described)
https://www.reveltronics.com/downloads/ ... manual.pdf

2. Pin 6 and Pin 7 - are you connecting them? Pin 6 is memory configuration (8-bit/16-bit) and in some circuits it should be NOT connected (left floating if it is already connected in circuit). Pin 7 is Write Protection / Program Enable - if it is connected in circuit you should also do not connect it from programmer. So you can try to read without connecting pin 6 or pin 7 or both. Mechanism is described in Chapters 5.1 and 5.2

3. If you have still overcurrent then you can try to decrease memory voltage (VPP). This trick is described in Chapter 4.4.3.
93xx devices are for +5V, but most of them still working with lower voltage (e.g. 2.7V ... 3V... 4V etc. depends on manufacturer - you can check minimum working voltage in device datasheet). When you use lower voltage then other elements on the some power supply line does not start and does not consume power (the effect is lower current consumption).

4. Do you know if others are using external power supply for this ECU? If yes, then you will need too.

5. How about hardware test for programmer? All values are green?

If everything seems to be correct and this is still not working then please send me pictures of your connections.

nitrogrease
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Re: Copying a 93c86 chip in circuit

Postby nitrogrease » Sat Nov 03, 2018 1:02 pm

Hello Art!

Thanks for your help. I tried lower voltage, at 3.3V and was able to read the eeprom. I am curious though will that also work when writing back to the other eeprom or could it cause issues?

Thanks!

ArT
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Re: Copying a 93c86 chip in circuit

Postby ArT » Mon Nov 05, 2018 7:21 pm

It depends on chip manufacturer and accepted minimum voltage for programming. But if verification pass then you can be 100% sure that it was programmed properly. If you have verification error or chip can not be erased then you need to use higher voltage. If higher voltage gives overcurrent (because you power all elements around) then you can try to use external power supply.

nitrogrease
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Re: Copying a 93c86 chip in circuit

Postby nitrogrease » Tue Nov 06, 2018 11:11 pm

Thanks! I tried it and it worked great!


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