Resolved EPROM Chip Direction

[CrazyM]

Okay so I'm kind of curious here.

I have an EPROM ECU. I've been doing some searching and EVERY EPROM I have found has the chips letter "E" closer towards the middle of the board.

The Chip that was in this EEPROM was so that the "E" was facing more towards the outside of the board.

By inside and outside I am looking at the ECU so that the Plug-Ins are facing up, the 2 side brackets to the left, and the single side bracket to the right.

Now the weird thing is...There is 2 different dots on the chip by where the "E" is, one on top and one on bottom. There is a scratch mark on the 'outside' of the board' that one dot lines up to (Chip facing the opposite way I've seen compared to any other)

Can anyone shed some light on this please!

 

[steve]

The label on the chip isn't the best reference. If you look closely at the EPROM chip, socket, and the silkscreen markings on the board you'll notice a notch in outline on one of the short ends. This marks the end with pin 1 on the left side.

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[CrazyM]

The only Notch I can see is on the chip. I know that it doesn't really matter which way the socket was installed it will still work if the notch is on the opposite side.

Is there anyway that a chip or the board was designed to work with the notch towards the right hand side?

EDIT: Also will a chip installed backwards hurt the board itself or just fry the chip?

 

[steve]

The only Notch I can see is on the chip. I know that it doesn't really matter which way the socket was installed it will still work if the notch is on the opposite side.

If the socket was installed backwards it won't have any electrical effect. Kind of an basic FU though.

Is there anyway that a chip or the board was designed to work with the notch towards the right hand side?

No. None of the DSM ECUs had a different orientation for the EPROM.

EDIT: Also will a chip installed backwards hurt the board itself or just fry the chip?

It usually just ruins the chip but I have seen board damage in the rare case that the chip fried and shorted internally.

 

[CrazyM]

Why would the socket being installed 'backwards' not work? Internally there is no connections changing its just a quick extension type thing I thought?

Well, Steve,

Thanks for the info on the notch. I read about it somewhere else as well but wasn't sure if possibly the board was designed differently. I swapped the chip around, and turned the key to 'On' waited to see if stock boost gauge did its thing, check engine like came on, then went off (which it never did before) So I gave her a couple cranks and she fired right up!

 

[tkelly27]

Pretty sure it will just fry the chip.

That sticker doesn't mean anything neither does the silk screen. If you have the board still complete. go with where the notch on the original eprom is. If you don't have it complete, there's no reason to have a flipped chip. The entire production procedure would have to be flipped around to get the right pins in the right place.

I'd pull mine to see if it's a '90 only thing, but I'm too tired, maybe someone else knows.

 

[CrazyM]

I just figured I would double check. It turned out the chip was already in wrong. Didn't fry it though. I flipped the chip around to the way the stock EPROM is and it works perfect.

 

[steve]

Why would the socket being installed 'backwards' not work? Internally there is no connections changing its just a quick extension type thing I thought?

Perhaps you misread my comment. I said that the socket doesn't matter but that it was a pretty basic error if the person installing it couldn't align it correctly.

 

[CrazyM]

Ah! Now that I've re-read it again, it totally makes sense. I read it as having 'no electrical effect' as being it would not work.

Thanks again Steve