Can't duplicate any disk
Here is a better picture where we can see that both chips look ok.

What you were mentioning in the red circle is the TI logo !! Smile

So again, write gate is stuck high when writing.


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More pictures through the magnifying glass...

Again, both chips are ok.

I also notice a solder bridge under the board between 2 pins of IEC connector. Is that expected?


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Well, either your cable is shorted to +5v, the drive is bad and shorting the write gate to +5v, or one of the two buffer chips is bad. How do you know for sure that the write gate is not changing states? What pin are you looking at?

Your screen shot of the flux shows that something is being written.

No, the IEC connector pins shouldn't be bridged. There is no support for the IEC connector, so that is not tested. You can just desolder the bridge or leave it and I will do that if you have to send your board back.

Do you have another cable and another drive to try?
Jim, please read carefully,

From my very first post:

Quote:- Tried 2 different ribbon cable.
- All drive were powered by external PS. Tried 2 different Power supply.
- Tried 3 different PC 1.44 floppy drives

All those 3 drives write fine in a PC using windows AND the SAME ribbon cables
Tried 2 different cables.

Quote: How do you know for sure that the write gate is not changing states? What pin are you looking at?

Again in my previous post:

Quote:I took my scope and looked at pins 22 (Write data)  and 24 (Write Gate).

Pin 22 looks fine, I see the signal, however pin 24 (Wgate) is always High

So I looked at pin 24.

Yes I can desolder the bridge, will it help?

No, de-soldering that bridge won't make any difference.  Those pins are connected to the PIC as open-collector outputs.

Return the board and I can look at it.  If the write gate is not going low, then DUEY is destroyed, the cable is bad, or the drive is bad.  The board worked when it left here.  I offer a lifetime warranty on all of my electronics, so just return it and I will replace it.
ok what is the return shipping address?
See here:
Board sent
Please tell me when you get it.

Thank you.

Will do!
I got your board back.  Duey was indeed bad.  I replaced it and made a change also to the media integrity test.  It turns out that the random pulse width was not working, so a test generated by a good SCP board would have good data when the write was not working (like in your case).  I don't know if the SCP board left here with Duey bad, or it was damaged by your drive or cable.  The new media integrity test will definitely now make sure the write gate is always working before leaving here.

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