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VIC20 Final Expansion 3 - debug help? (cross posted from Denial)


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Got my FE3 (Rev 10) late last week from Sinchai, and assembled it over the weekend.

I am having some trouble diagnosing what I think is an error. The unit boots up fine to the FE3 menu. I can select memory expansion configurations and so on.

Accessing the Disk Menu returns me to the main screen.

Starting BASIC and trying to access the contents of the SD card results in:


I have tried several SF cards from 64MB to 2GB using FAT16 and FAT32. A few of these work fine in a Jim Brain uIEC device.

I have read the other threads on this but they often point to dead links. Hoping someone might know where to focus the diagnostic effort.

Would appreciate any insights.



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Were all chips pre-programmed? Have you checked all soldering points, wires etc? I've got a FE3 as well and have faint memories of struggling with it in the beginning to get it to read SD cards, but eventually I think I succeeded. The message you got suggests it reads some other device/space than the actual memory card.

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Sinchai shipped the PROMs pre-programmed. The SD card slot and voltage regulator (the SMC devices) were pre-soldered. Everything else was soldered on by me.


I tested removing the SD2IEC chip to see if it was really blank, or faulty. When I do that I have no device 8 anymore, so I am guess it is working as expected.


It does seem that the uIEC device is not reading the SD card at all, and defaulting to the "EEPROMFS" pseudo device. I don't know where this pseudo device is coming from as my other uIEC device simply shows "device not present" if there is no SD card in the slot.


Is there a way to re-flash the SD2IEC chip?

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Dumb question, but do you have any other IEC device connected to the VIC, or is the FE3 on its own? I imagine if it defaults to device 8, and another device also is using it, strange things might happen.


I have very vague memories of going through a two step bootstrap process to initiate the FE3 for the first time, but perhaps I got mine with only partly or not at all programmed parts. I would still check soldering points for continuity and that you didn't put anything in the wrong position. It can happen to the most experienced of us, in particular if the instructions would be vague.

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Thanks for the efforts to help debug this! I do appreciate it.


To answer your question, no, when the FE3 is plugged into the IEC jack, it is the only IEC device connected to the VIC. I tested the SD cards in a different uIEC device to make sure they were readable and they are.


Using the stand alone uIEC device with the FE3 (the FE3's uIEC is disconnected) works fine. But relegates the FE3 to little more than a fancy RAM expansion.


Further testing shows that the FE3's uIEC device works normally about 1 in 20 restarts - a restart being a full power cycle. Also removing an SD card is fine, but inserting a new one, or the same one reinserted, causes the VIC to reset as if I pressed RUN/STOP + RESTORE. At which point the VIC freezes and must be power cycled again. I have tested this with two VICs - an original NTSC (gold/silver label) and a PAL (rainbow label). Same results.


All solder points have been retouched and there are no obvious dry joints, bridges or gaps.


If anyone has any bright ideas where to start I could use some magic!

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  • 1 month later...



I'm having the same problem here with a second FE3 I assembled for a friend. This second chip set work perfectly in my first assembled PCB with the a SD card but refured to work with the second one PCB with the same SD card.


No solution yet.


The reliability improved somewhat after I put the FE3 in a recycled "Programmer's Aid Cartridge" case.


It is still flaky, but works as expected about 75% of the time now, as opposed to 5% of the time before.


My guess in Sinchai got a bad batch of SD card cradles, which don't make proper contact with the PCB. Perhaps the case applies just enough pressure to make a solid contact? I am guessing here, based on observations. Since I have no idea how to surface mount solder I am not willing to try removed the SD card cradle and remount it.


The unit still resets/hangs on SD card insertion. Power cycling it usually allows the unit to read the card again.


Does anyone know enough German to reach out Sinchai and ask if he has any insights?


Also, I never got the label I paid an extra three euros for :(

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Also, for others who might be struggling to debug an FE3, note that:




Is what happens when you access the disk device and no SD card is inserted. This is different from my uIEC which reports "device not present" if no SD card is inserted.


This further leads me to think the SD card cradle is faulty, or the pre-soldered surface mount cradle was not installed correctly.

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