Strange problems turned out to be unstable power supply

[robert2098]

My HxC devices works great as replacement for an internal floppy. But I decided to use one externally. So I build a floppy interface cable and used a power supply of an USB2IDE adapter kit to power the HxC. But then I got strange problems.

First when reading from the HxC, I got read errors. Stepping to the next track or side went OK but the data read was just corrupt. At first I thought the cable was not good. But then when turning on the device, the SD-card was not found or it hanged while reading the SD-card's FAT. Using the external cable and the internal floppy power cable solved all problems so my floppy interface cable is OK.

Thus my conclusion is that the power supply of the USB2IDE kit was the culprit although I never had problems when using it with IDE disks on a PC. The measured voltage (under load of the HxC) was OK with just above 5V. But probably it does not deliver a clean and stable voltage (can't test that because I don't have a scope). So I suspect the power supply caused interference with the SD-card interface.

Is it known that the SD-card interface is sensible for interference? Hopefully this story will help others with similar problems.

Robert

[Jeff]

My HxC devices works great as replacement for an internal floppy. But I decided to use one externally. So I build a floppy interface cable and used a power supply of an USB2IDE adapter kit to power the HxC. But then I got strange problems.

First when reading from the HxC, I got read errors. Stepping to the next track or side went OK but the data read was just corrupt. At first I thought the cable was not good. But then when turning on the device, the SD-card was not found or it hanged while reading the SD-card's FAT. Using the external cable and the internal floppy power cable solved all problems so my floppy interface cable is OK.

Thus my conclusion is that the power supply of the USB2IDE kit was the culprit although I never had problems when using it with IDE disks on a PC. The measured voltage (under load of the HxC) was OK with just above 5V. But probably it does not deliver a clean and stable voltage (can't test that because I don't have a scope). So I suspect the power supply caused interference with the SD-card interface.

Is it known that the SD-card interface is sensible for interference? Hopefully this story will help others with similar problems.

Robert

Is it a rev B hardware ? There an issue with the Rev B hardware. you can correct this by adding a resistor.

[robert2098]

Is it a rev B hardware ? There an issue with the Rev B hardware. you can correct this by adding a resistor.

Yes, it is a Rev B board. Where and what value resistor should I add?

Thanks,

Robert

[Jeff]

Is it a rev B hardware ? There an issue with the Rev B hardware. you can correct this by adding a resistor.

Yes, it is a Rev B board. Where and what value resistor should I add?

Thanks,

Robert

You can put a 1800 ohms (1.8Kohms) resistor in parrallel of R28 (between pin 1 & 2 of U11 for example).

Have a look to the kit documentation for the part placement.

[robert2098]

Hmmm, on my board there is no R28, just two empty solder pads. That would explain the problems.

Since there in no resistor there, I assume I should put a 180 ohm resistor there as in the rev 3 schematics. Or should I use 220 ohm since R30 is probably 360 (rev b) instead of 330 ohm (rev c)? Or maybe around 196 ohm (1800 parallel to 220) as result of the suggested modification to a rev B board?

Robert

[Jeff]

Hmmm, on my board there is no R28, just two empty solder pads. That would explain the problems.

Picture please... i cannot believe it...

[robert2098]

Hmmm, on my board there is no R28, just two empty solder pads. That would explain the problems.

Picture please... i cannot believe it...

Unless the smd component are nowadays too small for me to see with the naked eye, there is no R28. So better believe it

To convince you, I've attached two pictures of the 3.3V power regulator area of the board. Sorry for the bad quality but they were taken with my phone.

Robert