Author Topic: A500+ Disk / Gotek problems (Read 940 times)

realloy · « **on:** April 24, 2017, 07:24:52 PM »

Amiga 500+ rescued from Varta Death, boots to kickstart screen but wont load from Floppy or Gotek..
Floppy connected makes the tick noice about three times then it stops,, but when inserted a floppy it starts to "read" etc but gives up,, same with Gotek.

Floppy reads and gotek with usb works in other A500+

I have tested Both CIA and changed them both works in other computer, changed and tested Gary and Paula, tested Agnus tested Kickstart and CPU..

Have changed and socket U36 74LS05 Checked all power to chip connections for 5v all looks good,, also tried a other floppy cable,,,

same issue both on extern floppyport and internal

Any suggestions on were to look further ?

/Johan :furious:

paul1981 · « **Reply #1 on:** April 25, 2017, 12:40:59 AM »

How's the motherboard looking after the leak? Any damage? There was a leak yes? A photo of the affected area may give further clues. Those friggin' batteries...

realloy · « **Reply #2 on:** April 25, 2017, 06:00:35 PM »

The board is repaired by me and all traces that was bad is fixed, only the thing with the floppy i have used and messured all traces from http://beta.amigapcb.org/ and i have messured ALL traces from ALL custom chips,,from start at the chip to the end of trace... time consuming, last night i hooked up one of my Harddrives ,,, and from that one i run the sysinfo software and choosed DISK to check the DF0 ,,, and it starts to read the disk,, well atleast the diod on the drive is blinking,, but gives up ,, and the Sysinfo program says that there is no disk inserted,, GOTEK ,,, so no bad switches in a drive or similar ,, and the Gotek and floppy drive works perfekt in a other A500,, Im thinking there is something fault with the RDY signal and its somewere on the road the signal is lost ,,

I will post a picture of the motherboard later,,,

Castellen · « **Reply #3 on:** April 26, 2017, 08:54:11 PM »

Could be a problem with no disk read serial data, check at Paula pin 37 using an oscilloscope. You should always see active data there while the disk is attempting to read.

Otherwise it could be a problem with interrupt 5, which is shared use for both disk read data and RS232 serial RX data. If you're able to boot from another source (A590), run a terminal program that uses RX interrupts (as opposed to polled I/O) and see if it can receive data or not. Term fits this category, but I don't think you'll run it in 1MB.

Check Paula is generating DMA requests - measure at Paula pin 12. In A4000, etc, there's always activity on DMAL, not sure if A500 is the same, it probably is. Else you should at least see DMA requests during floppy drive read.

Also check continuity of the three interrupt priority lines (IPL) between Paula and 68000. Check they're correctly pulled to 5V and not floating due to a damaged pullup resistor.

realloy · « **Reply #4 on:** April 27, 2017, 08:15:36 PM »

Thanks for all help,,, i found the problem,,, it was a VIA that lost contact a few sec after power up... a trace going from U12 pin2 ,,, up to even CIA thruu were its printed Audio Filter at the Battery point ,,, needed to heat up suck out all old solder ,,, that was blackish,,,, reflowed it with new solder and lots of solderflush,,, and used a thin wire to get a safe reliable contact thruu the VIA..

And thanks Castellen for your tip I find the fault before i read your post ,,, but did the messurements anyway just of curiosity ,,, Im a collector of computers and this was my 14th Amiga 500..

Author Topic: A500+ Disk / Gotek problems (Read 940 times)

realloy

A500+ Disk / Gotek problems

paul1981

Re: A500+ Disk / Gotek problems

realloy

Re: A500+ Disk / Gotek problems

Castellen

Re: A500+ Disk / Gotek problems

realloy

Re: A500+ Disk / Gotek problems