OJ's H5 A3 Troubleshooting

[olivier.jan]

I did the fix, just postponed the bodge wire until the floppy connector had been soldered...and forgot.
I also reworked the cpu socket and now both floppy and PLCC CPU works correctly.
Next step is DMA, I started connectivity checks, we’ll see, with my sub-par soldering skills I will surely find something...

[olivier.jan]

So, finally fixed it!
As floppy was working but not US on external port, I finally found out a solder bridge on IC17...actually under IC17. This was pulling HDINT always to ground.
No solder bridge was visible, and everything looked clean, but after removing the IC I discovered a bridge under the chip. This H5 was my first attempt at solder paste, and I need to pay more attention next time.
Anyway, I now have a fully functional H5 A3, many thanks for your help !

[exxos]

Well done!

[olivier.jan]

I recently got a Goex for my H5 and it works pretty well, until I try to write anything on it
Writing files seems to work, but the files are not actually written to the floppy image, formatting looks to be ok until the progress bar reaches the end and throws me an error. Diag cart is even faster to detect an issue : write failed.
This happens with or without the GAL, forcing 720k or not.
I tested the Goex in a stock STF, it works flawlessly.. the problem must be with H5 then...
I initially questioned my soldering of the floppy connector and replaced it completely, but same issue again.
What I don’t understand : I have a Panasonic and a Chinon floppy pulled from an A500 and an A600 and both works without issues in the H5.
I guess I’m going to need the oscilloscope on this one, does anyone knows where to start looking ?

[exxos]

The DRIVE AB being issued together on the internal cable isn't confusing it is it ? It shouldn't matter.. but who knows how much testing has been done on those fancy floppy emus.

[olivier.jan]

Now building the my second H5 and found a really bad DMA this time: https://youtu.be/vvIAXPJmcSM.
Luckily I had a spare one, so now I’m just stuck debugging why MFP isn’t working properly, like with the first H5. I hate MFP.

[olivier.jan]

It’s official I really really hate these plcc MFPs
My sockets don’t connect properly to the MFP pins, so I removed the socket, but hand soldering this stuff is really painful.

[exxos]

There was never a intention to use sockets on the MFP... Some fitted one, but again I stress 3M brand. It shouldn't be difficult to solder in the MFP.. You just need a fine tip soldering iron and a magnifier helps.

[olivier.jan]

Finally hand soldered the MFP, tested for shorts all pins with a meter, did a continuity check on all pins of the MFP,and it’s getting better, but still not perfect...
If I start with Mono forced, and diag cart, everything is fine, all internal tests pass without issue, keyboard and mouse are working.
Without the diag cart, I boot to desktop, I can even get a program to run if it’s in auto folder, but keyboard and mouse are not working !
If I boot in colour, I get multiple reboots, I can see with the diag cart some garbage on the screen, and sometimes it finally stabilize with diag cart menu and all tests pass. Booting to desktop produces the same behaviour, with multiple boots before stabilizing and then no keyboard nor mouse
All ICs but GLUE and MMU have been tested in a different machine.

[exxos]

I assume you have done the A3 fixes ?