DoG's Hx Mongrel build attempt

DoG · Post by **DoG** » 28 Dec 2019 17:37

derkom wrote: 28 Dec 2019 16:55 Looks like your keyboard connector is on backwards. Missing pin should be second from the front, not second from the rear.

Thank you! I just held up the connector from the keyboard. Didn't check that at all. I even have a original motherboard beside me. Clumsy.

DoG · Post by **DoG** » 28 Dec 2019 21:47

exxos wrote: 28 Dec 2019 16:46 ...When will power up be :)?

Now!

Well, it's working... but I got no floppy. I also got very faint red or missing red in display. Have to look into that tomorrow.

No floppy.jpg

No red.jpg

Audio is working and Blitter is working. Got 4Mb of ram and it's working. HDD/satandisk is working. External port. So ran GemBench:

GB with blitter.jpg

Post by **exxos** » 29 Dec 2019 00:06

:bravo:

Looks like you got a bit or 2 in the red line somewhere not contacting.

I assume you did all the fixes to the board and got all jumpers correct ?

DoG · Post by **DoG** » 29 Dec 2019 13:23

exxos wrote: 29 Dec 2019 00:06Looks like you got a bit or 2 in the red line somewhere not contacting.

You were right about a bit missing. First I checked all my soldering and they seemed fine. So I measured all the stuff on the red side of shifter, DAC and mux. I found that pin 27 (R2) of the shifter didn't have contact with pin 11 on the mux. I found that I got a missing trace on my board so did a little bodge wire and now it is working.

No track.jpg

Bodge wire.jpg

Bars with red.jpg

Desktop with all colours.jpg

Post by **exxos** » 29 Dec 2019 13:37

DoG wrote: 29 Dec 2019 13:23 You were right about a bit missing. First I checked all my soldering and they seemed fine. So I measured all the stuff on the red side of shifter, DAC and mux. I found that pin 27 (R2) of the shifter didn't have contact with pin 11 on the mux. I found that I got a missing trace on my board so did a little bodge wire and now it is working.

Good find! wow those boards are all supposed to be checked for continuity as well.

DoG · Post by **DoG** » 18 Feb 2020 14:22

Ordered a few DMA buffer fix pcb from coronaland and some 1 channel converters since @kodak80 have mention it is working now.

I haven't got a chance to check any further, what is faulty with my floppy drive access yet. Measured all of the resistor pack that is 10k around that area. Seems that I got 8k on one of the resistors in RP9. Ordered some new 10k bussed RP. I have also checked continuity of tracks without luck finding anything to get floppy working. I have changed DMA and 1772 chip. No change. Since Satandisk is working I'm hoping that it's the resistor pack that needs changing. I have not soldered in the external port so haven't tried that but I don't see any point of doing that. Anyone got any tip to proceed of finding the fault?

Post by **exxos** » 18 Feb 2020 15:06

Have you done this mod ? https://www.exxosforum.co.uk/forum/viewt ... 893#p31893

DoG · Post by **DoG** » 18 Feb 2020 16:45

exxos wrote: 18 Feb 2020 15:06 Have you done this mod ? https://www.exxosforum.co.uk/forum/viewt ... 893#p31893

Yes, already done that. Didn't help.

Post by **exxos** » 18 Feb 2020 16:52

Checked 1772 has 8Mhz clock ?

DoG · Post by **DoG** » 18 Feb 2020 18:17

exxos wrote: 18 Feb 2020 16:52 Checked 1772 has 8Mhz clock ?

Just bought a LA so haven't checked that. I also thought that I had checked all the traces but when i measured between pin 18 on the 1772 and R905 I had no signal. It was a very small scratch mark on the trace. So solder a small wire and now I got floppy drive access.

So thanks for leading me to check the 8Mhz pin :D

DoG's Hx Mongrel build attempt

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