exxos's Atari, Amiga & retro forum

Warning #1 - DO NOT SOLDER IN THE 3.3V REGULATOR

Don't solder in the regulator as it is the incorrect part and the pin out is incorrect.

Will update shortly with the right part number.

EDIT:

If you want to use the part in the BOM (AZ1084CD-3.3TRG1) for the 3.3V bus then there is an option to solder it in like so. I bent the legs in the opposite way and soldered. I just modified it to see if the 3V3 bus was working.


An alternative that will fit correctly is the LM2936Q

https://www.ti.com/lit/ds/symlink/lm293 ... er.it%252F

DO NOT SOLDER IN THE DB19 DMA CONNECTOR.. -

A WIP fix... more to come later...

SIDE0 FLOPPY SHORT FIX


There is a short from pin 21 of the YM2149 to GND at the right hand side hole of the DB19 connector..


It is not actually shorting on the top of the hole as it appears to in the image..It is one of the inner layers, but the inner of the via also excludes outwards from the hole which is causing the short.

The only fix I can come up with is to gently file away the hole as indicated below until the short is removed... I'll suggest using a meter to check pin 2 of the external floppy port, to the outer ground while you file to make sure you do not cut too far otherwise you will damage the track next to it which is what I did :(

I would suggest filing the sides of the hole as much as you are filing the top of the hole... Once you break continuity checked both sides of the track on pin 2 of the external floppy connector, to ground, then the YM chip side on pin 21 to ground..


Once both sides of the track are broken from ground you need to bodge wire from pin 21 of the YM chip to pin 32 of the floppy internal connector...



Done.



If you file to far you will break the track above which is what I did, and that then needed a bodge wire...


OTHER TRACK LOCATIONS TO CHECK

(2nd track)


(3nd track)


(4th track)

MONO SELECT FIX

Solder blob pins 2&3 together on the bottom of the PCB.

Icky wrote: 27 Oct 2020 15:50 Just checked my board and its the right way round.

Just checked and my ic11 is mounted correctly.

exxos wrote: 27 Oct 2020 23:10 Fix #5 - YM AUDIO BIAS FIX (NO AUDIO)


Remove and blob over C60.


IMG_5722.JPG

Just checked and my boards don't have the shorted cap. You didn't order yours with extra solder by any chance?

PaulJ wrote: 29 Oct 2020 20:06 Just checked and my boards don't have the shorted cap. You didn't order yours with extra solder by any chance?

huh ? C60 is fitted by default.. You removed it and blob over C60 pads..

Well shiver my timbers.... I thought the shorted cap was the issue and here its the solution! :dizzy: :chairsmack:

With the 3.3v bus vrm: LM2936Q
please could you specify which package? SOIC, TO-252, VSSOP or SOT-223.
Thank you.

Steve wrote: 04 Nov 2020 11:54 With the 3.3v bus vrm: LM2936Q
please could you specify which package? SOIC, TO-252, VSSOP or SOT-223...

TO-252 is the footprint for the old part, so I guess the same.