PaulJ's H4 Mongrel Build x 2

[PaulJ]

@exxos , @Icky I have been scoping a lot of the signals on the H4 and find everything a lot cleaner than on the Atari boards and even the Remake board. I believe you have a real winner with this board.

[PaulJ]

@Icky , @exxos I've got a board issue. It looks like rs232 in should go to pin 7 of the MAX238 but its now connected to pin 20 which is an output. I lifted pin 20 out of the socket and connect pin 7 and 20 together on the board and it now works.

I guess that explains why my serial dont work.

So Phil, what did you get when you applied power? I assume your using diagrom so you should still see output from the board but you can't select test options. Anyway hope you're close.

[PhilC]

Yes I'm not too far away, I get the double reset and garbage on the serial, so its alive, just confused, poor thing.

Not got a great deal of time at the minute though which doesn't help.

[exxos]

@exxos , @Icky I have been scoping a lot of the signals on the H4 and find everything a lot cleaner than on the Atari boards and even the Remake board. I believe you have a real winner with this board.

Glad to hear A stable foundation to build upon is what I am aiming for. I want to spend time developing add ons and upgrades, not debugging 30 year old stuff

[PhilC]

That's exactly what I have in mind too @PaulJ

[PaulJ]

Understand, back when I had a day job time was much harder to come by not to mention when I traveled I had to leave all the toys at home so it was 100 percent wasted time other than the pay check.

[derkom]

Like you said you may have fried the chips. Did you use hot air or soldering iron. I used a soldering iron which I'm comfortable with. I've tried hot air and have no faith in my ability to use it. Blowing the small components away or sitting there forever cooking things.

I used hot air, which I'm not really comfortable with either. I actually did successfully replace a dead SRAM chip on my Falcon that way (the success of which still surprises me) and maybe overestimated how well I could do hot air, because yeah, I ended up sitting there and just cooking things before I finally got it all to settle down, so I've been nervous about those ICs all along. (Although it seems like my reset and LS11 ICs were fine at least.

Over the course of this project, I got a camera attachment for my microscope (I swear, I'm spending more money on tools than I am the hardware I'm building!) and using that, I found it really easy to rework some of the SMT stuff by hand, but of course that won't un-cook it. Since they're available from a local supplier (and cheap!), I'm going to get ahold of some more of the selector/multiplexer chips and just replace those first, soldering by hand, and we'll see what happens from there. If necessary, I can pull the DAC off a defective Falcon board I use for various tests and whatnot.

[exxos]

@derkom

I have tried soldering with my gas iron, its mostly how I end up doing things anyway.

[PaulJ]

Things falling apart here.. My Chinese power supply I use to power the H4 is only capable of 1.8 amps even though they claim 4 amps. It appears to work, current maxes and then comes down to 1.6 amps, works for 15 seconds then voltage goes to zero and current stays where its at. Running with a standard ST supply now. I connected the ultra satan to the internal dam port and no joy so I'm taking a 19 pin connector off a old board to see if that works with the Atari cart DMA test. If we get the green pass screen I'll try the US to that connector.

[exxos]

China - self inflicted

Would help to know if the new DMA circuit works, internal and external.