exxos's Atari, Amiga & retro forum

I received the board today!


Removed and re-installed the amp chip. Audio works!


A little work to the reset switch and exposed a spot to solder onto the PCB.


Installed RGBtoHDMI to get video out.


Installed chips from donor ST. Booted into 1.04 but crashes with 2.06


Installed a Gotek and it ran GemBench from "floppy".



HOWEVER - I tried to run another file from the same .ST disk image (YAART) to test the memory and it threw a disk error. I hit the reset button - which does NOT work. I did a cold re-boot (power off/power on) and the computer now will not recognize there is a Gotek attached?!? I've tried multiple .ST disk images, another thumb drive from another ST, a new floppy cable, and there is no change. I put the Gotek into my other H5 and it works perfectly.

So, I have the following issues:
1) floppy was working - simply quit being recognized by this computer but works in another computer
2) Reset switch does not work (with computer powered down, checked with a multimeter and when I press it does break contact between top/middle pin)
3) four "bombs" when attempting to boot TOS 2.06 (crashes after memory test whether cancelled or allowed to run fully)

If anyone has any suggestions I would love to hear them. Thanks!

The TOS206 bombing is normal, that happens when it doesn't detect a floppy. So you probably need to take some high res photos of the motherboard around the floppy circuitry and any relevant jumpers. In the motherboard overview photo I noticed you don't have the 1.44mb GAL installed. Would that be a problem?

Your missing the jumper on the flashy clock jumper for starters..

As @Steve says, 206 will bomb with no floppy.

The GAL is needed for 1.44 floppies.

Most likely floppy not found is bad connection on floppy cable, 1772, DMA etc not sure how your powering the floppy aa the power cable isn't fitted going by your images.

With mine most of the issues I encountered were simply ALL the jumpers.

Some of them aren't too straightforward either.

I added the solder blob to Flashy Clock jumper. The reset button now works, sorry I didn't see the new location on this board compared to H5C1.

This H5C5B was working last night for a few minutes after I assembled enough components to test. The floppy was seen by the computer and it allowed me to run GEM Bench from floppy with TOS 1.04. After about ten minutes the issues began - there were no jumper setting changes done. Jumpers were checked multiple times and compared to my working H5C1 (but I will include more pics so other eyes can examine).

Today's testing:
I noted floppy 5V line to ground measures different ohms between this board and my H5C1 - not sure if this means anything. Voltage is fine on both power supplies and I have done all the following test with both power supplies to eliminate one of them being the problem.
5v-Ground H5C1 44 ohms
5v-Ground H5C5B 95 ohms

I attached an UltraSatan to ACSI internal pins in H5C5B. No activity shown on LED after initialization. Boots to desktop, no drives shown. UltraSatan removed, booted fine on H5C1.

DMA (C025913-38) from H5C5B in H5C1 - NO DISK DRIVES DETECTED in known working H5C1 computer - I thought maybe I'd found the issue...

DMA from H5C1 (IMP C100110-001) in H5C5B - TOS 1.04 DISK ACTIVITY on boot.

• Boots to desktop shows floppy drive. Allows opening the disk and launching a PRG but after a few minutes it crashes (locks up - no chime when pressing keyboard, mouse pointer freezes).
  
  Switched to TOS 2.06 crashes 2 or 3 BOMBS.
  
  Switching back to TOS 1.04 now crashes 2 bombs. Put this DMA back into H5C1 and machine works fine.

WD1772-PH and DMA (IMP C100110-001) from H5C1 in H5C5B

• TOS 1.04 - two bombs, sometimes will come to desktop shows drives, occasionally will allow opening drive and loading .PRG but locks up.
  
  Reset goes to white screen or white screen with 2 bombs. No beeps when pressing keyboard
  
  Cold boot will sometimes load to desktop with drive shown but it is very hit or miss
  
  TOS 2.06 runs memory test, crashes 2 bombs if allowed to run or if cancelled w/space bar

Put original VL1772-02PC and DMA (C025913-39) back into H5C5B

• TOS 2.06 crashes after RAM test or if RAM test runs all the way through (4 bombs) - obviously a no drive present crash
  
  TOS 1.04 boots to desktop no drives shown

I took more pictures of the H5C5B for a second set of eyes:

Maybe try cleaning the MFP pins and make sure no bent pins etc.

Checked the MFP 68901 socket and chip legs. Didn't see anything. Replaced the chip with a spare and no change. Boots to the desktop, no drives.

I found another ST with a socketed DMA (IMP C100110-001) in my spare pile. I put that in the H5C5B set for TOS 1.04. It boots to desktop, disk drive is recognized, allows me to open the disk, but as soon as I click a PRG it will begin to load but crash to 2 bombs.

TOS 2.06 just crashes with 2 bombs immediately. Switching back to TOS 1.04 it will give me a white screen, or a white screen with two bombs, or it will boot to desktop showing disk drives but behave as previous and crash as soon as I try to launch a PRG.

On a whim, I pulled the IMP GLUE and MMU from the working ST I had taken the DMA from and installed them in this board.

I don’t want to be too optimistic… but it’s executing code and accessing the floppy and accessing ACSI. On pass #8 of a RAM test. make that pass #9! :D
TOS 2.06 is functioning too.
My favorite game. played two levels and seems good to go.

Volfield I love but can't manage many levels :(

So likely MMU or GLUE was bad then? Assume no bent pins? Even if they a tiny bit out they won't contact properly..

Good your running now eitherway :thumbup:

exxos wrote: 25 Jul 2025 02:56 Volfield I love but can't manage many levels :(

So likely MMU or GLUE was bad then? Assume no bent pins? Even if they a tiny bit out they won't contact properly..

Good your running now eitherway :thumbup:

The DMA is all but confirmed bad - I've tried it in three machines now with it basically failing in each. Of the remaining chips (MMU/GLUE) I'm leaning to it being the MMU as it had a Marpet adapter crammed between the socket and the chip's pins for decades. I had been able to get that machine to work after a lot of fiddling but when it stopped working this last time I made the executive decision it would be a donor for your newest H5. I'll examine the chips eventually but not until after I get all the stuff de-soldered from the donor board... dreading that!

While I have your ear, what is the 5v DC power barrel jack for on the back of the H5 C5B? Is that power in or power out for like an ultrasatan or? Haven't had time to research or put a multimeter on it due to the other festivities of getting it running.

officer960 wrote: 25 Jul 2025 03:24 While I have your ear, what is the 5v DC power barrel jack for on the back of the H5 C5B? Is that power in or power out for like an ultrasatan or? Haven't had time to research or put a multimeter on it due to the other festivities of getting it running.

Yeah external power to devices.