exxos's Atari, Amiga & retro forum

Well, very annoying, the beeb has a new issue, no sound!!

There is good output from the SN76489, IC18, which is the sound chip, and I can see in game music and the Boo-Bip on my scope. Since my machine doesn't have speech synthesis on board, I can ignore that part of the circuit.

That leaves 2 more ICs, an LM324 at IC17 and an LM386 at IC19. I see input at IC17, but no output from it or any input at IC19. I suspect the 324 has died, but have ordered both a 324 and a 386 just in case and have installed sockets in those positions. I just need to wait for the parts to arrive.

:dizzy:

You do have a good -5V line don't you?

stephen_usher wrote: 08 Dec 2024 21:01 You do have a good -5V line don't you?

Yep, first thing I checked.

OK, sound is restored, LM386 was dead.

Pulling a chip out of a socket and dropping a new one in is all I can manage at the moment

OK, and drive 0 is now working, it boots both 80 and 40 track from the original disks I have and seems just fine and I can format both sides. It's odd that physical disk 0 represents 2 drives (0&2) as they are double sided, but only work one side at a time.

The other drive, representing 1&3 is not playing at all either in 40 or 80 track mode, so there must be a fault on the control board. The motor starts just fine but there is no other activity.

Still, happy to have at least one FDD working as it should.

rubber_jonnie wrote: 14 Dec 2024 13:28 Still, happy to have at least one FDD working as it should.

Still better than nothing.

HigashiJun wrote: 15 Dec 2024 02:39

rubber_jonnie wrote: 14 Dec 2024 13:28 Still, happy to have at least one FDD working as it should.

Still better than nothing.

I'll take it. I expect that there is a bad IC on the control board, but I'll probably park that until the new year now.

Another positive, the ATPL sidewise board is now fully populated, so this machine has a ton of ROMs, Sidewise RAM and a 177X floppy disk controller installed and working.


The one ROM that was interesting though is Defender. You have to *ROM into the ROM filing system, then do a *. to get a directory listing of 4 files. Then you run LOAD "DEF1" to load in the boot program, then RUN it to get Defender to start, which happens after loading another 3 items from ROM.

Feels weird being able to treat a ROM like a file system, but also very cool. Most other ROMs execute by using the *ROMNAME command where ROMNAME is the name listed when you either run *ROMS or *HELP.

Wish I'd had a BEEB back in the day when our school had them, but they were just too expensive. Nice to catch up with them now though.

@rubber_jonnie

Stop tempting me unconsciously.

I still have the BBC Master 128 on my mind...

:lol:

HigashiJun wrote: 20 Dec 2024 00:33 @rubber_jonnie

Stop tempting me unconsciously.

I still have the BBC Master 128 on my mind...

:lol:

I'm tempting you consciously :)