Search found 36 matches

by veegee
Tue Sep 05, 2017 4:55 pm
Forum: Hardware
Topic: Mega 1 Address Lines stuck
Replies: 0
Views: 714

Mega 1 Address Lines stuck

I've just finished resurrecting a Mega 1 board, and had it working fine with the diagnostic cartridge, however it crashed one time and now won't boot. The CPU is running but two of the address line pins are stuck high as it boots hence why it just has a white screen. I've traced the lines across the...
by veegee
Tue May 23, 2017 6:21 pm
Forum: Hardware
Topic: RTC test failure
Replies: 2
Views: 1155

Re: RTC test failure

Hi Kubik,

Both my Mega and diag cart are working at the mo!

I take it you've added the RTCPAL chip as well, an obvious test would be to leave it a couple of days and see if the control panel time is correct?
by veegee
Mon May 22, 2017 5:05 pm
Forum: For sale / Wanted
Topic: Wanted - ST/Mega reset switch, Megafile case top.
Replies: 1
Views: 1525

Wanted - ST/Mega reset switch, Megafile case top.

Hi All,

Looking for a reset switch for a board I just got that has been stripped.

Also need a top case for my Megafile if anyone has a spare...

Thanks

Andrew
by veegee
Thu Nov 03, 2016 10:08 pm
Forum: Hardware
Topic: Diagnostic Cartridge Rom issue
Replies: 13
Views: 7738

Re: Diagnostic Cartridge Rom issue

In the end I bought one from Kubik (see above posts) but the original site I found the circuit and roms on was here :-

http://gossuin.be/index.php/archives/2- ... t-atari-st

Hope you get it sorted!
by veegee
Mon Oct 03, 2016 6:50 pm
Forum: For sale / Wanted
Topic: Wanted - Mega ST 4 Shielding and Keyboard, Megafile 60, RTC
Replies: 2
Views: 2722

Re: Wanted - Mega ST 4 Shielding and Keyboard, Megafile 60, RTC

Quick bounce for this one - have sourced the RTC chips (thanks Chandler!) but still need the rest.

Most desperate for a top case for the MegaFile as my Mega4 needs something to sit on!

Thanks
by veegee
Fri Sep 23, 2016 8:50 pm
Forum: Professionals
Topic: Another Falcon in need of resuscitation..Please help! :-)
Replies: 49
Views: 13852

Re: Another Falcon in need of resuscitation..Please help! :-)

Can you post a pic of your ATX PSU spec label?, looking at the service guide a Falcon shouldn't draw more than 7A current from the +5v and the (Falcon) fan is driven by the +12v which could explain why yours doesn't spin up on the motherboard. From what I can see the power should be pins 1-3: 5v, 4-...
by veegee
Wed Sep 14, 2016 11:41 am
Forum: Hardware
Topic: Help with Atari STf - RGB - Cannot get video/sync
Replies: 85
Views: 35728

Re: Help with Atari STf - RGB - Cannot get video/sync

Just to confirm what Christian is saying - I have just checked with my scope and both my 1040STf and my Mega 4 have a TTL composite sync signal on pin 2 of the monitor socket. They both read about 3.6v peak to peak. Again backing up what Christian has said I think your monitors and cables are good a...
by veegee
Wed Sep 14, 2016 10:31 am
Forum: Professionals
Topic: Another Falcon in need of resuscitation..Please help! :-)
Replies: 49
Views: 13852

Re: Another Falcon in need of resuscitation..Please help! :-)

Hi, The ATX PSU should work no problem, I would put a switch on the green lead so you can ensure it works properly - an ATX PSU will run without a load so if it's shutting down after a few seconds it leads me to think that the green lead is the problem and it's switching itself off - make sure it's ...
by veegee
Fri Sep 09, 2016 1:13 pm
Forum: Hardware
Topic: 520 STE 2 bombs issue
Replies: 22
Views: 8218

Re: 520 STE 2 bombs issue

oissery77 wrote:Ok thanks a lot. i will do that, just need to find the Cpu pinout.
grab the schematic from here :-

http://dev-docs.atariforge.org/files/ST ... 3-1989.pdf
by veegee
Thu Sep 08, 2016 2:19 pm
Forum: Hardware
Topic: 520 STE 2 bombs issue
Replies: 22
Views: 8218

Re: 520 STE 2 bombs issue

Only way to be sure is to thoroughly clean the contacts and make sure they are all straight and the chip fits tight. You can check the continuity with the multimeter - get hold of the schematic and trace each CPU pin out - you show see 0 or very close to 0 ohms resistance anything more means a poten...
by veegee
Wed Sep 07, 2016 10:05 pm
Forum: Hardware
Topic: 520 STE 2 bombs issue
Replies: 22
Views: 8218

Re: 520 STE 2 bombs issue

Hi, 2 bombs is a bus error asserted by the GLUE or the CPU - I would suggest it might be TOS2.06 which you can check by using a software loader to put 1.62 into RAM. Alternatively you could have damaged one of the chips connected to line 1 of the ACSI port - either the buffer (U302) or the DMA chip....
by veegee
Mon Sep 05, 2016 8:36 pm
Forum: Hardware
Topic: Orphaned Machines need some help
Replies: 14
Views: 3724

Re: Orphaned Machines need some help

Just had a thought reading another thread - it could be that your PSU is not working as efficiently as it should - in mono mode the 12v is only needed for the floppy drive whereas in colour mode it is needed for RGB output and the floppy, can you swap the PSU out of one of the other machines tempora...
by veegee
Mon Sep 05, 2016 8:06 pm
Forum: Hardware
Topic: Orphaned Machines need some help
Replies: 14
Views: 3724

Re: Orphaned Machines need some help

You can use a multimeter but it's not a foolproof method, better to use a logic probe - colour modes the mono pin (30) on the shifter will be inactive and vice versa in the mono mode. I did a shifter chip transplant this morning. I took what I thought was a faulty Mega ST2 shifter chip and put it i...
by veegee
Sun Sep 04, 2016 11:48 am
Forum: Hardware
Topic: Orphaned Machines need some help
Replies: 14
Views: 3724

Re: Orphaned Machines need some help

You can use a multimeter but it's not a foolproof method, better to use a logic probe - colour modes the mono pin (30) on the shifter will be inactive and vice versa in the mono mode.
by veegee
Sun Sep 04, 2016 6:18 am
Forum: Hardware
Topic: Orphaned Machines need some help
Replies: 14
Views: 3724

Re: Orphaned Machines need some help

Does anyone know if older 520's or 1040's use the same shifter? I could try a transplant. Should be - I swapped shifters between a 1040STf board and my Mega 4 whilst I was testing chips and had no problems. Check that the MONOMON pin isn't stuck low (68901 pin 29) forcing mono mode, and also worth ...
by veegee
Wed Aug 31, 2016 9:12 pm
Forum: For sale / Wanted
Topic: Wanted - Mega ST 4 Shielding and Keyboard, Megafile 60, RTC
Replies: 2
Views: 2722

Wanted - Mega ST 4 Shielding and Keyboard, Megafile 60, RTC

Hi, I'm looking for the top part of the metal shielding for my Mega ST (or the complete part if needs be) and a preferably UK Mega keyboard condition not important but needs to be intact not bothered if it doesn't work properly either. Thanks in advance Andrew Edited to add - also need a top plastic...
by veegee
Wed Aug 31, 2016 7:57 pm
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

Just to bring this full circle - the logic analyser showed that the machine was doing basically nothing no reset vector or TOS running. I did learn that certainly in the Mega's case you need all the custom chips present for the machine to boot - odd things like the 1772 can be done without but not i...
by veegee
Wed Aug 31, 2016 7:50 pm
Forum: Hardware
Topic: Help with Atari STf - RGB - Cannot get video/sync
Replies: 85
Views: 35728

Re: Help with Atari STf - RGB - Cannot get video/sync

czietz wrote:@veegee: You still have composite sync without modulator. No composite video, though.
Ah yes - wasn't 100% sure I had that correct! - thanks.
by veegee
Wed Aug 31, 2016 6:30 am
Forum: Hardware
Topic: Help with Atari STf - RGB - Cannot get video/sync
Replies: 85
Views: 35728

Re: Help with Atari STf - RGB - Cannot get video/sync

I had a similar problem with my Mega, it sounds like the V Sync is not getting from the Glue to the monitor plug properly. I'm not certain but I think you won't have the composite signal since you don't have the modulator. Use your meter to trace the H and V sync (pins 37 & 38) from the Glue chip, i...
by veegee
Sun Aug 07, 2016 7:18 pm
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

I've managed to get a logic analyser and will leave this on the side until it arrives, however I did find another broken track which connected up the DE line on the MMU - this seems to have brought the RAS line back to life. I'm going to check the ram buffers are working and check if all the data li...
by veegee
Thu Aug 04, 2016 9:41 am
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

I've found a 16ch Saleae clone for around £35, I've got a Tenma? probe I inherited, it doesn't count pulses but can inject a pulse if needed - this is how I tested the DMA FCS/RDY line. The data bus goes HIGH on reset and then almost immediately goes LOW, I'm intrigued by the MFP at the moment - pin...
by veegee
Wed Aug 03, 2016 9:25 pm
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

It seems your checking signals with a scope or Dvm, i honestly would recommend you use a Logic analyzer, i see you ignored my previos post. Your previous post got a bit lost in the melee and I haven't had a chance to research what you suggested yet! so no disrespect intended. I'm using a logic prob...
by veegee
Wed Aug 03, 2016 6:57 pm
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

R/W on the CPU is stuck HIGH and BGACK is now LOW. BGACK should be high during normal operation -- i.e. apart from DMA or Blitter accesses. When the ST has no blitter, all bus arbitration lines (BR, BG, BGACK) should go from the CPU to the GLUE. Is maybe one of them damaged? However still no action...
by veegee
Wed Aug 03, 2016 11:49 am
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

Ok, lunchtime tinkering yields all change! Removed the DMA, and the FD1772 and this takes the CPU out of the HALT state with no pulses on the BERR line either. (Update - it's the DMA changing this 1772 is ok) However still no action on the screen or through the serial port, and the Data lines are al...
by veegee
Wed Aug 03, 2016 8:10 am
Forum: Hardware
Topic: Mega ST4 CPU stuck in HALT Condition
Replies: 31
Views: 8194

Re: Mega ST4 CPU stuck in HALT Condition

Just to clarify one thing - when talking about diagnostics, are we talking about serial port? Did you connect serial terminal (putty) to the Atari serial port? If the RAM is dead, nothing will show on the screen, not even the diag, and serial is the only way. Yes I'm using the serial connection for...

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