BusterKeaton88 Posted March 3 Share Posted March 3 Hello, i´m having trouble with my Atari 1040ST and need some help for troubleshooting. What happend: I had it turned on for a couple of hours while working with cubase and midi in and outputs connected to a synthezier. I also had the Modem port connected to a pc via null modem cable for Ghotlink and a disk insertet. Without any warnings the ST turned off. I tried to restart it by using the power switch. The Screen (SM124) stayed black. The left corner Power LED is on but the disk drive LED is off. The disk drive LED turns on for about half a seconnd after using the power switch. After that it stays off. No sound from the drive. What i tried: - Disconnected Midi an Modem port. No change - Disconnected Monitor and checked the connector pins. Looks alright. - Left the ST running for half an hour. No change - Opened the ST. It was sealed. - Checked Power Supply. 5,2V and 12V. - Disconnected disk Drive. No change - Changed the disk Drive. No change - Pulled out every socketed ic and checked for damage. They all look good. Put them all back in. No change. - Switched the ST on and pressed the main PCB and every ic at different places. No change. - Checked every capacitor for visual damage. The all look good. - Checked halt and reset at pins 17 and 18 at the 68000. The have a steady 5V. If i press the reset button they go to 0V and back to 5V. My equipment and abilities: - Multimeter - Oscilloscope - Soldering iron - Electrical engineer It´s a rev.1 GX-211 V0 3288 PCB and it looks brand new. Any help would be appreciated. Thank you Quote Link to comment Share on other sites More sharing options...
Zogging Hell Posted March 4 Share Posted March 4 Did you check the power supply with a dummy load, as you won't get the right readings without? It would certainly be my first suspicion if it hasn't been recapped. Quote Link to comment Share on other sites More sharing options...
Chri O. Posted March 5 Share Posted March 5 (edited) From Atari ST service m. https://archive.org/details/atari520st1040stservicemanual/page/n27/mode/2up Page 3.3 2. Disassemble the computer so that the printed circuit board is exposed (see Section 4, Disassembly). Power up the computer. Using an oscilloscope, verify the 8MHz clock to the 68000 CPU (pin 15'. Replace oscillator if necessary. Then check pin 17 (HALT) of the 68000 CPU. It should be a TTL high. If so, go on to 3 below- If not, the CPU is halted. The reasons may be: (1) bad reset circuir. (2) double bus error, 3) bad CPU. Check (1) by observing signal on input of the two inverters on the HALT line. Check (2) by observing pin 22 of the CPU (BERR) as the unit is powered on. It should be high always. If there are logic low pulses, some component is malfunctioning and Glue is generating the error. Verify the clocks to Glue and Memory Controller and replace these components to verify them (if socketed). If still failing, the CPU is unable to read ROM or there is a component which is not responding to a read or write by the CPU, probably the MFP 68901 or DMA Controller. The MFP should respond to an MFPCS with DTACK. The DMA chip should respond to FCS by asserting RDY. There is no way to check (3) other than by elimination of the other two possiblities, although a hot CPU (too hot to touch for more than a second) strongly indicates a bad CPU. 3. If the CPU is not halted, it should be reading instructions from ROM (cartridge, if installed) and data and address lines will be toggling. (If not, replace CPU.) At this point, there is the possibility that both the video and RS232 subsystems are failing. Verify the output of the MFP chip (pin while powering on the unit with the cartridge installed. If data is being sent, trace it through the 1488 driver. Edited March 5 by Chri O. ADD PIC Quote Link to comment Share on other sites More sharing options...
Chri O. Posted March 5 Share Posted March 5 ATARI DIAGNOSTIC CARTRIDGE £28 34 In Stock [0165] available at EXXOS STORE https://www.exxosforum.co.uk/atari/store2/ (Null modem cable) more or less for people that don't have it. Strongly recommend also buying a diagnostic cable to hook up your ST to your PC should there be no video output etc item #0191 Quote Link to comment Share on other sites More sharing options...
BusterKeaton88 Posted March 7 Author Share Posted March 7 (edited) Thanks for the replies. I worked my way back through the clock signals. 68000 Pin 15 > Nothing, should be 8Mhz 68901 Pin 35 > 5V, no clock, should be 4Mhz Video Shifter Pin 39 > Nothing, should be 16Mhz Y1 > 1,5V looks good 2,5Mhz Y2 > 10V, should be 32Mhz my oszilloscope has a max range of 20Mhz Y3 > Nothing, should be 4,4Mhz Edited March 7 by BusterKeaton88 1 Quote Link to comment Share on other sites More sharing options...
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