Help with nonworking Atari STE

[tr1x]

Hello,

 

    I have got Atari 520 STe which is out of order.

 

1. I connected this computer to a TV set with use of STe's monitor output (only composite and GND signals are used).

 

2. For testing purpose and better accessibility to the motherboard, the keyboard and the floppy are unattached.

 

3. After power turned on, it is visible white screen on the TV (no bombs, only white screen).

 

4. After pressing Reset button, for a short time it is possible to see white horizontal stripes (whole screen filled with white/black stripes) on the TV set. After a short time, screen becomes black, and then dark-green horizontal stripes appear. After releasing Reset button, the screen becomes white again.

 

5. I checked in a few motherboard's points that there is +5 VDC. Also, PSU gives +12 VDC.

 

*** CPU MC68000

 

6. There is 8 MHz square wave on CPU's CLK pin.

 

7. BERR pin is set (+5 VDC) all the time. There are no low signal pulses (0 VDC) events on BERR when Reset button is pressed nor released -- BERR pin is set all the time.

 

8. There is square wave 800 kHz (duty 50%) on E pin.

 

9. Normally, RESET pin is set (+5 VDC) all the time. When Reset button is pressed, then RESET pin goes low (0 VDC). After releasing Reset button, RESET pin goes high (+5 VDC).

 

10. HALT pin is in low state (0 VDC).  After pressing and then releasing Reset button, three pulses on HALT pin are visible.

* Please refer to the picture in attachment - pin HALT.

 

11. Normally, A (address bus) and D (data bus) pins are set (+5 VDC).

 

12. After pressing and then releasing Reset button, on at least a few of A pins we can observe pulses.
* Please refer to the picture in attachment - pin A9.

 

13. After pressing and then releasing Reset button, on at least a few of D pins we can observe pulses.
* Please refer to two pictures in attachment - pin D12.
* Please refer to two pictures in attachment - pins D12 and HALT.

 

14. The CPU is quite hot. It is possible to touch it for 7-10 seconds, but after this time the pain was too strong to keep it touching.

 

*** GST MCU

 

15. There is GST MCU type C302183-001. There is 16 MHz square wave on CLK16 pin. There are 8 MHz on CLK8 pin, 4 MHz  on CLK4, 2 MHz on CLK2, and 0,5 MHz on CLK0,5.

 

16. BERR  pin is set (+5 VDC).

 

I would be glad, if you could tell me what to check next in order to make my computer working. Thanks in advance for a reply.

 

tr1x

Ostatnio edytowany przez tr1x (Dzisiaj 14:50:36)

A9.png 13.83 kb, nikt jeszcze nie pobierał tego pliku. 

D12(1).png 14.01 kb, nikt jeszcze nie pobierał tego pliku. 

D12(2).png 14.4 kb, nikt jeszcze nie pobierał tego pliku. 

D12_HALT(2).png 9.66 kb, nikt jeszcze nie pobierał tego pliku. 

D12_HALT.png 17.49 kb, nikt jeszcze nie pobierał tego pliku. 

HALT.png 14.19 kb, nikt jeszcze nie pobierał tego pliku. 

IMG_9823.jpg 727.91 kb, nikt jeszcze nie pobierał tego pliku. 

Tylko zalogowani mogą pobierać załączniki.

[anzac]

Have you tried different memory sticks?

[tr1x]

On 8/16/2019 at 4:48 PM, anzac said:

Have you tried different memory sticks?

Not yet. I ordered 30-pin SIMMs, and waiting for a delivery.

[tr1x]

10 hours ago, tr1x said:

Not yet. I ordered 30-pin SIMMs, and waiting for a delivery.

Problem solved, thank to a guy how used his ROM with my STe.  My ROM was somehow damaged of stuff. Now, my STe works.

[anzac]

Good to know it's alive again. Enjoy your STe