x68000:soft_power_switch_troubleshooting_and_repair
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x68000:soft_power_switch_troubleshooting_and_repair [2012/11/20 22:57] – eidis | x68000:soft_power_switch_troubleshooting_and_repair [2012/11/21 00:18] – eidis | ||
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- | ===== Soft power switch | + | ===== Soft-power troubleshooting and repair ===== |
- | The following information is kind contribution by our forum members **Lydux** and **Caius**. This fix was applied to X68000 | + | The following information is kind contribution by our forum members **Lydux** and **Caius** |
- | The symptom: System | + | **The symptoms:** X68000 |
- | The problem is almost | + | If this is your case then the problem is almost |
- | Here is the power on/off logic behind the **/PSON** signal (named CH2 in the shematic). Click on it to enlarge. | + | Here is the power on/off logic behind the /PSON signal (named CH2 in the schematics). Click on them to enlarge. |
{{: | {{: | ||
- | A condition using 4 signals is used to get the X68K turn on/off correctly : | + | **A condition using 4 signals is used to get the X68K turn on/off correctly :** |
- | | + | *Via the RTC (Real Time Clock) alarm signal (/ |
- | *Via the **RTC** (Real Time Clock) alarm signal (**/RTC_ALARM**) | + | *From the expansion bus (/EXPWON) |
- | *From the expansion bus (signal **/EXPWON**) | + | |
- | *A signal from the system controller (the soft sequence you're talking about, signal **/MPWOFF**). | + | *Via the soft-sequence |
- | On normal operation, all these 4 signals must go logic High (+5v) to get a system shutdown. | + | In normal operation, all these 4 signals must go to logic High (+5v) to get a system shutdown. |
The problem might be due to a signal that is always stuck Low. | The problem might be due to a signal that is always stuck Low. | ||
- | If you look to the buffered | + | If you look at the Buffered |
+ | |||
+ | |/ | ||
+ | |/ | ||
+ | |/ | ||
+ | |||
+ | **A program for testing these signals can be found here :** | ||
+ | |||
+ | [[http:// | ||
+ | |||
+ | **Execute it more than one time. You should get :** | ||
+ | *RTC_ALARM = 1 or 0, depending on the current RTC configuration. | ||
+ | *EXPWON = 1 | ||
+ | *PSON = 0 | ||
+ | |||
+ | **If RTC_ALARM always stays 0 :** | ||
+ | *Bad RTC chip (RP5C15) | ||
+ | |||
+ | **If EXPWON = 0 :** | ||
+ | *Check the expansion riser, or remove it. | ||
+ | *Check the " | ||
+ | |||
+ | **If PSON = 1 :** | ||
+ | *Damaged resistor R54 (should act as pullup) | ||
+ | *Bad power switch | ||
+ | |||
+ | **And if all is ok, it could be :** | ||
+ | *Bad IC28 (74LS08) (stuck output). | ||
+ | *Bad Q9 transistor (shorted). | ||
+ | *Bad C64 capacitor (generating noise). | ||
+ | *IC29 (74LS244) might have bad output on pin 5. | ||
+ | *The power signal from the main board, which I miss infos actually. A fix to this could be soldering a 10K ohm resistor between IC28 pin 10 and 14. | ||
- | */RTC_ALARM ==> GPIP0* | ||
- | */ | ||
- | */ | ||
x68000/soft_power_switch_troubleshooting_and_repair.txt · Last modified: 2019/08/27 20:45 by 127.0.0.1