AR8600-MK2 What is the possible cause of this fault?

AOR-262

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What do you think is the possible cause of this fault?

When switching the 8600 Mk2 on, the screen repeatedly flashes as you can see in the video. The PSU is ok (rated output: 12v @500mA)

 

dwell1650

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To me it seems like a overcurrent issue and I think you need to know if your A8600 draws excess current or not.
How do you know if the PSU is ok? Have you tried to load it with another device with the same load?
 

AOR-262

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@dwell1650 The PSU is working fine, it's a regulated PSU and giving 12v without a load - so am happy that is ok. Have tried another 12v PSU and the same happens with the AOR. The screen flashes.

@ka3aaa This issue is beyond the scope of the manual possible faults. I suspect something far more serious with a component on the circuit board.
 

kruser

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Can you open the covers and get a volt meter on the power jacks wires so you can see what the voltage is doing while the screen is blinking?
That test may reveal something.
 

dwell1650

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Did you detect any magic smoke or smell when it happen first time? ....I hope not

It may be a short circuit somewhere and the intern voltage regulator is shutting down repeatedly due to overloading.
I think the best thing to do is to let someone with the right knowledge and test gear help you look at it.
A multimeter, a oscilloscope and a schematic may be handy in such situations.

Edit:
A service manual with schematics you may find here.
mods.dk -> Instruction, users and service manuals for Aor
 
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Ubbe

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Doesn't seem like hardware fault to me but a software error at boot. Does it use upgradable firmware and/or SD memory cards? Then try to reflash the (correct) firmware again and reformat the SD card and start up with default parameters without any user channels programmed.

/Ubbe
 

dwell1650

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I guess this is the type of regulator with short circuit protection and internal thermal protection who shuts down regularly. They are all over the schematics. You just have to find where the faulty component are. If you have a thermal camera it would be a way to track it down. A wild guess would be a faulty electrolytic capacitor since they are known to tend to get bad over time and sometimes cause short circuits.
TK11245MTL pdf, TK11245MTL description, TK11245MTL datasheets, TK11245MTL view ::: ALLDATASHEET :::

@Ubbe This device has an old school CPU. I don't think there is a way to just update the firmware on this one. I can't find anything in the the service manual that supports it anyway.
 
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Ubbe

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Is it possible to do a factory reset to rule out any software issues?

One technique I have used in tricky power on issues where to use a lab power supply and set that to the different voltages that exists in the device, lets say 5v that usually exists in all older electronic devices, and have the current limit set to 1A and see if it draws excessive current. And then try to power on the device while the lab power supply are helping out with extra current.

Then move on to next power rail and test. If the problematic power are found then let the power supply be on for a while to let a faulty component heat up so it can be felt by the touch of a finger, or it starts to tell you its location by smoke signals.

Many older devices use a tantalium capacitor at the reset pin of the CPU, to have it start after the voltages have been stabilised, and that capacitor have leaked and the voltage never rised enough to let the CPU start and a watch dog circuit where constantly restarting the device.

/Ubbe
 

stevecolumbus

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What do you think is the possible cause of this fault?

When switching the 8600 Mk2 on, the screen repeatedly flashes as you can see in the video. The PSU is ok (rated output: 12v @500mA)

I have the same receiver. Mine flashes JUST ONCE when turning it on. I have the backlight set to "off", so it doesn't even come on when hitting an active frequency. It almost seems as if the scanner cannot switch into whatever backight mode you have it in. Maybe try it in the "light off" mode and see if it still flashes?
 
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