ESQ1 no response from panel buttons

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ESQ1 no response from panel buttons

Postby micjax53 » Thu Feb 07, 2019 12:36 am

Unplugging serial data cable at mainboard, display shows buttons are working, but plugging back in, display is frozen and can't soft reset. Power supply voltages are correct, keyboard is working, output is good. Replaced DUART IC, but still have same problem. DSP IN signal to display board from mainboard is high, but no pulses are seen. Found and replaced IC1 on display board because pin5 showed less than 5 ohms to ground. DSP OUT signal shows pulses. Where can I go next?
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Re: ESQ1 no response from panel buttons

Postby Rasputin » Thu Feb 07, 2019 1:24 am

The title of your post seems incorrect compared to your symptoms.

If the display works in self-test but hangs when comms are connected then the display won't even initialize period, so it's not just the panel buttons.

If there is no serial comm traffic generated by the mainboard then that's different from the display board not being able to see it.

Check if the DUART is outputting serial comms. If so, then test for that same communication at the serial comm header as it leaves the mainboard. Still looking good? If so, then test the same comms at the serial comm header as it reaches the display board, etc.

If the DUART isn't putting out good serial Tx then you've got bigger problems. If it is putting out good comms then it's either getting lost along the way, or the 6500/11 is blind to it because it's serial Rx pin is stuck, etc.

Basically what I'm saying is to first test to see if the DUART is generating good serial Tx, and determine if
the problem lies at the origin, or further upstream.
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Re: ESQ1 no response from panel buttons

Postby micjax53 » Thu Feb 07, 2019 1:55 am

Since the keyboard is working, I thought the keyboard controller IC9 was working and the DUART was seeing pin10 KEYOUT and sending data. On the DUART, the Reset port is Low, the Chip Enable is clocking, RW and WE are also clocking.
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Re: ESQ1 no response from panel buttons

Postby Rasputin » Thu Feb 07, 2019 5:13 am

I'll put it more plainly:

Do you know where the serial Tx leaves the mainboard before it hits the display board? No need to guess what's going on, simply check if this has a proper signal.

Disconnect 4-wire comm connector between display and mainboard. Check for serial Tx on mainboard header.

If signal is not present or is not otherwise good, you've got a mainboard problem.
If signal is present and good, you've got a display board problem.

Your troubleshooting flowchart diverges depending on what you measure at this point because it's a natural bottleneck.
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Re: ESQ1 no response from panel buttons

Postby blueknob » Thu Feb 07, 2019 9:50 am

yes the microcontroller chip in the display/button board dies :( happened to me, the fix is from Rainer Buchty, pay the money and move forward.
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Re: ESQ1 no response from panel buttons

Postby micjax53 » Thu Feb 07, 2019 5:41 pm

The display micro U9 has been replaced by Dr B's substitute. U9 micro on the mainboard is passing keyboard signal, I can see SACK going low when keys are pressed, however there are no pulses when buttons on the keypad are pushed. There are pulses going in on pin23 and out on pin24. The only serial signal from the DUART to the display are two sets of pulses at power on.
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Re: ESQ1 no response from panel buttons

Postby Rasputin » Thu Feb 07, 2019 7:06 pm

micjax53 wrote:The display micro U9 has been replaced by Dr B's substitute. U9 micro on the mainboard is passing keyboard signal, I can see SACK going low when keys are pressed, however there are no pulses when buttons on the keypad are pushed. There are pulses going in on pin23 and out on pin24. The only serial signal from the DUART to the display are two sets of pulses at power on.


The only serial Tx that gets sent to the display from the DUART is the display initialization and textual data (when the menu changes, etc.)

So the question is: Do those two sets of pulses at power on also make it to the 6500 chip on its serial Rx pin? Yes or no?
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Re: ESQ1 no response from panel buttons

Postby micjax53 » Thu Feb 07, 2019 8:39 pm

Yes, they are on pin23 of the IC.
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Re: ESQ1 no response from panel buttons

Postby Rasputin » Fri Feb 08, 2019 7:52 pm

micjax53 wrote:Yes, they are on pin23 of the IC.


If the DUART serial Tx to initialize the display is making it all the way to the 6500/11 pin 23 and the display isn't initializing then you pretty much have to snoop the actual traffic because you know the display works in self-test.

If the display works in self-test and serial data is making it all the way to the serial Rx pin of the 6500/11 then it stands to reason that the serial data itself is either corrupt as it leaves the DUART, or is being corrupted on the way.

You can find out which one by comparing the data at the actual DUART serial Tx pin with the data arriving at the 6500/11 serial Rx pin.
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