PE e-ink side board - Page 2

ivanjt · 06-04-2011, 07:24 PM

The area of interest is D18, U28, FB23 and U29. I can't tell if there is any damage because you are using a single light source which leaves shadows. Q1 may be a switch and I think U28 may be a set of 3 diodes. I can't read what U29 is but if it connects in any way to Q1 and D18 then it may be the LCD control chip.

If it is you will need a data sheet to tell which pins are which, somewhere there should be an inhibit, or switch, line that is the one you are looking for to find out its state.

I would like it to be something simple like D18 being open bit it most probably isn't.

One thought, if you sort this out you might have the answer to the WSOD that is bugging some people.

emusan · 06-04-2011, 08:29 PM

Quote:

Originally Posted by ivanjt

One thought, if you sort this out you might have the answer to the WSOD that is bugging some people.

One user in another thread had the same thought, that the WSOD was due to the cable in the hinge, and was going to bring it to their local electronic repairman in order to see if they could get it fixed, though I'm not sure what became of it. It would make sense, as the hinge must put a lot of strain on that thin little cable...

jackr · 06-05-2011, 12:42 AM

I tested d18, and before the diode, I got a reading of 4.96v @ 0.25a and after the diode a reading of 4.88v @ 0.20a. I will also try to get a better lighted shot of the area tomorrow.

ivanjt · 06-05-2011, 05:37 AM

Something doesn't look quite right with those figures. Normal voltage drop across a standard diode, as this one appears to be, is 0.6v and you are showing 0.08v which could be almost correct if the diode was an avalanche type.

One other thing, how are you measuring the current?

jackr · 06-05-2011, 05:45 AM

Quote:

Originally Posted by ivanjt

Something doesn't look quite right with those figures. Normal voltage drop across a standard diode, as this one appears to be, is 0.6v and you are showing 0.08v which could be almost correct if the diode was an avalanche type.

One other thing, how are you measuring the current?

Got me in one

. I don't have a lot of experience, so I used a yellow led that I had on hand and took a quick measurement.

ivanjt · 06-05-2011, 11:02 AM

Thought it must be something like that - forget current measurements at the moment unless you have access to some very expensive equipment that gives you the figures after you plug in track width and thickness. The usual way is to unsolder one end of the component and put the meter between the solder pad and the unsoldered end of the component - not an easy task for the untrained (I some times make a mistake and break a component and I've been doing this type of work for over 30 years). When measuring voltage use the 'gnd' test points for the negative probe of your meter and be careful when applying the positive probe that you don't short anything out - could be very nasty.

For someone with little experience you are doing quite well so far. Just take care and we should get there.

jackr · 06-05-2011, 07:02 PM

Attached is an edited shot of the u29 chip. It appears to be A84A 0116. The other shot shows a brown bead on L5. I couldn't yet find a good light source.

jackr · 06-06-2011, 01:58 AM

I took readings on both sides of fb23 as well as the u29 side of c265 and each read @ 4.96v.

ivanjt · 06-06-2011, 03:06 PM

If I can get the picture up on here I'm looking for the voltages at the numbered points with respect to TP3 GND.

Another thing, My replies to anything you post will be a little sporadic for the next couple of weeks - I have a lot of work on a new contract that should keep us going unlike Entourage.

jackr · 06-06-2011, 04:25 PM

Quote:

Originally Posted by ivanjt

If I can get the picture up on here I'm looking for the voltages at the numbered points with respect to TP3 GND.

Another thing, My replies to anything you post will be a little sporadic for the next couple of weeks - I have a lot of work on a new contract that should keep us going unlike Entourage.

Hopefully it will be solved quickly then

. I took readings @ the points you want. The tilde ones are the ones where the reading fluctuated.

p1: 4.88v

p2: 4.96~4.97v

p3: 0v

p4: -0.1mV

p5: 3.25~3.26v

p6: 4.96~4.97v

p7: 3.23v

ivanjt · 06-07-2011, 07:37 AM

OK, I have a little time while the server racks are installed.

Something doesn't seem right here, I'm not saying your measurements are wrong. just that the backlight should work since you are getting the nominal 5v at point 1.

Can you check that you get the same voltage (4.88v) at the + terminal of the LED array.

There may be two other explanations, Pulsing the supply to a higher voltage or they are switching the negative supply line. The first is possible but there is no logical reason for the second.

jackr · 06-07-2011, 07:21 PM

Quote:

Originally Posted by ivanjt

OK, I have a little time while the server racks are installed.

Something doesn't seem right here, I'm not saying your measurements are wrong. just that the backlight should work since you are getting the nominal 5v at point 1.

Can you check that you get the same voltage (4.88v) at the + terminal of the LED array.

There may be two other explanations, Pulsing the supply to a higher voltage or they are switching the negative supply line. The first is possible but there is no logical reason for the second.

The closest I can get at the moment to the led's is where the led array ribbon is soldered to the lcd ribbon on the display. I have run 7.79v through it before and got the leds to light up; I also tried 6.47v but the leds didn't light up. 4.88v is present @ where the ribbon is soldered.

ivanjt · 06-08-2011, 07:10 AM

Umm, scratches head and changes mental gears from server setup and testing to edge repair mode.

So the LEDs are in series hence the need for higher voltage. I am assuming the PE battery is a nominal 7v which doesn't give much leeway for discharge and running anything else - WiFi etc.

I must try and track down that A84A - or is it an AB4A? and see if it is a pulse switch or something like that. If it is then we need to know what switches it on since it can be controlled to shut off the screen. I'll see if someone in the office can track it down - hopefully it isn't a generic number.

Now back to keeping Co in business.

jackr · 06-08-2011, 06:57 PM

I started a new thread with a more appropriate name of the problem over here: https://www.mobileread.com/forums/sho...d.php?t=138257.

Hopefully someone else will try their hand @ testing voltage points on a working unit.

ivanjt · 06-09-2011, 07:11 AM

Good idea jackr - if we get some comparisons we can move forward.

So far we've not been able to turn up anything on the A84A chip and some of my people think it is an OEM number but I'll keep trying.

Is it possible for you to get some high resolution pics of the board - by that I mean pics with enough resolution to be able to follow tracks.

End of lunch time so back to work - even the boss has to keep strict hours

06-05-2011, 07:02 PM	#22
jackr Connoisseur Posts: 67 Karma: 92 Join Date: Mar 2011 Device: Nook STR, Pocket eDGe	Attached is an edited shot of the u29 chip. It appears to be A84A 0116. The other shot shows a brown bead on L5. I couldn't yet find a good light source. Attached Thumbnails

06-06-2011, 03:06 PM	#24
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	If I can get the picture up on here I'm looking for the voltages at the numbered points with respect to TP3 GND. Another thing, My replies to anything you post will be a little sporadic for the next couple of weeks - I have a lot of work on a new contract that should keep us going unlike Entourage. Attached Thumbnails

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06-04-2011, 07:24 PM	#16
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	The area of interest is D18, U28, FB23 and U29. I can't tell if there is any damage because you are using a single light source which leaves shadows. Q1 may be a switch and I think U28 may be a set of 3 diodes. I can't read what U29 is but if it connects in any way to Q1 and D18 then it may be the LCD control chip. If it is you will need a data sheet to tell which pins are which, somewhere there should be an inhibit, or switch, line that is the one you are looking for to find out its state. I would like it to be something simple like D18 being open bit it most probably isn't. One thought, if you sort this out you might have the answer to the WSOD that is bugging some people.

06-05-2011, 12:42 AM	#18
jackr Connoisseur Posts: 67 Karma: 92 Join Date: Mar 2011 Device: Nook STR, Pocket eDGe	I tested d18, and before the diode, I got a reading of 4.96v @ 0.25a and after the diode a reading of 4.88v @ 0.20a. I will also try to get a better lighted shot of the area tomorrow.

06-05-2011, 05:37 AM	#19
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	Something doesn't look quite right with those figures. Normal voltage drop across a standard diode, as this one appears to be, is 0.6v and you are showing 0.08v which could be almost correct if the diode was an avalanche type. One other thing, how are you measuring the current?

06-05-2011, 11:02 AM	#21
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	Thought it must be something like that - forget current measurements at the moment unless you have access to some very expensive equipment that gives you the figures after you plug in track width and thickness. The usual way is to unsolder one end of the component and put the meter between the solder pad and the unsoldered end of the component - not an easy task for the untrained (I some times make a mistake and break a component and I've been doing this type of work for over 30 years). When measuring voltage use the 'gnd' test points for the negative probe of your meter and be careful when applying the positive probe that you don't short anything out - could be very nasty. For someone with little experience you are doing quite well so far. Just take care and we should get there.

06-06-2011, 01:58 AM	#23
jackr Connoisseur Posts: 67 Karma: 92 Join Date: Mar 2011 Device: Nook STR, Pocket eDGe	I took readings on both sides of fb23 as well as the u29 side of c265 and each read @ 4.96v.

06-07-2011, 07:37 AM	#26
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	OK, I have a little time while the server racks are installed. Something doesn't seem right here, I'm not saying your measurements are wrong. just that the backlight should work since you are getting the nominal 5v at point 1. Can you check that you get the same voltage (4.88v) at the + terminal of the LED array. There may be two other explanations, Pulsing the supply to a higher voltage or they are switching the negative supply line. The first is possible but there is no logical reason for the second.

06-08-2011, 07:10 AM	#28
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	Umm, scratches head and changes mental gears from server setup and testing to edge repair mode. So the LEDs are in series hence the need for higher voltage. I am assuming the PE battery is a nominal 7v which doesn't give much leeway for discharge and running anything else - WiFi etc. I must try and track down that A84A - or is it an AB4A? and see if it is a pulse switch or something like that. If it is then we need to know what switches it on since it can be controlled to shut off the screen. I'll see if someone in the office can track it down - hopefully it isn't a generic number. Now back to keeping Co in business.

06-08-2011, 06:57 PM	#29
jackr Connoisseur Posts: 67 Karma: 92 Join Date: Mar 2011 Device: Nook STR, Pocket eDGe	I started a new thread with a more appropriate name of the problem over here: https://www.mobileread.com/forums/sho...d.php?t=138257. Hopefully someone else will try their hand @ testing voltage points on a working unit.

06-09-2011, 07:11 AM	#30
ivanjt Guru Posts: 858 Karma: 1027478 Join Date: Aug 2010 Location: South of France Device: kindle dx; eDGe	Good idea jackr - if we get some comparisons we can move forward. So far we've not been able to turn up anything on the A84A chip and some of my people think it is an OEM number but I'll keep trying. Is it possible for you to get some high resolution pics of the board - by that I mean pics with enough resolution to be able to follow tracks. End of lunch time so back to work - even the boss has to keep strict hours

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