Nexus-s Rev2.2 & onboard IR circuit

Beginner

Thursday, December 22nd 2005, 2:39am

Hi, all
i was trying something with my nexus-s 2.2
i was trying to replace the sensor of the original remote control receiver with new one , and i did it, and it worked great
but when finalizing the circuit and while the card was pluged to my pc and running the white wire of the IR(5 VOLTS- i think) touched the ground wire, after that the IR circuit stoped responding

i've tested the old sensor and the new one, and i can tell that they work perfectly on another remote circuit.

i've sent pm to UFO, Thomas, and randy , and as a result for their advices i guess there is a broken transistor between the IR connector on the nexus board and the av7110 IR_IN, or the av7110 IR_IN itself is damaged.

so, what do you think folks?
if there is a defected transistor, how can i know it?
i dont know how to trace a circuit, HOWEVER i have some good experience with SMD soldering (did the memory mod ,and the budget patch by myself)

if some one who faced this problem before could send me some info on that issue , i'd be thankful

also i want a simple site that teaches tracing and messuring circuits(in english please) .

many thanks in advance

mas0h..
.

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UFO

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2

Thursday, December 22nd 2005, 3:40am

RE: Nexus-s Rev2.2 & onboard IR circuit

Quoted

Original von mas0h
but when finalizing the circuit and while the card was pluged to my pc and running the white wire of the IR(5 VOLTS- i think) touched the ground wire, after that the IR circuit stoped responding

Hm - in your PM you wrote that the red wire touched the ground. So what? It makes a big difference!

Please check the voltage on the white (5V) wire. If it is 0V you killed the SMD resistor which limits the current on the white wire. This resistor saved your card.

CU
Oliver

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mas0h

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3

Thursday, December 22nd 2005, 4:47am

RE: Nexus-s Rev2.2 & onboard IR circuit

Quoted

Originally posted by UFO

Hm - in your PM you wrote that the red wire touched the ground. So what? It makes a big difference!

Please check the voltage on the white (5V) wire. If it is 0V you killed the SMD resistor which limits the current on the white wire. This resistor saved your card.

CU
Oliver

Hey, UFO
Actually, i cant remember which wire touched the other
i mean, the red or the white touched the ground , or both of them.

anyway, i did some search online, and found that a simple remote receiver unit consists of:
-IR Receiver (Sensor)
-Capacitor
-Voltage Regulator
-Resistor
-Universal Diode

So, by ruling-out IR Receiver (because it is not defected).
the defected part could be one of the rest of the components
capacitor, Voltage regulator, Resistor, and Universal diode.

also i've tried to messure the voltage between the (Red, white) and ground while the card was running( i dont know if that is correct or not)
by adjusting my multimeter to 20 DCV.
and here is the result:

the voltage between the ground and the white is 5 VOLTS
the voltage between the ground and the red is 4.8 VOLTS

and i tried to push any button from my remote control while messuring
and i noticed that the voltage dropped from 4.8 to 4.3 between the ground and the red.

that all i can do according to my little info about messuring with multimeters

BTW, where is this SMD resistor on the board?
i hope to hear good news from you.

Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
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mas0h

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4

Friday, December 23rd 2005, 4:07am

where are you ?

I found some friend who has some electronical skills, and he suggested that the transistor in the picture ( the bottom arrow ) is broken

so i left it for him to test it and he said that it is really defected.
now i want to know what that transistor is responsible for, you will find another one in the picture with the exact shape, and size on the top of the picture ( i've removed the defected one, so you will notice that the arrow is pointed to an empty place)

even i cant read the nubers on it to search for it online or on some broken old boards.

is that transistor is a voltage regulator ? or what.

please help me

thanks

mas0h has attached the following image:

Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
Nexus-S Rev 2.2 (4MB) OSD
Debian Sarge ==> Kernel-2.6.10
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UFO

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Friday, December 23rd 2005, 6:15am

RE: where are you ?

Quoted

Original von mas0h
I found some friend who has some electronical skills, and he suggested that the transistor in the picture ( the bottom arrow ) is broken

so i left it for him to test it and he said that it is really defected.
now i want to know what that transistor is responsible for, you will find another one in the picture with the exact shape, and size on the top of the picture ( i've removed the defected one, so you will notice that the arrow is pointed to an empty place)

even i cant read the nubers on it to search for it online or on some broken old boards.

is that transistor is a voltage regulator ? or what.

The transistor inverts the signal of the ir receiver. On my Nexus 2.1 it is labelled "SA" (really hard to read so I might be wrong). According to http://www.tkb-4u.com/code/smdcode/smdcodeS.php "SA" is a BSS123 (N-channel mosfet).

CU
Oliver

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This post has been edited 1 times, last edit by "UFO" (Dec 23rd 2005, 6:16am)

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mas0h

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Friday, December 23rd 2005, 7:28am

RE: where are you ?

Quoted

Originally posted by UFO
The transistor inverts the signal of the ir receiver. On my Nexus 2.1 it is labelled "SA" (really hard to read so I might be wrong). According to http://www.tkb-4u.com/code/smdcode/smdcodeS.php "SA" is a BSS123 (N-channel mosfet).

CU
Oliver

Ok, now we know where is the defective part, and yes it begins with SA.

does this mean that any transistor that starts with SA will do the job ?
and is there any equivalents ot that part ?

thanks, again.

Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
Nexus-S Rev 2.2 (4MB) OSD
Debian Sarge ==> Kernel-2.6.10
Fedora Core 3 ==> Kernel-2.6.10

This post has been edited 1 times, last edit by "mas0h" (Dec 23rd 2005, 7:30am)

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randy

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Friday, December 23rd 2005, 8:24am

RE: where are you ?

waths about bs170?

http://www.semiconductors.philips.com/ac…ts/BSS123_3.pdf

vs

http://littlelights.de/doku/anhang/datenblatt-bs170.pdf

-- randy

projekte:

* vdr-sanitizer rev4 SMD (fertig)
* aurora led controller (beta/aufbau)
* graphlcd@projects.vdr-developer.org

smue.org:useless stuff

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mas0h

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8

Saturday, December 24th 2005, 2:02am

now, i have another problem.
when i tried to order one of these online, i found something called minimum order, and that varries between 20 and 30 $.

can i found these transistors on any type of broken boards, like hard disk, main board, VGA ...etc

thanks.

Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
Nexus-S Rev 2.2 (4MB) OSD
Debian Sarge ==> Kernel-2.6.10
Fedora Core 3 ==> Kernel-2.6.10

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UFO

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Saturday, December 24th 2005, 3:38pm

Quoted

Original von mas0h
now, i have another problem.
when i tried to order one of these online, i found something called minimum order, and that varries between 20 and 30 $.

can i found these transistors on any type of broken boards, like hard disk, main board, VGA ...etc

Well, how should we know what you can find on your broken boards?
IMHO any N-channel mosfet should work.

Look at your boards and find a N-channel mosfet.
Using the link above you can check whether
- a transistor is a n-channel mosfet
- the pins are wired the same way as the BSS 123.

CU
Oliver

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This post has been edited 1 times, last edit by "UFO" (Dec 24th 2005, 3:39pm)

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mas0h

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Saturday, December 24th 2005, 6:58pm

take it easy UFO

Quoted

Originally posted by UFO

Well, how should we know what you can find on your broken boards?
IMHO any N-channel mosfet should work.

Look at your boards and find a N-channel mosfet.
Using the link above you can check whether
- a transistor is a n-channel mosfet
- the pins are wired the same way as the BSS 123.

CU
Oliver

Hey, UFO
calm down please, i told you before that i dont have any experience with electronics except soldering.

i searched on my old boards, and i found 1 transistor marked 1A, so i returned to the link you gave to me:
http://www.tkb-4u.com/code/smdcode/smdcode1.php

and found 5 ones named 1A including this

1A IRLML2402 IR F SOT23 n-ch mosfet 20V 0.9A

and, the one on the card (the broken one) is

SA BSS123 Sie M SOT23 n-ch mosfet 100V 0.17A

actually, that is very confusing to me, i dont know if the (1A) transistor could do the job of the (SA).

and one more thing, there are in the same table in the link above another 4 transistors beginning with 1A and are not n-ch mosfet

for example

1A FMMT3904 Zet N SOT23 2N3904
1A MMBT3904 Mot N SOT23 2N3904
1A BC846A Phi N SOT23 BC546A
1A BC846AT Phi N SOT416 BC546A

sorry for the long post
thanks

Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
Nexus-S Rev 2.2 (4MB) OSD
Debian Sarge ==> Kernel-2.6.10
Fedora Core 3 ==> Kernel-2.6.10

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mas0h

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11

Friday, December 30th 2005, 9:49pm

Thanks, it's done !
By getting another SA transistor from the nexus board itself.
the one connected to the big CI connector at the end of the board.
Since, i dont use that CI connector, and i'll never do.

And the card is running as a charm from three days with its own onboard remote circuit.

one last question, will this affect the card on the future by anything?
thanks again.

Intel 865Perl, P4 2.4, nVIDIA GeForce 4 128 MB, WD 160 GB, Maxtor 80 GB, SBLive 5.1
Nexus-S Rev 2.2 (4MB) OSD
Debian Sarge ==> Kernel-2.6.10
Fedora Core 3 ==> Kernel-2.6.10

This post has been edited 1 times, last edit by "mas0h" (Dec 30th 2005, 9:53pm)

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