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RobertB's Asus P5K/EPU missing transistor problem

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This discussion became a bit much for the other thread so let's bring it here;

@xrror Thanks a lot for the time you took to help me! :toast: Indeed that transistor is 42t - I'll have to remove the 1p/A1p. Good thing that I didn't power up the board yet. :) :rockout::peace:
Not so fast @Robert B . There is one part that throws that conclusion into question. Let's look at both photo's.
P5KEPU-MissingTransistor02.jpg
p5kProA1p.jpg
The first image is obviously your damaged board. Notice the part circled in red. The second is @xrror's P5KPro. Notice the part circled in red.
The 2 circled parts do not match and after looking them up, they are slightly different. Unfortunately, there are a crap-ton of parts out there with both the "A00A" and "A009" designation. However some digging revealed information.
Both the "A00A" and the "A009" are low frequency amp 15v(max) parts. However, the A00A has a higher line trigger voltage threshold, which likely affects the signal output for the device. What this means is that while attaching a 42t might not cause damage(very unlikely), sound output will be affected and will likely be a bit muffled, if there is output at all. Granted, this conclusion is based on research done without the schematics for either board so I could be wrong.

Either way I am confident you will not do any more damage by trying a 42t, regardless of whether it works.
 
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Last night I also looked at the spec sheets for the A00A and A009 as this was the only difference that I could spot between my P5K/EPU and xrror's P5K PRO.

I already soldered a 1P transistor instead of the 42t but I didn't power up the board yet. I'll dig a little more.

In this thread a TK715xxAS replacement for the 42t transistor is suggested. http://www.s-manuals.com/pdf/datasheet/t/k/tk715xxas_toko.pdf



The thing is TK715xxAS is a PNP transistor and 1P si a NPN transistor so I'll better solder a 42t or a 42t equivalent.
 
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Thing is, you have nothing to lose. Neither transistor will harm the circuit. If one doesn't work, it just won't work. However, the 42t seems like the component that will likely work better. My original conclusion of an A1P being the missing part was based on information I looked up for a very similar board. That being said, I believe it possible that the 42t may be close to the right part but not exactly the right one. Try it and share the results!
 
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Will do. I'm digging through my pile of donor boards for a replacement. Not ideal but what the heck. :)

I might just power up the board with the A1p soldered and call it a day if I don't find a 42t or equivalent. :D
 
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Will do. I'm digging through my pile of donor boards for a replacement. Not ideal but what the heck. :)
The problem is finding solid documentation on the board or even a high res photo to show what part is actually supposed to be there.
 
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True words my friend.

This reminds me of some instances when I couldn't find information about new parts but I found a lot more information about stuff that was decades old. :D
 
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I powered up the board and it boots and works but the jack detection is kaput and the USB ports are kind of flaky. On power up they work but if I Safe Remove a USB stick it isn't detected in Windows after I insert it again. It needs another restart to be detected again. Also when I connect a USB keyboard or a mouse they don't work even if I see that the mouse sensor lights up. I set up various BIOS settings but to no avail.

The onboard sound outputs an annoying white noise when I connect the speakers. I removed the 1p transistor I soldered, thinking that it was the culprit. NO DICE!

The ALC883 chip gets scorching hot sign that it has a problem. I might remove it an solder another chip from another board.

This board has huge issues that I might not be able to solve. The damaged transistor is just the tip of the iceberg ...
 
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That sucks. It was worth the effort trying though.
I might remove it
And that will work. If it's not present, the system will just ignore it(I think). You can then disablle it in the bios and see what happens..
 
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A little backstory. I found this board at the flea market. It looked minty so I took it home with me. When I got home I saw that a little transistor (SOT-323) was slightly burned but otherwise the motherboard looked ok.

I tried to find the specs of that missing transistor and xrror(user here on TPU) sent me a picture of his ASUS P5K PRO in which a 42t transistor was present in that spot.

Initially, by deduction, I guessed that the missing transistor might be a A1p/1p judging from the components in that area.

Given the fact that I didn't have a 42t or a replacement transistor I powered up the motherboard with the 1p transistor installed.

The P5K/EPU posted nicely and I was able to install Windows XP in a matter of minutes. All the drivers installed without a hitch.

While I worked with the board I was greeted by the following things:

1. The USB ports worked but in a strange way. USB mice or keyboards would not be recognized even if I saw that they received current, a fact that was obvious when the mouse sensor lighted up.
USB sticks would be detected only after a restart. A safe removal from Windows meant no detection of the same USB stick no matter what. A restart fixed this.
2. The outputs of the onboard sound would give only a white noise and some interference when I connected the speakers. No sound could be played or heard.
3. In Windows after I inserted the jack from the speakers I would get endless notifications that a jack was plugged / unplugged.

The PS/2 ports work as intended. The motherboard otherwise works as intended. All other ports, slots and sockets work as intended.

I tried a BIOS update but that changed nothing.

I removed the 1p transistor that I soldered but that changed nothing. I disabled the onboard sound but that changed nothing. Still the same white noise and interference.

While the motherboard was working I put my finger on the ALC883 chip and it was extremely hot. Also while I moved my finger around the area, when I touched another IC labeled: ME 1117 A B803 I was surprised that a slight press of the finger in this chip changed the tonality of the white noise / interference I heard over the speakers. This IC ME 1117 A B803 was also very hot to the touch. The neighbouring capacitors were also too hot.

I like to restore and save parts that I find at the flea market but I guess that in this instance I have found my match. :D This motherboard has issues that I might not be able to solve.

What I might try in the future:

1. Remove the IC labeled ME 1117 A B803 and see if this changes something.
2. Remove the ALC883 chip and see if this changes something
3. Solder the correct transistor.
4. Inspect other possible causes of the white noise / interference. Maybe the ports are bad.
5. Try and talk nicely to the board and explain to her that if she doesn't work it will get minced and recycled. :D

Some of you that know me from the Project Logs section are accustomed with my way of not giving up no matter what. This little project will be put on the back burner for the time being but I think I might solve its issues at a later date.

Other suggestions are welcomed. :)

Looking back maybe I shouldn't've bought the board as there it was a reason it was dumped in the first place.

I managed to save many parts that were complete basket cases but once I started fiddling with newer stuff the casualty rate has increased by quite a margin.

The board has received just a mild clean and all the thermal paste was replaced.

Looks can be deceiving boys! Be careful!!! :D



gallery: https://postimg.cc/gallery/wqX0v7K
 
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I wonder if the USB issues might be related to the audio parts drawing too much power cooking themselves?
Was the original damaged transistor just physically damaged missing or was the part literally burnt off the board? Or is there no way to tell (was missing to begin with)?

But before giving up I like your plan to simply remove the audio chip(s) because yea something is definitely angry.

Also, could you humor me and see what the silk screen says underneath the P5K/EPU sticker? I really can't seem to find any differences to my board, down to the Rev 1.02G - unless some other eagle eyed viewer has already spotted something? It really looks like a P5K-Pro by another name.

Last the Pro for some reason is like the unloved middle child of the P5K family. It's like everyone ether got the SE or the Deluxe. Of course when P5Q (DDR3 vs 2) came out it's like everyone just forgot the K ever existed.

That said the 2 P5K-Pro boards I've had experience with have been great boards.

That e2200 you have actually is a great test chip, since you can play with the mult up to x11, and P5K you can just force FSB speed AND strap.

Me and a buddy bought essentially matched set of P5K-Pro + e7200's when they first came out explicitly to run them as 4Ghz gaming systems - and they did that with flying colors. I don't know what happened to his (which annoys me because his setup always seemed to clock a little better lol) but they were pretty awesome with the 45nm dual-cores. I still have mine (obviously) and it still works with an e8500 @ 4.5Ghz. I can try and get the BIOS settings off it for that (I probably should do that anyway before the CMOS battery dies) cause there was a bit of voltage mucking which I've long forgotten now.

I never really played with the quad core chips on it though - maybe I should do that sometime? hrm.

Anyway that big ramble is just to say that if you can get this board working even without audio, it's actually a good board! And it's actually pretty snappy even under win10 with a 4Ghz+ dual core + SSD + modern vid card.
 
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I wonder if the USB issues might be related to the audio parts drawing too much power cooking themselves?
Was the original damaged transistor just physically damaged missing or was the part literally burnt off the board? Or is there no way to tell (was missing to begin with)?
I thought about the audio chip messing with the USB ports. I need to investigate this before I do anything else.
The transistor was a little bloated and I saw that the area around it had a brownish color. As soon as I touched the casing of transistor it just disintegrated.

But before giving up I like your plan to simply remove the audio chip(s) because yea something is definitely angry.
I will remove the ALC883 chip just for kicks. I need to practice first on another board as I don't have a hot air station yet. I really like the board too. :D

Also, could you humor me and see what the silk screen says underneath the P5K/EPU sticker? I really can't seem to find any differences to my board, down to the Rev 1.02G - unless some other eagle eyed viewer has already spotted something? It really looks like a P5K-Pro by another name.
I usually don't mess with the stickers but for you I'll make an exception. :D :)


Last the Pro for some reason is like the unloved middle child of the P5K family. It's like everyone ether got the SE or the Deluxe. Of course when P5Q (DDR3 vs 2) came out it's like everyone just forgot the K ever existed.
Back in the day I had a Gigabyte EP35-DS3R DDR2 as I couldn't buy a DDR3 board as they were too expensive. I really liked that GiGi board. I sold it to someone in 2011.

That said the 2 P5K-Pro boards I've had experience with have been great boards.
They have all the data for a great board this is why I decided to save it.

That e2200 you have actually is a great test chip, since you can play with the mult up to x11, and P5K you can just force FSB speed AND strap.
As I have DDR2 1066 I played with the idea of OC-ing the little E2200. I might try this after I exterminate the gremlins from the board.

Me and a buddy bought essentially matched set of P5K-Pro + e7200's when they first came out explicitly to run them as 4Ghz gaming systems - and they did that with flying colors. I don't know what happened to his (which annoys me because his setup always seemed to clock a little better lol) but they were pretty awesome with the 45nm dual-cores. I still have mine (obviously) and it still works with an e8500 @ 4.5Ghz. I can try and get the BIOS settings off it for that (I probably should do that anyway before the CMOS battery dies) cause there was a bit of voltage mucking which I've long forgotten now.
On my Gigabyte board I had a E8400 that I kept at 3.6GHz and just before I sold it I used at 4GHz. It ran like a dream.

I never really played with the quad core chips on it though - maybe I should do that sometime? hrm.
I also never had a Core 2 Quad CPU. You might even try a Xeon Quad Core CPU if it is supported. The prices are lower that their desktop counterparts.

Anyway that big ramble is just to say that if you can get this board working even without audio, it's actually a good board! And it's actually pretty snappy even under win10 with a 4Ghz+ dual core + SSD + modern vid card.
You're right. I can't argue with this. :)

L.E.

ASUS P5K/EPU = ASUS P5K PRO

The P5K/EPU is missing the top VRM copper heatsink but otherwise they look the same. :D I'll investigate this further after I manage to sort out the audio codec.

Transformers, P5K/EPU more than meets the eye! :D
 

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Storage 16GB Samsung NAND
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ASUS P5K/EPU = ASUS P5K PRO

The P5K/EPU is missing the top VRM copper heatsink but otherwise they look the same. :D I'll investigate this further after I manage to sort out the audio codec.

Transformers, P5K/EPU more than meets the eye! :D
Interesting! Didn't see that coming. I wonder how often that happened?
 
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