Mother board problem

[Ken]

I have a HP Touchsmart 300-1020 computer that has no video and no
audible error code. The PS seems to be providing proper power for much
of the MB, its fans, its DVD, and HD. It has a APP78-CF mother board
that uses an AMD Athlon II x2 4200+ processor in an AM3 socket. I first
searched for some documentation on the processor since there is no heat
being generated by it, and that would mean it was not running. But it
is not available as far as I could find. (Years ago such info was
easily found on smaller processors.) My purpose was to determine where
the clock pulse was and to determine if the processor voltages were
present. I probed the MB and found the core voltages around the
periphery of the socket, so I think the processor is getting the proper
voltages. There is a clock generator chip on the MB (SLG8LP625T) and a
search for the pinouts also came up empty. I did determine it needed
3.3 volts however, and it appears to have it. Probing the clock
generator chip with my scope leads me to believe that the chip is not
running, as there are no active leads on it.

So my question is: Does the clock generator chip free run, or is it
enabled by some lead? Years ago it was free running on older MBs. I do
not intend to try to replace the chip, but I would like to know if it
has what is needed before I give up on the MB.

[Maynard A. Philbrook Jr.]

In article <m5l0il$sa2$1...@dont-email.me>, K...@invalid.com says...

Check your power switch and circuit ?

Jamie

[Ken]

If you mean does the power switch turn on power? The answer is Yes. If
you mean something else, please elaborate. I can turn on and turn off
power, the processor does not seem to be running.

[jurb...@gmail.com]

There is like a method to PC TShooting.

Pull all the cards except video.
If it has onborard video pull any video card and hook monitor to built in video.
try another power supply.

IF IT DOES NOT BEEP :

Remove all cards including video.
Remove all drives, even the USB card reader.
Remove ALL RAM.
Try another power supply.

One of those three actions should make the mobo beep. If not, the mobo itself as well as the processor are in question and at that point if it isn't too old you got so many options.

Make a new build, reregister the same OS, use the old RAM and drives, case all that shit.

Find a way to determine for sure if it is the processor, mobo or both. If not both, replace the bad one and you are all set. It CAN be both. I have seen where a processor shorted out and burned its socket, which is not replacable. So that is that.

But generally it is one or the other. usually there is only one main problem with anything. It may have caused more, but...

NOW, I forgot to mention something, when you pull all the cards and shit, remove the CMOS battery after that. Then try it again. See, WHEN IT BEEPS is what tells us what is wrong.

AND, in case you caught a BIOS virus (been there done that) when you see "CMOS CHECKSUM FAILURRE, DEFAULTS LOADED" is usually when you got it really fixed. Been there a few times. (when will I ever learn just to say NO when someone wants to touch my PC ?)

That's pretty much the scoop. Much more requires equipment, training, all kinds of shit.

And BTW to the people who say "CHECK THE POWER SUPPLY VOLTAGES CHECK THE POWER SUPPLY VOLTAGES !" I say this, "Just change the fucking power supply". Now if that is not possible at the moment, DO look up the pinout fo the ATX PS and check the voltages. but I like to knoiw quicker, just plug a new one in and let it hang off the side or whatever. You get a display, beeps, whatever, then you know.

Bout it for now. Get thorugh that and keep us "posted"...

[Ken]

I appreciate your suggestions, but this MB has everything built in and
things like the video card cannot be removed. I agree that most often
the problem is one item, and that is why I was trying to determine if
the clock generator should be free running. I have cleared CMOS and
some of the other suggestions you made along with removing the MB from
the unit and inspecting for damaged components. Everything points to
the processor chip not running even though it has the voltages it
requires. I tried another processor and again there was no activity by it.

My hope was that someone would have some insight to the clock generator
chip, as that would tell me if the problem was it or before it. Thanks
for your suggestions.

[chuck]

You are spot on about just changing the power supply instead of
testing voltages. Voltages will check fine on some Dell computer
power supplies but the computer won't boot. The problem is the power
supply. My guess is that the supply fails when current draw increases
on start up.

[Ken]

Replaced the PS, a good thought however. This still leads me back to a
clock generator that is not showing any leads moving. The processor
cannot begin to function without a clock pulse. My biggest problem is
not being able to find any documentation for the processor or the clock
generator. Unlike days of old when such info was available, the
manufacturers only give it to those purchasing (or about to purchase) a
large number of their devices today.

[jurb...@gmail.com]

What would be really nice is to find this the problem and then to fix a couple of old ones I have laying around. That would be great because one of them in particular though an XP class board is a really high end one and has some stuff I would like to have. The other is a Dell that an Win 7, hich means it is an adequate conmputer.

But the fact is that almost for sure, when the mobo is found to be at fault, it is usually software. That BIOS shit, it runs in no extended RAM, down at the bottom. Things have advanced a bit but the thing that makes it beep is still a very rudimentary system.

So anyway, did you pull the RAM ?

[stra...@yahoo.com]

On Wednesday, December 3, 2014 9:27:56 AM UTC-8, Ken wrote:
<snip>

> Replaced the PS, a good thought however. This still leads me back to a
> clock generator that is not showing any leads moving. The processor
> cannot begin to function without a clock pulse. My biggest problem is
> not being able to find any documentation for the processor or the clock
> generator. Unlike days of old when such info was available, the
> manufacturers only give it to those purchasing (or about to purchase) a
> large number of their devices today.

How old is the mobo ? We have some older (5+ year) servers at work that don't run if the caps are bad. Replacing bad caps almost always brings them back up. Computers are very fussy about the power supplies. 'Good enough' rarely is.

G²

[Ken]

The RAM is good, as I pulled it and tested it in another computer.

[Ken]

The computer is probably not older than 4-5 years. It has Windows 7
installed and of course is a touch screen unit. The thing that makes
trouble shooting difficult today is many (including this one) are "All
in one" units and they are not as accessible as they once were. Put
that together with the manufacturers not wanting to give out information
about the components, and you are often forced into buying a new unit.

For what it is worth, I checked the caps on the MB with my ESR meter.
Searching the web, I found others with the same type of problem on the
same model of computer. That does not mean there is a common problem,
but it does mean I am not alone.

[jurb...@gmail.com]

>"The RAM is good, as I pulled it and tested it in another computer. "

Fine and dandy, but did you try firing up this computer with no RAM in it ? It is supposed to beep. If it does not beep that is bad.

If it does beep it is probably not the clock generator, provided you are looking aty the right chip. What's the number anyway ? Maybe I'll have a go at getting some info on it.

[Ken]

Sure did try it without RAM. Even tested the RAM in another computer.
The clock generator is a SLG8LP625T Thanks.

[stra...@yahoo.com]

On Thursday, December 4, 2014 5:04:50 AM UTC-8, Ken wrote:
> stra...@yahoo.com wrote:
<snip>

> > How old is the mobo ? We have some older (5+ year) servers at work
> > that don't run if the caps are bad. Replacing bad caps almost always
> > brings them back up. Computers are very fussy about the power
> > supplies. 'Good enough' rarely is.
> >
> > G²
> >
>
> The computer is probably not older than 4-5 years. It has Windows 7
> installed and of course is a touch screen unit. The thing that makes
> trouble shooting difficult today is many (including this one) are "All
> in one" units and they are not as accessible as they once were. Put
> that together with the manufacturers not wanting to give out information
> about the components, and you are often forced into buying a new unit.
>
> For what it is worth, I checked the caps on the MB with my ESR meter.
> Searching the web, I found others with the same type of problem on the
> same model of computer. That does not mean there is a common problem,
> but it does mean I am not alone.

The thing to remember about ESR meters is that they can be fooled by parallel ceramic bypass caps so it can read good when it is in fact bad. If it reads bad it likely is. Bulging is a good indicator and ruptures have likely sprayed acid around the board.

I started using solid polymer caps instead of 'lytics on mobos at work and they're doing well. My 4 newer machines at home are all polymers and no 'lytics. I expect no problems before obsolescence.

IF you decide to change caps, go for the highest ripple current / lowest ESR and stay away from cheap junk.

G²

[jurb...@gmail.com]

>"Sure did try it without RAM."

OK, that was the specific information I wanted. the RAM is cleared as well as a possibly corrupted RAM controller. Sometimes those things take a virus or a cosmic ray or something and it needs to reset completely to straighten it out. (not kidding anymore about the cosmic ray, I recently read an article on exactly that corrupting memory)

I didn't find the sheet on that chip. This is one of those things that would probably require emailing Silllyonics or whoever made the thing and all that. However it does seem there are suppliers. What is the case style ? Is it something that doesn't take a million dollar rework station to change ? (like a BGA) If it's not that bad you might just try popping one in. Also if there is a crystal nar the thing change that as well, in fact maybe change that first as it is easier. If you can find it, if it is not built into the IC, if if if, of course.

And as stra...@yahoo said, make sure about the caps. hat I ddo sometimes is to determine which are in the same bank. Of course all the grounded sides read continuity, but when you get continuity on the other (usually +) lead, those are all in one bank. Then for testing purposes I just put in one. I don't even trim the leads, I leave them long and just see if the damthing works. If it does then I start changing the bunch of them. One hting about oscillators, if the power going to it isn't well bypassed it might just not work. Depends on how it is configured.

I assume since you said it is not clocking that you have seen AOME DC on the pins. If all the pins have 0V it is kinda obvious. (I run the scope in DC mode for things like this for reasons like that, then I know already)

This now depends on how good the board is. If you can get the same model generic you MIGHT be able to migrate the OS to it and avoid a reload, but I cannot say if it would have to come from Overpriced.com, err I mean HP. They might not have made the board. Like this Dell I got in the boneyard, ECS motherboard. Thought you were buying a good PC from a reputable source ? Well ECS is about ½ step down from Foxconn, meaning elcheapo. I would have replaced this ECS if I could get a fair price on it, which I consider to be about twenty bucks. I would get a decent Gigabyte or something but I wouldn't be able to reregister the OEM Windows 7 to it. So to the boneyard with it. Your HP is probably the same deal, you'll need a copy of Windows if you change it to a totally different type of board. (of course with Linux you wouldn't have that problem but that is beside the point)

Yup, caps, chip and crystal and if that doesn't do it, it is probably for the boneyard. You still have drives and a PS and all that right ?

[Ken]

All of what you say about the project is true. I have spent more time
on it than it is worth, but I am a persistent person who believes "the
answer is out there." I think I shall look for a scrap computer of the
same model that has a good MB but the rest of it is NG. A new MB
costing $200-300 is out of the question.

Finally, like you said about there being no voltage on the other pins of
the clock generator: It would be obvious as to why it did not work.
There were DC levels and the cap next to the chip was at the 3.3v supply
the chip needed. I thought someone might have some source of info about
the clock generator that would confirm my belief that it should be free
running. Thanks to you and the others for their comments.

[JC]

On 12/4/2014 1:06 AM, stra...@yahoo.com wrote:
> On Wednesday, December 3, 2014 9:27:56 AM UTC-8, Ken wrote:
> <snip>
>> Replaced the PS, a good thought however. This still leads me back to a
>> clock generator that is not showing any leads moving. The processor
>> cannot begin to function without a clock pulse. My biggest problem is
>> not being able to find any documentation for the processor or the clock
>> generator. Unlike days of old when such info was available, the
>> manufacturers only give it to those purchasing (or about to purchase) a
>> large number of their devices today.

Hi Ken,

There is a full schematic for your clock gen at

http://wenku.baidu.com/view/1207127f31b765ce05081419.html

About 2/3 down the webpage there is a document Clock Gen Silego
SLG8LP625TTR, it shows bad on the web but if you save it and open it its
very clear to read

posters here may not realize this is a one piece computer and probably
worth repairing.

http://h10025.www1.hp.com/ewfrf/wc/product?product=4007375&cc=us&dlc=en&lc=en

An image of the board is here :

http://www.ebay.com/itm/HP-TouchSmart-300-Series-Motherboard-APP78-CF-510762-002-Test-Ok-/261300571054?pt=Motherboards&hash=item3cd6ba4bae

JC

[Ken]

Thanks for the info, that is MUCH more than I had. It may not tell me
what is wrong, but it just might.

[jurb...@gmail.com]

>"There is a full schematic for your clock gen at

http://wenku.baidu.com/view/1207127f31b765ce05081419.html
"

Impressive, how the heck ddid you find that ?

[JC]

pure luck........... :)

[Ken]

I have been to the Mountain!!!! Thanks to the info you led me to, and a
little experimenting with another MB, I have come to the conclusion that
the Clock Generator (SLG8LP625TTR) is bad. My real question was if the
chip should be free running. In order to establish that, I found a MB
with a ICS 9250AF-23 and found it had the same number of pins as the
chip in question. It was not the same physical size, but I figured it
was probably very similar since it used the same value xtal. I removed
the processor chip on that MB and found that the clock generator was
free running, so I assume the SLG chip should also be. There ARE a
couple of outputs active on the SLG chip, but there are no CPU clk
pulses on the SLG chip and they are not grounded.

I am not going to attempt to repair this MB, since I do not have the
tools to replace the chip. It is nice however to arrive at a conclusion
based upon information rather than theory. Thanks.