[SOLVED] Are POST-test cards helpful?

[Brixit]

Greetings!
Request for help...

I am thinking of buying a POST-test card for trouble-shooting two comatose laptops. I have never used a POST card before.

I suspect both laptops have OK mobos but dead CPUs.

Does anyone here have experience with this tool?

 

[Darkbreeze]

Haven't used one in a LONG time, but in truth you are probably backwards on that. It's a lot more likely that the motherboard is faulty than the CPU in most circumstances, unless there has been a KNOWN thermal condition that may have likely contributed to a thermally damaged CPU (Such as a failed fan or continuous overheat condition) or a disassembly gone wrong. CPUs rarely just "fail". Laptop CPUs probably DO have a much higher failure rate than desktop CPUs simply due to the confined nature of the enclosure and the limited cooling capabilities for most notebooks and laptops, but even so, it's still "less" likely than a faulty mother, daughter or power board on most laptops.

Ribbon cable failure is another very high failure point in a lot of laptops as well. And unless you are fairly sure you have access to cheap replacement parts, most of the time they are simply not worth the expense to repair them these days because doing so often costs 50-75% as much as simply buying a brand new unit that is going to be much more capable, and have a warranty, which the repaired unit is not going to have. There are some circumstances where a repair might make sense, but there are far more circumstances where it completely doesn't unless you have a good source for cheap parts.

 

[Brixit]

Haven't used one in a LONG time, but in truth you are probably backwards on that. It's a lot more likely that the motherboard is faulty than the CPU in most circumstances, unless there has been a KNOWN thermal condition that may have likely contributed to a thermally damaged CPU (Such as a failed fan or continuous overheat condition) or a disassembly gone wrong.

Thanks for reply, Darkbreeze.
Well, there has been a long-standing issue with overheating on one of these machines (ACER). Its a model that is known for it, and when it quit (running under Windows) the CORETEMP utility was popping up alerts. I had told it several times to "give me another minute".
CPUs and whole parts machines are available cheap enough to make it attractive to fix if thats all it is.
The machine consistently runs coolly under Linux, so I would just wipe Windows off it if I could get it going again.

The other machine (Toshiba Satellite) is attractive to repair because it is one of the fastest I have, has Win-10 Pro instead of Home on it, and a nice 17" screen.
It failed differently - it simply wouldn't start one day.

Ribbon cable failure is another very high failure point in a lot of laptops as well. And unless you are fairly sure you have access to cheap replacement parts, most of the time they are simply not worth the expense to repair them these days because doing so often costs 50-75% as much as simply buying a brand new unit that is going to be much more capable, and have a warranty, which the repaired unit is not going to have. There are some circumstances where a repair might make sense, but there are far more circumstances where it completely doesn't unless you have a good source for cheap parts.

I don't know much about this stuff, but since both machines are powering on to the lights-and-fan stage (but no farther) and charging their batteries if left a while (according to the indicator-light color) I was thinking it was probably not a ribbon cable (you mean video ribbon-cable, right?) issue.
If I knew what the problem was, it would be easier to evaluate the cost-benefit. I thought the POST-test card might help with that, before even opening the case. Amazon has POST-test cards for very cheap.
I have never had a warranteed computer in my life. Its not that kind of life. So thats not a big factor.
I'd do all the work myself, so costs would be for parts & shipping only. Unfortunately I have only a 50% success rate for fixing other laptops. (Killed a Tecra & a Thinkpad, succeeded with a Compaq & a Eurocom).

SO, back to the original topic, do you think that a cheap POST-test card would give me any useful results? Wouldn't it at least be able to confirm whether mobo & CPU are alive/dead?

Brixit

 

[Darkbreeze]

Generally speaking, there are usually MANY ribbon cables inside. The may connect things like WiFi adapters to the motherboard, keyboard, display panel, sometimes hard drive connectors or CMOS batteries. There can be a variety of components that connect to the mainboard, including the power board and in some cases a daughterboard as well. The last laptop I took apart, about two weeks ago, had about 8 different ribbon cables that had to be disconnected in order to get the mainboard out.

I mean, it might, but it really depends on the model of board probably. Personally, I've never used one on a laptop, only desktops. I'm not even sure if what is out there would even work on a laptop, as they tend to entirely lack the types of connections that are found on desktop boards.

 

[Brixit]

Thanks for reply, Darkbreeze.

Generally speaking, there are usually MANY ribbon cables inside...

Okay, now I understand. So if I go in, I will check them all, by wiggling or looking for crud, or for signs of chafe?

I'm not even sure if what is out there would even work on a laptop, as they tend to entirely lack the types of connections that are found on desktop boards.

I only know what the product infos say, but they claim that some are for laptops only. These tend to require insertion into either a RAM slot or a modem/wifi/eth card slot. So it might require removing the case for the card slot type, but not for the RAM slot type.
Also available to connect to a LPT port (play laff track).

My understanding is that as the machine powers up, it achieves initialization tasks. Each completed task returns a code that the tester displays. If a task can't complete, no code is returned? This I am not sure of - maybe an error code?
So the last code in the list tells you where a problem is. There may be problems later in the sequence, but you don't get codes for them because the process halts at the first error.

Does that sound right?

Brixit

 

[Darkbreeze]

Sounds right to me. I guess it really comes down to how much you can get one for, and you have to consider as well that if it stops at VGA, is that because there is a problem with a ribbon cable, or is the CPU faulty, or does it have a separate discreet graphics adapter, or is it because something ELSE on the mainboard is not not allowing video, just as one example.

If it's the CPU it stops at, is it because the CPU is thermally damaged from electromigration, or is there a problem with power delivery to the CPU, or is the fan not working and there's no RPM signature so the system refuses to allow it to run, or is some other issue such as an unrelated short somewhere on the board causing disruptions to one of the traces related to CPU operations.

A POST card (Greetings from Shell beach!! Sorry, Dark City movie reference) can definitely help to NARROW things down, but I don't think it's going to tell you what is wrong necessarily. You'll still probably end up having to either swap parts to get a definite diagnosis and confirmation of repair or replace the entire board anyhow even if you can identify that only one specific thing on it is faulty since most of the functionality is integrated. If you can get a compatible one for cheap enough I guess it's worth a shot. Myself, and I repair and work on laptops fairly frequently, I don't think I'd spend the money on one these days, but that's just me.

 

[Brixit]

...I guess it really comes down to how much you can get one [a POST card] for...

...but I don't think it's going to tell you what is wrong necessarily. You'll still probably end up having to ... swap parts to get a definite diagnosis...

I don't think I'd spend the money on one these days, but that's just me.

Thanks again. This is useful perspective.
Your advice suggests that its a safer gamble to use a replacement CPU as the test item.
I can get a new CPU for the ACER for $20, ~half the cost of a POST-test card. If the new CPU doesn't fix the coma, I'm only out $20.

By contrast, a replacement machine would cost me at least $150, and gain me nothing I need or want. The only issue ever with this machine was the cooking CPU - and possibly, a newer CPU would address that fault. This CPU is an Athlon L310, and it looks like a whole bunch of newer chips are at least socket-compatible (if I understand the charts at cpu-upgrade.com).

But I think I'd better start a new thread for that.

Brixit

 

[Darkbreeze]

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