Just done my first re-flow

[Vipersan]

Hi friends ..
Perhaps not the best time to tackle such a repair ..but the lapop in question was donated by the owner ...after diagnosing the classic HP overheat problems ...
My hands are not working too well atm ..due to a re-visit of the TM I suffer from ..but having ordered a hot air re-work station a few weeks back ...it arrived today CSI825A ..
The Compaq 6735S ws already stripped down ..and I'd nothing to lose ..

Symptoms ..
Powers up ...but Caps lock light continually flashing ...hard drive ..and DVD drive constantly spinning up ...
Unable to power off by normal means ..
Neccessary to remove battery and or mains to shut it down ..
Nothing on the lcd display ...never posts bios ..
Cause - bad connections (dry joints) under the GPU (AMD) chip ...due to poor design and bad cooling ..

Its a surface mount bga chip ...so no connections accessible ..
The guaranteed cure is to remove ...reball ..and refit the chip in question ..
But the gear to do this is expensive ..and requires good eyes and steady hands ..neither of which I can claim these days ..
Next best cure (possibly only temporary...but proving the cause) ...is to wrap the main board in aluminium foil with only the chip exposed through a hole ..
The pre-heat to 100 deg C ..for 3 minutes ...then a 10 minute blast at 200 deg C ..

..et voila ..
Not fully rebuilt the lappy yet ..but it now posts bios ...

success ...?? ... well time will tell ..but its a first for me ..
rgds
VS

 

[Lazarus]

A man of many parts - most of which seem to work rather well!

 

[Topper]

Good going VS, you are a braver man than me

 

[sonnetpete]

Just Goggled the model number...looks a nice piece of kit......blimey, things have really improved since the 70's.

Errr......does it do toast??

 

[Vipersan]

Good going VS, you are a braver man than me

Hi Topper ...
Not that brave really ..
Had it still got an owner ...I would have dismissed it as a write off ...
I recovered all the data for the customer ...who bought a new lappy ...
Not HP ...I hasten to add ..
I didn't charge him at all for the diagnosis ..and data recovery ..
..In exchange he gave me the laptop ..for spares ...or as I explained to him ..to experiment on ..and test my reflow station when it arrived ..
So I guess not really brave ...just ..nothing to lose..
rgds
VS

 

[Vipersan]

..Well ..yeah ...I spose ...makes great toast ....
Certainly set fire to a lump of wood if left in the flow ..
;)
I'd have prefered a bga infra red rework sation ..but the start around £8000..
Well out of my league ..
The hot air station ain't cheap @ £100 approx ...but hopefully a good investment for the shop.
rgds
VS

 

[Vipersan]

Its certainly a good feeling whenever I get a result ..and an item goes back into service ..
I passionately hate the 'Consumer Society' ..and the ide of amassing landfill ...when an item fails ..
Sadly we are all to blame ...but are more or less forced into this way of life by 'Advertising' Consumerism ...and modern culture .
I was brought up differently ..as most of you guys probably were ..
Old fashioned they may be ...but durability and thrift ..were values to treasure ..
The idea that you saved up for ...and bought a thing ..once you could afford it with your own ...not borrowed money and/or credit.
Such things are alien to me ...and its this very culture ..thats led to the destruction of the manufacturing industries ...and the collapse of the economy ..imo ..
A bit off topic ..but you get the idea..
Old school ...and proud of it ..
;)
rgds VS

 

[2cvbloke]

Nice job, I've never been brave enough to attempt a reflow in that manner, so seeing it working, well, that's just superb...

And I know what you mean about the endless wasteful consumerism, TV ads always showing the latest gadget or must-have, and the endless offers for "payday loans", and it's financially crippling, I say that Mend & Make do is the way to go, if you can't afford something, don't get credit, just fix what you have and make do until you have the money...

 

[Llew]

Nice kit VS. Good range of nozzles too. I agree with the throw away society attitude that prevails today. Started with the circuit board replacement in TVs, rather than faulting to component level. Sad, really.

 

[Channel Hopper]

Nice kit VS. Good range of nozzles too. I agree with the throw away society attitude that prevails today. Started with the circuit board replacement in TVs, rather than faulting to component level. Sad, really.

Actually it started with vacuum tubes, pull out, insert another.

 

[Llew]

Oh, you mean Kirby accessories?

 

[Vipersan]

Nice kit VS. Good range of nozzles too. I agree with the throw away society attitude that prevails today. Started with the circuit board replacement in TVs, rather than faulting to component level. Sad, really.

Indeed Llew ...
I always try to repair to component level where possible ..
Surface mount devices make this extremly difficult ..unless you can afford suitable rework gear ..
..BUT ..even then you run accross component availablity issues ...
These days the likes of Chas Hyde ..my main supplier ..doesn't always stock the parts need ..
Often too expensive to carry stock ...but more often than not ...simply not in the UK ..
After all ..we don't make anything of note any more ...perhaps a few car parts ...but we are terribly good and pampering ...
God I hate that word ..
You walk down a high street now ...and every other shop is a fast food emporium ..boutique...hardressers ..or feckin nail-bar ...
Grrrr..
Suffice to say I get well over 80 % of my spares by ordering from the Far East these days ..
Thank gawd for ebay ..thats wot I say..
rgds
VS

 

[Vipersan]

Actually it started with vacuum tubes, pull out, insert another.

..Now thats triggered a few memories ..
;)
I still have 2 large boxes of valves up in the roof space at the shop ..
Can't bear to throw 'em out ..
PL504s
PY800s
ECC83s
PCL805s

..and one or 2 octal base valves ..like the versatile 6V6
etc ..
I even have 3 brand new EHT trays from the old Thorn ..3500s ...
The first panel changeable fully transistorized mainstream colour TVs..
But thats another story
rgds
VS

 

[Vipersan]

Just to round the thread off ..
Here are a few pix of the lappy in question ...and the CSI825A ...
The chip in question is under the heat sink ..which I'm not going to remove again ..as the Arctic Silver heat sink paste is expensive ..

X marks the spot ..

rgds
VS

 

[Vipersan]

...took me well over an hour to reassemble the lappy ...
Still 20 screws to fit ...
..but seemed like a good time to test ..
Running Vista o/s ..
Time to flatten the o/s and restore I think..after a decent soak test..
Hopefully it will have a restore partition
;)

..time for my bath now ..
Hospital visit tomorrow ..

rgds
VS

 

[Channel Hopper]

Hospital visit tomorrow ..

Are they testing for lead/tin ?

 

[Analoguesat]

..Now thats triggered a few memories ..
;)
I still have 2 large boxes of valves up in the roof space at the shop ..
Can't bear to throw 'em out ..
PL504s
PY800s
ECC83s
PCL805s

..and one or 2 octal base valves ..like the versatile 6V6
etc ..
I even have 3 brand new EHT trays from the old Thorn ..3500s ...
The first panel changeable fully transistorized mainstream colour TVs..
But thats another story
rgds
VS

Ive still got a few valves lying around my spares cabinet at work. They come in handy once in a blue moon when one of the older physics dept oscilloscopes goes wonky. Ive put 2 or 3 back into use over the years just by swapping out a bad valve.

Even though I know nothing about valves so far its been obvious which one is dead.

 

[Llew]

I've got scores of valves from servicing radios, TVs and DIY projects. Most ambitious project was a colour TV. In the early 70's I constructed one from a design in Practical Television using a PL503/PY500/tripler line output stage, semiconductors for the rest of the circuitry. All circuit boards had to be drilled out for the components, a tedious task indeed. I never managed to have a decent picture, as it was impossible to adjust properly for static convergence due no doubt to anomalies in the original design of the convergence stage. In fact, there were many months of errata/modifications for most of the circuitry to follow in the magazine, so I considered that project a noble failure.

I then made another TV using kit from Forgestone. They were better designed, and I could use the existing Mullard CRT and home-made cabinet. This TV served well for a year or so until the PY500 in the line output stage started glowing purple and needed to be replaced regularly. In the end the TV was consigned to the shack and raided for spare parts, where the CRT, LOPT etc. came in handy for repairing other TVs.

 

[Vipersan]

Are they testing for lead/tin ?

Thats not as funny as you might think ..
When I first developed TM ...the first thing I asked them to do was run blood tests for heavy metals and toxins ...
They found nowt and concluded it was most likely a viral trigger ..
No ..
I have to visit the hospital periodically ...as I'm on a drug trial ...
Testing a new drug from the USA ...which hopefully will help slow down or control a second or even third occurrance of my TM ...which if it does happen ..will mean I am the re-classified as having MS ..
Not nice at all ...
I even have to have brain and spine scans every 3 months ..to make sure no new lesions have developed..
rgds
VS

btw ..the MRI equipment is fascinating ..
The operator was kind enough to explain in detail how it functions ...and they even let me into the booth to take a peek inside my own head using the collected images ..
I was amazed at the detail and clarity..
anyway ..gotta go soon ...taxi will be here at 11 AM..

just time for another cuppa ..
;)

 

[Vipersan]

Hi friends ..
..a couple of weeks have now passed since I 'reworked the graphics chip on this laptop ..
As expected the cure ..although effective ..thus proving where the ploblem lay...was but temporary ...
The lappy failed to power up on the 4th day following the initial re-flow ..
So ..having nothing to lose I got a bit more creative ...
First I pre-heated the chip to 100 degress again ..thus softening the plasic cement the manufaturer had spread around the edges of the chip ..to secure it to the pcb ...allowing it to be sraped off
I figured some of this plastic glue ..may have leached under the edges of the chip making the chip less likely to bed down when re-worked.
This allowed me to inject a small quantity of liquid flux with a syringe around the edges where the plastic glue was previously ..
Hoping that capillary action would draw the flux under the bga chip when preheated ..
I then created a tin plate metal funnel which fitted around the perimeter of the chip ..thus directing heat exclusively onto the chip ..and doing away with the need to wrap the motherboard in aluminium foil..
The process was then repeated ..pre-heating at 100 degrees for 3 minutes ....then blasting the chip directly using the funnel for a further 10 minutes ..and allowing to cool naturally ..
This time tho' the blast temperature was set to 300 degrees ..
Hotter by far than recommended ..but hey ...what had I to lose ?

After cooling the motherboard was tested again ..
It powered up to a nice bright Vista screen ...and the lappy fully reassembled ..

It was then left to run a looped 720p video file for many days ..to really heat up the graphics chip ..with short cooling periods every 5 hours ..to give the reflow a chance to dry joint again ..if it had a mind to.
I ran the lappy right through the Indian summer so it get pretty darned hot...
We are a now 10 days down the line since the second re-flow ...and the lappy _still_ functions normally..
Fingers crossed as it may yet fail again ..
The ideal solution would be to re-ball the chip ..and maybe one day I will ..
...but need to get some practice in first..but
..I'm no longer as scared of these modern chip formats as I once was
rgds
VS