D
DaveC
Guest
> http://tinyurl.com/hvk5eac
Any chance of posting a super-high resolution image?
Any chance of posting a super-high resolution image?
L
legg
Guest
On Tue, 15 Mar 2016 20:01:54 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:
There's not much you can tell from a photograph of limited resolution.
Looking at what you've offered, you might re-examine locally:
http://www.magma.ca/~legg/TVS/EMU_captive_detritus.jpg
http://www.magma.ca/~legg/TVS/EMU_green_reflection.jpg
http://www.magma.ca/~legg/TVS/EMU_red_reflection.jpg
http://www.magma.ca/~legg/TVS/EMU_soluble_contaminant.jpg
http://www.magma.ca/~legg/TVS/EMU_soluble_contaminant_2.jpg
I expect these are mostly reflections in the protective epoxy, or
flow/tension marks formed in its application, but could be signs of
contamination or damage.
Even checking point to point contact is a trial with this stuff.
Vibration produces intermittent faults on assemblies (where the parts
don't actually shear off completely) The most suspect parts are those
with mechanical attributes - the crystal as previously suggested, the
connectors and bulky components. Reflowing the SJ of the latter might
be informative - any uncharacteristic loosness in the soldered
material of the melted joint is a giveaway.
As previous - an intermittent fault is unlikely to result in repeated
DOA symptoms, but it can be recorded for posterity in the firmware,
with DOA symptoms, or break small-signal paths with the same effect.
Did you try a reset on the 'dead' unit, before replacing it?
The fact that its replacement didn't involve the surrender of the
defect unit (for a discount in pricing) is a signal from the mfr
regarding their view on the viability of repair. They are in the most
sensible position to do so, after-warranty.
RL
<curd@notformail.com> wrote:
There's not much you can tell from a photograph of limited resolution.
Looking at what you've offered, you might re-examine locally:
http://www.magma.ca/~legg/TVS/EMU_captive_detritus.jpg
http://www.magma.ca/~legg/TVS/EMU_green_reflection.jpg
http://www.magma.ca/~legg/TVS/EMU_red_reflection.jpg
http://www.magma.ca/~legg/TVS/EMU_soluble_contaminant.jpg
http://www.magma.ca/~legg/TVS/EMU_soluble_contaminant_2.jpg
I expect these are mostly reflections in the protective epoxy, or
flow/tension marks formed in its application, but could be signs of
contamination or damage.
Even checking point to point contact is a trial with this stuff.
Vibration produces intermittent faults on assemblies (where the parts
don't actually shear off completely) The most suspect parts are those
with mechanical attributes - the crystal as previously suggested, the
connectors and bulky components. Reflowing the SJ of the latter might
be informative - any uncharacteristic loosness in the soldered
material of the melted joint is a giveaway.
As previous - an intermittent fault is unlikely to result in repeated
DOA symptoms, but it can be recorded for posterity in the firmware,
with DOA symptoms, or break small-signal paths with the same effect.
Did you try a reset on the 'dead' unit, before replacing it?
The fact that its replacement didn't involve the surrender of the
defect unit (for a discount in pricing) is a signal from the mfr
regarding their view on the viability of repair. They are in the most
sensible position to do so, after-warranty.
RL
J
John-Del
Guest
On Tuesday, March 15, 2016 at 8:59:44 PM UTC-4, Cursitor Doom wrote:
There may be nothing on the back side. I repair (take a shot at) a lot of car electronics from a nearby car dealership (mostly clusters) and have seen some PCMs that are pretty much bonded to the bottom of the pan for heat sinking purposes. Nothing to see on the other side except foil damage if there was a water leak.
Never been in a Rover PCM.
There may be nothing on the back side. I repair (take a shot at) a lot of car electronics from a nearby car dealership (mostly clusters) and have seen some PCMs that are pretty much bonded to the bottom of the pan for heat sinking purposes. Nothing to see on the other side except foil damage if there was a water leak.
Never been in a Rover PCM.
C
Cursitor Doom
Guest
On Wed, 16 Mar 2016 11:30:49 +0100, Look165 wrote:
I've heard that's a common failure point with these units, but all the
electros have checked out fine on this particular one.
I've heard that's a common failure point with these units, but all the
electros have checked out fine on this particular one.
L
Look165
Guest
I would say the 2 electrolytic caps.
Cursitor Doom a ĂŠcrit :
Cursitor Doom a ĂŠcrit :
C
Cursitor Doom
Guest
On Wed, 16 Mar 2016 09:42:30 -0700, DaveC wrote:
The ESRs were slightly high (in circuit) but not enough to cause sudden
total failure. But they appear to be easily removeable so I'll take them
out and check them independently.
I should repeat I don't have the time right now to go down every avenue
if this turns out to be more than a simple fix; I'm really just trying to
establish whether the thing is salvageable at all. However, I am noting
down all the suggestions made here for future reference for when I do
have time.
The ESRs were slightly high (in circuit) but not enough to cause sudden
total failure. But they appear to be easily removeable so I'll take them
out and check them independently.
I should repeat I don't have the time right now to go down every avenue
if this turns out to be more than a simple fix; I'm really just trying to
establish whether the thing is salvageable at all. However, I am noting
down all the suggestions made here for future reference for when I do
have time.
L
Look165
Guest
Check them instead of usisng random statistics.
Cursitor Doom a ĂŠcrit :
Cursitor Doom a ĂŠcrit :
C
Cursitor Doom
Guest
On Wed, 16 Mar 2016 11:45:04 -0700, DaveC wrote:
No signs of bulging or seepage.
I was just taking a closer look at the board a moment ago under a glass
and spotted something that requires further investigation. Going to have
to get my stereoscope out of storage for this one. Tiny clusters of what
look like *very* fine gauge enamel copper wire clearly bridging across
vias in various points around the board and obviously not *supposed* to
be there. If they turn out to be conductive, I could be in business!
Don't want to get my hopes up on this one, though. Probably just a false
alarm but *definitely* requiring closer examination with something more
powerful than a glass....
Turns out to get the caps out of circuit requires a 6mm ring spanner
which I shall have to procure from a local emporium tomorrow when they re-
open. Fortunately I already have a 13mm one for the other ends.
No signs of bulging or seepage.
I was just taking a closer look at the board a moment ago under a glass
and spotted something that requires further investigation. Going to have
to get my stereoscope out of storage for this one. Tiny clusters of what
look like *very* fine gauge enamel copper wire clearly bridging across
vias in various points around the board and obviously not *supposed* to
be there. If they turn out to be conductive, I could be in business!
Don't want to get my hopes up on this one, though. Probably just a false
alarm but *definitely* requiring closer examination with something more
powerful than a glass....
Turns out to get the caps out of circuit requires a 6mm ring spanner
which I shall have to procure from a local emporium tomorrow when they re-
open. Fortunately I already have a 13mm one for the other ends.
C
Cursitor Doom
Guest
On Wed, 16 Mar 2016 13:00:19 -0700, DaveC wrote:
I simply don't have anything that small (apart from sockets which are no
good in this case) in either metric or imperial, I'm afraid. It won't
kill me to buy one the correct size tomorrow.
I simply don't have anything that small (apart from sockets which are no
good in this case) in either metric or imperial, I'm afraid. It won't
kill me to buy one the correct size tomorrow.
D
DaveC
Guest
On 16 Mar 2016, Cursitor Doom wrote
(in article <ncbetl$tfi$1@dont-email.me>
:
âchecked out fine...â means you tested what? Capacitance? ESR?
In-circuit? Removed?
Details!
(in article <ncbetl$tfi$1@dont-email.me>
:âchecked out fine...â means you tested what? Capacitance? ESR?
In-circuit? Removed?
Details!
D
DaveC
Guest
Visually?
C
Cursitor Doom
Guest
On Tue, 15 Mar 2016 19:59:53 -0500, legg wrote:
I don't know how the hell you were able to spot those markings from the
poor detail in the photo. The last two details you posted show the
extremely fine enamel copper wire-looking debris which crops up in other
places on the board and across vias and traces. If this debris conducts,
it could easily be the cause of the problem. I have to hoist my
stereoscope out of storage and take a better look tomorrow. Well spotted
indeed. Remarkable!
As for the other bits you found, I'll investigate them at the same time
when my stereoscope is set up.
I don't know how the hell you were able to spot those markings from the
poor detail in the photo. The last two details you posted show the
extremely fine enamel copper wire-looking debris which crops up in other
places on the board and across vias and traces. If this debris conducts,
it could easily be the cause of the problem. I have to hoist my
stereoscope out of storage and take a better look tomorrow. Well spotted
indeed. Remarkable!
As for the other bits you found, I'll investigate them at the same time
when my stereoscope is set up.
D
DaveC
Guest
Try 1/4â. Thatâs 6.35mm. Might work...
J
Jon Elson
Guest
Cursitor Doom wrote:
suppress the whisker growth, but there are quite a few reports that the
whiskers just poke through the coating, they ARE real sharp.
Jon
Woo Hoo! Sounds like tin whiskers! The conformal coat is "SUPPOSED" to
suppress the whisker growth, but there are quite a few reports that the
whiskers just poke through the coating, they ARE real sharp.
Jon
L
legg
Guest
On Wed, 16 Mar 2016 23:21:41 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:
Looked to me more like dye concentrating as the curing epoxy puckered.
Did you ever reset this thing, while it was still in the vehicle?
RL
<curd@notformail.com> wrote:
Looked to me more like dye concentrating as the curing epoxy puckered.
Did you ever reset this thing, while it was still in the vehicle?
RL
C
Cursitor Doom
Guest
On Wed, 16 Mar 2016 22:50:06 -0500, legg wrote:
> Looked to me more like dye concentrating as the curing epoxy puckered.
So not likely to cause a fault then?
> Did you ever reset this thing, while it was still in the vehicle?
No. I think if the fix were that simple the service specialists who
swapped the unit over wouldn't have gone to the trouble of sourcing a
replacement. They charged me next to nothing for the job so I trust them.
> Looked to me more like dye concentrating as the curing epoxy puckered.
So not likely to cause a fault then?
> Did you ever reset this thing, while it was still in the vehicle?
No. I think if the fix were that simple the service specialists who
swapped the unit over wouldn't have gone to the trouble of sourcing a
replacement. They charged me next to nothing for the job so I trust them.
C
Cursitor Doom
Guest
On Wed, 16 Mar 2016 20:51:46 -0500, Jon Elson wrote:
Thank you, Jon. An interesting suggestion! But I was under the impression
that:
1. TW growth happened solely inside chips and so was normally invisible.
2. tin whiskers were invariably silver in colour.
These I have here are like the old kind of enamel copper wire. Nowadays
all enamel copper seems to be clear, but back in the day the enamel was a
sort of deep plum shade - which is what I see here. I'll do some searches
for pictures of TW and see if some match what I see on this board....
Thank you, Jon. An interesting suggestion! But I was under the impression
that:
1. TW growth happened solely inside chips and so was normally invisible.
2. tin whiskers were invariably silver in colour.
These I have here are like the old kind of enamel copper wire. Nowadays
all enamel copper seems to be clear, but back in the day the enamel was a
sort of deep plum shade - which is what I see here. I'll do some searches
for pictures of TW and see if some match what I see on this board....
L
Look165
Guest
I wonnder how you can determine an ESR visually !
And technically, it's not so easy to measure this parameter.
Cursitor Doom a ĂŠcrit :
And technically, it's not so easy to measure this parameter.
Cursitor Doom a ĂŠcrit :
C
Cursitor Doom
Guest
On Thu, 17 Mar 2016 08:04:41 -0500, legg wrote:
It wasn't a stock item. They had to order it in and it took about 10 days
in all. I'm normally suspicious, but not on this one.
It wasn't a stock item. They had to order it in and it took about 10 days
in all. I'm normally suspicious, but not on this one.
C
Cursitor Doom
Guest
On Thu, 17 Mar 2016 13:01:37 +0000, MJC wrote:
Sorry, no idea what you're getting at here.
Sorry, no idea what you're getting at here.