Repairing Lightning damage

[Puckdropper]

I have a Zonet ZSR1104WE Wireless Broadband Router. It's about 3 years
old, and until last night worked just fine. After a storm last night,
the router quit working. It shows no signs of life.

I've tested the AC adapter with a meter, and it's showing 16V (no load.)
So, I opened the case up and started tracing the circuit. One diode (D1,
IN5.... (can't see the numbers)) near the power input has shorted (tests
open both ways), but my question is where to go next? I've looked
unsuccessfully for a fuse of some sort, the next components in the
circuit are a B1412 transistor (Q5) and a choke (L1.)

From the B1412, the circuit continues to RT34063a (u9) and then to a
series of resistors (R9-R5).

Any help would be appreciated.

Puckdropper

 

[Eeyore]

One diode (D1, IN5.... (can't see the numbers)) near the power input has
shorted (tests
open both ways)

Is it open or short ? It can't be both.

Replace that first and go drom there.

Graham

 

[Wolfi]

Am 29.06.07 01.22 schrieb Eeyore:

Is it open or short ? It can't be both.

Replace that first and go drom there.

The diode has shorted, hence opened the path both ways ;-)

 

[Puckdropper]

Am 29.06.07 01.22 schrieb Eeyore:
The diode has shorted, hence opened the path both ways ;-)

Yeah... Something like that.

I should have said: The meter reads 0 both ways, just like a wire.

Puckdropper

 

[Puckdropper]

[email protected]:

*snip*

Yeah... Something like that.

I should have said: The meter reads 0 both ways, just like a wire.

Puckdropper

Ok, I've got another question: I've got only 1N400x series diodes in my
parts collection. Is it worth the trouble substituting one for the
1N500x series diode in the circuit? The AC adapter is rated at 12V
1000mA.

If it works, I'll definately order the proper replacement, I just hate to
blow components when I don't have to.

Puckdropper

 

[Leonard Caillouet]

The diode has shorted, hence opened the path both ways ;-)

What? Is this some sort of zen linguistic challenge?

Leonard

 

[Meat Plow]

[email protected]:

*snip*


Ok, I've got another question: I've got only 1N400x series diodes in my
parts collection. Is it worth the trouble substituting one for the
1N500x series diode in the circuit? The AC adapter is rated at 12V
1000mA.

If it works, I'll definately order the proper replacement, I just hate to
blow components when I don't have to.

Puckdropper

A 1 amp diode should be ok for a test but I think you've got problems
further down the line from my experience with lightning damage warranty
repairs. I hope you don't though

 

[Sam Goldwasser]

[email protected]:

*snip*


Ok, I've got another question: I've got only 1N400x series diodes in my
parts collection. Is it worth the trouble substituting one for the
1N500x series diode in the circuit? The AC adapter is rated at 12V
1000mA.

If it works, I'll definately order the proper replacement, I just hate to
blow components when I don't have to.

If it works, use it and don't worry about the diode.

12 V at 1 A can't hurt a 1N400X.

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[Puckdropper]

On Fri, 29 Jun 2007 07:30:22 +0000, Puckdropper wrote:


A 1 amp diode should be ok for a test but I think you've got problems
further down the line from my experience with lightning damage
warranty repairs. I hope you don't though

The diode was a 1N5817, a schottkey. Out of the circuit, though, it
tested fine. Guess that means there's problems somewhere else.

I tried putting it back in, but ran in to problems with one of the holes
filling with solder.

My guess is there's problems on down the line, and they're network side
related. All three network devices I had (2 routers and a switch) are
acting funny.

Puckdropper

 

[Meat Plow]

The diode was a 1N5817, a schottkey. Out of the circuit, though, it
tested fine. Guess that means there's problems somewhere else.

I tried putting it back in, but ran in to problems with one of the holes
filling with solder.

My guess is there's problems on down the line, and they're network side
related. All three network devices I had (2 routers and a switch) are
acting funny.

Puckdropper

Yeh I've replaced loads of switches and other net appliances after
lightning strikes when I worked for a networking company several years ago.
Those things just don't tolerate it well.

 

[w9gb]

The diode was a 1N5817, a schottkey. Out of the circuit, though, it
tested fine. Guess that means there's problems somewhere else.

I tried putting it back in, but ran in to problems with one of the holes
filling with solder.

Need a little more experience in sodlering -- don't you? Good techniques
can be demonstrated in 5 minutes or less to a 'newbee' or garage tree home
repairer -- and I have seen these devices ruined due to frustration, lack of
patience and anger management issues.

Get some good solder wick and a sewing needle.

My guess is there's problems on down the line, and they're network side
related. All three network devices I had (2 routers and a switch) are
acting funny.

You may not have taken a direct hit -- it may have been an "induced" power
surge.

You may also have damage through your Ethernet (10/100) ports.

I have seen an induced surge (from lightning striking within 500 feet of
location) vaporize copper traces right off serial (RS-232) cards from
external modems. That strike had no effect on AC, but rather came through
phone lines -- right through external modem (back to Hayes) and to serial
card (grounding through computer ground)

Jumpered the missing traces -- and everything worked (in my case).

gb

 

[Puckdropper]

Need a little more experience in sodlering -- don't you? Good
techniques can be demonstrated in 5 minutes or less to a 'newbee' or
garage tree home repairer -- and I have seen these devices ruined due
to frustration, lack of patience and anger management issues.

Get some good solder wick and a sewing needle.

I was getting frustrated earlier, so I quit. I'll try it again later
today, and hopefully get that hole cleared out without damaging the
board.

You may not have taken a direct hit -- it may have been an "induced"
power surge.

You may also have damage through your Ethernet (10/100) ports.

I have seen an induced surge (from lightning striking within 500 feet
of location) vaporize copper traces right off serial (RS-232) cards
from external modems. That strike had no effect on AC, but rather came
through phone lines -- right through external modem (back to Hayes)
and to serial card (grounding through computer ground)

Jumpered the missing traces -- and everything worked (in my case).

gb

Everything you said sounds like it's what happened. There's NO physical
evidence of damage on the boards, all three devices are acting strangely.
(Well, except the dead router.)

I've got a replacement router and switch on the way, I just wanted to try
to repair the ones I have for the experience.

Puckdropper

 

[w_tom]

Everything you said sounds like it's what happened. There's NO physical
evidence of damage on the boards, all three devices are acting strangely.
(Well, except the dead router.)

It is routine for a direct strike to leave no visible damage. Also
routine is for many to assume a surge entered on phone line when
unknown is a protector installed on all telephone subscriber lines
(for free).

Best evidence is the dead body. Damage is how a human learns where
effective protection was missing; where a surge was permitted to enter
the building.

How large was the surge? Routers already have effective internal
protection. The surge had to be so large as to overwhelm that
internal protection. The surge found earth ground, destructively, via
that router. That is a direct strike.

Long after surge electricity was flowing through everything in a
path from cloud to ground, only then something in that path failed.
What died inside that router? What was the path through that router?
A destrutive electical circuit formed by overwhelming internal
protection because a direct strike was not earthed before entering the
building. Learn from that damage so that future damage need not
occur. It is routine to have direct lightning strikes and no damage;
when an effective solution is installed. Use information from the
'dead body' - the electrical path in and out of the router - to find
and eliminate the problem. Where did a surge enter the building?
That is where a solution is installed.

 

[TMI]

Dear PD,

The transient that BBQ'ed the router, could have scrambled the
settings down stream. Follow the manufacturers instructions to reset
defaults.

It hardly seems worth your trouble but I know the Holy Grail Syndrome
all too well. No doubt, there are caps to ground, electrolytic,
tantalum, film or ceramic, that are placed both before and after the
diode. This should be the source of your short if the diode is in fact
OK. You need to use the 200 ohm setting on a good meter to narrow
things down. Touch the probes to each other to set or at least see
zero ohms then probe each component directly, looking for the least
resistance, then unsolder to verify.

Get yourself some solder-wick, rosin soldering paste and some quality
solder (Sn 63 multicore tin/lead if you have a choice). Clean your
iron's tip with scotchbright until you break through any dark oxide.
Sometimes scraping lightly with a single edged blade is better. This
is lead so, no food, wash hands etc. Do not scrape through the
plating.

Heat the iron and dip it in the rosin as it's getting warm. Hold a
piece of solder against it. As soon as it begins to melt, quickly coat
the entire tip. Wipe the hot tip to remove excess solder and rosin,
then apply a bit more solder. This is how the tip must look before it
is put away and just before you use it, Bright, shiny and fully coated
with a slightly noticeable bit of extra solder near the very tip.

The solder must be wiped and renewed just before each operation.

Touch the iron to the hole in question and add a bit of solder.

Remove the heat when it begins to flow.

Place the solder wick on top of the hole and press the iron on top of
the wick. The solder should be drawn into the wick.

A solder sucker could also be used but fresh solder wick is a better
bet for a beginner.

Tom

 

[Eeyore]

I should have said: The meter reads 0 both ways, just like a wire.

That's a SHORT.

An OPEN is when the meter reads 'infinity'.

Graham

 

[Chris Jones]

Yeah... Something like that.

I should have said: The meter reads 0 both ways, just like a wire.

Puckdropper

The terms "short" and "open" mean specific things in the field of
electronics and people will misunderstand you if you use them
interchangeably for anything that isn't working. "shorted" means that
something does conduct electricity, "open" means that it does not conduct
electricity.

Chris

 

[HapticZ]

i concur, impulse emf from millions of amperes flowing nearby does indeed do
some remarkable things!

almost as if by majic, i had a coiled extension cord on a bare plank porch,
it was clear of anything and completely unconnected to anything. after a
strike about 30 feet way, it was melted and fused together, no copper showed
any hint of black conduction damage, only the nice clean smell of lotsa
heat!

better u spend time finding a replacement router than hours trying to fix
this!

 

[Puckdropper]

i concur, impulse emf from millions of amperes flowing nearby does
indeed do some remarkable things!

*snip lighning story*

better u spend time finding a replacement router than hours trying to
fix this!

You're probably right... However, some of this is a bit of a learning
experience. I never realized there were 1N5x series diodes, let alone a
1N5817 being a schottkey.

I've got a replacement router ordered, it should be here in a couple
days.

Puckdropper

 

[Puckdropper]

The terms "short" and "open" mean specific things in the field of
electronics and people will misunderstand you if you use them
interchangeably for anything that isn't working. "shorted" means that
something does conduct electricity, "open" means that it does not
conduct electricity.

Chris

I shall endevour to be more careful with the terms in the future. Thanks
for not getting too confused. ;-)

Puckdropper

 

[Puckdropper]

Dear PD,

The transient that BBQ'ed the router, could have scrambled the
settings down stream. Follow the manufacturers instructions to reset
defaults.

I tried that first. I think it's press and hold reset for 20 seconds,
but it could be longer. I'm hoping the memory isn't fried.

It hardly seems worth your trouble but I know the Holy Grail Syndrome
all too well. No doubt, there are caps to ground, electrolytic,
tantalum, film or ceramic, that are placed both before and after the
diode. This should be the source of your short if the diode is in fact
OK. You need to use the 200 ohm setting on a good meter to narrow
things down. Touch the probes to each other to set or at least see
zero ohms then probe each component directly, looking for the least
resistance, then unsolder to verify.

There's about 5 of them near the power input. I'll give them a look and
see what they're doing.

Get yourself some solder-wick, rosin soldering paste and some quality
solder (Sn 63 multicore tin/lead if you have a choice). Clean your
iron's tip with scotchbright until you break through any dark oxide.
Sometimes scraping lightly with a single edged blade is better. This
is lead so, no food, wash hands etc. Do not scrape through the
plating.

I don't have the rosin soldering paste, but I do have ZnCl flux. Is this
the same kind of thing, or do I need to go looking for the rosin
soldering paste?

Heat the iron and dip it in the rosin as it's getting warm. Hold a
piece of solder against it. As soon as it begins to melt, quickly coat
the entire tip. Wipe the hot tip to remove excess solder and rosin,
then apply a bit more solder. This is how the tip must look before it
is put away and just before you use it, Bright, shiny and fully coated
with a slightly noticeable bit of extra solder near the very tip.

The solder must be wiped and renewed just before each operation.

Touch the iron to the hole in question and add a bit of solder.

Remove the heat when it begins to flow.

Place the solder wick on top of the hole and press the iron on top of
the wick. The solder should be drawn into the wick.

A solder sucker could also be used but fresh solder wick is a better
bet for a beginner.

Tom

I'll give your suggestions a try. I'm wondering if there's a lead free
solder used on the board, due to the trouble I had desoldering the diode.
(I had done other desolderings from other boards and this one was much
more difficult...)

Puckdropper