Topics

Electrolytic Capacitor Removal NO Desoldering Required

Steve Groesz
 

I just came across this video from "Mr Carlson's Lab". The method seems reasonable to me for reducing the chances of damage to the PCB when replacing the SMT caps. Any thoughts on this method? (Physically twisting caps off the PCB)

https://www.youtube.com/watch?v=X8N9O3a9jiM

Glenn Little
 

Be very careful, you might remove the trace under the capacitor by twisting it off.
I worked with a tech? that used this method and he destroyed a few boards.
I know of no reputable repair school that recommends this method.
I use desoldering tweezers to remove the caps.

Glenn

On 4/21/2020 2:48 PM, Steve Groesz wrote:
I just came across this video from "Mr Carlson's Lab". The method seems reasonable to me for reducing the chances of damage to the PCB when replacing the SMT caps. Any thoughts on this method? (Physically twisting caps off the PCB)

https://www.youtube.com/watch?v=X8N9O3a9jiM


--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Jim Ford
 

True, even the mention of TWISTING made me cringe....Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Glenn Little <glennmaillist@...> Date: 4/21/20 1:21 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Electrolytic Capacitor Removal NO Desoldering Required Be very careful, you might remove the trace under the capacitor by twisting it off.I worked with a tech? that used this method and he destroyed a few boards.I know of no reputable repair school that recommends this method.I use desoldering tweezers to remove the caps.GlennOn 4/21/2020 2:48 PM, Steve Groesz wrote:> I just came across this video from "Mr Carlson's Lab". The method seems reasonable to me for reducing the chances of damage to the PCB when replacing the SMT caps. Any thoughts on this method? (Physically twisting caps off the PCB)>> https://www.youtube.com/watch?v=X8N9O3a9jiM>>> >-- -----------------------------------------------------------------------Glenn Little                ARRL Technical Specialist   QCWA  LM 28417Amateur Callsign:  WB4UIV            wb4uiv@...    AMSAT LM 2178QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR"It is not the class of license that the Amateur holds but the classof the Amateur that holds the license"

Paul Amaranth
 

I use tweezers or a hot air station. Seems if the cap has leaked a bit
you will have to be rebuilding pads as well.

Also can he use a larger soldering iron? Also note 20V tantalums on a 15V rail.

A lot of people seem to like him and his videos are pretty popular, but the
devil is in the details.

Paul

On Tue, Apr 21, 2020 at 04:21:50PM -0400, Glenn Little wrote:
Be very careful, you might remove the trace under the capacitor by twisting
it off.
I worked with a tech? that used this method and he destroyed a few boards.
I know of no reputable repair school that recommends this method.
I use desoldering tweezers to remove the caps.

Glenn

On 4/21/2020 2:48 PM, Steve Groesz wrote:
I just came across this video from "Mr Carlson's Lab". The method seems reasonable to me for reducing the chances of damage to the PCB when replacing the SMT caps. Any thoughts on this method? (Physically twisting caps off the PCB)

https://www.youtube.com/watch?v=X8N9O3a9jiM



--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"





!DSPAM:5e9f55f6180571341013740!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows

Brendan
 

On Tue, Apr 21, 2020 at 11:48 AM, Steve Groesz wrote:


I just came across this video from "Mr Carlson's Lab". The method seems
reasonable to me for reducing the chances of damage to the PCB when replacing
the SMT caps. Any thoughts on this method? (Physically twisting caps off the
PCB)

https://www.youtube.com/watch?v=X8N9O3a9jiM

I replaced the surface mount caps on my TDS420 with that method. Every twist made my heart race. It worked. Did I like doing it? Nope. If I would have had tweezers I would have used those for sure. You still have to wipe off the pad with an iron to remove the left over lead that you twist off so you don't really save the pad from any heat cycles. I also had a really hard time getting a good thermal transfer due to the leaked electrolytic even after trying to clean with a scratch pen.

Gary Robert Bosworth
 

I prefer tweezer soldering tool.

On Tue, Apr 21, 2020, 11:48 Steve Groesz <steve@...> wrote:

I just came across this video from "Mr Carlson's Lab". The method seems
reasonable to me for reducing the chances of damage to the PCB when
replacing the SMT caps. Any thoughts on this method? (Physically twisting
caps off the PCB)

https://www.youtube.com/watch?v=X8N9O3a9jiM




Sam Reaves
 

I tried it on some scrap boards - I don't recommend it. Don't ever try
this on ceramic microwave boards. Don't ask how I know.

Sam Reaves
ARS W3OHM
Owner and Moderator of:
LeCroy Owners Group on Groups.io (Current and Future Group)

Roy Thistle
 

On Tue, Apr 21, 2020 at 01:43 PM, Paul Amaranth wrote:


A lot of people seem to like him
Not me... I find him irritating.
Roy

Roy Thistle
 

On Tue, Apr 21, 2020 at 01:22 PM, Glenn Little wrote:


I worked with a tech? that used this method and he destroyed a few boards.
With this sort of mechanical "extraction"... one's milage may vary (depending on whether you are extracting a component from a pcb... or extracting a pcb, from a component.) But remember... and if you've ever watched Mr. Carlson's videos who could possibly forget....If you are doing as he does... whatever he does... you are do so at your own risk.
Roy

Dave Wise
 

[re Mr. Carlson YouTube]
He irritates me too. Lots of subtle misinformation delivered with supreme confidence and way too many words.
I watched one video and said "Well, there's <xxx> minutes of life I won't get back."

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Roy Thistle via groups.io <roy.thistle=mail.utoronto.ca@groups.io>
Sent: Tuesday, April 21, 2020 3:06 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Electrolytic Capacitor Removal NO Desoldering Required

On Tue, Apr 21, 2020 at 01:43 PM, Paul Amaranth wrote:


A lot of people seem to like him
Not me... I find him irritating.
Roy

 

I like the guy because I see on the right what appears to be two 547 scopes side-by-side. Good choice!
I don't know where he lives, but hopefully he is not where he is in the video if an earthquake strikes and all that heavy hardware he is surrounded with falls on him.

Ernesto

Roy Thistle
 

On Tue, Apr 21, 2020 at 03:01 PM, Sam Reaves wrote:


I tried it on some scrap boards - I don't recommend it.
Well... IMHO the crux of it is... when they are leaky... or about to leak... and have disgorged... or will soon disgorge, corrosive electrolyte... how do you get them off, without getting more of the electrolyte... or heating/baking... the electrolyte that is on there already... and how do you de-solder them... without excess iron dwell time... when the solder has been "poisoned" by the leaked electrolyte? So, Mr. Carlson is implying/suggesting the method he shows is a kind of trade off?... sort of damned maybe, if you do... and damned maybe, if you don't.
Roy

Roy Thistle
 

On Tue, Apr 21, 2020 at 01:43 PM, Paul Amaranth wrote:


Also can he use a larger soldering iron?
I'm not sure if I know what you mean... but, according to his other videos... he likes to have a high thermal transfer rate... for a relatively low iron temperature... so he sometimes uses lower temperature whacking great irons, on little stuff. He likes to... and claims to have no problems with... soldering onto battery terminals...using that technique. Never worked for me so far (battery always fail prematurely... as it seem to do some kind of damage, whether visible or not.) On pcbs, I guess you don't want to completely melt, or boil away the epoxy adhesive, under the copper traces?
Roy

victor.silva
 

I saw this last year and didn't like when compared to my method that I have been using since 2005.
First of all how can he say no soldering required when the old terminals are still there.
Obviously soldering is required to remove the terminals and clean up the pads.

I use a similar method but it puts absolutely no force on the pads.

I use angled cutters and cut the capacitor off at the bottom, around the collar, leaving the rubber seal, a tiny piece of aluminum and the plastic base.
The remaining rubber seal and plastic base comes off very easily now, by grabbing a corner with the cutters.

--Victor

 

On Tue, Apr 21, 2020 at 10:59 PM, Brendan wrote:


I replaced the surface mount caps on my TDS420 with that method. Every twist
made my heart race. It worked. Did I like doing it? Nope. If I would have had
tweezers I would have used those for sure. You still have to wipe off the pad
with an iron to remove the left over lead that you twist off so you don't
really save the pad from any heat cycles. I also had a really hard time
getting a good thermal transfer due to the leaked electrolytic even after
trying to clean with a scratch pen.
Several years ago, I sidestepped into TDS400/500/600 land. Many in those series suffered from the leaking caps syndrome.
I must have "unscrewed" hundreds of caps and never lifted a pad. The bonding of the pads is very much stronger than it was with 70's PCBs.

I have watched some of the Mac laptop repair videos by Louis Rossman and was astonished what amount of hot rubbing and scraping the pads can endure. To think that in the 70's, normal quality copper pads could be just pushed across the epoxyglass substrate at soldering iron temperatures.

These days I own a fine Weller tweezer but I don't think I'd prefer using that. Unscrewing is effortless and quick.
I think I read someone recommend pulling while turning. I don't think that's a good idea. It defeats the idea of tearing (shearing?) the legs from/across the pad in parallel with the bond layer.
After removing the cap, the remaining solder and electrolyte residue can be removed from the pads by rubbing with a hot iron and flux, unless the pads have been damaged too much. Finish by cleaning the board. I can recommend having a look at how Louis performs his Mac repair work, it may surprise you. He's pretty rough on the boards but doesn't seem to do damage often.

Raymond

victor.silva
 

Louis is not repairing boards that have electrolyte leakage from capacitors.
Most of the stuff he repairs is not even 6 years old.

My experience is mostly with the 2465B SM A5 assembly.
In many cases the pads are not even there anymore, the corrosion is so bad.
The twist method would only work on a 2465B SM A5 with no electrolyte damage,
which is very unusual. Only the very late >1993 A5s that were conformal coated would show little damage.

I'm not going to be convinced to use the twist method. I've presented a method that puts much less stress on the pads.
I will let people decide to use what they want.

--Victor

 

Hi Victor,

On Wed, Apr 22, 2020 at 02:36 AM, victor.silva wrote:


Louis is not repairing boards that have electrolyte leakage from capacitors.
I know. I was referring to the amazing improvement in copper trace bonding that has happened since the '70's when traces could easily be pushed away with a hot soldering iron.
The 2445/2465 families lie between the two extremes, timewise.

Most of the stuff he repairs is not even 6 years old.
I know, of course, see above.


My experience is mostly with the 2465B SM A5 assembly.
In many cases the pads are not even there anymore, the corrosion is so bad.
The twist method would only work on a 2465B SM A5 with no electrolyte damage,
which is very unusual.
Re. the twisting method, I was specifically referring to the TDS400/500/600 families, with many dozens of leaking caps each.
My most recent experience reconditioning a 2445/2465-family instrument (A5 caps, PS caps, mains filter caps, NVRAM/FRAM) is about 3 years ago.

My current instruments from that family are a 2465B, a 2467B and a 2467BHD. All have SMD-equipped A5's and none were so bad that pads were gone or even came off while working on them (yes, mostly using the twisting method). In fact, only the familiar matte solder surface gave away the leakage, no real corrosion visible.

I remember some other samples that were in much worse shape. I unsoldered some caps in those. Never lost a pad unless it was coming off already.


Only the very late >1993 A5s that were conformal coated
would show little damage.
My 3 units above certainly don't have conformal coating, if you're talking about a thick layer, covering the whole pcb. Never seen it on one of those instruments even. Nice!


I'm not going to be convinced to use the twist method. I've presented a method
that puts much less stress on the pads.
I doubt if perpendicular forces put less stress on the pads than forces almost purely in parallel with the pad/pcb interface.


I will let people decide to use what they want.
Thanks -;)

Raymond

victor.silva
 

Raymond,

Yes, after around serial number B066xxx (guesstimate) Tek started conformal coating their A5 assemblies.
The latest serial number on a 2465B, that I have seen, is B079xxx, from 1996.
The early B051xxx A5s had already started leaking, so the conformal coating was their solution.

--Victor

Jim Ford
 

Supposedly conformal coating prevents tin whiskers, too. I'm not convinced on either point.

Jim Ford

------ Original Message ------
From: "victor.silva via groups.io" <daejon1=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: 4/21/2020 6:31:49 PM
Subject: Re: [TekScopes] Electrolytic Capacitor Removal NO Desoldering Required

Raymond,

Yes, after around serial number B066xxx (guesstimate) Tek started conformal coating their A5 assemblies.
The latest serial number on a 2465B, that I have seen, is B079xxx, from 1996.
The early B051xxx A5s had already started leaking, so the conformal coating was their solution.

--Victor


 

On Wed, Apr 22, 2020 at 03:31 AM, victor.silva wrote:


Yes, after around serial number B066xxx (guesstimate) Tek started conformal
coating their A5 assemblies.
The latest serial number on a 2465B, that I have seen, is B079xxx, from 1996.
The early B051xxx A5s had already started leaking, so the conformal coating
was their solution.
Hi Victor,
My 2467B and 2467BHD are both in the B050XXX range, so it seems I've been very lucky!
I have no serial numbers of my other 2465B/67B's at hand.
My 2465 is Heerenveen-made, so no easy dating.

Raymond