Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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  #11   Report Post  
Old June 22nd 18, 04:05 PM posted to sci.electronics.repair
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Default DMM banana jack inputs

Hints:
1. Beware of new and improved.
2. That which is most difficult to replace, is usually the problem.
3. When all else has been replaced, that which remains, no matter how
improbable, is the culprit.


I agree with that but you're using a misleading singular.

THAT.......is THE problem.......... falsely implies only one thing is wrong. I've been fooled a number of times because two things were bad simultaneously. Sometimes one caused the other but sometimes it's just random.

In fact there is no theoretical limit to how many things can go wrong at once.

  #12   Report Post  
Old June 22nd 18, 04:50 PM posted to sci.electronics.repair
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Default DMM banana jack inputs

On Fri, 22 Jun 2018 10:30:36 -0400, Phil Hobbs
wrote:

On 06/21/2018 05:42 PM, Jeff Liebermann wrote:
Hints:
1. Beware of new and improved.
2. That which is most difficult to replace, is usually the problem.
3. When all else has been replaced, that which remains, no matter how
improbable, is the culprit.


Except that while replacing all that stuff, the real fault blew up
several of the replacements, so it's quite possible to replace
everything and still not fix it!
Cheers
Phil Hobbs


4. When everything has been replaced, and nothing remains to replace,
it's time to give up.

I have a multiyear example of that happening to me. I am the not so
proud owner of an IFR1500 service monitor. Over the years, the power
supply had become more and more intermittent and refused to function
on 117VAC input. However, the 12VDC input does work. In multiple
attempts to fix the problem, I have systematically replaced every part
in the switching power supply section except the magnetics at least 3
times. The last time, I replaced everything with all new parts before
applying power. Something blew up anyway, so I gave up and have been
running it on a 12VDC bench supply for about 5 years.

At one point, I even thought I had found the culprit:
http://www.learnbydestroying.com/jeffl/IFR-1500%20Power%20Supply%20Repair/IFR-1500%20power%20supply%20repair.html
However, the celebration was premature. It died again in about a
month.

My current strategy is to find a 117VAC +5V/+12V only "brick" power
supply and replace the entire power supply. I can live without
battery operation and DC power. However, I can't seem to find
something suitable in a form factor that will fit. My latest scheme
is separate +5V and +12V bricks, which hopefully will fit.

At least I'm in good company:
http://www.repeater-builder.com/test-equipment/aeroflex/aeroflex-index.html
"Also, many old IFRs are having power supply problems. If anyone
would like to do an article on troubleshooting and repair we'd
be happy to put it here."

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #13   Report Post  
Old June 22nd 18, 06:15 PM posted to sci.electronics.repair
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Posts: 240
Default DMM banana jack inputs

On Friday, June 22, 2018 at 10:28:46 AM UTC-4, Phil Hobbs wrote:
On 06/22/2018 09:22 AM, wrote:
On Thursday, June 21, 2018 at 4:31:02 PM UTC-4, Phil Hobbs wrote:
On 06/21/18 16:08,
wrote:
I've got a Fluke 189 DMM. The banana jack inputs are getting flaky.
With the probes or input pushed up or down they sometimes loose continuity.
I opened it up and looked at the solder joints... they look fine.
The banana jacks are encased in plastic so it's hard to see exactly.
I tried squeezing them in some, it's maybe a bit better, but no one
wants even a bit of flaky in their test gear. Any ideas? (about how I might
fix it.)

George H.


You might drop $17 for a set of ProbeMaster 8000 series leads

http://probemaster.com/8000-series-test-leads-only/

All gold-plated, soft silicone leads, lots of accessories available.
Gorgeous.

Even if it turns out to be the meter that's broken, you'll be glad to
have the leads for the next one!



No whatever banana I stick in there is intermittent.
(I use a lot of BNC to dual banana plug adapters.. then I can watch
the fast stuff on the 'scope at the same time.)


Ah. Those put a lot of torque on the solder joints, of course.

The solder joints look fine... OK I just retouched them... same deal,
(just as well cause I already spent $30 on the part Jeff linked to. :^)

When I replace it, I'll butcher the old one and see if I can find anything.

George H.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net


  #15   Report Post  
Old June 22nd 18, 09:05 PM posted to sci.electronics.repair
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Posts: 118
Default DMM banana jack inputs

On Friday, June 22, 2018 at 6:22:58 AM UTC-7, wrote:
No whatever banana I stick in there is intermittent.
(I use a lot of BNC to dual banana plug adapters.. then I can watch
the fast stuff on the 'scope at the same time.)

GH


Banana jacks are so simple that, in the absence of obvious physical abuse, I find it hard to believe that it is intermittently faulty. I would try soldering test leads directly to the lugs; when that does not fix the problem, I would look somewhere downstream like a crack in a pc board or a cold solder joint.


  #16   Report Post  
Old June 22nd 18, 11:41 PM posted to sci.electronics.repair
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Default DMM banana jack inputs

On 06/22/18 11:50, Jeff Liebermann wrote:
On Fri, 22 Jun 2018 10:30:36 -0400, Phil Hobbs
wrote:

On 06/21/2018 05:42 PM, Jeff Liebermann wrote:
Hints:
1. Beware of new and improved.
2. That which is most difficult to replace, is usually the problem.
3. When all else has been replaced, that which remains, no matter how
improbable, is the culprit.


Except that while replacing all that stuff, the real fault blew up
several of the replacements, so it's quite possible to replace
everything and still not fix it!
Cheers
Phil Hobbs


4. When everything has been replaced, and nothing remains to replace,
it's time to give up.

I have a multiyear example of that happening to me. I am the not so
proud owner of an IFR1500 service monitor. Over the years, the power
supply had become more and more intermittent and refused to function
on 117VAC input. However, the 12VDC input does work. In multiple
attempts to fix the problem, I have systematically replaced every part
in the switching power supply section except the magnetics at least 3
times. The last time, I replaced everything with all new parts before
applying power. Something blew up anyway, so I gave up and have been
running it on a 12VDC bench supply for about 5 years.

At one point, I even thought I had found the culprit:
http://www.learnbydestroying.com/jeffl/IFR-1500%20Power%20Supply%20Repair/IFR-1500%20power%20supply%20repair.html
However, the celebration was premature. It died again in about a
month.

My current strategy is to find a 117VAC +5V/+12V only "brick" power
supply and replace the entire power supply. I can live without
battery operation and DC power. However, I can't seem to find
something suitable in a form factor that will fit. My latest scheme
is separate +5V and +12V bricks, which hopefully will fit.

At least I'm in good company:
http://www.repeater-builder.com/test-equipment/aeroflex/aeroflex-index.html
"Also, many old IFRs are having power supply problems. If anyone
would like to do an article on troubleshooting and repair we'd
be happy to put it here."


I power a lot of prototypes from random laptop bricks with eBay SMPSes
hung on them. The eBay units are generally quite okay as long as you
derate their output current by about 3X.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

  #17   Report Post  
Old June 22nd 18, 11:48 PM posted to sci.electronics.repair
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Posts: 613
Default DMM banana jack inputs

On 06/22/18 18:41, Phil Hobbs wrote:
On 06/22/18 11:50, Jeff Liebermann wrote:
On Fri, 22 Jun 2018 10:30:36 -0400, Phil Hobbs
wrote:

On 06/21/2018 05:42 PM, Jeff Liebermann wrote:
Hints:
1.* Beware of new and improved.
2.* That which is most difficult to replace, is usually the problem.
3.* When all else has been replaced, that which remains, no matter how
improbable, is the culprit.

Except that while replacing all that stuff, the real fault blew up
several of the replacements, so it's quite possible to replace
everything and still not fix it!
Cheers
Phil Hobbs


4.* When everything has been replaced, and nothing remains to replace,
it's time to give up.

I have a multiyear example of that happening to me.* I am the not so
proud owner of an IFR1500 service monitor.* Over the years, the power
supply had become more and more intermittent and refused to function
on 117VAC input.* However, the 12VDC input does work.* In multiple
attempts to fix the problem, I have systematically replaced every part
in the switching power supply section except the magnetics at least 3
times.* The last time, I replaced everything with all new parts before
applying power.* Something blew up anyway, so I gave up and have been
running it on a 12VDC bench supply for about 5 years.

At one point, I even thought I had found the culprit:
http://www.learnbydestroying.com/jeffl/IFR-1500%20Power%20Supply%20Repair/IFR-1500%20power%20supply%20repair.html

However, the celebration was premature.* It died again in about a
month.

My current strategy is to find a 117VAC +5V/+12V only "brick" power
supply and replace the entire power supply.* I can live without
battery operation and DC power.* However, I can't seem to find
something suitable in a form factor that will fit.* My latest scheme
is separate +5V and +12V bricks, which hopefully will fit.

At least I'm in good company:
http://www.repeater-builder.com/test-equipment/aeroflex/aeroflex-index.html

** "Also, many old IFRs are having power supply problems. If anyone
** would like to do an article on troubleshooting and repair we'd
** be happy to put it here."


I power a lot of prototypes from random laptop bricks with eBay SMPSes
hung on them.* The eBay units are generally quite okay as long as you
derate their output current by about 3X.


I should add that you can make negative supplies out of an eBay buck
regulator module by applying input power to +IN, grounding +OUT, and
taking the negative output between there and the original common ground.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

  #18   Report Post  
Old June 23rd 18, 12:47 AM posted to sci.electronics.repair
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First recorded activity by DIYBanter: Aug 2014
Posts: 1,055
Default DMM banana jack inputs

wrote:


I've got a Fluke 189 DMM. The banana jack inputs are getting flaky.
With the probes or input pushed up or down they sometimes loose continuity.
I opened it up and looked at the solder joints... they look fine.
The banana jacks are encased in plastic so it's hard to see exactly.
I tried squeezing them in some, it's maybe a bit better, but no one
wants even a bit of flaky in their test gear. Any ideas? (about how I might
fix it.)




** You have tried using cleaning fluid ???

PCB cleaner or even WD40 will do.

An old handkerchief pushed home with a small drill bit is one way to introduce some fluid and clean the inside surfaces.


...... Phil




  #19   Report Post  
Old June 23rd 18, 02:42 AM posted to sci.electronics.repair
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First recorded activity by DIYBanter: Nov 2008
Posts: 240
Default DMM banana jack inputs

On Friday, June 22, 2018 at 7:47:57 PM UTC-4, Phil Allison wrote:
wrote:


I've got a Fluke 189 DMM. The banana jack inputs are getting flaky.
With the probes or input pushed up or down they sometimes loose continuity.
I opened it up and looked at the solder joints... they look fine.
The banana jacks are encased in plastic so it's hard to see exactly.
I tried squeezing them in some, it's maybe a bit better, but no one
wants even a bit of flaky in their test gear. Any ideas? (about how I might
fix it.)




** You have tried using cleaning fluid ???

PCB cleaner or even WD40 will do.

An old handkerchief pushed home with a small drill bit is one way to introduce some fluid and clean the inside surfaces.


..... Phil


No! I wiped 'em with IPA and a wooden cotton swab thing.
I'm away from the lab for a while so I won't be able to try
some other cleaner til I return.

George H.
  #20   Report Post  
Old June 23rd 18, 03:22 AM posted to sci.electronics.repair
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First recorded activity by DIYBanter: Jul 2013
Posts: 660
Default DMM banana jack inputs

On 6/22/2018 10:05 AM, Tim R wrote:
Hints:
1. Beware of new and improved.
2. That which is most difficult to replace, is usually the problem.
3. When all else has been replaced, that which remains, no matter how
improbable, is the culprit.


I agree with that but you're using a misleading singular.

THAT.......is THE problem.......... falsely implies only one thing is wrong. I've been fooled a number of times because two things were bad simultaneously. Sometimes one caused the other but sometimes it's just random.

In fact there is no theoretical limit to how many things can go wrong at once.

Oh, sounds like you worked on the first NAP VCR switching power
supplies! The parts dept finally came out with a repair kit, I think it
contained 8 parts, and it was strongly suggested you replace all parts
before applying power.

Mikek


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