Re: 465M Junker


That was the problem I had with the modules in the 475. I gave the modules to an experienced assembler who worked on surface mount boards and had a soldering iron that could reach inside and reflow the joints. But unfortunately the assembler had no experience doing that kind of rework and failed to repair the modules. I had to move on.


-----Original Message-----
From: tekscopegroup@...
Sent: Sunday, January 05, 2020 8:59 AM
Subject: Re: [TekScopes] 465M Junker

On Fri, Jan 3, 2020 at 05:41 PM, KB6NAX wrote:
.... After fussing and fuming I
removed the shield from the ch 1 attenuator switch and spotted a possible
source of the problem. Some years ago I gave up on a 475 which had several
faulty attenuator plug-in modules. The 465M has two in each channel. I
worked them up and down in their sockets a few times and seemingly made a
reduction in the erratic behavior. But being a glutton for punishment I
wasn't going to give up yet. Just moving the scope around caused dramatic
changes in the chaos displayed on the CRT. And then suddenly it would stop,
I'd get nice noise free traces. Then it would start up again. .........
I encountered a very similar problem on a 2213A, in which the attenuation modules are also plugin type and it has two on each channel. The levels where all over the place but sometimes things seemed to settle after unplugging and plugging the modules several times or wedge them with some foam squares against the metal top covers to immobilize etc. But then the problem would invariably always return in short order. It looked like a bad contact on the pins of the modules or that the contact fingers on the receiving board where perhaps stretched or loose. But in the end it turned out to be a cold solder joint at one of the pins right inside one of the attenuation modules. In the end opened all four modules and carefully reflowed the solder joints on the pins and all problems where gone for good. There where at least one or more really poor looking solder joints inside each module. The thread I opened about this is somewhere here among the group messages.

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