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SDS200 Hum repaired, but returned

bravo14

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I'm waiting on Uniden to ship out the unit I turned in the 2nd time cause of the hum. If unit 3rd unit does the hum I may sell it or ask for refund since I can't stand the loudness of the hum.
 

TailGator911

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It's the law of averages - someone will invariably damage their scanner attempting to perform this modification/repair. Some kid who has never opened up an electronic component in his life. Please, be careful, and make sure you UNPLUG your scanner from the electrical outlet before you go into the circuitry with a metal object. *ack* Just a word to the … wise.
 

werinshades

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It's the law of averages - someone will invariably damage their scanner attempting to perform this modification/repair. Some kid who has never opened up an electronic component in his life. Please, be careful, and make sure you UNPLUG your scanner from the electrical outlet before you go into the circuitry with a metal object. *ack* Just a word to the … wise.
Why? Since Uniden's warranty policy is illegal (according to one non-owner), than they can can screw it up and Uniden will fix it for free..:LOL: :LOL: :LOL:
 

StaticDischarge

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Is there a convenient location where an ohmmeter could be used to verify that the screws have been properly modified and good continuity established?
Use a magnifying device and confirm the lacquer is gone and you can see good copper where the screw head will touch then go on to tighten, loosen and tighten again.. Should do the trick..
 

radio3353

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Most RF devices I worked with have had serrated washers that creates proper grounding thru any lacquer. Too bad if Uniden isn't using them.



/Ubbe
Same here. We always used star washers under ground lugs in hi-rel electronics.
 

frazpo

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Sorry but my edit time ran out.. Here is the full version of the above post:

Here are my 2 cents on this hum issue..

In the beginning I reported that I could not hear the hum. Well if I have the audio time off setting to infinite and have ear plugs in I can tell it is there but not terrible. Very, very low with internal speaker and could not hear it with an external speaker unless it (like the ear plugs) is up against my ear. So NO, as far as I am concerned there isn't any hum from my radio.

Regardless...

I took the cover off and I do have a factory installed NMP200 so I removed it.. The hum did get much more noticeable!

So I took it all apart to see what, if anything could be done and here are my findings at this time:..

The NMP200 simply connects the "screen ground" of the display to the chassis.. That is it!! (which explains why, over time, people start hearing the hum return - loose fitting part and oxidation.)
So on further inspection I see that the "screen ground" is in fact soldered to the front board's ground plane pretty well. I also saw (the main issue I am about to explain a fix to) is the four mounting screws that hold the front board to the chassis ARE NOT CONNECTING the front boards ground plane to the chassis! Which in fact is EXACTLY WHAT THE NMP200 DOES. Simple fix really... without soldering! (or voiding your warranty ~ just a disclaimer for the warranty police on the forum so they will finally STFU already!)

The tools I used:

No. 1 & No. 2 Phillips screwdriver
Small flat jewelers screwdriver
X-Key tool
Credit card (or similar to not mar the faceplate or knobs upon removal)
X-acto or utility blade
To help removal of the wire plugs that connect the front to the main boards I used curved hemostats
If your eyes are going (like mine are) some type of magnification

Once you have the radio taken apart (explained elsewhere on the forum) and have the front panel in your hand, display towards you, you will see four (No. 1) screws towards the corners of the front board (notice the green lacquer all over and under the screw heads?). One at a time remove the screws and CAREFULLY scrape the lacquer from under the screw heads but DO NOT SCRAPE AS HARD THAT YOU REMOVE THE COPPER FROM UNDER THE LACQUER!! and replace the screw. Now to make sure you have good contact, tighten, loosen, tighten, loosen and tighten the screw a few times.
Now carefully put the scanner together without the NMP200 and test..
I hope your results are as satisfying as mine..

If you do anything I have explained here, you will not hold me responsible for anything that may happen, what-so-ever. You will assume full responsibilities for your own actions (which you should always do... period!). This includes but not limited to the leakage of liquids from your body due to the misuse of sharp objects!

Normal scanning may now resume...
I can confirm this also. Just finished this procedure and now humless. I mean humless. Nothing. Thanks for the fix!!!
 

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StaticDischarge

Ouch! That hurt!!
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I can confirm this also. Just finished this procedure and now humless. I mean humless. Nothing. Thanks for the fix!!!

Makes it worth it if at least one other SDS200 scanner enthusiast benefited from my tiresome 20 minutes to figure this out and post it..
Made my goal!!! and you are welcome!

Enjoy...

Normal scanning may now resume...
 

allend

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Makes it worth it if at least one other SDS200 scanner enthusiast benefited from my tiresome 20 minutes to figure this out and post it..
Made my goal!!! and you are welcome!

Enjoy...

Normal scanning may now resume...
I think for your time and the brain power it took to figure out the perm fix that Uniden should send you a FREE scanner of your choice for this HUM fix. This saves so much headache and time for Uniden to figure out. Now they can go back to their R & D team with this fix and no more extra part needed and the factory from tomorrow on-ward can make sure this HUM problem is gone for good.

This also takes pressure off of UpMan to figure out on how to fix another issue with this SDS-200 radio. The radio is only going to get way better now. 2 thumbs for you on this fix. Thanks a bunch. I just ordered on Amazon the X Key Tool for 11 bucks.
 

buddrousa

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This goes back to show that paying non tech low wage people is not always the best option plus the use of star washers would work.
I took mine apart both of my ground wires were good had no hum even with the case open and grounds connected but I did the screw fix and put it back together still have no hum but for sure will not have one now. Did not even install the mitigation part.
 

frazpo

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This goes back to show that paying non tech low wage people is not always the best option plus the use of star washers would work.
I took mine apart both of my ground wires were good had no hum even with the case open and grounds connected but I did the screw fix and put it back together still have no hum but for sure will not have one now.
I did look for some star washers at lowes before I fixed mine but couldn't find any. Probably could have found some in my junk box but once I could tell how good of a copper surface I could obtain with the exact knife I wasn't too worried. Plus that was some thick lacquer! It would take effort for even grounding washers to get through and make good contact. Imo
 
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