Unauthorized modification to fix hum

[kruser]

Thanks for taking the time to look inside your SDS200 and sharing the information.

Looking inside was the least I could do, especially after seeing the pics you took of that horrible job someone did putting that ring terminal on the end of the ground wire!

Thanks for all the pics you have posted.

 

[frazpo]

Are some people simply more sensitive to this hum? That's possible.

Or the opposite,,,,
I think this is very possible. I've wondered this many times. The hum does not elevate or decrease with volume adjustment. That said, and I'll be easy here, ha, but I'm sure there are some old ears here. Or maybe your ears are less secceapable to the frequency that it is in. Also, like it has been mentioned any times, you just cant hear it with hardly any existing ambient noise in the room.

 

[kruser]

Or the opposite,,,,

The opposite is very possible!

The data artifact sounds one could hear with a 536HP also did not vary with the volume level. That one drove people crazy also but not as bad as this hum seems to be.
I'm giving my radio some time and if it does develop a hum, I'll surely try grounding the display frame better as that area does seem suspect. Especially after seeing the poorly made ground wiring that tumegpc found in his.

 

[TexScan780D]

Does this Uniden famous SDS200 hum come from the scanner speaker or somewhere else in the unit?

 

[frazpo]

Does this Uniden famous SDS200 hum come from the scanner speaker or somewhere else in the unit?

Speaker.

 

[Anderegg]

It comes out the headphone and speaker jack also...you can hear it change pitch as the scanners CPU is doing work, locking a control channel, scanning etc, the sound changes as the workload does.

Paul

 

[n2pqq]

Did you see the black wire grounded on the opposite side of the radio from where you where working ?
On my radio that wire was loose I pushed it in to the ground connector that is there already
My hum noise is completely gone now.
It's worth looking at .

 

[tumegpc]

Did you see the black wire grounded on the opposite side of the radio from where you where working ?
On my radio that wire was loose I pushed it in to the ground connector that is there already
My hum noise is completely gone now.
It's worth looking at .

I checked that ground connection for continuity and made sure that the screw on the pcb was secure and it all checked out on my SDS200. Never made a difference on mine. To access that screw you'll need to approach it from the top. Be carefull not to push on it too much as you can short something out if your ring connector is loose. There is a very thin insulator sheet under the connector protecting several solder pads, you don't want to knock that off. Here is picture I took.

 

[seth21w]

I checked that ground connection for continuity and made sure that the screw on the pcb was secure and it all checked out on my SDS200. Never made a difference on mine. To access that screw you'll need to approach it from the top. Be carefull not to push on it too much as you can short something out if your ring connector is loose. There is a very thin insulator sheet under the connector protecting several solder pads, you don't want to knock that off. Here is picture I took.

Is this factory ground for the display or something else? Should I check to make sure mine is connected securely?

 

[tumegpc]

Is this factory ground for the display or something else? Should I check to make sure mine is connected securely?

A quick search shows- Pulse H2019NL Audio Transformers / Signal Transformers. n2pqq seemed to have solved his hum by pushing on the wire but no update has been given to see he continues to be hum-free. That's your call. Just be careful.

 

[n2pqq]

The wire was as you show in your most recent photo .
The wire I checked was the one on the side of the metal case ( shown by your arrow in photo )
24 hours later no hum .

 

[frazpo]

I can confirm the fix of the hum that is posted in another related thread. Removing the front display and removing the lacquer from the around the mounting screws on the PCB totally fixed my hum also. Just wanted to spread the word in hopes of others repairing theirs if they wanted to give it a try. This didnt just quiet it down either. No hum at all. Even with the mitigation part my hum was audible. With additional grounding it was tolerable but still there. Now nothing

 

[KevinC]

I can confirm the fix of the hum that is posted in another related thread. Removing the front display and removing the lacquer from the around the mounting screws on the PCB totally fixed my hum also. Just wanted to spread the word in hopes of others repairing theirs if they wanted to give it a try. This didnt just quiet it down either. No hum at all. Even with the mitigation part my hum was audible. With additional grounding it was tolerable but still there. Now nothing

Thanks for the pictures!

 

[trentbob]

The opposite is very possible!

The data artifact sounds one could hear with a 536HP also did not vary with the volume level. That one drove people crazy also but not as bad as this hum seems to be.
I'm giving my radio some time and if it does develop a hum, I'll surely try grounding the display frame better as that area does seem suspect. Especially after seeing the poorly made ground wiring that tumegpc found in his.

Also the data artifact sound on a 536 occurred when the radio was scanning. It stopped when you held on an object.

The hum on the 200s I use is definitely a different sound than that.

I just want to say that it is amazing the progress that has been made on this project through the observations and corroboration of everybody.

 

[kruser]

Also the data artifact sound on a 536 occurred when the radio was scanning. It stopped when you held on an object.

The hum on the 200s I use is definitely a different sound than that.

I just want to say that it is amazing the progress that has been made on this project through the observations and corroboration of everybody.

I agree that the two sounds heard between the models are not the same.
I do wonder now if better grounding of the little SD card socket part of the 536HP would not help with the data artifacts that can be heard when there is I/O activity with the card.

I did a test with my newest SDS200 that I received in the past two weeks or so. It was basically hum free even with the mitigation part removed.
After watching these threads about the poorly made ground strap wires and poor or no grounding of the display board, I opened up my SDS200 again and lifted the ground wires. That did allow me to hear the hum. I found that just doing the ground wire from the soldered area around the metal display frame to the chassis was enough to remove me hum. I went ahead and added that new ground wire as insurance.
I also looked at the factory ground strap wires again as someone said they used aluminum wire. That did not sound right. I looked at one crimp connected ring terminal that was not very good looking. I heated it up with the iron and it took solder just fine.
So I went ahead and soldered all the crimp only ends of the ground straps before I closed my radio back up.
It's still running hum free so I'll leave it be. At least I know I can also improve on the display boards ground to the actual chassis should any noise occur down the road but for now, I'll leave that one go as I don't feel like scraping the PCB down to copper at the screw locations. That find is an excellent find though and I'm fairly confident that is responsible for most of the hum problems users are hearing.
It's too bad the fix for that cannot be done easier though.

 

[tumegpc]

I can confirm the fix of the hum that is posted in another related thread. Removing the front display and removing the lacquer from the around the mounting screws on the PCB totally fixed my hum also. Just wanted to spread the word in hopes of others repairing theirs if they wanted to give it a try. This didnt just quiet it down either. No hum at all. Even with the mitigation part my hum was audible. With additional grounding it was tolerable but still there. Now nothing

Good job , I might give this a try.

 

[trentbob]

I agree that the two sounds heard between the models are not the same.
I do wonder now if better grounding of the little SD card socket part of the 536HP would not help with the data artifacts that can be heard when there is I/O activity with the card.

I did a test with my newest SDS200 that I received in the past two weeks or so. It was basically hum free even with the mitigation part removed.
After watching these threads about the poorly made ground strap wires and poor or no grounding of the display board, I opened up my SDS200 again and lifted the ground wires. That did allow me to hear the hum. I found that just doing the ground wire from the soldered area around the metal display frame to the chassis was enough to remove me hum. I went ahead and added that new ground wire as insurance.
I also looked at the factory ground strap wires again as someone said they used aluminum wire. That did not sound right. I looked at one crimp connected ring terminal that was not very good looking. I heated it up with the iron and it took solder just fine.
So I went ahead and soldered all the crimp only ends of the ground straps before I closed my radio back up.
It's still running hum free so I'll leave it be. At least I know I can also improve on the display boards ground to the actual chassis should any noise occur down the road but for now, I'll leave that one go as I don't feel like scraping the PCB down to copper at the screw locations. That find is an excellent find though and I'm fairly confident that is responsible for most of the hum problems users are hearing.
It's too bad the fix for that cannot be done easier though.

I think you might have something there with the 536 and the data card holder grounding, it makes sense. I still have one of my 536s by my bed with my other radios and that noise doesn't bother me.

I'm amazed that you were able to create the hum on a humless radio just by lifting the ground wires and then stop the hum again.

This is just amazing stuff and very very cool!

 

[tumegpc]

I can confirm the fix of the hum that is posted in another related thread. Removing the front display and removing the lacquer from the around the mounting screws on the PCB totally fixed my hum also. Just wanted to spread the word in hopes of others repairing theirs if they wanted to give it a try. This didnt just quiet it down either. No hum at all. Even with the mitigation part my hum was audible. With additional grounding it was tolerable but still there. Now nothing

Did you do just the one screw or all 4?

 

[tumegpc]

I can confirm the fix of the hum that is posted in another related thread. Removing the front display and removing the lacquer from the around the mounting screws on the PCB totally fixed my hum also. Just wanted to spread the word in hopes of others repairing theirs if they wanted to give it a try. This didnt just quiet it down either. No hum at all. Even with the mitigation part my hum was audible. With additional grounding it was tolerable but still there. Now nothing

CONFIRMED! It worked, the hum is gone! I did the fix using a Dremel and cleaned all 4 screw holes. A big thank you to StaticDischarge, frazpo and the rest of the gang for their continued efforts to finally solve this huge problem.

 

[cpetraglia]

What's funny is I have had my SDS200 for around 9 months and never heard any hum. Using the internal speaker or any form of an external speaker amplified or other wise.

I guess if it aint broke, don't fix it. !!