SDS100/SDS200: SDS200 Has Gone Totally Deaf

[W3AXL]

Hello all!

I received an SDS200 today and started playing with it. Had some basic trunked channels programmed in and it was receiving well.

I came back to it an hour later and it's stopped receiving anything at all. Thinking it was an antenna issue I threw it on the rooftop antenna - no dice. Tried reformatting the SD card & clearing user settings, same result.

As a quick test, I took it to the bench and fired up the signal generator. Tuned the scanner to WX mode, 162.550 MHz, and injected a 1kHz FM signal at -60 dBm. Nothing on the RSSI meter and nothing but noise from the receiver - the scanner's gone totally deaf it seems.

Curious what could've happened. Is the frontend going out a known issue with these scanners? Would be a shame to have to send it in for repair after less than an hour of use.

 

[doctordialtone]

This is a perhaps case of SD card issues which are common with these models.
Try a different SD card.

 

[wgbecks]

Wow! That sounds more serious than the frontend without so much of a hint of your signal generator at -60 dBm. LO? Have you tried
injecting a known signal on any of the other bands?

 

[W3AXL]

This is a perhaps case of SD card issues which are common with these models.
Try a different SD card.

I'm formatting a new card as we speak. If a bad SD card could cause what's probably the simplest scanner operation (analog FM reception) to fail, that would be... interesting to say the least.

Wow! That sounds more serious than the frontend without so much of a hint of your signal generator at -60 dBm. LO? Have you tried
injecting a known signal on any of the other bands?

I'll make a quick favorite list with some NFM channels at different frequencies to see if anything is working right.

 

[bearcatrp]

Have you tried resetting to factory specs?

 

[W3AXL]

Have you tried resetting to factory specs?

Several times, both clearing user settings & resetting.

 

[bearcatrp]

If you just got this, does the place you purchased from have a XX amount time of return policy? If so and you can’t figure it out soon, send it back.

 

[W3AXL]

If you just got this, does the place you purchased from have a XX amount time of return policy? If so and you can’t figure it out soon, send it back.

Hah, I knew someone was going to ask. It was bought used off of Ebay. I sent the seller a message asking what they'd like to do. I know eBay has decent buyer protection but I'm also not opposed to just sending it to Uniden for their flat rate repair, since even with that it's still considerably less than what a new one would've cost me.

 

[bearcatrp]

Your call but I would send it back to the seller and get your money back. Better to buy from someone here selling one. What happens if uniden tells you it’s not fixable? Good luck.

 

[W3AXL]

Formatted a new SD card, put in a smattering of test channels from 50 to 900 MHz, and injected 1kHz @ -60 dBm. Other than some extremely faint signals on a few of the upper frequencies (500-800MHz) every band seems to be deaf.

Almost makes me wonder if it's a component early in the RX chain that's gone out.

Your call but I would send it back to the seller and get your money back. Better to buy from someone here selling one. What happens if uniden tells you it’s not fixable? Good luck.

I would hope they'd be able to repair a scanner they currently produce and has presumably a relatively simple fault in the RF chain. If not, I'll go back to my BCD996P2 and never touch the SDS line again since they're apparently both extremely fragile and unrepairable.

 

[W3AXL]

Problem solved!

I couldn't help myself - it was bothering me too much that the thing was totally working fine one minute and dead the next, so I did what any good engineer would and opened the thing up.

I had planned on just reseating every connector inside, but I pretty quickly noticed the small 2-wire (brown & black) jumper was disconnected from the control head board. I reconnected that (and reseated the other connectors for good measure) and fired the thing back up. Perfect received down to -120 dBm across the board.

I'd be curious to know what that little jumper is for. It's very helpfully labeled "BRN" but evidently whatever it is is vital to the operation of the receiver section.

 

[bearcatrp]

Good job figuring it out. Probably came loose from the USPS playing football with the package. Past year, most of my packages coming through the USPS had outside damage.

 

[gary123]

Problem solved!

I couldn't help myself - it was bothering me too much that the thing was totally working fine one minute and dead the next, so I did what any good engineer would and opened the thing up.

I had planned on just reseating every connector inside, but I pretty quickly noticed the small 2-wire (brown & black) jumper was disconnected from the control head board. I reconnected that (and reseated the other connectors for good measure) and fired the thing back up. Perfect received down to -120 dBm across the board.

I'd be curious to know what that little jumper is for. It's very helpfully labeled "BRN" but evidently whatever it is is vital to the operation of the receiver section.

Good find. Maybe next time your inside the unit if you can post a picture of the connector. I doubt that this will ever reoccur but having it as a simple troubleshooting test would be good. On my to do bucket list is to look for a connection or point off one of the Ics that can be used as a discriminator tap point. Even if it already wave formed to logic levels would be fine.

 

[ratboy]

I'm paranoid from stuff that got banged around over the years and always check the plugs, etc, unless there's a seal on it. Even then, I've called a couple of service centers for various things and they have told me to go ahead, break the seal. and reseat everything, and a couple of times, that's all it was. I used to see new Uniden made scanners with unsoldered antenna leads, speaker cables that had fallen into the epoxy they put on the board to keep you from accessing the CPU and pulled out the plug when the radio jostled around. Over the 60 years (WOW, that's scary!) I've been messing with radios, I've fixed a lot of dead stuff by reseating plugs and fixing bad solder joints.

 

[crippledchicken]

Maybe someone did the static discharge mod and forgot to plug it back in.