796D Low audio output

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kd0fx

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So I got a 796D from Ebay. Looks good. I test it out by receiving the local 162 weather channel since I know that's good. I get 4-5 bars on the s-meter and full quieting, but the volume is so low I need to turn it all the way up to hear it at all (soft). Attenuator is set to off. The external speaker jack in the back has the same problem with headphones.
Is this a common 796D problem? Google doesn't say much about it. Is there anything I can try or should I look at trying to return it to Ebay?
 
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kb0nly

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I have two 796's and have worked on numerous others, can't say i ever came across one with low audio in this exact same way, but i have seen them with the audio stuck at full or none due to a bad volume control. When you turn it all the way up and down do you hear the actual audio level change some? If not it could just be a bad volume control, which could be replaced easily enough, i did one that was stuck at full volume.

If you got it cheap enough i say put a few bucks into fixing it. I doubt its the audio amplifier, its most likely the volume control.

As a test, you could jumper the volume control trimpot if your familiar enough with working on stuff like this, see if you then get full audio output.
 

kd0fx

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Yes, I get some level change. It goes from zero to whisper by the end of the turn. The knob appears to have full range of motion.
 
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kb0nly

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Hmm... Ok, then the only thing i could suggest would be to bypass the volume trimpot and see if it then produces more audio, otherwise it could be a failed audio amplifier. I don't remember off hand what exact component the 796 uses for its audio amp, but its very possible that a quick replacement would fix it up.

Mind if i ask how much you paid for it?? If you don't want to post PM me about it. If you got it for a good price i would fix it and keep it if your otherwise happy with its condition. A good 796 is worth close to $300 in todays market.

If you are planning on using it as a base scanner in the house i would just buy a cheap set of amplified computer speakers. Something like the creative models that have a volume control on them. Then see if the amplified speakers bring the level up loud enough. Would sound better than the builtin speaker anyway!
 
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kd0fx

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I paid about $260 after shipping. I thought that was kinda on the high side for such an old unit, but I used the buy it now for instant gratification. I also don't like the single din form factor on all the new ones that are out so I wanted a large one like this. I really wish they'd make an updated 895.

Anyway, where can I find info on how these work? I'm probably up to replacing surface mount if it's not too fine a scale. Do they have a service manual?
 
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kb0nly

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Same here, i don't like the newer models, the 796 seems to have a better receiver than the 996 in my opinion also. Side by side my 796 does better than others 996.

Thats a good price on a 796, older unit but still very useful in todays market. Its not surface mount, through hole mount for most of the components in these including the audio amp. However i would try working on the volume control first, chances are good that its bad as many have had them fail after years of use. I will dig around and see if i can find the part number on it, still might be available from Uniden. Also you can try contacting UPMan on here, he is our Uniden guru.

No service manual, sad to say but they are not available for scanners due to the whole cellular receive debacle of years past.
 

kd0fx

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Through hole is even better for me. Part numbers would be much appreciated.
 

kd0fx

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I've had just a little bit of time to spend listening to it. The volume appears to actually get louder and softer. It never gets as loud as it should, but it vacillates between usable to unusable.
Anyone have a guess to what component that points to?
 
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kb0nly

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Worth a shot, otherwise if you have the time jumper the volume pot and see if you get blasted out of your seat when you turn it on, then you can eliminate the volume control one way or the other.
 

kd0fx

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OK, sounds like a plan.
I was a little hesitant to open the case and mess with it - I was thinking I'd just return it to the guy for a refund. But he gave me a partial refund. For the amount I ended up paying, I am satisfied enough to take a chance that I can fix it. I have to say the seller treated me fair.

So, do these knobs just pull straight out to take them off? No hidden things I need to unscrew first? I'll see if a little contact cleaner works first, and then I'll jumper the pot like kb0nly suggests.
 

kd0fx

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Deconstruction is pretty straight forward, except I can't figure out how the VFO comes off. It won't pull off with the same force that the squelch/volume knob did and I'm reluctant to just start increasing force till it pops off. Is there a trick to it or do I just need to gently get a pry bar in there???
 
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kb0nly

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You shouldn't even have to take the knobs off to get to it for troubleshooting, just remove the cover.
 

kd0fx

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Really? I can't really see it from the top because the motherboard is in the way. I could get at it from the bottom, but I can't really see what's going on. There's 8 connection joints there that I assume the pot is connected to, but I don't know what is doing what. I can get at the top of the wiring harness, but again I don't know what is doing what. I'm hesitant to just start jumpering things together.
 

kd0fx

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Anyway, it looks like the contact cleaner did the trick. Seemed to work well this morning anyway. I'll spend some time just listening to it in the back ground tonight and make sure it doesn't return to it's bad ways.
I might still order an extra volume pot just to have on hand. And knobs. Those look like they're easy to lose.
 
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kb0nly

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Yeah from the bottom is how i got to them... But anyway, to answer the other question you had above yes the knobs all just pull off. The knobs are available fairly cheap on eBay, there is a guy selling new ones. As for the volume control i looked back through my notes and can't find the part number. Your probably best off calling Uniden parts and asking them or sending a message to UPMan on here.

If the contact cleaner did the trick you might get lucky, just work the volume back and forth a lot and add a bit more, see what happens, it might last it might go intermittent again after time.

Good job!
 

kd0fx

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it might last it might go intermittent again after time.
But I know for sure where the problem is located now. If it fails again I'll just replace it instead of messing with it again. I got the parts # from the Parts Request page yesterday. Supposedly only $1.67 apiece so having a couple on hand will be cheap insurance.
 

W9NES

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I would recomend that you send the 796D to Paul (UP Man) at Uniden Repair.After the unit is fixed you will have a 90 day warranty.When the unit is in for repair it will be updated and tuned up.When you get the scanner back it will be like new.
 
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