This one has been sitting largely unused for a number of years..... possibly 10 years. I'd like to see about bringing it back to life.
I bought it at a garage sale for $10 so I'm not out that much!!! Since I got it... it always worked...as far as the scanner goes. I could program it easily. It would scan, it would stop when a programmed frequency came on, play the audio, then scanning would start up. The only issue at the time was that the audio ... while clear... was so low that I had to put the speaker to my ear to hear it at all. I guess I just lost interest at the time.
Now, I have pulled it out and all three caps next to the TDA 1905 audio chip were in bad shape. High ESR, high Vloss and usually significantly lower capacitance than it's value. Also there was the 100 uF 50 volt cap that tied to the speaker. It was just as dead as the others with an ESR of 39 and was around 33 uF in value. So... NOW... I get reasonably loud "crackles and static" out of the speaker that I can actually here.
That... is where NORMAL seems to stop.
First, it LOOKS like the scanner part of this thing is performing its work. The scan is happening.... it seems to stop on various programmed channels (I only have 5 in it at this time) but there is a lot of weirdness.
For one... it stops on random channels, pauses, then resumes scanning as if it were working fine. The only thing is.... there is only crackles and mild static coming out of the speaker.
Here comes the part where you get to think..... "idiot"!!!!!!!
I didn't have an antenna to hook up to it at the time this testing was going on. I figured I would get hiss/crackle... but I expected the rest of it to work. SO at this point all I could do was cut off 18" or so of solid core hookup wire and stick it in the center pin of the antenna jack.
It really didn't change anything. The thing would sit there... looking like it was working. It would stop now and then on a random channel, pause, and resume scanning..... but no kind of sound. For fun.... I got my HT out and went simplex on one of the channels that it was stopping on. When the scanner would stop.... there was absolutely nothing on the HT that would have triggered it. His.... yeah.... but no signal (and, yes, I totally unsquelched the HT so that it was wide open!). SO it's like....I THINK it LOOKS like it is working... but no signal.
So, I wanted to program in a simplex frequency in a safe space so that I could use my HT to transmit and see if THAT woluid come through the scanner.
First off... the MAN button would not halt the scanning. (and the lock switch on the back was verified OFF). But I could not get it to stop scanning so that I could program it. It never would accept anything I punched in on the number keypad.... I presumed that was because I wasn't able to get it to stop scanning. I would hit MAN and at the MOST it would pause...and then resume scanning... so that MAY have just been one of the many flaky stops I had been seeing all along anyway.
So I chose one of the frequencies programmed into the scanner, put my HT in Frequency mode at that frequency, and dropped to low power and gave a brief transmit test. The scanner.... didn't see it. Not at all. So transmitting a good signal in close proximity... did nothing. The scanner didn't hear it.
It would pay attention to all of the buttons in the middle keypad where the Service Search buttons are. But MAN would absolutely not stop it.
I decided I would call it a night looking at the thing... but decided I would come here to whine.... and see what kind of suggestions I might get.
All four of the electrolytic caps that I replaced next to the TDA 1905 were shot! I mean badly.
This has me wondering if every single electrolytic cap IN the thing is bad. I could see where that might affect sensitivity in certain stages... possibly even sensitivity in switching circuits for the buttons....
At this point... I am open to suggestions. As I am sure most of you know... Uniden did not distribute service manuals for these things. I have already contacted them and the first tier person said that THEY did not have any such materials but that he was going to refer my inquiry to one of the repair side folks to see what they had. I was not feeling overly confident that I would ever get a response back from the repair side.
So here I sit.... I could most likely gather up all of the caps that I can see in the thing and change them out. A nice soldering/desoldering station is a real help... and I do have that. But the question becomes.... is it worth it? If I replace all the caps.... might it even spring back to life? Or do I just have a new door stop?
Are there things inside that it might help to clean?? Inter-board connections? Pots? Switches?
What do you think????
I'd love to have it working as it did when I first got it...but apparently letting it sit idle has not been good for it. (Again, it used to work/scan/configure... everything when I first got it. But it sure won't now!!!!
I bought it at a garage sale for $10 so I'm not out that much!!! Since I got it... it always worked...as far as the scanner goes. I could program it easily. It would scan, it would stop when a programmed frequency came on, play the audio, then scanning would start up. The only issue at the time was that the audio ... while clear... was so low that I had to put the speaker to my ear to hear it at all. I guess I just lost interest at the time.
Now, I have pulled it out and all three caps next to the TDA 1905 audio chip were in bad shape. High ESR, high Vloss and usually significantly lower capacitance than it's value. Also there was the 100 uF 50 volt cap that tied to the speaker. It was just as dead as the others with an ESR of 39 and was around 33 uF in value. So... NOW... I get reasonably loud "crackles and static" out of the speaker that I can actually here.
That... is where NORMAL seems to stop.
First, it LOOKS like the scanner part of this thing is performing its work. The scan is happening.... it seems to stop on various programmed channels (I only have 5 in it at this time) but there is a lot of weirdness.
For one... it stops on random channels, pauses, then resumes scanning as if it were working fine. The only thing is.... there is only crackles and mild static coming out of the speaker.
Here comes the part where you get to think..... "idiot"!!!!!!!
I didn't have an antenna to hook up to it at the time this testing was going on. I figured I would get hiss/crackle... but I expected the rest of it to work. SO at this point all I could do was cut off 18" or so of solid core hookup wire and stick it in the center pin of the antenna jack.
It really didn't change anything. The thing would sit there... looking like it was working. It would stop now and then on a random channel, pause, and resume scanning..... but no kind of sound. For fun.... I got my HT out and went simplex on one of the channels that it was stopping on. When the scanner would stop.... there was absolutely nothing on the HT that would have triggered it. His.... yeah.... but no signal (and, yes, I totally unsquelched the HT so that it was wide open!). SO it's like....I THINK it LOOKS like it is working... but no signal.
So, I wanted to program in a simplex frequency in a safe space so that I could use my HT to transmit and see if THAT woluid come through the scanner.
First off... the MAN button would not halt the scanning. (and the lock switch on the back was verified OFF). But I could not get it to stop scanning so that I could program it. It never would accept anything I punched in on the number keypad.... I presumed that was because I wasn't able to get it to stop scanning. I would hit MAN and at the MOST it would pause...and then resume scanning... so that MAY have just been one of the many flaky stops I had been seeing all along anyway.
So I chose one of the frequencies programmed into the scanner, put my HT in Frequency mode at that frequency, and dropped to low power and gave a brief transmit test. The scanner.... didn't see it. Not at all. So transmitting a good signal in close proximity... did nothing. The scanner didn't hear it.
It would pay attention to all of the buttons in the middle keypad where the Service Search buttons are. But MAN would absolutely not stop it.
I decided I would call it a night looking at the thing... but decided I would come here to whine.... and see what kind of suggestions I might get.
All four of the electrolytic caps that I replaced next to the TDA 1905 were shot! I mean badly.
This has me wondering if every single electrolytic cap IN the thing is bad. I could see where that might affect sensitivity in certain stages... possibly even sensitivity in switching circuits for the buttons....
At this point... I am open to suggestions. As I am sure most of you know... Uniden did not distribute service manuals for these things. I have already contacted them and the first tier person said that THEY did not have any such materials but that he was going to refer my inquiry to one of the repair side folks to see what they had. I was not feeling overly confident that I would ever get a response back from the repair side.
So here I sit.... I could most likely gather up all of the caps that I can see in the thing and change them out. A nice soldering/desoldering station is a real help... and I do have that. But the question becomes.... is it worth it? If I replace all the caps.... might it even spring back to life? Or do I just have a new door stop?
Are there things inside that it might help to clean?? Inter-board connections? Pots? Switches?
What do you think????
I'd love to have it working as it did when I first got it...but apparently letting it sit idle has not been good for it. (Again, it used to work/scan/configure... everything when I first got it. But it sure won't now!!!!