BCT15 Audio

[gregkaderli]

I recently zapped my BCT15 audio when I had the ext speaker plugged into my computer and I was removing the power cable and the center positive touched a screw on the back of the radio. Of course the ground was complete via the extension speaker to the computer. I sent it to Uniden for repair. I purchased another BCT15 (used) off of Ebay and the unscrupulous teller did not inform me his radio had the same problem. The earphone plug works but of course with attenuation, I guess to protect the ears.

I await the return of my original one from Uniden but is the zapped audio a common problem and an easy fix? or do I need to depend on Uniden repair? Thanks in advance and apologies if this is a prior question...I did try to research it but found no posts.

Greg

 

[DaveIN]

Welcome to Radioreference gregkaderli!

Without a schematic it's hard to diagnose the problem. I suspect that the audio amplifier was damaged and needed replaced.

 

[gregkaderli]

DaveIN, thanks and yes, it would be very difficult without schematic and test equipment. And since everything else functioned ok, I know you are right - that it was the audio amp. I was hoping someone had experienced this before and it was one discreet component that needed fixing...if this particular break had happened to lots of people before.

I did do some review inside the first BCT15 that I messed up here at home and made some notes and took some pictures and maybe can figure out what Uniden Repair Shop did.

Thank you again.

 

[Pyr8]

DaveIN, thanks and yes, it would be very difficult without schematic and test equipment. And since everything else functioned ok, I know you are right - that it was the audio amp. I was hoping someone had experienced this before and it was one discreet component that needed fixing...if this particular break had happened to lots of people before.

I did do some review inside the first BCT15 that I messed up here at home and made some notes and took some pictures and maybe can figure out what Uniden Repair Shop did.

Thank you again.

What was the symptom you experienced exactly? Was there absolutely no sound...did you get a humming out of any of the jacks (with headphones/external speaker or regular speaker? Please explain.

 

[gregkaderli]

No audio, no humming, not any type of audio....just dead. The headphone jack worked fine with both earphones and a speaker but of course the amperage is not there to drive a speaker so the audio was greatly attenuated. I believe DaveIN is correct - it is the audio amp stage.....Thanks for your interest. Greg

 

[Pyr8]

No audio, no humming, not any type of audio....just dead. The headphone jack worked fine with both earphones and a speaker but of course the amperage is not there to drive a speaker so the audio was greatly attenuated. I believe DaveIN is correct - it is the audio amp stage.....Thanks for your interest. Greg

Any interest in getting rid of one of those scanners?

 

[gregkaderli]

Uniden has a really super service in that they allow a user to input the user's work order number on the Uniden Repair Status page and track the repair process. The first BCT15 I sent - the one I zapped - has been reapaired and on its way back to me.

The webpage even indicates the parts used. It shows a J502 which I am fairly certain is a diode. When I receive the radio back, I will post my findings.

I note from other posts that different users experience different issues with audio. Before too many people take my info and run with it, I want to emphasize that I think mine was clearly user related. I was unplugging the power and the center positive on the pin hit a screw on the rear chassis. Since I had my extension speaker jack plugged to a cable to my computer the chassis was grounded and that is when I zapped it.

It sounds like other users still have some humming or other audio issues. Mine was totally dead except for the Headset jack which probably does not utilize the audio amp. Greg

 

[zonian149]

I also have no audio except the headphone jack.

I was just wondering if anyone had an update on this problem. I can't afford to send my BCT15 in for repairs now (unemployed for a 1.5 years) so I was wondering if a DIY fix or work around is possible?--Gary

 

[gregkaderli]

No audio / except headphone

I have had two repaired / both return work orders indicated that the J502 was replaced. No other information.

I have had the scanners apart several times to try and find the component J502 and have not. I cannot remember now, but I think a number of the diodes were marked J so I believe it was a diode.

The mistake that caused the problem appears to be due to over voltage applied to the case.

I am working from memory so I will stand corrected but I think if you read around you will find a warning in the manual to NOT use a Grounded Speaker with an external antenna. I guess because of static build up. It woud make its way to ground and damage the audio along the way.

My mistake on one of the scanners I broke was plain stupid. I had the audio out jack in the rear connected to my computer. So the case of my scannner was grounded to the computer case which is grounded. Regarding my power supply, I do not use the wall wart but have a 20 amp 12 v power supply that I use to power many radios. I have a standard power cable with the 2.1 mm center positive plug. As I was removing the the plug and fumbled the cable when the inside (positive) part of the jack hit one of the screw heads on the back of the scanner case. Normally this would not have resulted in anything if the scanner had been sitting independent of any ground. But since the scanner was connected to my computer, the positive inside of the 2.1mm jack found a ground path thru the scanner when the inside of the jack hit the screw head.

How or why that gets into the audio I do not know without the schematic, but the resulting damage makes sense in light of the warning from uniden about not using an exterior grounded antenna with a grounded speaker.

In any case I suspect the J502 might be a SMD and difficult to replace with out some special tools....but if you don't have a job, I guess you might have time to look for it on the board. I looked around the audio amp chip and found some component numbers that made me think it might be close...but I never found it.

By the way, If you have amplified speakers or can pick up some for free or cheap, they make the headphone audio loud enough to be more than adequate.

If you find something, please let us know........Greg

 

[norcalbusa]

Man, if they're replacing the audio amp- have put a bigger one in! I'd pay extra for that...

 

[ka3jjz]

Things might have changed, but usually a part marked with a J is a jack of some kind - diodes would be a D.

Uniden has had numerous QC issues with the headphone jacks on several of the DMA scanners, not just the BCT15X. I seem to recall it being reported on the 996, 396 and perhaps a few others as well. Cut corners with a cheap jack, I guess...73 Mike