BCD536HP Date and Time reset.

[n4txf]

OK, I know the Clock Reset issue is an old one and Uniden has ended the repair campaign and the other threads are closed. My current issue seems to be a little different. I have searched and scoured the web and learned there used to be a small hearing aid type battery on the "BT401" spot on the front PCB board (see pic). I have TWO BCD536HPs. One unit I purchase NEW and has been keeping date/time as normal for years. I picked up a used BCD536HP and it resets date/time after being off for more than 5 seconds. I have left it powered ON for over a week and the memory battery doesn't seem to charge. I don't get a warning message on start up as others have, I just have a reset clock. I cracked the USED radio open to look for and replace this notorious "BT401" battery. I found the spot on the PCB where the battery should be...but nothing was there...never was...it was virgin. I cracked open my working BCD536HP to get a view of its battery ....there wasn't one either! So how is it keeping time? I'm guessing the backup memory is no longer being managed by the mini hearing air type battery pictured. I have no idea what other component/capacitor is now responsible for backing up the clock. Hate to send to Uniden and spend $100 to replace a $4 part. If you know of the new failing component for the clock, please share.

Thanks!

 

[donc13]

A capacitor. Typically an electrolytic capacitor.

 

[morrisr3nd]

I'm in the same boat. I've got a 436HP and a 536HP that are doing the same thing. I also hate to spend ANOTHER $100 each to get them repaired. I'll just troll this post to see what they come up with.

 

[n4txf]

A capacitor. Typically an electrolytic capacitor.

There are no caps on the front PCB board. No new ones on the main board. The existing caps all appear well and in good health. Do you know of a specific problematic cap?

 

[gary123]

Use a high impedance voltmeter on the BT401+ pad. The good scanner may have a voltage on it from the current keep alive circuit. The bad one may show 0 volts or something close to that. From there you may be able to trace back to a cap. I expect a large value cap will be in use if it is a cap. I have a couple of 536 that are unplugged for weeks at a time and they keep the time.

 

[donc13]

One would presume, although I don't know for a fact, that if the unit's battery isn't completely depleted, even when the unit is turned off, the battery will supply power for the clock chip.

Attached is a copy of the fix instructions supposedly for the 536,. I presume similar for 436. Also, shows fix for dim display leds

 

[n4txf]

One would presume, although I don't know for a fact, that if the unit's battery isn't completely depleted, even when the unit is turned off, the battery will supply power for the clock chip.

Attached is a copy of the fix instructions supposedly for the 536,. I presume similar for 436. Also, shows fix for dim display leds

Yep. Have it. These instructions speak to a battery BT401 that does not even exist on newer BCD536HP. Thanks!

 

[morrisr3nd]

That looks like a VERY easy repair. I might just give it a try on my older unit that has both the display issue and the time issue. I found a socket that will hold a 2032 battery with leads that can be soldered to the board. I've also found the LED's and resistors. I think it might be worth a shot. I haven't worked with surface mounted stuff in a lOOOOOOnnng time. Might be fun.

 

[n4txf]

That looks like a VERY easy repair. I might just give it a try on my older unit that has both the display issue and the time issue. I found a socket that will hold a 2032 battery with leads that can be soldered to the board. I've also found the LED's and resistors. I think it might be worth a shot. I haven't worked with surface mounted stuff in a lOOOOOOnnng time. Might be fun.

If you have an older unit WITh an old button cell battery in place, that would be an easy fix. Mine are not like that. Mine have NO batteries in the BT401 spot where older units have a button cell. Yet, one radio keeps time...one does not. The potential for damage is high if I just start adding components where none originally existed. If you are replacing the button cell...remember to use an LIR2032 (rechargeable), not a CR2032. You can find pre-wired LIR2032 batteries all day on Amazon/eBay and would be easier to mount. Good luck!

 

[morrisr3nd]

If you have an older unit WITh an old button cell battery in place, that would be an easy fix. Mine are not like that. Mine have NO batteries in the BT401 spot where older units have a button cell. Yet, one radio keeps time...one does not. The potential for damage is high if I just start adding components where none originally existed. If you are replacing the button cell...remember to use an LIR2032 (rechargeable), not a CR2032. You can find pre-wired LIR2032 batteries all day on Amazon/eBay and would be easier to mount. Good luck!

Yep. I agree with the LIR's. Don't want to accidentally charge a CR. Might not be too fun after that.

 

[morrisr3nd]

 

[morrisr3nd]

I just ordered most of the parts (except for the battery). I'll let y'all (I'm from the south) know how it goes when they get here and I can get them installed.

 

[dave3825]

The existing caps all appear well and in good health.

I do not believe you can rate the health of a cap by just looking at it. Pretty sure caps need to be desoldered from the board to be tested unless you can measure their equivalent series resistance with an ESR meter.

 

[morrisr3nd]

I do not believe you can rate the health of a cap by just looking at it. Pretty sure caps need to be desoldered from the board to be tested unless you can measure their equivalent series resistance with an ESR meter.

Some electrolytics will swell beyond their label when they reach end of life (usually around 10 years). Some just blow out the bottom. Others just short out and show no signs of issues.

 

[n4txf]

I just ordered most of the parts (except for the battery). I'll let y'all (I'm from the south) know how it goes when they get here and I can get them installed.

Does your BCD536HP have the old button cell mounted in the BT401 spot or is it empty like mine?

 

[morrisr3nd]

Not sure yet. I'll let you know when I open it back up.

 

[morrisr3nd]

Yes BT401 is there.

 

[n4txf]

Yes BT401 is there.

OK, the mod should work for you. I'm in another boat. I have two radios...both with no battery on BT401. One keeps time, the other doesn't. What kind of witchcraft are they using now to back up the clock?

 

[n4txf]

OK, the mod should work for you. I'm in another boat. I have two radios...both with no battery on BT401. One keeps time, the other doesn't. What kind of witchcraft are they using now to back up the clock?

Hey, do me a favor. When you have your radio OPEN, take a good pic of the front and main PCB. I'm curious to contrast and compare any component differences between yours and mine.

 

[morrisr3nd]

I'll take that picture when I start doing the repair. If I remember to.