HP-1: HP1 - Real Time Clock battery

[centauri61032]

Hey all!
Has anyone ever replaced the RTC battery in their HP-1?
My HP asks for a time set every time I turn it on. I opened it up, and found the RTC battery. And it shows signs of corrosion, so I think it's time to change it out.
Uniden does spot-weld this battery into place. But it was easy to remove by grabbing with some needle nose pliers and giving it a turn.
However... I am at a loss for finding a suitable replacement.
The original battery measures (approx) 6.77mm in diameter, and 1.51mm tall.
There are markings on the battery that say 'ELNA 3.3v, 0.2 E JP'
I can't find anything like this online anywhere. I don't know if it is rechargeable, or just a plain lithium.
The closest thing I have found is a CR1025. It is noticeably larger overall, but probably would fit. But the voltage isn't correct either.
Any ideas??
Thanks!

 

[FedFyrGuy]

Digikey may be able to cross reference it for you:

https://media.digikey.com/pdf/Data%20Sheets/Seiko%20Instruments%20PDFs/MS_Series.pdf

Otherwise, Uniden Service charges about $90 to do the repair. Others might have a more precise answer.

 

[RFI-EMI-GUY]

I think that is a super capacitor not a battery. You don't want to put a battery in there or it will burst.

https://www.trustedparts.com/en/part/elna-america/DSK-3R3H204T614-H2L

 

[centauri61032]

Yeah, thanks much! Using that chart, it looks like the MS614 is the best option, at least from the physical characteristics.
Now if someone could only confirm if it is supposed to be rechargeable?
Thanks again!

 

[AJAT]

RFI guy is correct. It is a super capacitor. I got some from mouser to replace mine.

https://www.mouser.com/ProductDetail/elna/dsk-3r3h224u-hl/?qs=QQsyD2Kvh2ftLwsh6FwcaA%3D%3D&countrycode=US&currencycode=USD

after replacing it you need to let it charge for a long time. Really long. Be careful I broke the ribbon cable holder after opening it up a few times.

 

[RFI-EMI-GUY]

It is a capacitor, so yes it recharges when turned on. You could put a larger value in and get some added memory time, but fitting it may be problematic. It sounds like a high value slow charge resister is in series with power.

 

[centauri61032]

RFI guy is correct. It is a super capacitor. I got some from mouser to replace mine.

https://www.mouser.com/ProductDetail/elna/dsk-3r3h224u-hl/?qs=QQsyD2Kvh2ftLwsh6FwcaA%3D%3D&countrycode=US&currencycode=USD

after replacing it you need to let it charge for a long time. Really long. Be careful I broke the ribbon cable holder after opening it up a few times.

OK, great! Thanks much for the info!
The supercap makes sense. I just wasn't sure, since it had 'BT401' on the PCB. That kind of suggested the component was a battery. But Elna is known for making caps.

Thanks again!

 

[AJAT]

The below thread is for the 536, but it was suggested it needed about 50 hours of charge time. I don’t know if it has the same cap as the HP1. I did not let mine charge that long and it did not last long at all. I kept opening up thinking I did something wrong soldering it in until I eventually broke it. I wish I just let it charge longer, but it worked out, I replaced it with the 436.

BCD436HP/BCD536HP: - Charge complete - really?

The Uniden website says that the unit requires a 50-hour initial charge cycle so that the clock function will work properly. After charging my new unit for about 12 hours, the display says, "Charge Complete". I presume this refers to the main batteries. Evidently charging stops when this...

forums.radioreference.com

 

[n1chu]

The capacitor provides power to the clock when the scanner is off. What other functions does the capacitor provide power to while the scanner is off? It’s an HP1, and sending it in for a new cap doesn’t seem to be worth it… not when the fee for repair can go a long way towards the purchase of a newer version (HP2) or another model. If the cap only retains memory of the clock, and you can tolerate the needed resetting notice every time you turn the scanner on, use your watch instead (and look for someone to come up with a firmware mod that ignores the need to reset the clock each time the scanner comes on). The work-around could be to leave the scanner on, connected to external power, with the volume turned down instead of turning it off.

In certain cases such as this one, I’m a bit old school. I ask myself “Did I even considered a need of a clock on a scanner when I bought it?” My answer is no, I’ve never considered if the inclusion of a clock was a deal breaker when buying a scanner. So why should I care when the cap died? (Yes, I’d be concerned if the scanner came with a clock when it was new and it died, but that’s what new equipment warranty’s are for!)

 

[phask]

The capacitor provides power to the clock when the scanner is off. What other functions does the capacitor provide power to while the scanner is off? It’s an HP1, and sending it in for a new cap doesn’t seem to be worth it… not when the fee for repair can go a long way towards the purchase of a newer version (HP2) or another model. If the cap only retains memory of the clock, and you can tolerate the needed resetting notice every time you turn the scanner on, use your watch instead (and look for someone to come up with a firmware mod that ignores the need to reset the clock each time the scanner comes on). The work-around could be to leave the scanner on, connected to external power, with the volume turned down instead of turning it off.

In certain cases such as this one, I’m a bit old school. I ask myself “Did I even considered a need of a clock on a scanner when I bought it?” My answer is no, I’ve never considered if the inclusion of a clock was a deal breaker when buying a scanner. So why should I care when the cap died? (Yes, I’d be concerned if the scanner came with a clock when it was new and it died, but that’s what new equipment warranty’s are for!)

The main reason for the clock is for timestamps on audio recordings, some of the advanced features also have timestamps.

 

[centauri61032]

The capacitor provides power to the clock when the scanner is off. What other functions does the capacitor provide power to while the scanner is off? It’s an HP1, and sending it in for a new cap doesn’t seem to be worth it… not when the fee for repair can go a long way towards the purchase of a newer version (HP2) or another model. If the cap only retains memory of the clock, and you can tolerate the needed resetting notice every time you turn the scanner on, use your watch instead (and look for someone to come up with a firmware mod that ignores the need to reset the clock each time the scanner comes on). The work-around could be to leave the scanner on, connected to external power, with the volume turned down instead of turning it off.

In certain cases such as this one, I’m a bit old school. I ask myself “Did I even considered a need of a clock on a scanner when I bought it?” My answer is no, I’ve never considered if the inclusion of a clock was a deal breaker when buying a scanner. So why should I care when the cap died? (Yes, I’d be concerned if the scanner came with a clock when it was new and it died, but that’s what new equipment warranty’s are for!)

Yeah, understood, and agreed for the most part.
My HP-1 is in a car, so leaving it on 24/7 isn't really a good option.
And the clock is pretty much worthless to me. I don't do recordings, which is the only thing I believe it is used for. If the scanner allowed me to just skip the clock setting step, I wouldn't mind it as much. But it does force you to go through the full setting, which is plain annoying.
The extra annoying part is that I have a GPS attached to this scanner. And Uniden apparently ignores the GPS clock, when it is available. Otherwise, it would be 'self setting', and I wouldn't have any issue.
As far as the cost, yeah having Uniden repair it would be kind of silly. But I have eBay, and a soldering iron. And my cap is already in the mail.

 

[RFI-EMI-GUY]

The super cap claims an "endurance" of 1000 hours. I assume this to be its self discharge rate if fully charged. So if the scanner is used infrequently it could be depleted in about 40 days or less. If your old cap had corrosion, the self discharge rate would be much higher and affected by humidity. When you get it installed, leave it on for several days to make sure the cap is charged.

 

[centauri61032]

The super cap claims an "endurance" of 1000 hours. I assume this to be its self discharge rate if fully charged. So if the scanner is used infrequently it could be depleted in about 40 days or less. If your old cap had corrosion, the self discharge rate would be much higher and affected by humidity. When you get it installed, leave it on for several days to make sure the cap is charged.

Yeah, thanks.
I do wonder, though... Does the cap charge when power is applied? Or only when the scanner is actually turned on?
I guess I'll have to leave it on for a few days once I get it installed, jut to be sure. But it would be nice to know these little details.
Uniden has pretty good products. But pretty lousy documentation and support. Been that way going back to the 70's.

 

[RFI-EMI-GUY]

Yeah, thanks.
I do wonder, though... Does the cap charge when power is applied? Or only when the scanner is actually turned on?
I guess I'll have to leave it on for a few days once I get it installed, jut to be sure. But it would be nice to know these little details.
Uniden has pretty good products. But pretty lousy documentation and support. Been that way going back to the 70's.

It pretty much depends on how the circuit is designed. A schematic would be needed.

I have some older equipment, a Pioneer 300 disc CD changer with earlier generation super cap that will only last a few days of no power when turned off. It has a standby mode I have to leave it in and that is backed by a UPS. The real fix would be to install an actual battery.

I doubt your HP1 has room for a decent battery and in running the clock you will be changing it annually.

 

[kruser]

I just opened my HP-1 and the supposed Super Cap at location marked BT-1 charges in all operating modes of the HP-1.
So... as long as the AC power adapter is plugged in, the BT-1 device sees charge voltage in mine even if I never select Yes for the charge icon on the touch screen. Or if I select No at the charge prompt regardless if the HP-1 is on or off, BT-1 gets charge voltage at all times the external wall wart is plugged into the radio.

It's odd that it's marked as "BT" when all the caps are properly marked with the letter C prefixing their number.
Either there was a design change and a battery was replaced with a small super cap or it really is a small rechargeable Lithium cell like the early model 536HPs had in them which always failed and caused the RTC recall. Those 536HP Lithium cells were replaced with a super cap but it's significantly larger than the thing marked BT-1 in the HP-1. In fact, the BT-1 item is the same size as the 536HP's rechargeable Lithium cell was before they replaced the entire front board with a super cap and proper LED's for the dimming problem.
I measured mine and it only showed just over 1 volt before I plugged it in for the charge test. When plugged in, it was slowly approaching 3.15 VDC but I didn't wait to see where it would stop charging.
Even with just 1 VDC on BT-1, my RTC was still holding time in my HP-1. I sometimes leave it unplugged for weeks on end and have never had to set the clock. I do check the clock now and then just to see how much it drifts but that's it.
I'm not going to unsolder BT-1 from the board and look for any part numbers but I may be doing that soon being as it only had 1 VDC showing on my DVM.
I had just had my HP-1 plugged in to power for about a week within the past two days or so. I think that's a sign my BT-1 may be failing regardless it it's a super cap or a tiny rechargeable lithium cell.

I also wonder what the two large Elna brand super caps are for that are mounted right next to each other laying flat on the PCB.
I lifted one and they are rated at 2.5 VDC 1 Farad (not microFarad!) so they are also a super caps. They are Elna Dynacap DZN series wired in series so each sees about 1.65 VDC across it and of course 3.3 VDC across the pair.
Possibly something to hold a setting through a AA cell battery change perhaps. These large super caps measure 0.320 inches in diameter and 0.915 inches in length. They are mounted to the PCB via thru holes on one end and then they folded them down to lay flat on the PCB and affixed them with some type of glue to hold them in place. They are located very close to BT-1.

I know Elna makes caps but I do wonder now if BT-1 is a tiny rechargeable Lithium cell like the early design 536HP's used or if it really is a small super cap.
I swear I can remember Paul (UPMan) saying the HP-1 did use a lithium cell for its RTC backup. I also seem to recall some HP-1 owners having similar RTC battery failures in their HP-1s but there was never much said about that.
My HP-1 is an early model bought not long after they became available and it's never been back for any service so it should be the original design.

 

[JoeBearcat]

Original design might have been a battery (BT) but a change before production may have changed it to the capacitor.

 

[centauri61032]

Well, FWIW I have confirmed that the component in my HP-1 definitely is a supercap. The replacement that I ordered has the exact same markings as my original. And to my knowledge, Elna has never made batteries.
But you do see my initial confusion. I also assumed it was a lithium, based on the PCB markings. And also because of the way mine was leaking like a typical worn out button battery sometime does.
I wouldn't be surprised if the original plan was to use a battery instead of a cap. It also seems strange that the other two caps that you mentioned don't maintain the clock, as well as whatever function they already do. Why have two separate retention systems?
It would be fun to get hold of a full schematic.

 

[kruser]

Original design might have been a battery (BT) but a change before production may have changed it to the capacitor.

That's my thoughts as well.

I definitely remember Paul saying something about the HP-1s RTC circuit and a design change to a super cap could very well be what he'd said way back then!

 

[kruser]

But you do see my initial confusion. I also assumed it was a lithium, based on the PCB markings. And also because of the way mine was leaking like a typical worn out button battery sometime does.
I wouldn't be surprised if the original plan was to use a battery instead of a cap. It also seems strange that the other two caps that you mentioned don't maintain the clock, as well as whatever function they already do. Why have two separate retention systems?
It would be fun to get hold of a full schematic.

Yep, I noticed corrosion on my BT-401 device as well between the inner round negative plate and the outer positive ring. Exactly like you found.
It seems the RTC circuit must maintain time down to a pretty low voltage as mine was just barely above 1.0 VDC when I opened it up tonight! And it was still holding the time just fine.

I have seen super caps fail like this with the corrosion and all in my weather station. They start leaking just like an old coin cell sometimes does so being a tiny super cap is the deal then.
Like JB said above, probably a design change just before initial production.

 

[RFI-EMI-GUY]

Not sure these are exact replacements, but the picture should help.
Elna SMD capacitor DSK-3R3H204T614-H2L 3.3V 0.2F 6.8*1.4mm farad capacitor

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