Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #11   Report Post  
Old January 7th 21, 07:25 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jun 2020
Posts: 11
Default Finding the cmos battery

On Thu, 07 Jan 2021 14:26:06 +0000, Cursitor Doom
wrote:

On Wed, 6 Jan 2021 21:40:39 -0600 (CST), Chuck
wrote:

The .47 to 1F caps have been used for 30 years in stereo receivers.


I'm suitably amazed. Mind you I've never had much to do with them.

Come to think of it, a Denon tuner that I bought in 1988 has a super
capacitor for memory.

  #12   Report Post  
Old January 7th 21, 07:33 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Apr 2007
Posts: 411
Default Finding the cmos battery

On Wed, 06 Jan 2021 20:51:28 +0000, Cursitor Doom
wrote:

On Wed, 06 Jan 2021 13:44:19 -0600, Chuck
wrote:

On Wed, 06 Jan 2021 18:00:32 +0000, Cursitor Doom
wrote:

Hi all,

I have a Roberts Stream 105 internet radio which I bought about 9
years ago. It's been fine up until maybe 18 months ago when it could
no longer remember my preferred settings. I'm guessing it has a little
backup cell in there somewhere that's gone way past its sell-by date.
I've opened up the case and it must be very well hidden indeed. I
asked Roberts for info on where it is but they obfuscated and told me
to return it to them and they'd fix it for 40 quid! There are no
manuals for this model on line (not service manuals anyway) and I *do*
like to fix things for myself as a matter of course anyway. The inside
consists of only 3 boards apart from the display: an audio board (as
it describes itself) the wireless card (I deduce from the fact that
although it's fully screened it's got a MAC address label on it) and
controller board interfacing to the user controls.
The only place this battery could be hiding is within a screened
enclosure on the "audio board". Now, I should have done this sooner
obviously, but time shortages and whatnot, I've probed the underside
of the screened area and found a persistent 0.3V above ground on some
of the joints. Does that sound like the sort of voltage a backup cell
would fall back to after 9 years? This 0.3V is with all external power
removed and after shorting out any capacitances.

Look for a 1/2 to1 farad electrolytic capacitor. Probably near the
upc.


At that value it would be a supercapacitor I'd imagine. Were they
installing those in new equipment 10 years ago?


They were showing up as surplus 20 years ago.

RL
  #13   Report Post  
Old January 8th 21, 12:35 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jan 2019
Posts: 586
Default Finding the cmos battery

On Thu, 07 Jan 2021 13:33:31 -0500, legg wrote:

On Wed, 06 Jan 2021 20:51:28 +0000, Cursitor Doom
wrote:

On Wed, 06 Jan 2021 13:44:19 -0600, Chuck
wrote:

On Wed, 06 Jan 2021 18:00:32 +0000, Cursitor Doom
wrote:

Hi all,

I have a Roberts Stream 105 internet radio which I bought about 9
years ago. It's been fine up until maybe 18 months ago when it could
no longer remember my preferred settings. I'm guessing it has a little
backup cell in there somewhere that's gone way past its sell-by date.
I've opened up the case and it must be very well hidden indeed. I
asked Roberts for info on where it is but they obfuscated and told me
to return it to them and they'd fix it for 40 quid! There are no
manuals for this model on line (not service manuals anyway) and I *do*
like to fix things for myself as a matter of course anyway. The inside
consists of only 3 boards apart from the display: an audio board (as
it describes itself) the wireless card (I deduce from the fact that
although it's fully screened it's got a MAC address label on it) and
controller board interfacing to the user controls.
The only place this battery could be hiding is within a screened
enclosure on the "audio board". Now, I should have done this sooner
obviously, but time shortages and whatnot, I've probed the underside
of the screened area and found a persistent 0.3V above ground on some
of the joints. Does that sound like the sort of voltage a backup cell
would fall back to after 9 years? This 0.3V is with all external power
removed and after shorting out any capacitances.
Look for a 1/2 to1 farad electrolytic capacitor. Probably near the
upc.


At that value it would be a supercapacitor I'd imagine. Were they
installing those in new equipment 10 years ago?


They were showing up as surplus 20 years ago.

RL



Well I can't understand in that case why there are so few of them
listed on Ebay currently. I may have to imrovise here and go back to
my initial idea of using a lithium button cell in series with a diode
to prevent it being charged.

Anyone see any issues with that approach?
  #14   Report Post  
Old January 8th 21, 12:37 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jan 2019
Posts: 586
Default Finding the cmos battery

On Thu, 07 Jan 2021 12:25:54 -0600, Chuck
wrote:

On Thu, 07 Jan 2021 14:26:06 +0000, Cursitor Doom
wrote:

On Wed, 6 Jan 2021 21:40:39 -0600 (CST), Chuck
wrote:

The .47 to 1F caps have been used for 30 years in stereo receivers.


I'm suitably amazed. Mind you I've never had much to do with them.

Come to think of it, a Denon tuner that I bought in 1988 has a super
capacitor for memory.


Hmmm. I think clearly the older one gets, the harder it is keeping up
to date with new innovations if you're not fully immersed in the field
as a career (I'm not!)

  #15   Report Post  
Old January 8th 21, 12:51 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2020
Posts: 65
Default Finding the cmos battery

Anyone see any issues with that approach?

Yes. Purchasing anything of that nature from eBay is an issue. Given that a counterfeit - not unknown from that source - could destroy your unit.

Peter Wieck
Melrose Park, PA


  #16   Report Post  
Old January 8th 21, 06:44 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jun 2020
Posts: 11
Default Finding the cmos battery

On Thu, 07 Jan 2021 23:35:36 +0000, Cursitor Doom
wrote:

On Thu, 07 Jan 2021 13:33:31 -0500, legg wrote:

On Wed, 06 Jan 2021 20:51:28 +0000, Cursitor Doom
wrote:

On Wed, 06 Jan 2021 13:44:19 -0600, Chuck
wrote:

On Wed, 06 Jan 2021 18:00:32 +0000, Cursitor Doom
wrote:

Hi all,

I have a Roberts Stream 105 internet radio which I bought about 9
years ago. It's been fine up until maybe 18 months ago when it could
no longer remember my preferred settings. I'm guessing it has a little
backup cell in there somewhere that's gone way past its sell-by date.
I've opened up the case and it must be very well hidden indeed. I
asked Roberts for info on where it is but they obfuscated and told me
to return it to them and they'd fix it for 40 quid! There are no
manuals for this model on line (not service manuals anyway) and I *do*
like to fix things for myself as a matter of course anyway. The inside
consists of only 3 boards apart from the display: an audio board (as
it describes itself) the wireless card (I deduce from the fact that
although it's fully screened it's got a MAC address label on it) and
controller board interfacing to the user controls.
The only place this battery could be hiding is within a screened
enclosure on the "audio board". Now, I should have done this sooner
obviously, but time shortages and whatnot, I've probed the underside
of the screened area and found a persistent 0.3V above ground on some
of the joints. Does that sound like the sort of voltage a backup cell
would fall back to after 9 years? This 0.3V is with all external power
removed and after shorting out any capacitances.
Look for a 1/2 to1 farad electrolytic capacitor. Probably near the
upc.

At that value it would be a supercapacitor I'd imagine. Were they
installing those in new equipment 10 years ago?


They were showing up as surplus 20 years ago.

RL



Well I can't understand in that case why there are so few of them
listed on Ebay currently. I may have to imrovise here and go back to
my initial idea of using a lithium button cell in series with a diode
to prevent it being charged.

Anyone see any issues with that approach?

Here is one that is genuine and exactly like the ones I used to use as
a replacement.
https://www.newark.com/kemet/ft0h474...al/dp/78AC5690
  #17   Report Post  
Old January 8th 21, 06:55 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jan 2019
Posts: 586
Default Finding the cmos battery

On Fri, 08 Jan 2021 11:44:55 -0600, Chuck
wrote:

On Thu, 07 Jan 2021 23:35:36 +0000, Cursitor Doom
wrote:

On Thu, 07 Jan 2021 13:33:31 -0500, legg wrote:

On Wed, 06 Jan 2021 20:51:28 +0000, Cursitor Doom
wrote:

On Wed, 06 Jan 2021 13:44:19 -0600, Chuck
wrote:

On Wed, 06 Jan 2021 18:00:32 +0000, Cursitor Doom
wrote:

Hi all,

I have a Roberts Stream 105 internet radio which I bought about 9
years ago. It's been fine up until maybe 18 months ago when it could
no longer remember my preferred settings. I'm guessing it has a little
backup cell in there somewhere that's gone way past its sell-by date.
I've opened up the case and it must be very well hidden indeed. I
asked Roberts for info on where it is but they obfuscated and told me
to return it to them and they'd fix it for 40 quid! There are no
manuals for this model on line (not service manuals anyway) and I *do*
like to fix things for myself as a matter of course anyway. The inside
consists of only 3 boards apart from the display: an audio board (as
it describes itself) the wireless card (I deduce from the fact that
although it's fully screened it's got a MAC address label on it) and
controller board interfacing to the user controls.
The only place this battery could be hiding is within a screened
enclosure on the "audio board". Now, I should have done this sooner
obviously, but time shortages and whatnot, I've probed the underside
of the screened area and found a persistent 0.3V above ground on some
of the joints. Does that sound like the sort of voltage a backup cell
would fall back to after 9 years? This 0.3V is with all external power
removed and after shorting out any capacitances.
Look for a 1/2 to1 farad electrolytic capacitor. Probably near the
upc.

At that value it would be a supercapacitor I'd imagine. Were they
installing those in new equipment 10 years ago?

They were showing up as surplus 20 years ago.

RL



Well I can't understand in that case why there are so few of them
listed on Ebay currently. I may have to imrovise here and go back to
my initial idea of using a lithium button cell in series with a diode
to prevent it being charged.

Anyone see any issues with that approach?

Here is one that is genuine and exactly like the ones I used to use as
a replacement.
https://www.newark.com/kemet/ft0h474...al/dp/78AC5690



Thanks, but you guys have avoided answering the question about
replacing the supercap with a cell of whatever capacity in series with
a low reverse-leakage diode. Anyone know what the likely voltage that
cell would need to be?

NB: when I say "whatever capacity" I refer to A, AA, AAA, C, D etc.
cells.
  #18   Report Post  
Old January 8th 21, 07:52 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Oct 2020
Posts: 65
Default Finding the cmos battery

There is a somewhat detailed answer to that question.
a) Do you know what voltage is needed to keep the memory function in operation?
b) Given that a battery is the mother of all capacitors, just a bit slower as a chemical engine, you should be able to do a proof-of-concept.
c) And once you have determined the operating voltage (somewhere between 1.2 and 3.5 VDC at a guess), you will have several choices, including your diode option. BUT:

Caveat: Batteries do not like seeing a dead/partial short. So when diode you install is not in use and the circuit is OFF, the battery is in parallel with whatever device is in place, whether a super-cap or a button cell, or something else. If that is shorted, so is the battery. OOPS! It really does behoove you to find the OEM source and repair/replace it as designed. You do not want to wake up one morning and find that your installed battery has spilled its guts all over everything.

Remember the Revox B760 tuner? It had two AA cells under the fold-down door on top of the faceplate. Trust the Swiss to take the very simple brute-force approach.

Peter Wieck
Melrose Park, PA
  #19   Report Post  
Old January 8th 21, 08:23 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Jan 2019
Posts: 586
Default Finding the cmos battery

On Fri, 8 Jan 2021 10:52:24 -0800 (PST), "Peter W."
wrote:

There is a somewhat detailed answer to that question.
a) Do you know what voltage is needed to keep the memory function in operation?
b) Given that a battery is the mother of all capacitors, just a bit slower as a chemical engine, you should be able to do a proof-of-concept.
c) And once you have determined the operating voltage (somewhere between 1.2 and 3.5 VDC at a guess), you will have several choices, including your diode option. BUT:

Caveat: Batteries do not like seeing a dead/partial short. So when diode you install is not in use and the circuit is OFF, the battery is in parallel with whatever device is in place, whether a super-cap or a button cell, or something else. If that is shorted, so is the battery. OOPS! It really does behoove you to find the OEM source and repair/replace it as designed. You do not want to wake up one morning and find that your installed battery has spilled its guts all over everything.


I'm grateful for your observations. I would just point out that it was
never my intention to leave the original power source in situ! I'm not
quite *that* stupid!

Remember the Revox B760 tuner? It had two AA cells under the fold-down door on top of the faceplate. Trust the Swiss to take the very simple brute-force approach. ical


I don't know that item,I'm afraid. My experience of electronic repair
is typically 95% vintage boat anchor test equipment, generally at
*least* 25 years old minimum and more likely closer to 40+.

Thanks again.


Peter Wieck
Melrose Park, PA


  #20   Report Post  
Old January 8th 21, 10:54 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Aug 2020
Posts: 41
Default Finding the cmos battery

On Friday, January 8, 2021 at 12:55:24 PM UTC-5, Cursitor Doom wrote:
On Fri, 08 Jan 2021 11:44:55 -0600, Chuck
wrote:

On Thu, 07 Jan 2021 23:35:36 +0000, Cursitor Doom
wrote:

On Thu, 07 Jan 2021 13:33:31 -0500, legg wrote:

On Wed, 06 Jan 2021 20:51:28 +0000, Cursitor Doom
wrote:

On Wed, 06 Jan 2021 13:44:19 -0600, Chuck
wrote:

On Wed, 06 Jan 2021 18:00:32 +0000, Cursitor Doom
wrote:

Hi all,

I have a Roberts Stream 105 internet radio which I bought about 9
years ago. It's been fine up until maybe 18 months ago when it could
no longer remember my preferred settings. I'm guessing it has a little
backup cell in there somewhere that's gone way past its sell-by date.
I've opened up the case and it must be very well hidden indeed. I
asked Roberts for info on where it is but they obfuscated and told me
to return it to them and they'd fix it for 40 quid! There are no
manuals for this model on line (not service manuals anyway) and I *do*
like to fix things for myself as a matter of course anyway. The inside
consists of only 3 boards apart from the display: an audio board (as
it describes itself) the wireless card (I deduce from the fact that
although it's fully screened it's got a MAC address label on it) and
controller board interfacing to the user controls.
The only place this battery could be hiding is within a screened
enclosure on the "audio board". Now, I should have done this sooner
obviously, but time shortages and whatnot, I've probed the underside
of the screened area and found a persistent 0.3V above ground on some
of the joints. Does that sound like the sort of voltage a backup cell
would fall back to after 9 years? This 0.3V is with all external power
removed and after shorting out any capacitances.
Look for a 1/2 to1 farad electrolytic capacitor. Probably near the
upc.

At that value it would be a supercapacitor I'd imagine. Were they
installing those in new equipment 10 years ago?

They were showing up as surplus 20 years ago.

RL


Well I can't understand in that case why there are so few of them
listed on Ebay currently. I may have to imrovise here and go back to
my initial idea of using a lithium button cell in series with a diode
to prevent it being charged.

Anyone see any issues with that approach?

Here is one that is genuine and exactly like the ones I used to use as
a replacement.
https://www.newark.com/kemet/ft0h474...al/dp/78AC5690

Thanks, but you guys have avoided answering the question about
replacing the supercap with a cell of whatever capacity in series with
a low reverse-leakage diode. Anyone know what the likely voltage that
cell would need to be?


Generally speaking, I've found that supercaps used as memory devices are generally run *very* close to their voltage rating, so if your supercap is a 2.7V, there's a good chance there could be 2.5 volts on it. But, you don't need to make this complicated. Plug the radio in and see what the voltage is across the supercap. Most of the supercaps I've changed just go low value/high ESR and don't short. Whatever the voltage is under test, add that via cell. Since the value you need is unlikely (Murphy's Law) to be a direct value of a cell you want to add, you may have to add more than one diode to drop the voltage to or even a bit below the memory voltage.


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
HP Pavilion N3390 Laptop CMOS Battery Location [email protected] Electronics Repair 2 January 7th 13 10:36 PM
Cmos battery in Micron Transpoet Trek 2 mike[_12_] Electronics Repair 5 June 20th 09 12:44 PM
CMOS battery lasts only 6-9 months [email protected] Electronics Repair 11 May 4th 08 05:37 PM
Bad CMOS Battery -- Dell Optiplex System Crash? EdwardATeller Electronics Repair 4 December 24th 06 01:45 AM
help! laptop's CMOS battery is dying ziliath Electronics Repair 11 August 4th 04 03:15 AM


All times are GMT +1. The time now is 04:27 AM.

Powered by vBulletin® Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Copyright 2004-2021 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"

 

Copyright © 2017