Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Something definitely wrong there. Fully charged is around 1.4V. Are there two in series? Possible one has gone short

Nope, just the one cell, a AA sized with solder tabs, like this one https://www.ebay.co.uk/itm/Toothbrush-Replacement-Battery-for-Braun-Oral-B-42mm-x-17mm-Ni-MH-Rechargeable/254489273293

4.2V charge voltage no load...? Sounds like you have a 14500 LiIon cell like I use in my EDC flashlights.

mnem
 

It is a Ni-MH, here is the photo of the removed battery.

[tautech]

It is a Ni-MH, here is the photo of the removed battery.

Last resort before it goes in the bin is zapping it with 30V from a PSU.
Sometimes it wakes them up, other times not. 

[Specmaster]

Oh, it seems to be charging OK, just not powering the toothbrush unless it has come of being charged. Leave it alone for 20 mins and it refuses to run the brush. Pop it back on the charger for a few seconds or so and runs OK.

[tautech]

Oh, it seems to be charging OK, just not powering the toothbrush unless it has come of being charged. Leave it alone for 20 mins and it refuses to run the brush. Pop it back on the charger for a few seconds or so and runs OK.

Yeah get that but a zap at higher current than its charger can provide can sometimes reverse the ageing degradation. Never liked leaving such devices on charging stands and rather draw them lower for deeper charging cycles primarily to extend battery life.
Ymmv.

[bd139]

May be browning out i.e. cell has gone high impedance. Stick 10 ohms or so across it and measure the voltage then.

[Specmaster]

Yeh, I did that as well, 1.34V down to 1.24V with 10 ohms across it and holds that voltage for a long time and the battery gets very toasty. Remove the load and the voltage creeps up again, as expected. After 10 mins with the 10 ohm load, voltage drops to 1.22V, and after disconnecting the load it is now upto 1.28V and climbing.

[bd139]

Sounds ok. BMS controller probably knackered. Got a similar thing here with a camera slave flash thing someone gave me to look at.

[mnementh]

It depends on the exact model, but most of the rechargeable toothbrushes with Nimh (or NiCad in the older ones) cells used the the poor coupling (leakage inductance) between the base and brush to limit the charging current. The cell limits the voltage. Sounds like the cell has gone high impedance. Personally I'd jut go buy a new one. The motor gears and bearings are probably well worn by now.

Given that the battery is indeed a NiMH (weird that the unloaded voltage is exactly 4.2V, but hey... that's Murphy for ya) I'd say that the BMS circuit is either preprogrammed with a given number of cycles or it is detecting a high internal impedance and going into shutdown as you suggest.

Seems to me the simple solution is to replace the cell with a known healthy one and see if it can complete a normal charge-discharge cycle.

mnem
 

[mnementh]

Urrrk. I just plopped down ~CAD$600 and have begun on a 3-6 day project doing something I swore I'd never do again: building a steel storage shed kit. 

Who wants to take bets on whether having the help of my 12-yr-old son makes it an adventure or something akin to a week of root canal? 

mnem
*toddles off to ded*

[Neomys Sapiens]

Urrrk. I just plopped down ~CAD$600 and have begun on a 3-6 day project doing something I swore I'd never do again: building a steel storage shed kit. 

Who wants to take bets on whether having the help of my 12-yr-old son makes it an adventure or something akin to a week of root canal? 

mnem
*toddles off to ded*

Root canal. Definitely. With tool losses amounting up to the half of the mentioned sum.

[med6753]

Urrrk. I just plopped down ~CAD$600 and have begun on a 3-6 day project doing something I swore I'd never do again: building a steel storage shed kit. 

Who wants to take bets on whether having the help of my 12-yr-old son makes it an adventure or something akin to a week of root canal? 

mnem
*toddles off to ded*

Yikes, have fun. The steel sheds are a freakin nightmare. Been there. But I did assemble a plastic one for a friend and that wasn't too bad. Was more like getting a cavity filled rather than a root canal. 

[bd139]

Yeah they’re a PITA. Got one myself. Got it after someone got into the wood one and nicked the mower 

[capt bullshot]

So I found this amplifier alike box at some other departments scrap box, free for take away:
**snip**

Dude, if you're so desperate for stuff to tinker with, I got **stuff** for you...

What kind of stuff 

Prrff.. in essence, pick your poisson. Pick a category and I have something that needs repair. But... what about a Datron 1071? I actually have a series of these that seem to work fine but all throw selftest errors. They all have depleted batteries in common but simply replacing them does not work. So, my working theory is that it needs at least halfway right correction parameters to pass selftests. And that's how far I got.

Try calibrating them more than once.  What you describe sounds familiar, I have a 1061A that lost its calibration and needed two or three calibration iterations to final success.
These things can have quite interesting and subtle faults:
http://wunderkis.de/datron1061a/index.html
https://amplifier.cd/Test_Equipment/other/Datron1061/Datron_1061.html

So if you can't get any further with them, I should be able to help you. As I've already got two 1061, you'd most probably get them back.
I've got no dedicated wish list, It's more a "I see it, repair it and I like it" process. Some stuff that I don't have yet: an SMU, a general purpose SA with 9k to maybe 2G range and narrow RBW, something like a HP53310A ...

Think I aborted at the 1000V cal stage as I have no decent source for that. Only later I figured out that I could use the photomultiplier PSU for it. Eh, maybe I'll find the time..

How about a Keithley 238? I think I have one in parts, with most parts OK except for the output bridge. I semi-repaired it but, well, time.

That's the kind of box that I've always wanted to get my hands on

[BravoV]

Something definitely wrong there. Fully charged is around 1.4V. Are there two in series? Possible one has gone short

Nope, just the one cell, a AA sized with solder tabs, like this one https://www.ebay.co.uk/itm/Toothbrush-Replacement-Battery-for-Braun-Oral-B-42mm-x-17mm-Ni-MH-Rechargeable/254489273293

4.2V charge voltage no load...? Sounds like you have a 14500 LiIon cell like I use in my EDC flashlights.

mnem
 

That's definitely a plausible explanation. Does it mention the cell chemistry on the thing?

Yep, when 4.2V when no load, clearly its LiIon, as coincidentally just bought two flashlights AA and AAA sized recently (attached below), and also two 14500 LiIon Sanyo/Panasonic batteries, size wise they are identical to AA.

Photo shot with Eneloops AA & AAA for references.

[Robert763]

Yep, when 4.2V when no load, clearly its LiIon, as coincidentally just bought two flashlights AA and AAA sized recently (attached below), and also two 14500 LiIon Sanyo/Panasonic batteries, size wise they are identical to AA.

Photo shot with Eneloops AA & AAA for references.


[/quote]

No it's not.
If you look at post #68777 you will see an image of the cell
It is marked Ni-MH TWICE

[PA0PBZ]

No it's not.
If you look at post #68777 you will see an image of the cell
It is marked Ni-MH TWICE

I have exactly the same cell, rescued from a toothbrush, and it measures 1.2V

[BravoV]

No it's not.
If you look at post #68777 you will see an image of the cell
It is marked Ni-MH TWICE

Ops, missed that late post.

[Specmaster]

Quick update on the toothbrush (I didn't think it would provoke so much discussion), it is the battery and it is 1.2V Ni-MH. This morning I set up a test with a new AA alkaline cell (1.6V) and it would not start, pop it back onto the charger base for a moment (yes I know, not supposed to charge alkaline batteries  ) and if you press the power button just as you remove the brush from its base it kicks into life (extra power boost).

Once the brush has been activated, it will start each and every time you press the button, regardless almost of the battery voltage it will restart, even with the voltage dropped to as low as .9V. Therefore, it seems to have a reset system once the battery gets so low that won't restart and giving it a pulse from the charger resets it?

New battery will be ordered now and see how that goes.

[Robert763]

Update on th HP 5335A. The shipping cost was only £8 so I sent the seller a nice message asking them to make sure it was well packed. I got a prompt response saying it would be. The seller seems to mostly be car boot type stuff, not much technical but they have good feedback.
Yesterday I got a message saying it had been shipped but they had forgotten to put the power lead in and would send it Monday. I told them to keep it as I have plenty.
Lets hope their packing is as good as the rest of their customer service.
 

[mnementh]

Meanwhile, at Specmaster's house... 

mnem
"...And hire a decorator to come in here quick cuz... Dayumm!"

[bd139]

Curve tracer project progress (this one might stick). All the switching is worked out for all device classes and I have worked out how to produce voltage and current steps out of the step amp. Now looking at power limiting for the collector supply.  This /should/ be nearly as capable as a 576 or CT71 when complete.

I may do a PCB and stuff if it carries on working out.

[Cerebus]

Quick update on the toothbrush (I didn't think it would provoke so much discussion),...

It's Sunday, people are bored... 

I've just put my soldering iron away without re-tinning the tip. Ooh the excitement, ain't I a Webel!

[bd139]

I clean mine before I put it away like my mother told me to.

[Saskia]

did some long walk today including about 4 km through sand. Tired as hell.

[Cerebus]

I clean mine before I put it away like my mother told me to.

Normally on a Sunday I'd have done that, but I'm feeling a bit off today so decided to do some soldering instead.