wtf is this weird component? solved, thermistor.

[coppercone2]

I am trying to fix something (DSA) and it has this inside of it. I cannot recognize it.

It does not look like a battery that I know of

I cannot find the designator for it, the batteries are BT. this does not seem to have a BT nearby

Looks a little like a coin cell but not really.

[Alex Eisenhut]

A tortured piezo buzzer maybe?

[coppercone2]

hmm. it reminds me of a MOV for some reason but its position makes no sense

[coppercone2]

the in circuit resistance is 8 ohms.

so that does sound like an audio thing ?

why is it trashed, the rest of the circuit is pristine, save for some crusty dip sockets

[T3sl4co1l]

What's it wired to, AC power maybe?  Could be an NTC.  8 ohms might be healthy.  See if it drops when heated.

Haven't seen an uncoated one since... vintage TV sets maybe, I think?  Or maybe that all burned off somehow, yeech.

Tim

[I wanted a rude username]

Silver-plated copper sometimes corrodes weirdly, and without needing an electrolyte ... may be triggered by sulfur outgassing from plastics.

[coppercone2]

it only has DC power input from a regulated supply

the power draw is ~400mA to a linear regulator. I will try to trace the circuit before heating it

[t0m]

VL2020 maybe

[coppercone2]

no, it does not have the typical coin cell profile I don't think, and it reads real close to 8ohms, not a coincidence I think.

It looks nothing like the picture of a VL2020

The outline for it looks like a rectangle also, it does not match the pcb silk screen (it is small in comparison, so its overloading the artwork). It looks like 2 things set in a ring, not like a crimped coin cell, the outer radius is very geometrically nice, looks like it was taken out of a mold or something. The other cell in this thing is a renesas fully encapsulated one in a orange plastic box with a bunch of epoxy, it makes no sense that the designers would go crazy for 1 coin cell but not the other one in terms of safety/reliability (the other one is swiss made!). And it already has a 3Vaa battery and a coin cell, i don't think it would have 2 coin cells. 3 batteries on 1 pcb?? It is also across the entire PCB from the voltage input.

the dimensions are 3.5mm by 16 mm measured with a machinists rule

[coppercone2]

I decided to pull it off the PCB double sided tape because it looks like a huge piece of shit anyway, the designation underneath is TH1. The batteries are designated BTx

So thermistor 1 makes sense? This unit was powered by NICAD batteries.

[coppercone2]

i put a little bit of solder on top, it dropped to 7 ohms, so it is maybe a NTC

any ideas on a part number? Do you think this thing is fine?

The problem I am troubleshooting is intermittent turn off, I thought it was crashing because both batteries are totally dead, so I thought to replace those first.

Not sure what a peizo buzzer does when measured, but I thought they would be high impedance, so if its 8 ohms, with a 10% chance in resistance from a little bit of heat, it is the main contributing circuit element to the low resistance  in the circuit I think. I am a little scared of desoldering it because of how it looks. It fits the description of a RTC device without a coating.

I guess it used to look nice and something took it out. When I replace the batteries I will measure it with the device turned on to see if its contributing


It powers off after it is turned on for a little bit, I am not exactly it is correlated to on time , but when it turns off, you do need to wait a little bit before it can turn back on, but I thought it was something to do with a dead battery and charge draining or whatever. The amount of time it has before it turns off is a little random.