Help Identify Device

[Deleted member 133]

Folks,

The pics below are of the input terminals / fuse holder from a Koss CM/1030 speaker, and were sent to me by the owner of the speaker.

The first shows the outside of the panel, from left to right: fuse holder and positive and negative spring loaded connections.

The second show a device wired in series between the positive terminal and fuse holder.

The third shows a close-up of the device.

"The device" shows up nowhere on the Koss-original schematics that I have.

"The device" could not be the work of a single owner since, two out of three of the salvaged boards that I have in my possession have the device installed. I therefore conclude that it is original equipment. The speakers date from 1977-84.

"The device" has the following stamped on it: ESB714E1H. A Google search turns up nothing relevant.

So the question is: what is it?

My best guess is that it is an additional form of protection (in addition to the 3A fuse), and is either a thermistor or "light bulb".

Can anyone confirm, or offer another suggestion?

Jeff

 

[Deacon]

How do you keep getting these?

 

[mcad64]

It's a dohicky...for sure a dohicky...or maybe a thingy. I will check and get back to you!! :teasing-neener:

 

[The DirtMerchant]

I'm thinking a widget.

 

[Zing]

Dohicky? Thingy?? Widget??? You're both wrong. Quit speculating. If you don't know for certain, please don't opine. The man came here for help, not conjecture and humor.

Jeff, the technical term for the item in question is whatchamacallit.




























:teasing-tease:

I'm with Deacon. I don't know how you - and seemingly you alone - find these bizzare, obscure gizmos inside your electronics. Hopefully someone such as rammisframmis will be able to help you identify it.

 

[heeman]

Come on man, there are two many 2's in that device..............

I know what it is, but I am not telling....................

bscene-birdiedoublered: bscene-birdiedoublered: bscene-birdiedoublered:

 

[Deleted member 133]

How do you keep getting these?

I think the more important question is why!

I've posted my contact email on dozens and dozens of forums and boards offering to help any Koss CM speaker owners with any question they may have. I get several requests each month, from around the world, and it's a very rare case that I've not been able to provide the requested assistance, which has included shipping replacement parts, for free. (And while it's not why I do it, I now have offers of free accommodation should I ever wish to visit quite a few world-class cities on different continents.)

It's really neat to hear back from folks after they've restored / refurbished a pair to like-new condition and how much they like listening to them.

At some point in the next year or so I intend to build a whole new section onto jeffmackwood.com dedicated to the Koss CM speakers, including technical info, reviews, brochures, sources for parts and refurbishing, and dozens of representative Q&As that I have handled over the years.

As to this specific request: I'm truly surprised that this device, whatever it is, has escaped my attention up until now. Mind you, you should see what a typical Koss CM/1030 crossover board / wiring looks like. Actually I'll go take some photos of an old salvaged one that I pulled out of a "junker" and post it below (it's missing a few bits and pieces, but you should get the drift).

Jeff

ps. to Mike, Dirt, Zing and Heeman: :text-thankyoublue:

 

[Deleted member 133]

Ok, given all the great suggestions you savants put forward, I was left with but one course of action: take it to an expert.

So this afternoon I dropped in at SpeakerMart - the place that has refurbished all of my Koss speakers over the years.

Bill confirmed what I had suspected - sort of.

The device is an additional form of protection and behaves like a thermistor - even though it's not. It's intended to protect against steady high current (likely in the lower frequencies). So instead of having a fuse that would fail way too often, this device rides along and slowly increases in resistance as it heats up due to steady high current. It sets a limited on the amount of current that can pass through. As the high current level is reduced it cools and its resistance drops down again. So the fuse protects against sudden high overloads and this device against continuous high current levels.

In practice it should never need replacing - except in the case of the guy who contacted me because he had pulled out his fuse holder and tore the lead out of the body of the device.

If anyone has the actual name of the device I'd love to know it. Even Bill had none for it.

Jeff

 

[Towen7]

Wasn't there a similar mystery component you asked about in the not-too-distant past?

 

[MakeMineVinyl]

Looks like a bi-metal thermistor (circuit breaker) to me. The function is as you described. I believe regular household circuit breakers use the same technology.

 

[Deleted member 133]

Looks like a bi-metal thermistor (circuit breaker) to me. The function is as you described. I believe regular household circuit breakers use the same technology.

Much thanks!

 

[Deleted member 133]

Wasn't there a similar mystery component you asked about in the not-too-distant past?

Yes. See a few threads down the list. That one involved the improper labeling on a wiring diagram for the CM/1020 - slightly smaller sibling to the CM/1030.

Jeff