What's inside a Blob?

[Crystaleyes]

Is something I had often wondered.

After picking up a DMM with a fried selector circuit trace, I thought I'd have a look and find out.


And now you know too


Tell you one thing, it's some seriously tough shit.

[R_J]

Re: What's inside a Blob?

That is/was the microprocessor die that was under that blob

[Crystaleyes]

Re: What's inside a Blob?

Yeah.

I had just always wondering why it was hidden under a blob?

Judging by the toughness of the resin, I would say that is to ensure that no-one can ever do a repair

[stj]

Re: What's inside a Blob?

it's an ICL7106
a classic chip used in most old lcd meters.
there is also an ICL7107 for use with led displays.

[stj]

Re: What's inside a Blob?

Yeah.

I had just always wondering why it was hidden under a blob?

Judging by the toughness of the resin, I would say that is to ensure that no-one can ever do a repair

the chip is cheaper without it's package.

[Crystaleyes]

Re: What's inside a Blob?

it's an ICL7106
a classic chip used in most old lcd meters.
there is also an ICL7107 for use with led displays.

I see. That makes sense as I've seen them in more DMM's than I can remember, but that's interesting to know, as I had assumed it was where 'all the magic' happened.

Just out of interest, are these programmable? I mean, if they are a display controller, then how many display variaations are there for example?

I'd thought it would be really easy to scrape the blob away to see but it was feckin hard work!
Won't be doing it again in a hurry.

[eccerr0r]

Re: What's inside a Blob?

No they are not programmable, and likely the board was made to take the bare die plus encapsulation or a QFP hence the pads on the board...

The 7106/7107 are integrated LCD/LED controllers plus the ADC all in one monolithic chip.

BTW I've seen some other integrated LCD+ADCs so it may not be specifically a intersil 7106 or its clones, ... so be careful making assumptions.

[R_J]

Re: What's inside a Blob?

Some information for the O.P.
It is called Chip-on-Board, here is a link to how they are done: https://learn.sparkfun.com/tutorials...s-are-made/all

[stj]

Re: What's inside a Blob?

No they are not programmable, and likely the board was made to take the bare die plus encapsulation or a QFP hence the pads on the board...

The 7106/7107 are integrated LCD/LED controllers plus the ADC all in one monolithic chip.

BTW I've seen some other integrated LCD+ADCs so it may not be specifically a intersil 7106 or its clones, ... so be careful making assumptions.

it wasnt an asumption, i have the DT830 schematic

[redwire]

Re: What's inside a Blob?

Chip-on-board still has the packaged part's pinout. OP you could check the pinout verses TC7106C in 44-pin QFP or PLCC package, what ever fits.
https://www.instructables.com/Replac...With-a-44-Pin-
Or just toss it and get a new multimeter? These low dollar multimeters have minimal input protection and are easily fried.

[eccerr0r]

Re: What's inside a Blob?

in this case it is a 7106/7116/7136, but I have a DMM with a COB that's not one of these... it's some taiwan company I forget, and didn't look like an intersil clone.

[jiroy]

Re: What's inside a Blob?

Those blobs are useful for light weight devices , like Christmas trees lights or tiny multimeters etc .. Mostly can be replaced .

[Crystaleyes]

Re: What's inside a Blob?

Some information for the O.P.
It is called Chip-on-Board, here is a link to how they are done: https://learn.sparkfun.com/tutorials...s-are-made/all

Wow.. That is fascinating!

I never imagined that they had actual wires inside.


Nice one. Thank you for that

[Crystaleyes]

Re: What's inside a Blob?

Chip-on-board still has the packaged part's pinout. OP you could check the pinout verses TC7106C in 44-pin QFP or PLCC package, what ever fits.
https://www.instructables.com/Replac...With-a-44-Pin-
Or just toss it and get a new multimeter? These low dollar multimeters have minimal input protection and are easily fried.

It was bought for a quid from a street seller so not a problem. I've already striped down what might be reusabe in the future and the binned the board