What is the Mystery Opamp in this Vintage Equipment?

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Discussion Overview

The discussion revolves around identifying a mystery operational amplifier found in vintage equipment. Participants explore various hypotheses regarding the opamp's identity, its potential age, and the context of its use within the equipment. The conversation includes technical details about the component's markings and possible manufacturers, as well as inquiries into the equipment's schematics and circuit design.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that the opamp may have been "black topped" and re-labeled, noting discrepancies in the markings.
  • There is speculation about the age of the equipment, with guesses pointing to the late 1970s based on the component's characteristics.
  • One participant proposes that the partial trademark 'D' could be a clue to the manufacturer, while another suggests that the component might have a military prefix.
  • Some participants reference the possibility of cross-referencing the part with JEDEC equivalent lists or manufacturer-specific part numbers.
  • There is a discussion about the LM318 opamp, with some expressing skepticism about its suitability for the application in question.
  • Concerns are raised regarding the lack of a functional description or additional context about the PCB, which complicates identification.
  • Participants note the standard layout of tracks on the PCB, suggesting it aligns with typical op-amp supply lines.
  • One participant mentions the military part number system 'MIL-M-38510' and its relevance to identifying the component.
  • There is a humorous exchange about the challenges of gathering more information from the original poster, who is actively participating in the thread.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the identity of the opamp, with multiple competing views and hypotheses presented throughout the discussion. Uncertainty remains regarding the component's specifications and the context of its use.

Contextual Notes

Limitations include the absence of a functional description of the PCB and the lack of definitive markings or date codes that could aid in identification. The discussion is also hindered by the reliance on assumptions about the component's application and manufacturer.

JohnNNN
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Hi, pals! I'm in process of restoring vintage equipment. And I was failed to identify one of the operational amplifiers.
Does anyone have any idea what kind of animal this is? This is link to opamp photo: https://postimg.cc/HVZ2hjRm
 
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Welcome to PF, John. :smile:

That's a strange photo. Did you add the orange lettering to enhance the photo to make it more readable? If not, it looks like the component has been "black topped" and re-labeled (note how the pin-1 mark misregisters between the orange marking and the injection molded mark).

What year is this PCBA probably from? Paging @davenn and @Baluncore for their expertise...

Edit/Add -- what exactly is this piece of vintage equipment? Have you had any luck at all trying to find the schematics? I'm guessing probably not... Have you been able to trace most of the circuit to decide that this is an opamp? Have you tested the circuit powered-up (hopefully using an Isolation Transformer if it is AC Mains powered) and been able to measure the DC and AC voltages at this component's pins?
 
berkeman said:
Welcome to PF, John. :smile:

That's a strange photo. Did you add the orange lettering to enhance the photo to make it more readable? If not, it looks like the component has been "black topped" and re-labeled (note how the pin-1 mark misregisters between the orange marking and the injection molded mark).

What year is this PCBA probably from? Paging @davenn and @Baluncore for their expertise...
I just did a Google search and got this TI page:
https://www.ti.com/lit/ds/symlink/t...28778&ref_url=https%3A%2F%2Fwww.google.com%2F
 
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Wow, thanks Don. Sorry I paged the wrong @d____ !

I have trouble keeping meteroids and earthquakes and vintage equipment expertise straight in my tiny little brain! o0)
 
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berkeman said:
... my tiny little brain!
Now, I know that's wrong!
 
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My guess would be the late 1970s. The chip was poorly stamped.
I think the partial trademark 'D' with the internal dot, will be a big clue.
But I can't yet find my old list of (TM) symbols from the industry.

Maybe 00318 is a military manufacturer prefix, with product as -029.
As a second or third source, there may have been very few made.
Search in the JEDEC equivalent lists?
 
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Baluncore said:
My guess would be the late 1970s. The chip was poorly stamped.
I think the partial trademark 'D' with the internal dot, will be a big clue.
But I can't yet find my old list of (TM) symbols from the industry.

Maybe 00318 is a military manufacturer prefix, with product as -029.
As a second or third source, there may have been very few made.
Search in the JEDEC equivalent lists?
Yes. This is likely the correct approach.

Also, large equipment manufacturers will have their own part numbers assigned and have the suppliers label them as such. HP, for example, nearly always did this (although this one doesn't fit the HP format). If you can find a cross-reference list, maybe JEDEC (Mil parts) or from the OEM, you will likely find it is actually a common part.

Sorry, I don't recognize the manufacturer graphic on it. It's not one of the big US companies.

Who was the OEM for this PCBA?
 
  • #10
DaveE said:
Nope. We're looking for something in a DIP-8, this has way too many pins. It's likely too new also (2016).
Dang, You're right. Sorry about that. So the one @hutchphd posted in post #6 above is the right one?
https://www.ti.com/product/LM318-N
 
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  • #11
dlgoff said:
Dang, You're right. Sorry about that. So the one @hutchphd posted in post #6 above is the right one?
https://www.ti.com/product/LM318-N
Well, I wouldn't assume that. But if you put a gun to my head and no time to research, that would be my guess. I'd sketch out the circuit it's in first and try to guess the application/function. For example, is it one amp or two, etc. ?
 
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  • #12
A 318 is a fairly fast opamp. I have to wonder if there would be a good reason to have something that fast in the equipment that it is in.
 
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  • #13
Averagesupernova said:
A 318 is a fairly fast opamp. I have to wonder if there would be a good reason to have something that fast in the equipment that it is in.
The 318 would have had LM in front of it's number if it was the fast bipolar amp. LM stands for Linear Monolithic.

We still do not have a functional description or picture of that PCB. Without a date code from some other component we are out of clues.
Was it US Govt, British or a European design?
 
  • #14
Baluncore said:
The 318 would have had LM in front of it's number if it was the fast bipolar amp. LM stands for Linear Monolithic.

We still do not have a functional description or picture of that PCB. Without a date code from some other component we are out of clues.
Was it US Govt, British or a European design?
Do we even know it's an opamp...
 
  • #15
Averagesupernova said:
Do we even know it's an opamp...
The layout of tracks on the component side of the PCB are the standard op-amp supply lines. That was an optimal manual routing technique that held power on the component side, signals on the solder side, and used components or wire links to cross tracks.

There was a 5 digit military part number system known as 'MIL-M-38510' with a date sequential numbering system. Many of the early parts have 00xxx format numbers, but I found no reference to 00318 in the year 1977. M38510 was then used for linear chips by AMD, Fairchild, Intersil, NSC, Dignetics and TI.
The dotted 'D' icon that looks like an OR gate is not a TM for any of them, so there must be another manufacturer and military M38510 tester of those chips.
I would next look for a full part number "M38510/00318" and convert that through a mid-1970s list, from the military to a commercial part number.

It would be nice to have some information from outside that square inch.
 
  • #16
Baluncore said:
It would be nice to have some information from outside that square inch.
Given the high level of participation in this thread by the OP @JohnNNN that may be hard for us to get... :wink:
 
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  • #17
berkeman said:
Given the high level of participation in this thread by the OP @JohnNNN that may be hard for us to get... :wink:
You mean PF helps those who help themselves? I think I'm done.

PS: Wait, I'm not implying I think we're god.

prudent-george-w-bush.gif


But I have forsaken him.
 
Last edited:
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  • #18
Oh c'mon. Let's all have some fun and say we've got it completely figured out and when asked what it is just say: Sorry, not tell'n.
 
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