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Old 16th May 2024, 11:29 pm   #1
Julesomega
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Default SN76131N datasheet

Looking for some data on this dual audio preamp device. Nearest that Google search gets is a page on Radiomuseum.org which shows a photo of one and a schematic which equates them with µA739 and TBA231 which might be functionally the same but the pinout is different so this doesn't help me with my repair. Mine were mfd. from 1973–5.
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Old 17th May 2024, 12:24 am   #2
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Default Re: SN76131N datasheet

The datasheet for the TBA231 from https://cdn-reichelt.de/documents/da...TBA231_STM.pdf shows it is equivalent to the µA739 but that doesn't get me any closer to the TI device. A full datasheet is available from https://datasheetspdf.com/pdf-down/T/B/A/TBA231-ETC.pdf
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Old 17th May 2024, 3:58 am   #3
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Default Re: SN76131N datasheet

https://www.alldatasheet.com/view_da...hword=SN76131N
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Old 17th May 2024, 5:02 am   #4
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Default Re: SN76131N datasheet

By "the pinout is different", do you mean the offset spacing of the pins or the actual pin function?

Used to come across the offset pins often at one stage - just "re-adjusted" the legs of standard DIL devices to fit.
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Old 17th May 2024, 7:57 am   #5
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Default Re: SN76131N datasheet

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Originally Posted by FrankB View Post
The link says "no match", and offers a list of unrelated devices.

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Old 17th May 2024, 8:43 am   #6
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Default Re: SN76131N datasheet

The pin functions of the SN76131N are different from the 'equivalents'.
I am also puzzled that the pins are staggered in my examples, despite having the package suffix 'N', I would have expected a different suffix. I am now wondering if the pins were bent before insertion, probably using the spacing device shown in the upper device in my picture.
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Old 17th May 2024, 9:14 am   #7
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Default Re: SN76131N datasheet

"QIL" or quad inline pin, as opposed to DIL.

Presumably easier people with fat soldering irons to deal with

Your RM link leads to their page for the Uher CG361 which has a circuit diagram attached. Might this be of slight help?
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Old 17th May 2024, 9:52 am   #8
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Default Re: SN76131N datasheet

There's also a broken link on the RM page but I didn't see any more on the pinouts. Just looking now at the Goodmans 120 I am repairing and I see that it's a socket, not a spacer. RM doesn't have anything on the 120, and there is only one mention of the model on here. It's not worth the cost and delay of ordering a replacement from eBay so I aim to replace it with a more recent device, mounted dead bug style.
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Old 17th May 2024, 10:17 am   #9
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Default Re: SN76131N datasheet

It's said (online!) that the 120 was barely more than a cosmetic rework of the 110.

The 110 used the µA739 mentioned upthread, also in a QUIL package, see snippet attached.

Any help?
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Old 17th May 2024, 10:25 am   #10
Ted Kendall
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Default Re: SN76131N datasheet

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It's said (online!) that the 120 was barely more than a cosmetic rework of the 110.
That is certainly how it was perceived at the time.
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Old 17th May 2024, 11:43 am   #11
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Default Re: SN76131N datasheet

Quote:
Originally Posted by Ted Kendall View Post
Quote:
Originally Posted by Nickthedentist View Post
It's said (online!) that the 120 was barely more than a cosmetic rework of the 110.
That is certainly how it was perceived at the time.
Indeed! The only difference was the change from µA739 to SN76131N, along with the renumbering of all devices throughout the main amplifier stages

But not to worry, since tracing which pin is the output from the pre-amp I find that the channel levels are unbalanced but present, so I'm now looking for the fault in the main amplifier.
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Old 17th May 2024, 7:50 pm   #12
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Default Re: SN76131N datasheet

Julian, there was an article featuring the SN76131, "Disc Preamp", in the April 1975 issue of Elektor magazine. Elektor downloads used to be available on WRH website but no longer are. I have a copy that I can scan if required.

Incidentally, I think the same article was available from Elektuur, the Dutch version of Elektor in the December 1974 issue. I found this article (attached) from the circuitsonline.net site.

Regards,
Symon
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Old 17th May 2024, 8:08 pm   #13
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Default Re: SN76131N datasheet

Quote:
Originally Posted by Nickthedentist View Post
It's said (online!) that the 120 was barely more than a cosmetic rework of the 110.

The 110 used the µA739 mentioned upthread, also in a QUIL package, see snippet attached.

Any help?
At least some of the 1-10s were factory fitted with the SN76131.
If you look at my scribbles on that service manual, you'll see that I noted that IC2 was a SN76131.
(I replaced it because it suffered from popcorn noise on one channel.)

Jim

ps The original post is here

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Old 23rd May 2024, 5:18 pm   #14
Julesomega
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Default Re: SN76131N datasheet

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Originally Posted by Philips210 View Post
Julian, there was an article featuring the SN76131, "Disc Preamp", in the April 1975 issue of Elektor magazine.
Oh brilliant, Simon! The article says the LM 1303 has the same connections, but the gain, noise and stability are all slightly worse. A quick look on datasheetarchive finds the attached datasheet.
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