NJM2147D Substitute?

[T9c]

Need a NJM2147D (Dip-8) for an AC30C2 I'm working on. Supply voltage is +/- 27vdc, which seems high but posts on the Ampage forum indicate this is correct. The schematic (AC15C1) doesn't say. All other common opamps I've looked up are rated around 15Vdc supply. Tried a 4458 and it's getting warm after awhile, so it's out.

The only 2147D's I have found are from UTSource on eBay from China. Not sure if I can trust them and it will take a long time to receive, so has anyone found a suitable replacement for this part?

[J M Fahey]

Mouser has them in the SMD version (half size) for 1$ , so I'd get one of them and an SMD>DIP8 adapter board.

NJR njm2147 Operational Amplifiers - Op Amps | Mouser

adapters:
SMD Adapters


you will need to supply your own pins, which are bought in break off strips,


end result will be similar to:
Iit includes homemade adapters)


Personally I'd buy a dozen or two of adapters (to justify postage), DIP 8 are disappearing and this will be needed more and more.

[T9c]

Thanks Juan. Great idea there!

[T9c]

Rats! Mouser doesn't stock the smd's either! Will have to look elsewhere.

[J M Fahey]

Ouch!!
Missed the non stocked label.

I found a few suppliers, with stock from 78 to 45000 ... but most of them in HK ... and I suspect that even the one called "European Chip Supplier" must also be Asian, so Ebay or HK it will be

Just curious, what does that IC do exactly?

Do you have the schematic?

IF the original can be found, even with 1 or 2 weeks delay, wait for it; if it were some vintage Pro equipment which justifie$$ the effort and it were unobtanium then something can be kludged .

Is it in the power amp or, say, driving the reverb?

Maybe it does not NEED +/- 28V rails for what it's doing and you can "steal" 10 or 12V from the high ones (hint hint )

I read the datasheet and it's a CRAPPY Op Amp, much worse than LM741 , its only redeeming quality is that it stands +/-28V .

EDIT: just downloaded the schematic (thanks JPB ) and found they use it everywhere: channel mix, power amp drive, reverb drive and loop return.

Looks like they used it "just because they could" or to annoy others, he he.

Oh well, you'll have to wait

[Jazz P Bass]

Schematic.

I have included both versions that I have.

[T9c]

Oh! Nice one JPB. Many thanks! The one in the folder (in living color, no less) is the direct match for this amp.

The problem child here is U5, the pwr amp pre-driver. Voltage on all pins and dropping the +27v to 15v. Scares me that they are operating all these OA's at the top of their high power capability too. If it were mine to keep, I'd be modifying that supply down to +/- 15vdc and slap a 4558 in there/

I'll try an order off of the Evil Bay for a few pieces, ~$10 or so. If they turn out fakes, then I'll start modding the p/s.

Thanks Juan & Jazz!

EDIT: I see U5 is actually the FX loop driver, not the PA predriver (right schemo makes all the difference).

[J M Fahey]

Voltage on all pins and dropping the +27v to 15v. Scares me that they are operating all these OA's at the top of their high power capability too. If it were mine to keep, I'd be modifying that supply down to +/- 15vdc and slap a 4558 in there/

Exactly the same here.

Being in USA means you should at least try to get the proper ones, although Mouser not having stock and not even mentioning the DIP version should be clear red flags.

When something can only be sourced from dubious Orient/EBay sources, it enters the category of unobtanium.

Here in Argentina?
I wouldn't even try , after checking some reputable supply such as Mouser or a couples similar ones, I';d straight mod the supply to +/- 15V.
In fact +/-18V is well within specs for 4558/TL072 and a little closer to +/-27V

In the real world, a modern rail to rail Op Amp fed +/= 18V will practically swing the same (36Vpp) as those piss poor NJM2147 fed +/-27V which can swing 44Vpp , no big deal.
Rereading the datasheet now I understand their purpose: they are designed for Phone line operation , which nominally runs on 48V , of course it's convenient to have a device which can simply be powered from that without much fuss.

FWIW many tube amplifiers (think Laney and some Peaveys) drive the power amp input with +/-15V TL072 with ease.

[T9c]

I received the opamp order from Utsource (eBay merchant) China yesterday and the 2147's are indeed genuine. Amp's working fine now.

[Jazz P Bass]

That is good to know.

I have often looked at UT Source but did not know what they where about.