jwhmca

Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« on: September 08, 2012, 09:28:16 AM »
Finally!

Well, maybe. I've been working on this for years. Here is the Schematic that I reversed from an NE80100.

Here is what we need to do. If any of this looks funky please let me know and I will take a look and see if there is any errors... I will be double checking this over the next few days as well...

I can't really find any of these transistors in existence any more. Maybe we can get recommended replacements? Also, I can pull and test any diodes or try to identify them if somebody thinks any particular ones are/should be special.

**backstory**

Years ago I ordered a replacement NE-80100 from Yamaha. They guy was excited that I was still wanting to get the old Pm-700 going. He helped me diagnose the problem and sent me the DOA.

At the time I didn't think much of it, but it wasn't "potted" in the same way as all the rest. Instead of the Hard, Black, impossible to get off resin, it was potted with clear, regular silicone. Fast forward to now. I love the way these OpAmps sound and want to DIY them... I was obviously able to remove the Silicone and take a look at the parts.

This NEW one the guy from Yamaha sent me is NOT like the originals that were in the PM-700. I smashed one of them apart and can at least see that there are differences, must not able in the large transistor pair, marked as Q5 and Q8 on my schematic.

I hope we can make this Happen!
« Last Edit: June 23, 2016, 09:07:30 AM by jwhmca »


Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #1 on: September 08, 2012, 09:47:08 AM »
As drawn the schematic is extremely hard to read, and thus difficult to spot errors. Just as an example: Q1/Q4 form a differential pair, biased by tail current source R1/Q2/D3/D4. This is usually drawn like this (here for NPN input, so everything upside-down):



Bias current should flow from top to bottom, and the basic signal flow (input to output) from left to right.

What I can tell without redrawing the entire schematic:

* D2 and D3 likely need some sort of DC bias. Probably a resistor from Q2 base to the negative supply (or ground, as R5 in the schematic shown in this post).
* R9 doesn't make sense to me as drawn.
* Q5/Q8 probably have different pinout--their emitters should go to R5/R8 and their collectors to the supplies.

There's probably more wrong, but I suggest you first check these points before we dig deeper.

Samuel

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #2 on: September 08, 2012, 10:01:56 AM »

jwhmca

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #3 on: September 08, 2012, 11:41:52 AM »
Yes, I've learned so much since a made this. I'll dig in deeper tonight.  I just thought it would be better to jump in.

PRR

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #4 on: September 09, 2012, 04:18:52 PM »
> As drawn the schematic is extremely hard to read

Agree. Re-weaving in Conventional Form (rails at top and bottom, in at left middle, out at right middle) is not just pretty, it aids comprehension (yours and others).

> I've been working on this for years.

Also, proof-checking transistor pinouts is grunt work, should be done before you show it. I assume you know the transistor types have a missing "2S" in front; however I know the datasheets are sometimes lost and occasionally wrong (alternate pinouts might have been available). However it is un-likely that the only low-resistance no-diode output is "from transistor Bases". A skim of common opamp plans would show *emitters* through few-ohm resistors to outputs.

But it is a gloomy day, ideal for puzzles. I think this is 90% correct.

Contrasted to Jensen's iconic opamp: PNP instead of NPN input, current-mirror load on the input pair, lacks Jensen's patented emitter chokes, maybe less-heroic output capability. Nothing jaw-dropping.

PRR

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #5 on: September 09, 2012, 04:35:20 PM »
When you re-re-draw that: Q7 would best be directly under the Q1 Q4 pair. See good drawings of standard Current Mirrors. D1 and Q7 are the mirror. (In IC technology, D1 would be a diode-connected transistor for some decrease of DC error and for fabrication reasons. In that case, "D1" and Q7 would match. Here they don't, so R3 R6 swamp the mismatch.)

Gain-bandwidth is near 20MHz.

> transistors ... diodes ... are/should be special.

To a first approximation: the input pair should be low-hiss, high-gain, and fairly matched; output pair good-gain and beefy (but not BIG); D8 D5 selected to give 0.5mA-5mA current in Q8 Q5.

I'd expect about any handful of jellybean parts to work really fine.

> This NEW one the guy from Yamaha sent me is NOT like the originals

If you are hearing a sonic difference, with essentially the same topology (and have done double-blind audtion), then you may be into the same problem as wine and violin and piano makers. Certain blends of certain vintages are "different" in ways nobody understands. If you can't quickly fake a new equivalent, it might be best to corner the market in pre-owned NE80100s.

jwhmca

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #6 on: September 10, 2012, 02:23:10 PM »
Thank you!

Here is the "picture" of the layout... I made this at the same time so... it should match the schematic.

Does this help?

PRR

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #7 on: September 10, 2012, 07:45:54 PM »
> Does this help?

There's two of Q6?

jwhmca

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #8 on: September 10, 2012, 09:37:48 PM »
fixed. It should have been Q8

okgb

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #9 on: September 23, 2012, 06:51:30 PM »
I'll have to take a better pic , but if this helps at all [ maybe the 200 vs the 100 , not sure ]

GKB Audio / Greg Boboski


audiomixer

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #10 on: September 25, 2012, 05:55:09 AM »
question:

is that not the  schematic you are looking for / debugging / reverse  engineering?

http://www.groupdiy.com/index.php?topic=44501.0 or at least it looks like someone did the job of reverse engineering already?

- michael

jwhmca

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #11 on: September 27, 2012, 01:23:38 AM »
question:

is that not the  schematic you are looking for / debugging / reverse  engineering?

http://www.groupdiy.com/index.php?topic=44501.0 or at least it looks like someone did the job of reverse engineering already?

- michael

I don't think so... there were a few schematics in that thread...

PRR

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #12 on: September 28, 2012, 01:52:41 AM »
> I don't think so... there were a few schematics in that thread...

Argh.

It would have been nice to link to your prior thread.

abechap024's post _IS_ your reverse-engineer, direct from Yamaha, with only trivial differences which may be your typos.



Build it and listen.

steveh

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #13 on: October 01, 2012, 06:42:36 AM »
Why might D6//D8 & D7//D9?

And the 68pF compensation capacitor includes the output stage as another difference from the JE990.
« Last Edit: October 01, 2012, 06:46:14 AM by steveh »

JW

Re: Yamaha NE-80100 Discreet OPAMP Reversed/Schematic
« Reply #14 on: January 08, 2019, 11:02:00 AM »
Anybody know the current draw for the 80100?

Here's a link to the technical docs page with schematic: https://groupdiy.com/index.php?topic=44874.20



 

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