Maestro - The Sustainer  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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analogguru
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Post by analogguru »

Up for sale on evilbay:
https://cgi.ebay.com/vintage-MAESTRO-TH ... 240%3A1318

Looks like EH-made..... somebody has more infos or even guts ?

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Post by DiscoFreq »

I asked to bid, but I received the sellers reply too late to use the Buy It Now button...

I hope he removes the restrictions because I tried to bid (it was ok for him) but I couldn't...
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Post by modman »

Still nothing on this one?
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Post by Greenmachine »

That board is swimming in goop.
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Post by theehman »

In the process of de-gooping one of these today. So, far I can see the bottom of the PCB and it has (2) transistors and (2) 14-pin ICs.
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Post by toneman »

EHman,

did you get any numbers off the transistors or the ic's yet??

an earlier post of the layout shows 4 transistors(?)
the power connections to the IC's look strange (4139?)

there's another one on ebay now--
https://www.ebay.com/itm/360599747082?s ... 1423.l2649

there's this version of the box and a "big muff" box style, without the slide switch.

which version are you de-gooping?

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T
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Post by theehman »

That's the one I'm degooping.

toneman wrote:EHman,


there's another one on ebay now--
https://www.ebay.com/itm/360599747082?s ... 1423.l2649

there's this version of the box and a "big muff" box style, without the slide switch.

which version are you de-gooping?

afn
T
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Post by theehman »

Not much more to go. The ICs are Fairchild U6A7757393. Couldn't find any info on the interwebs on those. The transistors are 2N5133 and 2N3565.
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Post by Dirk_Hendrik »

and these are opamps. Dil-"how much"? After which my first impression would be a (LM)393. Tracing the circuit while attempting to draw in a basic opamp stage would verify wether the assumed pinout would lead to a circuit that makes sense.
Sorry. Plain out of planes.

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Post by theehman »

Dirk_Hendrik wrote:and these are opamps. Dil-"how much"? After which my first impression would be a (LM)393. Tracing the circuit while attempting to draw in a basic opamp stage would verify wether the assumed pinout would lead to a circuit that makes sense.
Sounds reasonable. They're 14 pin DIL.
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Post by grizzlytone »

This was my attempt at making sense of the PCB layout presented here: viewtopic.php?f=16&t=3552&hilit=maestro+sustainer.
Without having actually seen the component side I guessed on the use of FET's. This is the SS-3 version though -is this the version you're working on Ron?

So. For what it's worth...
Attachments
Maestro SS-3 Sustainer schematic -small and lo-res.bmp
Maestro SS-3 Sustainer schematic -small and lo-res.bmp (492.05 KiB) Viewed 3187 times

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Post by analogguru »

theehman wrote:Not much more to go. The ICs are Fairchild U6A7757393. Couldn't find any info on the interwebs on those. The transistors are 2N5133 and 2N3565.
Hows about some pictures ?

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Post by theehman »

analogguru wrote:
theehman wrote:Not much more to go. The ICs are Fairchild U6A7757393. Couldn't find any info on the interwebs on those. The transistors are 2N5133 and 2N3565.
Hows about some pictures ?

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grizzlytone: This must be an SS-1. There's only the 2 transistors and no FETs.
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Post by toneman »

The LM393 is a comparator and usually comes in an 8pin DIP package.

maybe the U6A7757393 is some sore of "house brand"??

hard to draw a schematic when one doesn't know what the opamp package is :shock:

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Post by toneman »

grizzly,

that blob that Ron has looks like only 1 9V connector :hmmm:

He also said it was in the same box as the ebay unit.

T
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Post by theehman »

toneman wrote:grizzly,

that blob that Ron has looks like only 1 9V connector :hmmm:

He also said it was in the same box as the ebay unit.

T
I didn't get the box with the block so I may be wrong on that.
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Post by grizzlytone »

theehman wrote:
toneman wrote:grizzly,

that blob that Ron has looks like only 1 9V connector :hmmm:

He also said it was in the same box as the ebay unit.

T
I didn't get the box with the block so I may be wrong on that.
I haven't seen the blob in question. From the pictures that I've seen all three versions used two 9V batteries but it is possible that some of the SS-1's presented on eBay has been upgraded or modified I guess (SS-1 cover and SS-2 innards?). Here's pics of the three versions, notice same version blob in SS-1 and SS-2:

SS-1:
$T2eC16F,!y0E9s2S5V4gBQeLqKhOVw~~60_57.jpg
SS-2:
$(KGrHqZ,!hQE+!WZ0yiRBP)R9TH82!~~60_57.jpg
SS-3:
maestro_ss-3_005.jpg

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Post by Effectsiation »

Have you guys seen this?
Image

Obviously AnalogGuru has since it's hosted on his site, but I wanted to post it here in case it helps the conversation.

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Post by Effectsiation »

Sorry, forgot to add, that's the SS-3 according to the ILoveFuzz forum folks.

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Post by grizzlytone »

Effectsiation wrote:Have you guys seen this?
[ Image ]

Obviously AnalogGuru has since it's hosted on his site, but I wanted to post it here in case it helps the conversation.
Yep. That's the one PCB layout I was refering to in my post with the guesswork schematic. Thanks for the clarification.

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