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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toneman
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Post by toneman »

Yeh, grizzly,
that's what I thought too (layout vs schematic).
strangly, I thought I've seen that schemo before.
gonna search my compressor archives.

hey, thanks for those "blob" pics!!!!

The first blob looks like it's in a Muff chassis(?)

I see 2 9Vers in the 2nd pic.

I make out 2 9V connectors in the 3rd pic.

T
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Post by grizzlytone »

toneman wrote:Yeh, grizzly,
that's what I thought too (layout vs schematic).
strangly, I thought I've seen that schemo before.
gonna search my compressor archives.

hey, thanks for those "blob" pics!!!!

The first blob looks like it's in a Muff chassis(?)

I see 2 9Vers in the 2nd pic.

I make out 2 9V connectors in the 3rd pic.

T
Yes, the SS-1 really had a very similar look to the EH pedals at the time -maybe that's why they redesigned it?. The dual 9V battery connectors doesn't show in the SS-1 pic but they're there.

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Post by DiscoFreq »

theehman wrote:I didn't get the box with the block so I may be wrong on that.
I also bought an SS-3 with an extra "block" once, both don't work IIRC.
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Post by theehman »

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.

Update: one IC is a U6A7757393. The other is a U6A7723393, which seems to be a 723 voltage regulator. Since it's a U6A7723393, I thought the other might be a U6A7757393 but that doesn't seem to help.
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Post by theehman »

De-gooping is done.

The electrolytics lost their labels so I'll need to pull and measure all of them. Also, most of the resistors will probably need to be pulled/measured.
Interestingly, I found 3 small tape packages among the components. 2 consisted of a transistor and diode, all leads removed. The third was an 8-pin IC with all leads clipped.
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Post by theehman »

grizzlytone wrote: 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-2:
$(KGrHqZ,!hQE+!WZ0yiRBP)R9TH82!~~60_57.jpg

This looks like the one I just de-gooped.
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Post by theehman »

theehman wrote:
grizzlytone wrote: 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-2:
$(KGrHqZ,!hQE+!WZ0yiRBP)R9TH82!~~60_57.jpg

This looks like the one I just de-gooped. Any idea how the Hi-Lo switch is wired?
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Post by toneman »

This looks like the one I just de-gooped. Any idea how the Hi-Lo switch is wired?
thought the "hi/low" switch was for input impeadence selection(?)
you know, low Z or Hi Z, mixer input vs guitar input(?)

3 small tape packages

what's a "tape package"??

EHman:
how many transistors?
how many IC's?? 14pin? 16pin

looking forward to your reveal :thumbsup
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Post by grizzlytone »

theehman 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.

Update: one IC is a U6A7757393. The other is a U6A7723393, which seems to be a 723 voltage regulator. Since it's a U6A7723393, I thought the other might be a U6A7757393 but that doesn't seem to help.
U6A7757393 = uA757 = Gain-Controlled IF Amplifier. I seem to recall that this IC was used in the Jen Fuzz & Sustain pedal as well. Anyway it makes perfect sense in a sustainer/compressor/limiter

I'll look for better pics of the Hi/Lo -switch wiring when I get to my other laptop where I have all my pedal pics.

Good work. I look forward to seeing the final schematic!

/MB

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Post by theehman »

toneman wrote:
This looks like the one I just de-gooped. Any idea how the Hi-Lo switch is wired?
thought the "hi/low" switch was for input impeadence selection(?)
you know, low Z or Hi Z, mixer input vs guitar input(?)

3 small tape packages

what's a "tape package"??

EHman:
how many transistors?
how many IC's?? 14pin? 16pin

looking forward to your reveal :thumbsup
They were little packages of non-working parts wrapped in tape.

2 transistors, 2 14-pin ICs. See earlier post for details.
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toneman
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Post by toneman »

reference to the uA757--
https://www.freestompboxes.org/viewtopic.php?f=1&t=18552

so...it seems it's like an OTA??
was going to say that OTA's didn't exist then...
but,
now,
I see that I would be wrong....

never did see any schematic with a uA757 in it....as a gain control...

:hmmm:
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Post by grizzlytone »

theehman wrote:
theehman wrote:
grizzlytone wrote: 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-2:
The attachment $(KGrHqZ,!hQE+!WZ0yiRBP)R9TH82!~~60_57.jpg is no longer available

This looks like the one I just de-gooped. Any idea how the Hi-Lo switch is wired?
Here's another pic showing the Hi-Lo switch:
$(KGrHqZ,!q!E-wl2PhS7BP)R9bibew~~60_57.jpg

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toneman
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Post by toneman »

On the "Muff-sized" version, I just noticed the switch is on the back, between the jacks.

btw grizzly, do you have any part values for the layout/schematic you posted??

8)
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Post by grizzlytone »

toneman wrote:On the "Muff-sized" version, I just noticed the switch is on the back, between the jacks.

btw grizzly, do you have any part values for the layout/schematic you posted??

8)
Nope, like I say in the post, I have only ever seen the drawing of the PCB solder side mentioned in the post (and later on added to this thread) so the resulting schematic stems from educated guesses governed by the criteria of conforming with the PCB solder side layout (+ part designations) and making sense circuitwise. I'd be excited to find out how close to the truth I got -hopefully one day someone on this forum will degoop the SS-3 as well...

Looking forward to the SS-1/2 schematic -How's it coming along Ron?

/MB

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Post by theehman »

grizzlytone wrote:
toneman wrote:On the "Muff-sized" version, I just noticed the switch is on the back, between the jacks.

btw grizzly, do you have any part values for the layout/schematic you posted??

8)
Nope, like I say in the post, I have only ever seen the drawing of the PCB solder side mentioned in the post (and later on added to this thread) so the resulting schematic stems from educated guesses governed by the criteria of conforming with the PCB solder side layout (+ part designations) and making sense circuitwise. I'd be excited to find out how close to the truth I got -hopefully one day someone on this forum will degoop the SS-3 as well.

Looking forward to the SS-1/2 schematic -How's it coming along Ron?

/MB
Coming along. I pulled and measured the electrolytics today. There's one tantalum (?) cap that the lead came out of that I'll need to decipher from the color code.
After that, I'll get a schematic drawn up and post it here. I also have the factory SS-2 schematic but it only shows connections outside the block.
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