freestompboxes.org

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 ?

analogguru

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...

Still nothing on this one?

That board is swimming in goop.

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.

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?

afn
T

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

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.

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.

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.

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...

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 ?

analogguru

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 ?

analogguru

Have to borrow a camera. Mine's lost somewhere.

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

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

grizzly,

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

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

T

toneman wrote:grizzly,

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

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.

theehman wrote:

toneman wrote:grizzly,

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

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: SS-2: SS-3:

Have you guys seen this?


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

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

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.