Suhr - Eclipse  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Frabbio
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Post by Frabbio »

Hello everybody, here are some photos of the Eclipse, i desoldered some components to expose traces, I will post part values and components in the following days.
https://www.dropbox.com/sh/vh346l9r9mov ... 5oz0a?dl=0

I will also post my schematic when I will have time to trace, but if somebody wants to start the photos provided should be enough for the purpose.
Missing ICs in the photos are CD4053

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jhergonz
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Post by jhergonz »

I can't access through the link, I don't know the reason, maybe I'll just wait.

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Frabbio
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Post by Frabbio »

It's strange, try downloading from here (Wetransfer) https://we.tl/t-WxjBn9AxTt

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modman
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Post by modman »

Hi, thanks for the contribution. It should be possible to host the images through the attachment function, 12MB pictures are a bit overkill. Tried to save some of the dropbox previews (<1MB)....
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ANYQDE6Q.jpeg
TBT8TyKB.jpeg
VKVPxq4Q.jpeg
1RVvWEqQ.jpeg
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Frabbio
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Post by Frabbio »

Tracing this board is a huge PITA. Looks like Suhr either used autoroute indiscriminately or intentionally made the layout extremely intricated.

As of now I traced everything apart the uC section that feeds the a,b,c control pins on the CD4053, should be correct but i hope somebody will have the patience to give a second check. I don't think i will, at least for the next 2 months or so, i have to take a break from this pcb lol.
If somebody can help with the uC identification i will try to put up a complete schematic.
Capacitor, ICs, Resistor in my schematic use the same names as in the pedal, so it will be easier to give a second check, and the schematic will be useful for repairs/modifications.
I added photos of unsoldered components and some of the notes i used for tracing in the dropbox folder, sorry for the mess and the coffee stains.

Some notes:
-unconnected resistors in the schematics are in the pedal but belong to untraced sections.
-100nf caps used as decoupling for ICs power pins are denoted in schematic as 100nf(D).
-capacitors values should be all correct, i only have some doubts about C23,C24,C28,C29 (they measure between 680 and 750 pF) and about C4 that i almost destroyed while desoldering, and measures 13.92nF. Using the Riot schematic (there are some similarities) i choosed 22nF as the value for the input cap.
-C13 looks a bit small in value, but I measured it out of the circuit as all of the capacitors.
Attachments
eclipse.png

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alexradium
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Post by alexradium »

It looks similar to a reloaded Riot with 3 band active eq,isn't it?

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Frabbio
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Post by Frabbio »

Yes, it looks pretty similar.
I forgot to specify that the led in the hard clipping section is blue.

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sego91
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Post by sego91 »

I've been working on a clean up version of the schematic, removing the 4053 and going straight forward, having on sight the idea of having double circuits and a 3pdt to toggle to switch in between both circuits...
But now that I think a bit more ... the 4053 are acting as a DPDT, so it could be possible just to add a 3pdt for the switching functions and the LED.
But my main doubts comes form the EQ section, reminds me to a banxandall but not quite llike that, anyone with some experience on this type of tone stack to clarifiy?
Suhr Eclipse provisional schematic
Suhr Eclipse provisional schematic

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Frabbio
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Post by Frabbio »

Hello everybody, I rearranged a single channel simplified schematic so now it's a lot easier to read.
Tone control is definitely a James-Baxandall type, but it's ground referenced (vb referenced here, our virtual ground), in the rearranged schematic it should be clearer.
I also corrected a cap value, which i damaged during desoldering.
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suhr eclipse simplified.png

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HamishR
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Post by HamishR »

Please excuse my ignorance - I looked up OPA171AIDBVR and found that it's an op-amp chip. What role does it play here? I see that all of the operating voltage for the circuit comes from the OPA171AIDBVR so assumed it must have been some kind of charge pump but it seems that it's not. So what does it do??

Thanks!

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Intripped
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Post by Intripped »

That opamp is used here to stabilize Vb.
it's a buffer, and it's not used on signal but on reference voltage Vb (also called virtual ground) instead.
you can find this configuration in other pedal schematics as well.

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HamishR
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Post by HamishR »

Thanks! So you could possibly build a decent overdrive pedal from this schematic without using the buffer? Or is it necessary to keep things from oscillating?

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Frabbio
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Post by Frabbio »

The fact that in the original pedal there is a specific part (it's not half unused opamp from another section of the circuit) for buffering vb makes me think that the load on the unbuffered voltage divider would lightly change the vb voltage.

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HamishR
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Post by HamishR »

That makes sense - thanks!

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