Guyatone - PS-011 Distortion/Sustainer Schematic

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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clarisso11
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Post by clarisso11 »

Hi,

is there anyone out there who owns a Guyatone PS-011 Distortion/Sustainer, and would be willing to post a photo of the wiring inside, with PCB? Maybe even schematics, but I won’t get my hopes up.

I’m working on repairing one that was in terrible shape, can’t find any reference images to help reconnecting the cables right. Looks like an interesting circuit, with a LM308N chip, like the old Rats!

Thanks!

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SwedishWings
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Post by SwedishWings »

Please do share a schematic if you make one! I just noticed that I have modified the circuit :) There a two LED's replacing what probably was clipping diodes. Perhaps you can see if it was germanium or silicon originally? I think I will restore to original.
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clarisso11
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Post by clarisso11 »

Incredible, thank you for sharing those pictures! Mine actually turned out to have a bad LM308N chip, along with other issues, and it is long gone. Hope this will help someone else though!

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SwedishWings
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Post by SwedishWings »

Oh, too bad i was late. Do you have any pictures of your PCB? I suspect the clipping diodes were 1N4148 (like the other diodes on the PCB) but would love to know for sure.

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clarisso11
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Post by clarisso11 »

As a matter of fact I do! Still had the gutted PCB, but repurposed the enclosure. Send me a message if you want the original diodes (they are quite unusual), I don't have any use for them anymore.

Here are some photos:
IMG_0140.jpg
IMG_0141.jpg
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SwedishWings
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Post by SwedishWings »

Wow, thanks a lot!

What kind of diodes have Vf=1.3V at only 4mA? Is it in fact two silicon diodes connected in series internally? Never seen anything like that before.

Thanks! I would really appreciate if I could have them, but I'm currently located in Asia with horrible postal service. I'm moving to Sweden later this year, I'll get back!

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clarisso11
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Post by clarisso11 »

Yes, please do! I’ll still have them by then.

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SwedishWings
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Post by SwedishWings »

I got really curious about the diodes, so I took the liberty of asking about the diodes on Stack exchange. In hindsight, I realize i should have asked in advance when using your picture. I will erase the question if you do mind in any way, just say the word!

https://electronics.stackexchange.com/q ... -33v-3-9ma

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Post by clarisso11 »

No worries, I'm interested in this as well, so thanks for doing that!

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Paulcats
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Post by Paulcats »

Hi, did you finally find the schematics of PS-011? Alternatively, if you share pictures of the components (side views also to read resistors' code, etc.) I can draw and share the respective schematics. Thanks.

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SwedishWings
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Post by SwedishWings »

I started to trace it but run out of time. I created a gimp file with layers to translate to schematic. If you pm your mail i can send the xcf file. If you make a schematic from that I'll try to help with component values.

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Paulcats
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Post by Paulcats »

SwedishWings wrote: 21 Feb 2024, 14:14 I started to trace it but run out of time. I created a gimp file with layers to translate to schematic. If you pm your mail i can send the xcf file. If you make a schematic from that I'll try to help with component values.
I just sent you a PM. I will definitely trace down the schematic and share.

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krystal
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Post by krystal »

I traced it also but my schematic isn't very nice, it lacks pot values, power section, switching and diode types (nothing written on them, they all look like 1N4148 would except for the clipping diodes which are black and red and roundish).
I didn't do a very rigorous job, as usual, but this one is worse as I only traced it to know what the sustain pot was doing (it's a dynacomp) rather than to make an exact clone.
Please don't go building one just based on this thing, it may contain mistakes, approximations or guesses, and it could make you sad.
I think the extra op amp was buffering vref.
Hopefully it can help if someone wants to do a GOOD job of tracing it, or you are just looking to find out how it works.
A dynacomp type into a opamp distortion with clippers to ground and a simple little tone section.
Enjoy!
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Guyatone PS011.png

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Post by Paulcats »

Hi krystal, I also traced down the schematic of PS-011 based on pictures by SweedishWings (I don't own the stompbox) and I must admit that... your schematic so far is damn accurate! I also included the power the switching sections and, as soon as SweedishWings sends me the additional pictures I need, I should be able (hopefully) to complete it with values and notes. The only discrepancy I found is related to: (1) the sequence of R2/C1 (in my schematic C1 comes first); (2) the connection to ground of R1, R7 and R20 which seems not reflecting the PCB shown in the picture I have (R1 is also missing in my pictures). Can you please countercheck them in your real PS-011 (or, at last, send me clear picture of the PCB's back tracing)? From a circuitry standpoint, your schematic makes more sense but I must stick to the pictures that I have at hands. Thanks for your support.

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krystal
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Post by krystal »

Hi Paulcats,
Thanks for your input, you were correct on all counts.
-There is no R1
-R2/C1 were switched in mine (but that wouldn't matter)
-R7 goes to ground but i had omitted R29
-R20 goes to VREF
Additionally :
-VREF voltage divider is 10K/5.6K with 47uf cap (i think, please double check this in particular)
-Distortion pot wasn't drawn right, it really is just wired as a feedback resistor between - and output pins one would expect (lugs were drawn switched but that doesn't matter)
-Contrary to what i stated in my previous post, the second half of the 1458 is left unconnected

The pots are a pain to get to and probably need desoldering to get values, i didn't have time for that today sorry.
My PCB is the same as SweedishWings's as far as i can tell (appart from the clippers, modded on his)
Honestly this thing sounds ok, it sustains for days, especially when stacked with more gain, but if i were to build one i'd go with a different distortion stage and tone stack. It lacks character and sounds a bit flat and boring to me.
Hopefully this helps a bit, also let me know if there is anything else i can do.
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Guyatone PS011.png

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Paulcats
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Post by Paulcats »

Hi krystal, thanks for the quick reply and the valuable information! Now we are almost aligned! With respect to Vref, I found an additional 100 Ohm resistor between R27 and R28 which seems driving the switching section at sightly higher value than Vref (however, the impact is negligible to the value of Vref). R26 in my schematic is not grounded but seems in series after C18. Do you have any information about the trimpot? It seems to be a 2k2 but I am not sure. I also assume that is used to fine tune the offset between the inverting and non-inverting inputs of opamp 3080 but I am not sure. Finally, can you at least check if trimpots are linear or logaritmic? This should be easily checked with a multimeter by turning at constant low speed the pot and check if readings change linearly too. I would really like to build one PS-011 as I would like to hear it after my PS-015 over drive which sounds very good to me. I was interested by the sound got by this Japanese player on youtube (min 3:40 onward). OK, the sound is not "innovative" and rather traditional but I believe that is a good starting point to make modifications... "stompbox nerd..." ;)

PS: I do not understand a word of the Japanese guy... but he smiles continuously and he seems happy with the PS-011 :lol:

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krystal
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Post by krystal »

Got round to measuring pots. Had to measure in circuit because i couldn't for the life of me figure out how to extract the pot board.
This is what i got:
Distortion A1M
Sustain A500K
Level B50K
Tone B100K

There is indeed a 100ohm at VREF, don't know why, maybe they ran out of jumpers or have a "no more than 10 jumpers per board" policy. I didn't bother adding it to the schematic, just seems like a waste of a resistor.
R26 is grounded as drawn (it's hiding behind the small multicable plug thing) but you are correct there is a resistor in series with C18 (R29 1k)
The trimpot is 2.2k indeed.
I took a look at the other available Guyatone PS series schematics available and the PS021 Guitar exciter/compressor has a very similar compressor section so i guess that confirms the 2.2k trimpot and weird VREF. Schematic and boards at AionFX : https://aionfx.com/app/files/docs/merid ... tation.pdf

In my previous post i didn't mean to suggest that the PS011 isn't useable or is bad in anyway, just not to my taste. My main beef is with the tone pot, anything past 11 oclock is just shrill with my setup, i mostly use it for the compressor part. I would say that it is indeed a good basis for modding. The japanese guy also has a ton of reverb and possibly other stuff, my setup sounds nothing like that.
The PS-015 seems like a nicer overdrive, maybe a mashup of both could be good, the PS-011 compressor followed by the PS-015. Have you taken a look at the PS-025 also? That one looks pretty crazy. Schematic and boards at Deadendfx : https://drive.google.com/file/d/1hJsfI ... sEHgv/view

EDIT: Just noticed R15/C8/R16/C11 can't be right. I'll look into it tomorrow.
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Guyatone PS011.png

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krystal
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Post by krystal »

It's tomorrow now.
I checked and there is a jfet between R15/C8 and R16/C11, it's part of the switching. Instinctively i would drop C8 but i'd test it on a breadboard first. You can also save a resistor by making R15/R16 one 20K resistor (or stick with one 10K, probably fine too).
I measured the voltage drop across that strange 100ohm at VREF and it's 0.05V (from 3V to 2.95V). Go figure why they wanted that to happen.
Also did you see Fuzzhead did a layout, it could be very helpful if you want to build one ! (and they might have jumped the gun there, it could need correcting once we see Paul's schematic) http://dirtboxlayouts.blogspot.com/2024 ... ainer.html

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Post by Paulcats »

Finally, the output. As I do not own the PS-011, this is based on the pictures of SwedishWings. It seems pretty accurate as it matches 100% with the schematic of krystal that already traced the main circuitry (if I new it before... I would have saved days and nights... :)). However, the schematic is complete with all sections and they are higlighted with different colours. I also incuded reference to the coloured wires connecting the two boards, the jacks and the footswitch. I hope that it is usefull.
Let me know of any mistake that you may find.
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Schematic_Guyatone SP-011_2024-03-20.pdf
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Post by twotees »

Hey thanks a bunch Paulcats for that very detailed schematic draw on the Guyatone PS-011, appreciate the effort. Cheers.
Have not had a real thorough go over on it, but did notice one slight error, nothing major.
The Jfet used is a Toshiba 2SK30A-GR
not 6R
as far as I am aware.

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