BOSS CS-1 v1 vs v2

[Souleyman]

Hey all of there!

I've got the pair of CS-1 compressors. The first older was dated Aug 78 and the younger Apr 79.
They have difference in schematics and a very different sounds.
I've got a usual schematic of CS-1 in internet. This is similar to my older one. I can't find the next version schematics but I see the difference on boards.
I never heared CS-1 before and I was surprised the huge difference of the sound two this versions.

The younger sounds quite expected for me as an optical comp. Yes it has strange Sustain knob working quick after the zero but almost unchanged the rest of the adjustment range. No problem, but it has its own sound. It's known as quiet pedal and many users returns 47k resistor before the sustain pot for more gain as it was on the first version. No problem too.

But I heared unexpected killer huge compression on the oldest V1.
Is this normal working condition of this version? Large compression and even ripple if playing with chords and other dissonanse things. Playing only single notes and quart and quint intervals not rippling. It sounds as a very cool overboost or even tremolo. Sometimes sounds very cool and fat but very unexpected.
With the Sustain knob turned off rippling disappears.

Is this a fault or a cool vintage stuff? But I have more older Roland AS-1 the father of BOSS CS-1 and it hasn't this huge compression and pulsing release.

I partly studied the nature of these fluctuations soldered one LED instead of LED part of one LDR and noticed when we have some not an absolutely consonance sound the LED starts to pulsing in release. That is why the IC according the LDR's changing the gain with those ripples.
But in the V2 LED lighting not so bright and the ripple of lighting not so noticable by eye and by ear.

I repeat my question guys. Isn't it normal for the Version One of CS-1 or I need to check something to find the cause of LED ripple or the cause of this huge compression.

My goal is not to make this pedal to be the compressor that I prefer. I have another some compressors on a sheld. I just want to make sure it's work as it should when it was made or I must to fix some bugs.

I'll be very appriciate for any advices.

This is exactly the V1 on the pics.

[Ry]

I can't totally answer your questions, but I can tell you that they don't all match the schematics online.  I recently brought one back to life (it had a burned out zener).  What surprised me is that the schematic online shows two zeners, where mine only had the one that was faulty.  So I'm guessing that the difference in sounds can be attributed to differences in the circuit.  I know some of them also had slightly different resistor values for a couple of the components...that may be what you're hearing as well.

It's not my favorite compressor by any means, Boss did a much better job with the CS-2.

[NFX]

I can't totally answer your questions, but I can tell you that they don't all match the schematics online.  I recently brought one back to life (it had a burned out zener).  What surprised me is that the schematic online shows two zeners, where mine only had the one that was faulty.  So I'm guessing that the difference in sounds can be attributed to differences in the circuit.  I know some of them also had slightly different resistor values for a couple of the components...that may be what you're hearing as well.

It's not my favorite compressor by any means, Boss did a much better job with the CS-2.

http://www.diystompboxes.com/smfforum/index.php?topic=118666.0

[Souleyman]

Thanks for the responce Ry.

What surprised me is that the schematic online shows two zeners, where mine only had the one that was faulty.

This is what I wrote. You tell about the V2. It really has no one zener on LDR driver circuit. V1 and the schematic on the picture have three zeners:

• for the main power of circuit
• for the indicating LED
• for the LED part od LDR's (LDR driver cirquit)

In V2 was changed some resistors and capacitors values and one electrolytic cap was replaced by green mylar. And as you noticed the one zener dissapeared too in this part of circuit.

I know some of them also had slightly different resistor values for a couple of the components...that may be what you're hearing as well.

I hope so. But this is very huge difference with V2. And a fairly audible ripple of release. It's hard to believe that the BOSS engineers released a pedal with such artifacts for sale. But who knows...
Seems I need to find users with the same V1 circuit CS-1.

It's not my favorite compressor by any means, Boss did a much better job with the CS-2.

Agree. And I have CS-2 too. VCA. More usable of course. But as a historical value and for that interesting sound of optical compression using sometimes as effect I want to be sure if all ok with my unit because it has a very srange behavior.

[ElectricDruid]

If it's got bad ripple, that suggests that the envelope signal isn't getting well smoothed. A dead/dying electrolytic cap somewhere, perhaps, after so long? I doubt they used top quality parts...

But then again, there may be nothing wrong with it, and it's possible it was always like that.

HTH,
Tom

[Souleyman]

I checked all electrolytics (Matsushita anywhere) with my ESR meter and Fluke multimeter too. They shows all electrolytics are good.
Some of them I tried to swap with V2 which has no ripple. No changes...
1uf that is after Q4, Q5 and before LDR change the frequency of ripple. If I use 4.7uf as in V2 the frequency of ripple decreases but not disappearing.

[Souleyman]

Question about LDR driver: what's the role of the 1uf 50V electrolytic cap before Q3 transistor? And what will change if it is replaced by a 0.047uf mylar?

[PRR]

> what's the role of the 1uf 50V electrolytic cap before Q3 transistor? And what will change if it is replaced by a 0.047uf mylar?

Q3 Base wants to be near 1/4 of supply. Opamp's DC output is about 1/2 of supply. We need to break the DC yet pass the audio.

The 1uFd against ~~66K is flat to 2.5Hz. 0.05ufd would be flat to 50Hz. "Roll-off" here is really a rise of output. So it won't correctly control tones 50Hz and lower. For guitar, the difference may be insignificant. It is quite possible that at the factory, 1u electrolytic was a half-cent cheaper than 0.05u film.

[Souleyman]

The 1uFd against ~~66K is flat to 2.5Hz. 0.05ufd would be flat to 50Hz. "Roll-off" here is really a rise of output. So it won't correctly control tones 50Hz and lower. For guitar, the difference may be insignificant. It is quite possible that at the factory, 1u electrolytic was a half-cent cheaper than 0.05u film.

This kills my assumption that the replacement for that film capacitor was made to reduce the pulsations of the LDR LEDs with many-voiced sound... 

[Souleyman]

Just made the schematic of V2 used V1 pictures and my own V2 dated Apr 79.



I hope I haven't forgotten anything.

[nikStomp]

The images are not there anymore so I have retraced Boss cs-1 v2 schematic
Schematic

Board back

Board Front

the main difference is the detector circuit

[Rob Strand]

The images are not there anymore so I have retraced Boss cs-1 v2 schematic

Thanks.  I didn't know about that one, or at least I can't remember it.


Here's the *updated* links Souleyman's 2017 post:

Sch:
https://postimg.cc/2VXMdWfC
https://i.postimg.cc/q4Kv2j2w/Boss-CS1-V2-schematics.jpg

Layout:
https://postimg.cc/image/q6x8skhpn/
https://s25.postimg.cc/q6x8skhpn/Boss_CS1_V2_layout.jpg


For the layout I just noticed Souleyman's overlay is a mark-up of the old overlay whereas your PCB pic clearly shows some parts have changed (eg. no holes for the zener D5 near the optos).
[EDIT:   wait!  I can see a D5 on the right near the big Electro.]

On your PCB pic the soldered resistors look like mods (not from Boss).

[nikStomp]

Sorry the soldered resistors are my fault (I was trying to put it like v1)
The 47k before the pot helps having a more usable volume but the 1.2k on the "treble" is better than the 560ohm of the original -> too much noise.
I want to try to put back a 1uf/330k on the detector part to get a little faster attack

Could also be nice to have a way to have less compression maybe play with the gain a bit? Or remove one of the fotoresistor?

[Rob Strand]

Could also be nice to have a way to have less compression maybe play with the gain a bit? Or remove one of the fotoresistor?

Yes, playing with the gain is pretty much the way to do it.

Sorry the soldered resistors are my fault (I was trying to put it like v1)
The 47k before the pot helps having a more usable volume but the 1.2k on the "treble" is better than the 560ohm of the original -> too much noise.
I want to try to put back a 1uf/330k on the detector part to get a little faster attack

No worries. 

So I just quickly traced over your PCB pic.  Here's what I found:
- D5 on your board goes to the LED circuit.  Also it's not a zener.
- The Vcc/2 supply doesn't use resistors.  It uses a Zener D7.
- The two transistor "rectifier" circuit has diodes across the base and emitters of the transistors.

At this point I stopped because I realized this circuit is following a lot of the circuit of the CS-2!
So what I'm thinking is this is largely a CS-2 circuit *but* it uses the optos.  So it's kind of
a bridge between the old CS-1 and the CS-2.

Sorry, mostly crap.   I do think D5 and Q10 are the LED.
The fine details need checking more thoroughly.

[Rob Strand]

Quote

    Could also be nice to have a way to have less compression maybe play with the gain a bit? Or remove one of the fotoresistor?

Yes, playing with the gain is pretty much the way to do it.

Actually lifting a pin of the input opto resistor PH2 might also do it.

[nikStomp]

Hi

No worries.

So I just quickly traced over your PCB pic.  Here's what I found:
- D5 on your board goes to the LED circuit.  Also it's not a zener.
Yes I think that the marking on my pcb are different from the other schematic
D5 and Q10 (and there's an extra resistor on the right) are to buffer the output of the led so they are not relevant

- The Vcc/2 supply doesn't use resistors.  It uses a Zener D7.
No this is the same as the old schematic. D7 is actually across the 9V and is a 12V zener (to protect from over voltage/reverse voltage
The Vcc/2 is done with the two 10k resistor also on my board

- The two transistor "rectifier" circuit has diodes across the base and emitters of the transistors.
No I checked. -> D1/D2 are the diode towards gnd on the old schematic -> look at q8/q9 in the schematicWhat tricked you (and me for a while) is that that track is GND

> At this point I stopped because I realized this circuit is following a lot of the circuit of the CS-2!
> So what I'm thinking is this is largely a CS-2 circuit *but* it uses the optos.  So it's kind of
> a bridge between the old CS-1 and the CS-2.

No sadly not
the CS2 (and the CS1 and the ibanez CP9) they all use mostly the same circuit for the voltage level "detector"

I think that the diodes on the CS2 /CP9 are there to help the transistor recover more quickly in case of large signals

[Rob Strand]

So I just quickly traced over your PCB pic.  Here's what I found:
- D5 on your board goes to the LED circuit.  Also it's not a zener.
Yes I think that the marking on my pcb are different from the other schematic
D5 and Q10 (and there's an extra resistor on the right) are to buffer the output of the led so they are not relevant

- The Vcc/2 supply doesn't use resistors.  It uses a Zener D7.
No this is the same as the old schematic. D7 is actually across the 9V and is a 12V zener (to protect from over voltage/reverse voltage
The Vcc/2 is done with the two 10k resistor also on my board

- The two transistor "rectifier" circuit has diodes across the base and emitters of the transistors.
No I checked. -> D1/D2 are the diode towards gnd on the old schematic -> look at q8/q9 in the schematicWhat tricked you (and me for a while) is that that track is GND

Cool.  I was just checking the same things and that looks spot on!

So I marked up the schematic with all the info:

BTW, I wasn't sure why you marked-up the 47uF electrocap since it was there before.



FYI, to anyone reading this in the future:  On Version 1 the LED only lights when you press the footswitch, sort of a battery check.  On version 2 the LED toggles when you press the footswitch, like all modern Boss pedals. So you can tell which version it is without opening the unit.

[Ry]

Wow, I forgot all about this thread.  I'll have to pull mine out and see which version it is now that you guys have done such amazing legwork!

[Rob Strand]

Wow, I forgot all about this thread.  I'll have to pull mine out and see which version it is now that you guys have done such amazing legwork!

If you are going to open your unit there's a couple of parts that aren't 100% certain.



I noticed I left off the "D6" text on the schematic.

Another thing worth mentioning is that the changes 560R ---> 1k2 and 47k ---> 150k aren't unique to V2.  The V1 schematic (dated Oct 1978) actually has these marked-up as changes so I think V1 units can have either of the two values depending on its age.   

The location of D5 is fairly easy to spot as a difference, also the presence of Q10.

[Ry]

I'll open it up this weekend and report back.