EH Small Stone slow startup

[p1_ind]

I have an early 80s Small Stone phaser that takes a long time to start working correctly. When I first power it up the volume is low, then after about 5 seconds or so the volume goes to normal without phase shift. It takes the pedal several more seconds anywhere from 5 to 10 seconds sometimes more depending on the placement of the rate knob before it starts the phase shift any ideas would be helpful.
I have already replaced the electrolytic caps.

Adam

[Scruffie]

Going from memory here but I'm pretty sure every vintage Small Stone I've used has had this to some extent, the oscillator just takes a second to get running and with no oscillator the phase stages aren't running which messes up the wet/dry mix hence the low volume.

The values of the resistors and caps drifts over time as well which probably exacerbates the issue but it's not something to be concerned about I don't think.

[miketbass]

Mine is a 70s model and does this too. If I kick it on and crank the rate knob it gets it going. Always figured it was caps charging up.

[p1_ind]

I went ahead and replaced the 3 0.1uf film caps and it seems better.

Adam

[p1_ind]

It must have been in my mind. I plugged it in today and it did the real slow start up again. Oh well.

[antonis]

Does it use CA3080 or CA3094 for OTA..??

[Mark Hammer]

The GGG clone used 3080s, but the EHX unit has only ever used CA3094 or LM13600 chips.  The 3080s were used in the GGG version to compensate for the decreasing availability and increasing cost of CA3094 chips.

Given that power is always applied to the circuit, and switching in the early days was SPDT and only selected between outputs, it is hard to believe that bypass/effect selection would impact on the LFO "starting up", since there is nothing about the LFO circuit that relies on having an input signal, or sending the output anywhere.  The circuit is always working in the background; you just don't get to hear it unless you hit the stompswitch.

Having said that, is there some obscure issue/version of the SS that switched the power along with the output?

[Scruffie]

Given that power is always applied to the circuit, and switching in the early days was SPDT and only selected between outputs, it is hard to believe that bypass/effect selection would impact on the LFO "starting up", since there is nothing about the LFO circuit that relies on having an input signal, or sending the output anywhere.  The circuit is always working in the background; you just don't get to hear it unless you hit the stompswitch.

Having said that, is there some obscure issue/version of the SS that switched the power along with the output?

He only said on 'Power up' which I took to mean when first turning the supply on, not hitting the foot switch because mine definitely exhibit the same behaviour after trying them, the bypass works fine on power up however.

[Mark Hammer]

You're right.  My oversight.  In which case, the pedal is behaving in a perfectly normal manner.  Absolutely nothing wrong with it.  I was beginning to wonder if it was one of those instances where someone had wired up a stompswitch along the way that killed the power in bypass to save on batteries.  But thankfully, no such issue.

[Digg-Dugg]

Hi folks, dredging up old articles aside, I found this in search anyway. I was curious to know if anyone has found a solution for this yet. I have a version 2 EHX Small Stone that does work, but upon power up, it sometimes takes days to start the LFO to sweeping the phase circuit. Once it is sweeping however, its fine. It sits in my home studio and is usually left on along with the rest of my rig since I do perform several shows online everyday. I have added my modded MXR Phase 90 in series with it to use until it decides to start sweeping finally. I would really like to resolve this problem, any ideas as of yet? Also any V2 specific schematics for this thing? I can only seem to find issue J schematics. I also have a heavily modified Russian black box Small Stone that does not have this problem. I do not plan on modding this one however and wish to keep it as stock as possible other than whatever repair is needed. Please advise!

Thanks,
Digg-Dugg

[anotherjim]

I don't know how different the issues are -  changed OTA type?
Well, anyway, the LFO seems to depend on the charging of the 33uF cap, so first of all, that needs to be in good order with low leakage. Any old tantalum type in that position would be suspect to me.
The charge on that cap, probably lives somewhere above 0v when it's running in order to meet the input switching thresholds. From power-on, an initial charge will be at 0v and some may have to leak in until the input comparator action tells it to charge up.

A fix might be to arrange an RC network from +9v to give the oscillator a one time kick-start every time power comes on - but it would take some experimentation which would be for somebody else to do - because I don't have one!

[Digg-Dugg]

Thanks for the suggestion. I have no idea of how to go about building such a "trigger" circuit nor where to apply it. One of the previous posts mentions that they tried this to no avail however.

That's the Issue J schematic I was referring to. It is said to have errors, though I cannot currently confirm this.
I did however find the original schematic of Version 1, but alas, no version 2 yet.

Here is Version 1:



Can anyone add to this.

[miketbass]

I have had an issue J small stone for decades, and it has always had this slow start problem. Cranking the rate knob always got it going. A few weekends ago I received another issue J for repair, which displayed the same problem after a faulty 1uf cap near the input was replaced. I decided to go further and replaced the remaining electrolytics including two 33uf caps, one of which was in the lfo, the other power supply.

After this the problem is gone (or greatly reduced) to where it gets going perceivably instantaneous. I suspect the old 33uf cap in the lfo is the culprit but do not know for sure as I shotgunned them all after the initial fix.