Vintage EHX Small Clone problem/question ?

[tubula]

Hi,
I’ve got an ‘83 Small Clone chorus and it works fine and sounds great,
except that it takes about 5 seconds to get going when I click it on.
It does this not only when I first click it on, but even after using it for a
session (meaning, even when warmed up and already clicked on several times.
So, after use, it still takes 5 seconds or so before the chorus effect kicks in.
The guitar signal comes through unchanged after clicking the footswitch,
then after about 5 seconds, the chorus effect comes through as normal
and sounds and performs perfectly normal.
Wondering if anyone knows what might be causing this. I’ve had a few
replies in another forum that it’s not uncommon for chorus pedals to take a second
or 2 to kick in, but this one does it not only the first time you turn it on,
but every time, and as I said, takes more like 5 seconds to start the chorus effect.
Would this be related to a capacitor kind of thing? I’m not that technically savvy
with pedals, so any help would be appreciated. By the way, the pedal does this
with both a 9v adapter and/or a 9v power supply.
Thanks !

[Mark Hammer]

The dry/clean path remains on all the time in a folded-steel-box Small Clone, whether in effect or bypass mode. The footswitch turns on a FET that allows the wet signal to pass and be combined with dry to create the effect. The circuit that turns the FET on has a small-value cap to ground that slows the turn-on just the tiniest bit, so that it doesn't produce a click. If you continue to hear the clean signal, then that means the power is reaching the rest of the circuit. If it were an electrolytic cap, I would suggest maybe it has dried out in the past 35 years, as they can do. But the cap is .047uf, and usually plastic.

So something is amiss with the switching, but just what I can't tell.

[alexradium]

if its from 83 maybe its time to revamp the electrolytic caps first,shouldn't make it worse.

[tubula]

Thanks. So, when you say ''But the cap is .047uf, and usually plastic'', does that mean you're doubting that it is the culprit?
Are you saying it won't dry out? Can't old caps go bad anyway? I'm asking, not suggesting. I don't know.
Also, is the value .047 a factor? Just trying to understand.
Thanks!

[tubula]

if its from 83 maybe its time to revamp the electrolytic caps first,shouldn't make it worse.

By revamp, I'm assuming you mean replace. (?) I don't mind attempting that, just don't want to do it if it's not a likely culprit...
but maybe it is. I don't know much about 'pedal workings' (obviously, lol) .

[tubula]

The dry/clean path remains on all the time in a folded-steel-box Small Clone, whether in effect or bypass mode. The footswitch turns on a FET that allows the wet signal to pass and be combined with dry to create the effect. The circuit that turns the FET on has a small-value cap to ground that slows the turn-on just the tiniest bit, so that it doesn't produce a click. If you continue to hear the clean signal, then that means the power is reaching the rest of the circuit. If it were an electrolytic cap, I would suggest maybe it has dried out in the past 35 years, as they can do. But the cap is .047uf, and usually plastic.

So something is amiss with the switching, but just what I can't tell.

I replied in another post without quoting...so I'm replying again w/ a quote....see other post. Thanks.

[Mark Hammer]

Electrolytic caps can dry out over the space of decades. Plastic caps are generally immune to drying out.

On the other hand, when something takes a while to happen, that often recommends considering one or both of two things: a) something with respect to the charge-up time of electrolytic caps, and/or b) something that happens because of heat buildup.

Last year, I repaired a buddy's pricey analog delay. He had two of the same model, but one of them produced a very audible and annoying whine. I exchanged several e-mails with the tech support person at the company who was very helpful). It wasn't until after several e-mails that I mentioned the whining didn't start until after the unit was on about 5-10 minutes. This triggered a recollection on his part that in an early run of that model, they had received a shipment of defective voltage regulators. Assuming that regulators from a reputable manufacturer, coming from a reputable distributor, would be safe as milk, they installed them, only to find that the heat sinks on them were much thinner than normal. The unit in question used three such regulators, for 5, 9, and 12 volts. He sent me a picture of what to keep my eye out for, and sure enough,oone of the three in the offending unit was just like the picture. I replaced it with a proper-thickness regulator, and the whining problem went away. The three regulators were free-standing, rather than thermally-coupled to anything, so I gather it took a while for enough heat to build up in the "thin" one to make it misbehave, and cause the whining.

That is HIGHLY unlikely to be the cause of your current difficulty, but I mention it to illustrate how sometimes malfunction due to heat can occur in ways we didn't suspect.

I'll assume that the board shown below is the board for your particular unit, and the schematic is too...more or less. More recent schematics show a 220uf cap to ground in parallel with that pair of 56k resistors you see in the left-hand side of the schematic. The 220uf smooths out the overall supply voltage, and the 10uf provides the stability of the floating ground, AKA "reference" voltage. If either of those is somehow "off" you should probably NOT get a decent clean signal at any point. If the clean signal clips very easily, then maybe those could be "off", and needing replacement. If the picture of the board IS your unit, I'm not seeing a 220uf on it, although EHX would often tack on "floating" components on the copper side. So there may well be 220uf on the unseen side.

[tubula]

Electrolytic caps can dry out over the space of decades. Plastic caps are generally immune to drying out.

On the other hand, when something takes a while to happen, that often recommends considering one or both of two things: a) something with respect to the charge-up time of electrolytic caps, and/or b) something that happens because of heat buildup.

Last year, I repaired a buddy's pricey analog delay. He had two of the same model, but one of them produced a very audible and annoying whine. I exchanged several e-mails with the tech support person at the company who was very helpful). It wasn't until after several e-mails that I mentioned the whining didn't start until after the unit was on about 5-10 minutes. This triggered a recollection on his part that in an early run of that model, they had received a shipment of defective voltage regulators. Assuming that regulators from a reputable manufacturer, coming from a reputable distributor, would be safe as milk, they installed them, only to find that the heat sinks on them were much thinner than normal. The unit in question used three such regulators, for 5, 9, and 12 volts. He sent me a picture of what to keep my eye out for, and sure enough,oone of the three in the offending unit was just like the picture. I replaced it with a proper-thickness regulator, and the whining problem went away. The three regulators were free-standing, rather than thermally-coupled to anything, so I gather it took a while for enough heat to build up in the "thin" one to make it misbehave, and cause the whining.

That is HIGHLY unlikely to be the cause of your current difficulty, but I mention it to illustrate how sometimes malfunction due to heat can occur in ways we didn't suspect.

I'll assume that the board shown below is the board for your particular unit, and the schematic is too...more or less. More recent schematics show a 220uf cap to ground in parallel with that pair of 56k resistors you see in the left-hand side of the schematic. The 220uf smooths out the overall supply voltage, and the 10uf provides the stability of the floating ground, AKA "reference" voltage. If either of those is somehow "off" you should probably NOT get a decent clean signal at any point. If the clean signal clips very easily, then maybe those could be "off", and needing replacement. If the picture of the board IS your unit, I'm not seeing a 220uf on it, although EHX would often tack on "floating" components on the copper side. So there may well be 220uf on the unseen side.

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[ATTACH=CONFIG]50943[/ATTACH]

Thanks very much for the detailed response, Mark. Now that you mention it, I think it might have been clipping a little.
It's actually the first chorus pedal I've owned, so I didn't know if this was typical or a weak battery or what. Let me get it out
tomorrow and take a look at it. I'll probably take the board out and take a few photos. Sure appreciate the help!

[Mark Hammer]

A stock Small Clone does not do this, but sometimes people will install bypass switching that turns the battery off when in bypass mode, under the assumption that it will save battery life. Obviously, in a power-brick/pedalboard era, this is much less common or perceived as necessary. However, if someone before you HAD done this, and if the unit DID have the aforementioned 220uf cap, the slow turn-on behaviour would not be surprising at all. Indeed, the time it takes for such caps to charge up again is the principal reason why the practice of switching off the power is recommended against.

But again, that would entail a number of assumptions about your own pedal.