Lab Rat Gated on LED Setting

joelorigo

joelorigo

Well-known member
My Lab Rat is sounding gated as a note fades or is gently plucked on the LED clipping selection. It does not do it on the 1N4148 selection. Picking hard it seems normal. It did not do this previously. I don't see anything jumping out at me looking at the guts. Anyone have any suggestions on what the issue is?
 

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I like it too! That LED selection was one of the reasons why I wanted to build the Lab Rat. I mean, I would have built it anyway but...
I have no problem removing the LEDs. I've removed many components successfully at this point. It's just the switch that gives me a little pause.
 
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joelorigo said:
I like it too! That LED selection was one of the reasons why I wanted to build the Lab Rat. I mean, I would have built it anyway but...
I have no problem removing the LEDs. I've removed many components successfully at this point. It's just the switch that gives me a little pause.
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Where did you get the LEDs? Tayda LEDs are dodgy at best. Switches are a little more delicate, but it can be done. Solder wick can help. Suck out the solder and see if you can rock it a little. See what moves and what doesn’t. But don’t take it out just yet.
 
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I really don't think it's the switch.
If you do a resistance check, that's good enough.
Position 1 should be infinite resistance in one direction and a few ohms in the other(lug 1 to 2 and 2 to 3)
Position 2, the same but reversed.
The only way I could see it being the switch was if in the LED position, the internal mechanism contacts have a near intermittent connection. This could be tested by puting light stress on the switch, jiggling the switch lever and thumping/vibrating the switch. Something that would cause a shoddy internal connection to possibly open.
Also try jumpering the relative pins to see it it resolves the gating(1+2 or 2+3, whichever it is). Aligator clips or tack solder a resistor leg across them.
I'd pull the cap and stick a big ass film in there before desoldering the switch.
 
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jwin615 said:
I really don't think it's the switch.
If you do a resistance check, that's good enough.
Position 1 should be infinite resistance in one direction and a few ohms in the other(lug 1 to 2 and 2 to 3)
Position 2, the same but reversed.
The only way I could see it being the switch was if in the LED position, the internal mechanism contacts have a near intermittent connection. This could be tested by puting light stress on the switch, jiggling the switch lever and thumping/vibrating the switch. Something that would cause a shoddy internal connection to possibly open.
Also try jumpering the relative pins to see it it resolves the gating(1+2 or 2+3, whichever it is). Aligator clips or tack solder a resistor leg across them.
I'd pull the cap and stick a big ass film in there before desoldering the switch.
Click to expand...
I agree, it’s not likely it’s the switch. I’ll expand on the Tayda dodgy LEDs. A couple of us have noticed that when a pedal was in bypass, the LED was still dimly lit. It drove me nuts until I found out someone else was having the same issue.
 
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jwin615 said:
Is that the LEDs fault, or dodgey Tayda caps leaking DC...?
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You are definitely not confident about that 10u cap!

The cap and LEDs are easy enough to replace. Even for me! I have more 10u electrolytics but they are most likely also from Tayda. I dont have any 3mm LEDs at the moment however.
 
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Oh, btw, I was getting 1.3 ohms on pin 1&2 and nothing on pin 2&3 in the LED selection. And the opposite in the 1N4148 selection. I am calling pin 1 the upper most one. Does that suffice that it is not the toggle that is the problem?
 
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joelorigo said:
Oh, btw, I was getting 1.3 ohms on pin 1&2 and nothing on pin 2&3 in the LED selection. And the opposite in the 1N4148 selection. I am calling pin 1 the upper most one. Does that suffice that it is not the toggle that is the problem?
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That look good but flip the switch into the other position and repeat.
 
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Sorry that is what I meant.

With the toggle in the LED position:
Pin 1 & 2 = 1.3 ohms
Pin 2 & 3 = nothing

On the 1N4148 position:
Pin 1 & 2 = nothing
Pin 2 & 3 = 1.3 ohms
 
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I picked up a couple of 10u 25v caps today from a local shop. I’m lucky that there’s something like this close by for the times I screwed up in ordering parts. Thought it would be good to not use the caps I already have because I’m sure they are also from Tayda. I’m going to replace C8 and see what happens. If it’s still having the problem I will order some new LEDs. Just to make sure though, C8 is circled in white below?
 

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The T7 says that the ESR is 0.46 ohms and 0.43 ohms. Is that low?

I also noticed that if I kept them in and re-test, the number goes up. After an about a minute they got up to 0.62 and .0.57. Is that normal?
 
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I measured the other 10u electrolytic caps I had in my stash. I found one that had an ESR of .17 ohms and after a half hour .26. That was lower than the 2 I just bought, and it is also not from Tayda. So I pulled the original one and tired it. It still is having the same issue. Maybe it’s a little better.
So, I guess I will or some red 3mm LEDs from Stompbox Parts and pull the current ones. Sound good?

Also, what is low ESR? Are the measurements I got from these caps low?
 
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