Soldano SLO LDR location

H

halebox

Active member
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Hi there, do you know location of VR2? I believe that's the one I need to change. I labeled the black square ldr's 1-4. I don't know schematics but can do basic stuff. I ordered the parts but looks to be an ordeal to pull the board off. I may just clip legs of old one and attach to those. I believe the dirty channel is leaking into the clean causing weird ring mod type sounds at low volume but goes away when turned up. I know its normal for the clean to leak into the lead channel but not the other way around.
 
I'm not certain but I believe you have them exactly reversed. In other words, your 1-2-3-4 is actually LDR4-LDR3-LDR2-LDR1. But LR1 and 2 might be reversed (just because LDR1 is closer to the ground trace). LDR2 is one of the two on the right. Just look for the one that does NOT have one of it's signal legs grounded (LDRs have two signal legs and two switching legs to turn it on/off). The one with the grounded signal leg is LDR1. Which brings up the next issue.

LDR1 is there to shunt the Lead channel signal to ground when in Crunch/Clean mode. So if it is working, there shouldn't be any lead signal to bleed back into the Clean. If you have a multi-meter, you can easily check this by checking the ungrounded leg on LDR1 to ground while the amp is on (it can be on standby for this). Now switch channels back and forth and you should see that leg go from 0ohms to 'no connection'.
 
It's the one you have labeled 3.

Before you do the replacement pull V2 (second 12ax7 from the input jack) fire up the amp and see if the problem still exist.
BTW the clean and crunch should still work with v2 removed, OD channel will not.
 
CrazyNutz":2fg94uwr said:
It's the one you have labeled 3.

Before you do the replacement pull V2 (second 12ax7 from the input jack) fire up the amp and see if the problem still exist.
BTW the clean and crunch should still work with v2 removed, OD channel will not.
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I pulled v2 and clean was normal no weird sound. I added v2 back and the sound came back (with the pre normal vol 5 or less) above 5 the sound goes away. Then I swapped out v2 for another tube and it seems way less (noticeable at pre volume 2 or less) above vol 2 weird sound would start to dissapear. Could it be a preamp tube? I believe I swapped them all out for others and same thing happened.
I returned the batch or LDR's I got on eBay as they looked like funky pulls with solder on short legs. They were sold as NOS. New ones coming in from antique electronics.
 
halebox":2nynbjd3 said:
CrazyNutz":2nynbjd3 said:
It's the one you have labeled 3.

Before you do the replacement pull V2 (second 12ax7 from the input jack) fire up the amp and see if the problem still exist.
BTW the clean and crunch should still work with v2 removed, OD channel will not.
Click to expand...

I pulled v2 and clean was normal no weird sound. I added v2 back and the sound came back (with the pre normal vol 5 or less) above 5 the sound goes away. Then I swapped out v2 for another tube and it seems way less (noticeable at pre volume 2 or less) above vol 2 weird sound would start to dissapear. Could it be a preamp tube? I believe I swapped them all out for others and same thing happened.
I returned the batch or LDR's I got on eBay as they looked like funky pulls with solder on short legs. They were sold as NOS. New ones coming in from antique electronics.
Click to expand...

Yeah I would definitely buy new LDR's. Your problem could also be the switching filter cap, its that long silver cap. How old is your amp? To test you can parallel another 1000uf 25-100v cap (use alligator clips to clip onto existing cap leads) If your problem goes away you need to replace that cap.
 
It's a 2003 and caps look fine and not bulging. I'm not an electrician but can do basics. I'm going to swap out that ldr VR2 from the top of board. Just clip legs and attach and solder new one. Is that silver cap deadly? Can you tell me where not to touch? I always thought it was caps. I know things can hold charge even unplugged
 
halebox":261xn0se said:
It's a 2003 and caps look fine and not bulging. I'm not an electrician but can do basics. I'm going to swap out that ldr VR2 from the top of board. Just clip legs and attach and solder new one. Is that silver cap deadly? Can you tell me where not to touch? I always thought it was caps. I know things can hold charge even unplugged
Click to expand...

The silver cap is not deadly. However I strongly encourage you to ground out the positive+ leads on all the other caps (the blue ones).
 
Ok LDR 1 and 2 replaced....that wasn't problem, should I do 3 and 4?...I want to order the silver cap I'll look in ebay unless you have a link.
 
halebox":29jt6w3n said:
Ok LDR 1 and 2 replaced....that wasn't problem, should I do 3 and 4?...I want to order the silver cap I'll look in ebay unless you have a link.
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No. 3 and 4, just switch the active volume pot od volume, or norm volume.

I would piggy back another cap on the sliver cap to see if that help.

Also you have some non-stock mods going on, I can see, they do not look official, could be problematic too.

And have you tried replacing v2 with a new, or known good tube?
 
I tried replacing tube and they all make the sound I'm talking about some more some less. It has an great sounding egnater tube loop with a level that becomes a global master. The problem persist with that loop on or off. At realistic volumes this weird sound doesn't even happen and dissapears but when I turn down at home I can hear it. Maybe I should just leave it. I don't even use clean live. I use crunch but I'm a bit obsessive and like to fix things

1000uf 16vdc 500d sprague....
Does it have to be exact?
 
halebox":wkgy3eky said:
1000uf 16vdc 500d sprague....
Does it have to be exact?
Click to expand...

Any 1000uf 16vdc or more will work. you don't have to remove the old one to test, just use clip leads to parallel the new one in.

You may have some oscillation issues. Use a chopstick to poke around, and move wires around. See if the noise becomes more, or less. This can fix, or give you an indication of what is problematic.
 
That will probably work fine to test. However I would not use NOS electrolytic capacitors. They can dry up just sitting on a shelf.
 
Ok installed new cap and was great for a bit then I put back in headshell and it started again. So i opened up again and did chopstick test. I got confident and replaced chopstick with hand and I got shocked! But I think I found out what it was/is. Its associated with the blue and white wire that goes to the footswitching jack. I noticed the white wire looked like it had a possible sever close to jack area. I shortened it and reattached. I hope that was it. But I swear it sounds better than ever after that cap swap, am I trippin?
 
halebox":262qvcu5 said:
Ok installed new cap and was great for a bit then I put back in headshell and it started again. So i opened up again and did chopstick test. I got confident and replaced chopstick with hand and I got shocked! But I think I found out what it was/is. Its associated with the blue and white wire that goes to the footswitching jack. I noticed the white wire looked like it had a possible sever close to jack area. I shortened it and reattached. I hope that was it. But I swear it sounds better than ever after that cap swap, am I trippin?
Click to expand...


:LOL: :LOL: [SCOLDING] Welcome to the 500v club! That'll teach you a lesson huh? I've been zapped several times, but do not take it lightly. If you have one hand grounded, and the other hand takes the jolt YOU ARE POTENTIALLY SENDING 500v across your heart, it can instantly kill you. You got lucky. :gethim: [/SCOLDING]

That whole switching circuit can have a effect on the tone. If its not working right, then the LDR's are not going to be stable, and/or at the correct values. LDR = "Light Dependent Resistor" which means the switching circuit illuminates an LED in the LDR, and a photoresistor in the LDR changes value based on how bright the LED is. Just imaging a resistor in your signal chain at the wrong value, or resonating at 60hz, etc.

Anyhow, you should check the footswitch jack a little closer. That jack to the chassis is the only path to ground the switching circuit has. I suggest you take the jack out of the chassis hole, use a bit of sand paper, or sharp knife and clean the chassis where the jack makes metal to metal contact. Put it back in and get it nice and tight (dont break it off, i've seen that before).
 
Yeah I've been shocked before. Once almost died. I rigged up a strobe lite to work with a footswitch. Don't know what I did but I grabbed both and was stuck to it while the strobe was going. I let out a weird death scream and fell and luckily I got separated from it.
Regardless SLO is working proper and does sound even better than before. Thanks for the help. Saved some repair money. I'll be more careful next time I open an amp
 
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