ibanez SD9 problem

[Diamond Fur]

i have an ibanez SD-9. when the pedal in bypassed (off) there is a weak lofi fuzz sound thats almost inaudible and nothing else. when the pedal is engaged (on) it works as normal and sounds great. what's the problem and is it an easy fix? i can solder but don't know how to find the problem.

[ampdoc]

I believe that box is a true by-pass, which would make me suspect the foot switch first.

If you can get to the foot switch from inside the unit, try putting a drop or two of WD40 on it, let it soak in a bit, then switch the hell out of it for about a minute.

See if that does anything.

It's a double pole single throw switch.
You can check it with an ohm meter.

[Diamond Fur]

thanks mate, but it didn't work. i've tried resoldering all the contacts on the jacks but still no luck. i'll take it to a repairer nless you have another suggestion.

the SD9 is like a TS9. not true bypass. big silver switch on the front. there is no problem switcing the pedal on and off. there is no signal going through when the pedal is off.

[ampdoc]

Hey, sorry, the schem. I was looking at was a modernized SD9.

If yours uses a 4558 or TL072 op amp chip (8 pin) it's likely one of the op amps in the chip is dead, but you're gonna need a scope to check that.
Or, if you're a gambling man, replace the IC.

[Diamond Fur]

Dude, you're awesome. i put a LM833 in there cos i didn't have a 4558 lying around and its working beautifully. now i gotta decide if i track down a 4558 chip to put in it or leave the 833 in there cos its sounding pretty good right now.

thanks ampdoc, i really appreciate your help.

[ampdoc]

Cool !

I haven't compared the 833 with the others spec for spec, but I know it's a high bandwidth / low noise device probably as good (maybe better) than the 4558. If it sounds good, leave it in.

Good work guy!

[Diamond Fur]

shit. i plugged it in today and the problem is still there. any other ideas? it was working yesterday.

[ampdoc]

Maybe the IC was not the REAL problem, and your messing with the unit may have unearthed the <STRIKE>actual</STRIKE> cause. You might have the little *$&@* on the run.

I wonder if there's a cold solder problem ?
Try re soldering the IC ?

If you have access to the pc board with the box on, switch it to bypass and using a plastic or wooden dowel press on the pc board in various places and each component to see if there is a change.

If not a physically intermittent problem , you may have a component that's thermally intermittent. Take a hair dryer and heat the board up for a minute or so and see what happens.

If the sound comes back, you're on your way.
It helps to have some kind freeze spray for this so you can bring the suspected components from say 200 degrees F. to below zero C. in a second or two. This usually unearths a thermal prob.

You can make a funnel for the hair dryer out of aluminum foil or an index card to get the heat in a smaller area.

I know this sounds elaborate, but I've cornered a lot of demons this way.
LMK

[Eunice Waymon]

hey ampdoc, this is diamond fur. i changed my username because i had trouble logging into the new forum under diamond fur.

i took the SD9 to a friend who couldn't fix the problem either so i took your advice and found that it is thermally intermittent.

i plugged the pedal in while the PCB was exposed and strumed a guitar and the problem was there. as i heated up the PCB with the hair dryer, the pedal kicked in. i don't have a thermal spray (not really sure what it is) so i then put the pedal in the fridge for a couple of minutes. plugged it in, the problem is back. hairdryer on the board and it kicks in again.

the problem i have is i still don't know which component it is. i've narrowed it down to an area where there is mostly resistors and 1 transister and 3 capacitors. which is more likely to be affected by temperature?

[ampdoc]

Hey Diamond fur;

Nice piece of detective work !

I would suspect the transistor first, the caps second, the resistors last.
but any of them could be the trouble.

Here's what I do;
I use a freeze spray ( you can get a can of compressed air for blowing dust and tip it upside-down while spraying and it will come out very cold)

And I frost the suspected area, then while the pedals on and you're strumming,
I lay the side of the tip of a hot soldering iron and touch the top of the suspect components one at a time and heat them for a moment. Don't melt them !~

If there's a thermal component problem, this test usually exposes it.

It's best to use a 2 wire and not a 3-prong AC wire iron for this as the 3-prong is a grounded tip and you may short out something touching the metal "cans" of the caps.

If you can't get the freeze stuff, your fridge trick may suffice.

You got it on the run now dude,
Let me know....