Help. What's wrong with my vintage DOD?

[scubaduba]

The led is acting strange. See this link. LED lights all the time. Pressing pedal once and no led change. Pressing pedal again and LED goes off for a moment and then back on. Pedal activates on/off normally but what's going on with LED?

 

[Sunset Shalom]

Check inside for loose wires perhaps? If the pedal works fine maybe the LED is starting to break or something.

 

[bongomania]

There may be a broken solder joint causing this fault. The LED depends on voltage at one side dropping or raising when you hit the switch, so if the voltage at that point stays above or below the threshold, the LED won't work right--even if the LED itself is not broken, and even if the rest of the pedal works more or less normally.

 

[scubaduba]

I've looked the insides over. Nothing loose and all of the solders look great. I'm getting a bit of a popping when activating/deactivating too. Maybe a new switch is needed?

 

[Spidey2112]

Is the pedal programmable? How old is it and when did it start?

 

[scubaduba]

Programmable? No. This is a vintage 1984 DOD FX10. It's done this as long as I've had it. I'm realizing that is not right though. At least I don't think it is.

 

[Sunset Shalom]

Programmable? No. This is a vintage 1984 DOD FX10. It's done this as long as I've had it. I'm realizing that is not right though. At least I don't think it is.

Well if it has been happening for years at least it isn't getting worse, might just be a weird design flaw or something.

 

[Spidey2112]

I saw this, thinking I hit the motherlode, soon realizing it was you who posted it on a different forum...

"I have an old FX10 and the LED stays on all the time. Is this normal? If flashes once when I switch it off but then stays on. I'm powering it with a CIOKS DC5 with 9 volt 100ma port using a 3.5mm pin center positive connection."

The LED is just a visual output... as long as the pedal is functional, I'd leave it. Unless you have a schematic, that is...

... probably the switch, since they take the most abuse on any and all stomp boxes.

 

[Spidey2112]

Looks like a momentary type switch. If you press and hold the switch down, does the LED stay off?

 

[scubaduba]

First tap which engages the pedal the led doesn't flash. It just slightly dims. Tap again to turn pedal off the led flashes off and then turns back on. With this second tap you can hold the button down and led will stay off until you release.

 

[Spidey2112]

When it rains, it pours... another member had a similar 'problem' (different device), recently.

What's interesting is the dimming of the LED, for 'ON', and fully lit, for 'OFF'... almost like the IC controlling the LED is doing the exact opposite of what it should... have you contacted the manufacturer of the pedal, yet? If the IC is socketed (which controls the LED), it would be a cheap fix... as long as you respect the Antistatic Law of 1910....

 

[D.A.R.K.]

I've had this happen to older DOD envelope filter pedals before, it was indeed the switch.

 

[Mosfed]

Well if it has been happening for years at least it isn't getting worse, might just be a weird design flaw or something.

It’s not.

Something is up with the pedal for sure.

 

[Calvera]

There is momentary microswitch inside, which needs to be replaced. I had to do it twice with my DOD FX62 Bass chorus. (During 28 years, though).
Very easy and cheap repair.

 

[scubaduba]

Tell me more. Where do I get the switch?

 

[TWood97]

I think it could be the switch, I have a DOD stereo chorus (FX65?) from the early 80s and the switch is very finicky, when it comes to turning on and off, to the point I've debated putting it in a loop. The later pedals like the distortion I've got have much better switches.

 

[scubaduba]

I'd be happy to try a new switch. Does DOD have them?

 

[Calvera]

When you remove from the top side 2 (or 3) screws, holding the switch cover, you will see the switch, which looks like 6×6 mm silver plate with small black button in center.
Desolder it and replace with new piece.
Here in Czech republic is possible to buy one piece for near to nothing. You can try some shops with electronic parts.
Or I found this set, if you don´t mind to buy 25 pcs when you need only one.
25X Tactile Push Button Switch Tact Switch 6X6X5mm 4-pin FREE SHIPPING US SELLER | eBay

I actually repaired it, but I put it in true bypass loop anyway, as I use it rarely and FX62 is tone sucker.

 

[scubaduba]

Thanks. The button on the old FX10 is different than the ones at the link. All black box with button that is flush with rest of box. I don't see any online. I'm going to contact DOD.

 

[flowmastergfunk]

Stumbled across this old thread, and I almost hate to dig it back up...but I have seen this problem often while restoring old DOD's. If your LED is always on, but the effect itself turns on and off...IT'S NOT THE SWITCH! The tact switch is merely a trigger for the buffered switching circuit. If you have a fancy power supply, feed your DOD's 12v DC. The original PSU was 10v, not 9v...so they do not complain having a little bit more juice (don't step up to 18v on the fx series though). Just yesterday, I went to test a pedal with battery power (measured 8.6v)...pedal worked as it should, but LED would not switch off. Hooked it up to 12v, and it performed flawlessly.

I think some of these old transistors and IC's need that extra kick to keep them going. Definitely feed it 12v before looking for problems. If that fails, The LED is usually switched over by a 2n5088, which is fairly easy to replace compared to the IC. And be careful opening these up...the wires like to jump right off when you look at them!