Full Tone Deja Vibe not "Vibing"

[MikeH]

Been a while since I've been on here; I've actually turned my focus onto building guitars at the moment, but it feels good to be back.

So my Deja Vibe just went kuput on me... Still passes signal, just no effect. The volume control still works when the effect is engaged and I can hear the relays clicking on and off when I move the rocker, so I don't think it's that. I popped the photocell cover and the LED is not lighting up. What are the chances it's a bum LED? I would think not very likely, and that the culprit lies in the oscillator. Any advice as to how I should approach diagnosing this monster?

[kaycee]

You could put a known working LED legs against the legs of the suspect one, as long as the existing one isn't shorting you may see it flash and that will let you know if the LFO is working at least.

[MikeH]

That was a good idea; when I put another LED against the contacts it lit up. Bad LED. Go figure.

Anyone have any idea what color LED I should replace this with? I'm assuming white, but I want to be sure.

[PRR]

White LEDs are expensive, need lots of voltage, and Red works perfectly well for photocells.

[duck_arse]

over at perkins-elmer, they say the spectral response of their ldrs is most closely matched by orange leds. there is a big catalouge of their stuff lurking somewhere on the webs, full of inneresting opto info.

[deadastronaut]

ive heard yellow was ideal....kind of orangey..

[PRR]

> spectral response of their ldrs is most closely matched by orange leds

My experience is that if you put the LED right AGAINST the LDR (or within 2mm), you get TONS of response with red.

Don't try this: put a well-powered LED right against your eyeball. Across the room it may not be bright, but UP-CLOSE it sure is. Will possibly burn your retina (and trust me, you'll have enough old-eye problems without such abuse). Inverse Square Law is applicable. (Though I just read a book had me questioning ISL.)

[Liquitone]

Are you sure it is a LED? I always assumed these used  'Incandescent Lamps' ;
http://www.banzaimusic.com/Incandescent-Bulbs/

[MikeH]

I'd never claim to be an expert on anything, but it looks exactly like a 3mm LED, end I've never seen any kind of incandescent that looks like this. I put an email in to fulltone about a replacement, but have not heard back.

[johngreene]

I'd never claim to be an expert on anything, but it looks exactly like a 3mm LED, end I've never seen any kind of incandescent that looks like this. I put an email in to fulltone about a replacement, but have not heard back.

I'm pretty sure it is an incandescent bulb. Just like the Univibe.

[Liquitone]

On the Fulltone site is says;
The Bulb: Getting the correct Voltage rating on this is no big deal, but does size really matter? Yes, but don't look at the size of the Glass, look at the size of the Filament (wire inside the glass)! We got it right.. And this is crucial to achieve the correct amount of brightness... it also has to flash consistently at all speeds. Our does.

Seeing the dejavibe is Fulltone's take on a vintage correct Uni-Vibe I can't imagine anything else being used than a lamp and not an LED, also the gut pictures show a lamp.
Did you buy it new or used? and can you post a picture of yours? If you bought it used the lamp may have been replaced with an LED.

[MikeH]

Upon closer inspection I think it is an incandescent bulb, but it is literally the exact   size and shape as a 3mm LED. Either way, Fultone refused to tell me what to replace it with. Refused to even discuss it with me, all they said was "ship it to us and we'll fix it".

[Liquitone]

hmm, sounds like paranoia for reverse engineering... I guess having a replacement lamp shipped to you so you can fix it yourself is not an option then either.
I have tried a number of different voltages and mA ratings, In my last 2 vibes I used 24v 40mA, which where bigger than 5mm LED's even. my Vibes both run on 24V, and I think the Fulltones run at 18V? (R.G. mentions 28V 40mA in most of the original Uni-Vibes he's repaired)
I noticed these big 24V ones I used are a bit difficult to dial in right, in the way that; when adjusting it to the right 'off' state the vibe lacks a bit of the intensity it should have on higher speed settings.
In my Tremolo I replaced that same 24V 40mA for a smaller size (about the size of a 3mm LED) 15V lamp which gave a lot more response, I think a lot of Vibes out there use 12-18V lamps so those might work better for you.
I do not know if the physical size of the lamp has any influence on the response, just that the smaller lamps coincided with lower voltage ratings on the ones I had.
Incandescent bulbs aren't that expensive, so you could order a bunch with different voltage ratings ranging from 12v to 18V and 20mA to 40mA and just try them all out to see which one sounds best.