Eventide Instant Flanger

[Ampzone]

Just picked this unit up and it is not working. I have never used or worked on one. On power up LED flickered for a second on initial power up then it was lights out out and there was mild smell of smoke (shut off right then), I noted the regulators were getting very very hot. There are a few tantalums downwind from the regulators so I am going to look there first.

Anyone with exp on these?

schematic
http://img.photobucket.com/albums/v3...ide_contrl.jpg

[Mark Hammer]

Given its age, probably the first step ought to involve replacing the electrolytics in there.

[Leo_Gnardo]

Just picked this unit up and it is not working. I have never used or worked on one. On power up LED flickered for a second on initial power up then it was lights out out and there was mild smell of smoke (shut off right then), I noted the regulators were getting very very hot. There are a few tantalums downwind from the regulators so I am going to look there first.

Anyone with exp on these?

I'd suspect any and all old tantalum caps as well as the any other style electrolytics. Replace 'em all, & you can use affordable electrolytics instead of Ta's. Hopefully the fuse blew before any major damage. I put in this answer yesterday and it mysteriously disappeared. How that happen? WOops no it didnt - now I see you posted same question in 2 categories. In the future please just one, I'm sure you will get you good answers and prevent time wasting like I just did. Mild smell of smoke now coming out of my ears.

[Ampzone]

Hey Leo, thanks for chiming in. Well I found 3 bad tants and replaced them, one was smoked. I had a bag of good high grade Panasonic 3.3uf caps 50v that were perfect and the Flanger uses all 3.3uf 25v tants save one or two. I have replaced about 6 so far as some had drifted as well. There maybe 15 more still there that read good on the cap meter.. I did find a totally burnt 10ohm resistor which I replaced as well. After all of this it powers up and I can switch the circuit in and out with the "line" switch. "doppler" makes it louder but no flanging to be had.
OSC light does pulse so now I am puzzled. At least we no more smoke and it it alive. PS caps are good as well.

So now why will it not flange?

[Mark Hammer]

Hopefully it is not due to any smoked BBDs. Posted schematics do not show which BBD it uses, though I'm guessing one of the Reticon chips. Could you maybe tell us what's in there?

[Ampzone]

Hi Mark, check these pix

mode zero - phase shifter phaser flanger chorus delay vintage effects photos mp3 demos some pictures...note the removable card has two 10ohm and two 470ohm resistors in the middle by the pinouts. The top 10ohm was cooked (now replaced). Should i just shotgun all tants with the 3.3uf panny caps?

[Ampzone]

Card pix...the red circle was the burnt 10ohm.

more pix
http://www.modezero.com/instant_flanger.htm

[Leo_Gnardo]

Should i just shotgun all tants with the 3.3uf panny caps?

Yes, before they go bad too. Once you get your prize working it will be decades before you'll have to worry about that again. Who needs a "time bomb" in their gear?

At this point the LFO works presumably, that's what gets the light blinking and sets the period of flanging whoosh. Is the unit passing audio at all? IIRC it does not mix the modulated signal with dry, you have to do that externally at the mix console. And if you don't mix them together you don't hear the flange effect. Since the time delay involved in flanging is so short, a couple milliseconds at most, you may be hearing the modulated signal alone & not realizing it's working as it should. That was one of the PIA factors in Eventide, mixing not done within the unit. OTOH circuits on cards makes for much easier repair & maintenance so we'll forgive them.

[Ampzone]

Yes, before they go bad too. Once you get your prize working it will be decades before you'll have to worry about that again. Who needs a "time bomb" in their gear?

At this point the LFO works presumably, that's what gets the light blinking and sets the period of flanging whoosh. Is the unit passing audio at all? IIRC it does not mix the modulated signal with dry, you have to do that externally at the mix console. And if you don't mix them together you don't hear the flange effect. Since the time delay involved in flanging is so short, a couple milliseconds at most, you may be hearing the modulated signal alone & not realizing it's working as it should. That was one of the PIA factors in Eventide, mixing not done within the unit. OTOH circuits on cards makes for much easier repair & maintenance so we'll forgive them.

Leo by god you may be right, Yes I am getting signal to pass after replacing a dozen caps and one resistor, and as you say I can go ahead and shotgun the rest. I will try and mix the dry with the unit and see what gives.
Does this dry signal mixed with the output of the unit apply to the Instant Phaser as well?

[Ampzone]

And just to confirm, IYO was there any "tonal" footprint the Tants were adding opposed to the 3.3uf panny 50v caps (which I just t had a whole box of thank God)?. There were about 25 of them to start but now another 15 or so to go.

[Ampzone]

That would be a negative mixing the two signals. I do not when nothing is running through the flanger output is making a hissy swooshing sound that does chage when you adjust the osc rate knob. however this does not seem to do anything with the signal. It actually makes the bass cone pump in and out when I turn up the studio monitors (with no signal running) it just pumps the bass cone.

[Leo_Gnardo]

Does this dry signal mixed with the output of the unit apply to the Instant Phaser as well?

Yes I believe so, and the phaser delay is even shorter than the flanger, on the order of 1 millisecond. ALSO their harmonizers at least up to the 969. For instance the output of the 910 harmy by itself sounds awfully "bitty" but can add a beautiful "dimension" when dialed just a tiny fraction off pitch and added back to the original signal.

Many of the tantalums are power supply local on-board filters, no audio "footprint". Any used to pass signal, I think you're better off with electrolytic and you could select non-polarized ones if you like.

I don't know why but it's apparent some of the modulating signal is sneaking out. I'd punch in a hi pass filter on the mix channel if there is one, or roll off the bass. Flange isn't much apparent on low frequencies anyway so nothing will be lost by losing the lowest frequencies through the flanger.

I'm still not sure from your answer whether the flanger is passing audio through.

[Ampzone]

Yes I believe so, and the phaser delay is even shorter than the flanger, on the order of 1 millisecond. ALSO their harmonizers at least up to the 969. For instance the output of the 910 harmy by itself sounds awfully "bitty" but can add a beautiful "dimension" when dialed just a tiny fraction off pitch and added back to the original signal.

Many of the tantalums are power supply local on-board filters, no audio "footprint". Any used to pass signal, I think you're better off with electrolytic and you could select non-polarized ones if you like.

I don't know why but it's apparent some of the modulating signal is sneaking out. I'd punch in a hi pass filter on the mix channel if there is one, or roll off the bass. Flange isn't much apparent on low frequencies anyway so nothing will be lost by losing the lowest frequencies through the flanger.

I'm still not sure from your answer whether the flanger is passing audio through.

I was out of town but now back. The unit when turned off will not pass signal, when turned on it will pass signal. The line switch when engaged will allow the "doppler" section controls to make the signal louder. Other than that the oscillator light is pulsing and there is low pumping sound and hiss that pushes the speakers in and out when when the LFO knob is adjusted. Otherwise no effect when mixed with original signal.

Hmmm