ibanez ad-80 problems...

[marrstians]

ok... i've finally got the beast working... but there's a few weird problems... first one; when i turn up the "mix" knob all the way my original guitar signal leaves.. i just get the delay signal... second one; the repeat knob seems to go from a littlw effect to alot... maybe a dirty pot? i see that there's a bunch of trim pots on the inside of the pedal... would i mess anything up by turning them...? i just don't want to blow the bbd in it....

[Mark Hammer]

This is a good set of questions.

"Mix" controls can vary in delay units.  In some cases, the Mix control just sets how much delay signal is added to a straight signal whose level is fixed.  Very often the manufacturer will have two output jacks, one for dry only, and one for wet only, wired up so that if you use only one jack they two signals get mixed.

In other cases, and this tends to be more true of single-output-jack units in my experience, the Mix control is essentially a panpot that gives a wet/dry balance in the middle, more wet than dry to one side, and more dry than wet to the other.  Here, the capabilities of the Mix control are harmonized with the jack complement.  Putting the two approaches to design together, if you can get it with the jack, then you don't need the contro to get it, and if you can get it with the control, then you don't need the jack. (the "it" being a delay only signal).

So, the functioning of the Mix control may not be a sign of anything problematic, merely how this unit works.  Ofc ourse I've never played one so you may just be able to fill up your hot air baloon here.

As for feedback, it is common for delay units that have any sort of feedback control (flangers, echo) to have a trimpot which sets the maximum amount of regeneration.  There is a critical point where regeneration will break out into irritating howling.  On the other hand, you want to be able to get as much feedback as you can possibly achieve, and have that in reserve.  the trimpot is set to that point JUST before it breaks out into howling.  In your case, the trimpot may have drifted.  Not to worry.  Just set the regen control for max, and adjust the feedback trimpot so that you hear the howling, then trim it backa bit so the howling just stops.  The trimpot will likely NOT be the one immediately adjacent to the BBD.

Adjusting trimpots inside a delay pedal will NOT damage anything. It may screw with your sound so that you have to fiddle around a bit to restore things, and it may blow your ear drums if you have your amp on too loud, but it will not blow up any chips.

[marrstians]

as always, you are awesome... thanks for the info...

[Nasse]

:? I think my Ibanez delay has a trimmer that trims the clock range. I messed with it (I was greedy to push the delay time just little longer) and maybe I have a little overdo on that, there is clock feedtrough when delay time maxed. But really I have not messed with it for years

***EDITED***

when i turn up the "mix" knob all the way my original guitar signal leaves

Could it be how it works, if you have 50/50 mix at the middle position, and delay only at max? I must try to fix my pedal and try how it works, dont remember but something rings a bell...

Just opened my AD-80 and found this (if anyone not interested dont read)

Thereis five trimmers named CLOCK, REPEAT, BIAS, LEVEL, BAL

chips NE570N compander, MN3101 MN3005 clock and bbd, and what looks like an opamp, maybe TLo22 or somethin, lots of transistors and components stuffed in small size, nice job, one mystery component to me looking like big black plastic transistor but five legs, text C1583 OZF

I might try to fix my AD-80 later today, only some battery leads broken and few wires looking suspicious, it should work

[marrstians]

here's the schematic for the pedal... it helped me a little... a layout probably would have helped more cause i had some broken traces on the pcb... but now it works...

http://www-public.rz.uni-duesseldorf.de/~pelz/schematics/Ibanez_Analog_Delay_AD80.pdf

[Eddie]

I have the Ibanez UE 405 unit.
I would like to dial in the delay dry/wet mix easier because I like the delay in front of the amp with preamp distortion. Thats why adjusting the mix pot is hard, every slightest pot movement causes a lot more /less delay mix.

What can I do?

Could I adjust the internal Balance trimpot (does it control the wet/dry mix?)?

Or should i insert a resistor in front of the 50 kohm wet / dry mix pot?

Thanks for help! I´m a bit frightened to change the trimpot settings...


Eddie

[Nasse]

:? Just did a quick look at the circuit and I believe that "balance" trimmer does not control what you suggest, it is some kind of distortion nulling/trim-off for that BBD chip, maybe some info is available  dunno. But if I am right some BBD project suggested using oscilloscope to adjust that kind of trimmer...

There is not much room in the Ibanez case but maybe you could mess with that pot controlling wet/dry balance, like connecting a fixed resistor(s) to the end lugs to make the available "range" smaller, maybe you have to replace the pot with another value then...

[fluxus]

Hello, I made this web page with some AD-80 informations and pictures  if could be useful....

http://www.sonicurbs.com/ibanezAD-80/index.htm

[Dan N]

one mystery component to me looking like big black plastic transistor but five legs, text C1583 OZF

2SC1583- A matched NPN transistor pair with common-emitter.

Interesting, not in the schematic. My Ibanez Delay Champ has a dual transistor in the clock circuit. Yours must be in the switching, unless Ibanez really changed things from the pdf.