AD9 bias voltages?

Started by liddokun, September 15, 2008, 09:07:09 PM

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liddokun

Any ideas what the voltages should be for biasing an Ibanez AD9? It's been true bypassed.  I bought it off someone on this forum, and he said the lower repeat settings don't work (no slapback echo) because the trimpots need biasing.  Doesn't bother me too much, but I'd like to have the low delay settings in the future.


EDIT: and for that matter, which trimpot is for which?  There's 4, and I know one each corresponds to the outside pots, and one is bias, but which is which?
To those about to rock, we salute you.

liddokun

To those about to rock, we salute you.

liddokun

I managed to get some time to measure chip voltages today. 

Clock Chip (cool audio V3102D)
1- 7.74v
2- 4.15v
3- 0.5v
4- 4.15v
5- 7.73v
6- 0.59v
7- 6.26v
8- 7.28v

Don't know what chip this is, it's the big one with 16 pins....(compander?) SA571N
1- .97v
2- 1.77v
3- 1.77v
4- 0v
5- 1.77v
6- 1.77v
7- 3.04v
8- 1.77v
9- 1.77v
10- 3.95v
11 3.95v
12- 1.77v
13- 8.57v
14- 1.77v
15- 1.77v
16- 1v

Opamp (has a jrc 4558 in it)
1- 4.26v
2- 4.26v
3- 4.26v
4- 0v
5- 4.26v
6- 4.25v
7- 4.25v
8- 8.54v

These are 3028A chips....BBD I think...there are 2 in the pedal
1- 0v
2- 4.16v
3- 4.88v
4- 7.29v
5- 7.15v
6- 4.15v
7- 4.83v
8- 4.77v

Second one:
1- 0v
2- 4.15v
3- 4.88v
4- 7.3v
5- 7.76v
6- 4.15v
7- 5.41v
8- 5.41v

The delay pedal works fine, the only problem is that I can't a single delay, so I can't get a slapback effect.  Can anyone help me?
To those about to rock, we salute you.

andrew_k

Have you got the schematic that Dirk Hendrick drew up? That'll solve your "which trimpot does what?" query.
Here you go.

Have a go and see if that gets a result. If not, let me know and I'll take voltage readings from my reissue AD9 for you. I'm not good at debugging, but I can provide a working unit for reference.

liddokun

So I basically gave up on this guy for a while, now I'm coming back to it.
The problem is basically that it works, but no single repeat delay, so no slapback. If I turn the repeats pot all the way down, there are no repeats, then if I slowly turn it up, it jumps from none at all to about 5 or 6 repeats.

I'd really like for this to be properly functioning again, the person I bought it from "gluedtogether" told me it's probably a bias problem with the pots, but I can't seem to find that to be the case. I've played with the trimpots a lot, no dice.

If anyone could be kind enough to send me voltages of the trimpots for their functioning AD9?

Or maybe link me to a page that shows me how to true bypass the unit, maybe it was wired incorreclty? I'd like to double check everything.
To those about to rock, we salute you.