MN3205 vs V3205; why won't my delay work

Forum dedicated to helping people debug and troubleshoot non-functional pedals or builds. Please use an clear and informative title, indicating circuit and basic problem. Don't forget to mark the issue as fixed if this is the case.
Post Reply
User avatar
Bernardduur
Transistor Tuner
Information
Posts: 1219
Joined: 24 Aug 2007, 07:36
my favorite amplifier: Welagen - ODR
Location: Losser.........
Has thanked: 94 times
Been thanked: 735 times

Post by Bernardduur »

Hi all!

I have this old Pearl AD-08 that uses a MN3205 and a MN3102. It broke like a month ago without any real issues.
Upon inspection all seemed to function except for my MN3205. I scope the signal up to the input of the BBD where it disappears.

I tried it with a V3205 without succes. The BIAS setting makes no difference. No signal comes from the BBD.

I tried it with a BL3208 (because I have some laying around) and that works.

Do I need to buy a MN3205? Is there any difference between a MN3205 and a V3205?

Attached is the schematic
Pearl - AD08.JPG
'No more....... loud music.......'
Follow my love for pedals and amps on https://bernardduur.blogspot.com and https://www.instagram.com/bernardduur1

User avatar
Dirk_Hendrik
Old Solderhand
Information
Posts: 4193
Joined: 03 Jul 2007, 08:44
Location: Old Amsterdam
Has thanked: 232 times
Been thanked: 888 times
Contact:

Post by Dirk_Hendrik »

I used V3205's without a problem in the past. I couiild be your V3205 is broken. BBD's are very vulnerable to ESD.

And.. the signal flow in your schems contines to amaze me! :mrgreen:
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

User avatar
Siro78
Information
Posts: 19
Joined: 02 Sep 2009, 07:28
my favorite amplifier: Crate VC5212
Location: Parma Italy

Post by Siro78 »

I know that v3205 work with limited power supply like 7V.
Try limiting V+2 at 7V if it start to work.
Bye

User avatar
allesz
Cap Cooler
Information
Posts: 523
Joined: 15 Jun 2009, 16:29
Location: Italy
Has thanked: 41 times
Been thanked: 97 times

Post by allesz »

I agree with Siro: coolaudio bbds are no good for full 9V supply.

User avatar
Bernardduur
Transistor Tuner
Information
Posts: 1219
Joined: 24 Aug 2007, 07:36
my favorite amplifier: Welagen - ODR
Location: Losser.........
Has thanked: 94 times
Been thanked: 735 times

Post by Bernardduur »

Siro78 wrote:I know that v3205 work with limited power supply like 7V.
Try limiting V+2 at 7V if it start to work.
Bye
Thanks!
I tried limiting it by adding back the 100R resistor on the ground of the adapter jack. I removed that one because it worked on a 'standard' battery for years and that battery gave me more then 9V.
Afterwards it worked like this for approx 6 years :)

I've added that 100R resistor back but still the unit would not function. No sounds from the delay line. I now tried it with 2 more v3205's to make sure I wasn't killing them.

In a last resort I replaced all power ELCO's and replaced all ELCO's around the BBD. They were replaced around 6 years ago when I was busy modding this pedal (TB, less noise, etc).

AND YES, IT WORKS AGAIN. Also the 'old' v3205's I still had in my parts bin work. I'm pretty happy :) Dunno why the ELCO's went bad..... measurements are all normal.
'No more....... loud music.......'
Follow my love for pedals and amps on https://bernardduur.blogspot.com and https://www.instagram.com/bernardduur1

Post Reply