MXR Analog Delay schematic?

[JRobinson]

Sorry if a link has been posted before, but I can't find one. I tried looking at all my bookmarked pages and google, but no luck.  I got a broken one dirt cheap, so if anyone can asisst, it'd be appreciated.
Jodyrobinson@hotmail.com   thanks!

[BillyJ]

It is for sale here..
:cry:
http://www.schematicconnection.com/store/asp/prodtype.asp?prodtype=66&ph=cat

[JRobinson]

Yeah I found that one, too!
But the board # isn't the same as mine. Mine has a potentially blown Reticon 5101. I know these also came with an SAD124. If I can't find a schem I might see if Analogmike has one for sale.

[ExpAnonColin]

Funny thing abuot MXR delays... broken ones keep popping up on ebay and selling for like $60 while the non-broken ones sell for $150 or so.  Normally the difference is much greater...

Oh well, I'm interested in a schem too, if anyone finds one.

-Colin

[JRobinson]

I got the auction for the broken MXR and boss dm3 delays, plus a jordan comp and a KMD comp. The DM3 is just about working (getting delay signal, needs to be tweeked) and I stripped the two comps for the cases, both are heavy duty aluminum, in fact the Jordan case appears to be the same as the old Maxon metal switch effects (pre square TS808 type). I went out on a limb and bid $110 for the lot, I'm hoping the Reticon chip isn't blown. I figure if i get one of the delays working, it was worth the $.

[ExpAnonColin]

If you're going to try to fix the pedal, and can't get a schematic, I highly highly recommend getting a datasheet for the BBD...  often this can be very helpful, because the pedal is BASED on the thing.

-Colin

[mattv]

AE,

Where can one procure such a datasheet? :wink:

[ExpAnonColin]

AE,

Where can one procure such a datasheet? :wink:

I'm assuming it's a SAD1024, although I'm not sure at all-in any case, you can probably find it in http://www.synthdiy.com/

-Colin

[JRobinson]

The one I've got has the Reticon 5101 BBD. I don't have any of the specific reticon BBD datasheets, but I have a reticon "how they work" infosheet, courtesy of Mark Hammers BBDemantia.
  I've got an OK understanding of BBD chips, and though the MXR works along the same lines, the support cicuitry  is not like most analog delays. It has  variable filtering, somewhat similar to the variable filtering in the MXR envelope filter if I recall. Basically, as you turn the delay time down (shorter delays), the filtering eases up allowing better fidelity, since at shorter delays, the clock freq. is moving up higher and not bleeding into the audio spectrum as much. At longer delay settings, the filtering increases, so the low freq of the clock required for long delays doesn't bleed in to the audio spectrum.
  Anyhow the DM-3 is coming along, I've got the delays showing up on the 'scope, but I'm not getting any delay out, It seems to be getting lost around the compander. Hopefully I can mess with it more tomorrow.

[ExpAnonColin]

It has  variable filtering, somewhat similar to the variable filtering in the MXR envelope filter if I recall. Basically, as you turn the delay time down (shorter delays), the filtering eases up allowing better fidelity, since at shorter delays, the clock freq. is moving up higher and not bleeding into the audio spectrum as much. At longer delay settings, the filtering increases, so the low freq of the clock required for long delays doesn't bleed in to the audio spectrum.
.

The DMM does this as well, at least as far as I can tell via ear.

-Colin

[ExpAnonColin]

Ah, the R5101... Very very hard to obtain, equally as hard to get information for...

-Colin