MXR Analog Delay

[bioroids]

I'd like to see it too, if you dont mind. I'm trying to implement the MXR filtering on a PT2399 based delay, and it would be nice to see that schem.

bioroids@yahoo.com.ar

Thanks!

Miguel

[TELEFUNKON]

tryin`to do the through-forum-time-warp

[bioroids]

Well the nofify emails work it seems!

[Fret Wire]

Wow! I've been out all day, and the forum looks different . Anyways, Mark had posted links to the MXR & Ross Schematics, so one more time....Thanks to Mark and Mike for sharing the schematics, it is much appreciated.

[puretube]

Fret: indeed this is a parallell universe thingy...

[ISC]

I would like to thank Mark Hammer and Mike (VSAT) for their help with the schematic. I have given life back to my freinds vintage delay pedal.
With the aid of you guys and the schem I was able to find a broken 10k resitor and a failing 4016 IC ( relpaced with a new chip and a socket). Without the schematic I would never have been able to restore this nice sounding delay.

Thanks
Trevor

[Mark Hammer]

Posting stuff is easy.  The persistence and dedication it takes to track down a problem, learn stuff along the way, and FIX things....now there's something I can tip my hat to.  Congrats.

[rtcook]

Hello everyone!

I too have a sick MXR Analog Delay.  I see that a schematic is out there in a .zip file.  Would one of you please email it to me?  I could really use it.

Thanks in advance,

Roger

rtcook@adelphia.net

[Mark Hammer]

I posted a number of relevant files over on photobucket.  You can find them at:
http://img.photobucket.com/albums/v474/mhammer/rossdelay.png
http://img.photobucket.com/albums/v474/mhammer/MXRAnalogDelayschem2.png
http://img.photobucket.com/albums/v474/mhammer/MXRAnalogDelayschem1.png
http://img.photobucket.com/albums/v474/mhammer/MXRAnalogDelaylayout.png
http://img.photobucket.com/albums/v474/mhammer/mxr_analogdelay.png

[PlasterPirate]

I have an MXR Analog Delay as well as a Stereo Chorus, neither of which are usable because of a loud, rumbly white noise. If I kick the box sometimes it will stop it, or change the way it is doing it. Does that sound like any one thing to you guys? Thanks---

[jxoco]

Sounds like a bad solder joint.
Common for old effects.

You reheat the solder connections one by one and add a tiny bit of new solder to each one.

The second cause can be a pot (volume, tone, blend, whatever) that is worn out and is not always making contact internally with the resistor that is contained within the pot.
Sometimes a spray can fix this and sometimes a new pot (potientometer) is needed.

[Eb7+9]

... also, a bad foot-switch can do what you describe (output connected, input floating) - check that before applying heat to the board

Thx for the schems Mark 

[rtcook]

Hi all,

I hate to open this thread again, but I need some help fixing my MXR Analog Delay.  I have one that is a 1978 (from date on pots) and it is almost mint condition.  Problem is that is doesn't work.  It passes signal, but no effect can be heard and when you turn up the mix the pass thru signal goes away.  Someone else described the same thing.  I for sure thought it was the Reticon R5101 chip, so I put it aside figuring it would be a total loss.  Low and behold, I managed to find several NOS Reticon R5101 chips.  I thought I had it made.  Well, I swapped my original out for the NOS replacement and it still does not work.  I desperately need some help now to get mine fixed.  I know that someone out there can help me, but unfortunately they will have to baby step me through it.  I can offer a NOS Reticon R5101 to any one person willing to help me through this till I get mine functioning again.  Just so everyone understands, I can find my way around the circuit and I have some electical background and the proper tools.  I just don't know how to troubleshoot this thing without a readable schematic.  I can't even find the information on the Reticon R5101 pinouts.

Thanks to anyone that can help,

Roger

[rtcook]

Hi again,

I have done some probing around in this circuit and I'm hoping someone can tell me what they think of what I found.  I have checked the power supply and it seems to be functioning correctly.  I am getting 12.13V DC to the board.  I went further and tested the VCC+ to all the chips and get the same reading of 12.13V DC.  But, the VCC- is 0 on all the chips.  I was expecting -12.13VDC.  Am I thinking correctly?  If so, why would I be getting 0 and what could the problem be?

Thanks,

Roger

[rtcook]

What is the 340L12?  A transistor?  I can't find any info on it.  I do know that 24VDC enters one side and 12VDC out the other.  The middle leg goes to the - voltage track throughout the board, so could this be my problem since it measures 0 as well?

Roger

[rtcook]

Well, it appears that is a voltage regulator.  I cannot find anything on a 340L12.  Can anybody help me on this with a data sheet or a suggestion for a substitution?

Roger

[Maneco]

hi!
that regulator is working fine,is an lm340l012,an equivalent of the 7812,so that's the right behaviour,0v is the middle leg,24v to the input (left leg),and 12v at the output,right leg...

In many mxr delays,the problem is the tracking filter built around the cd4016 analog switches ,or the clock circuit that drives those ( check with an oscilloscope that)

[rtcook]

Maneco,

Hi!

Thank you very much for responding.  After going over the voltage regulator test points, I determined that yes it was working correctly.  I was putting my probes in the wrong place.  I do get -12VDC and +12VDC at the 4558 op amps and the other ICs.  Could you PLEASE elaborate on your suggestion on testing the circuit.  Unfortunately, I do not have a scope.  How can I proceed to test this?  Like I said in a prior emai, I changed out the Reticon R5101 for a NOS one and I still have the same problem.  I am guessing it is not the R5101, but I am not sure how to go about following the siganal through the circuit.  I have been studying a schematic of it, but I just can't quite follow it, nor read it very well since it is a poor photocopy.  Could you please help me any further?

Thank you,

Roger