MXR - M-118 Analog Delay SAD1024

musopaul · Post by **musopaul** » 12 Oct 2013, 13:51

Hi there,

I have a green box MXR 118 Analogue delay that i have brought back from the dead and am trying to align but cannot find the alignment procedures for clock frequency and location of trim pots anywhere...

It is the SAD1024 version with 118-3001 102 board.

I have found a couple of alignment sheets on here but they are for the PT2399 modded version and refer to trim at point A with no reference to what point A is.

Thanks,

Dirk_Hendrik · Post by **Dirk_Hendrik** » 12 Oct 2013, 14:54

have a schem?

next question? Do you have an oscilloscope?

uncleboko · Post by **uncleboko** » 12 Oct 2013, 17:58

Great shame that this was scanned at such a low resolution.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 12 Oct 2013, 18:03

Sorry. It's the only thing I have.

At the other hand, I've had a few on the bench and have to say, this will never be my ultimate analog delay.

musopaul · Post by **musopaul** » 12 Oct 2013, 20:58

Thanks for the schematic, I do have an oscilloscope and signal generator and what not for aligning but no direction...

Thanks for your help

uncleboko · Post by **uncleboko** » 12 Oct 2013, 21:38

Dirk_Hendrik wrote:Sorry. It's the only thing I have.

At the other hand, I've had a few on the bench and have to say, this will never be my ultimate analog delay.

No problem thanks for it anyway, it was probably scanned years ago when only very small files could be emailed!

Bernardduur · Post by **Bernardduur** » 10 Apr 2024, 23:23

Hi all!

I had one in for some TLC!

Here's the readable schematic and the trimpotsettings

And the trimpot location:

I've added some pics of the unit in a post on my blog and insta; check them in my sig

drewl · Post by **drewl** » 11 Apr 2024, 18:21

Wow, that's much nicer!

B3ar · Post by **B3ar** » 06 May 2024, 03:37

Is there a service manual with info on how to adjust the trimpots?

uncleboko · Post by **uncleboko** » 06 May 2024, 10:32

Excellent - drawn in Excel?

Bernardduur · Post by **Bernardduur** » 14 May 2024, 07:08

B3ar wrote: ↑06 May 2024, 03:37 Is there a service manual with info on how to adjust the trimpots?

No, just use the trimpot setting as described in the schematic.

One point of care: TP5 is set really low and this unit had some feedback issues (it got pretty fast into feedback); I've adjusted TP5 to match the settings of the other trimpots and with that tamed the feedback drasticly and made the unit much more usefull

VintageGFX · Post by **VintageGFX** » 15 Aug 2024, 09:35

Excellent work on tracing this pedal. Got one on the workbench and am trying to wrap my head around the workings of the pedal. I am losing the signal at IC5b (pin 4 is OK, pin 3 no output). But pin 5 is 0 volt so I should expect no output. So, tracing further, I reach the CD4069-part. I don't really understand what's happening here -- why did they choose to go with these hex inverters? Why would the designer wish to 'mute'(?) the line?

Voltages on the CD4069 (IC12)

Pin 1: 11.57v
Pin 2: 1.03v
Pin 3: 1.03v
Pin 4: 11.78v
Pin 5: 11.78v
Pin 6: 0v
Pin 7: 0v

Pin 8: 11.52v
Pin 9: 11.81v
Pin 10: 11.81v
Pin 11: 1.35v
Pin 12: 0v
Pin 13: 11.78v
Pin 14: 11.82v

I would expect 0 volt instead of 1.35v/1.03v so my best guess would be to replace this chip, but I try to understand stuff prior to replacing, especially in these vintage units... Anyone care to educate me?

GorillaHuman · Post by **GorillaHuman** » 01 Oct 2024, 19:16

Interested in this as well

Lani · Post by **Lani** » 02 Oct 2024, 00:18

Well there not there to mute the signal if that's what you mean. I believe they are used as oscillators to switch the 4016 which makes a switched capacitor filter used for the pre & de emphasis filters.
https://en.m.wikipedia.org/wiki/Switched_capacitor

Fernando JFET · Post by **Fernando JFET** » 04 Oct 2024, 14:42

Hi, I'm currently trying to trace this SAD1024 version. If anyone has any good pictures both top/bottom pcb will be much appreaciated!

MXR - M-118 Analog Delay SAD1024 [schematic]