EH Deluxe Memory Man V5 Effect Pedal Needs Help

[misterc57]

Got this pedal in a partial trade deal. The effect does not work and I wanted to start a topic on it as I go through it.

The on/off switch works. The power LED lights up.

Pressing the effect on/off switch creates a slight change in sound but there are no effects happening. I cannot even tell which position is ON vs OFF.

Here are some weird observations.

Power ON. Level pot works in either on/off effect switch position.
Power OFF. Level pot becomes a backwards volume control

Power ON. Blend knob is a backward volume control with effect on/off in one position, in the other position it does not.

The feedback, delay and chorus/vibrato pot do nothing.

The chorus - vibrato switch does nothing but seems to be operating properly as a switch verified at the switch and at the board.

The delay pot has had a resistor installed across the outer legs.

I am not sure of the exact board model as the designation on the board is written in pen and must have been written in an alien language.

I am attaching some pics and what I think may be the schematic.

The PS to the board reads -15.7 V.

Also a link I found that may be helpful to me and others... https://sites.google.com/a/davidmorr...ry-man/eh-7850

On both MN3005 chips I see

-16 V on pins 7 (good)
-10 V on pins 8 (schematic says it should be -15 V)

electro-harmonix_deluxe_memoryman_delay_sch.pdf

electro-harmonix_deluxe_memoryman_delay_sch.pdf

[misterc57]

Seeing the following voltages which may be okay. Any suggestions on what to try next? Thank you

All measured V are negative

Both 4558 pin 4 = -15.8

Both M3005 are practically the same as follows

pin Voltage

2	-7.9
6	-10
7	-10
8	-15.8
9	-7.9
13	-8
14	-14.8

4047 IC

pin	V
1	-15.8
2	-15.8
3	- 7.9
4	- 7.9
5	-15.8
6	-7.4
8	-7.4
9	-8.4
10	-8.4
14	-15.8

[misterc57]

Forgot to include the NE570

[misterc57]

Forgot to include the NE570


All measured V are negative

Both 4558 pin 4 = -15.8

Both MN3005 are practically the same as follows

pin Voltage

2	-7.9
6	-10
7	-10
8	-15.8
9	-7.9
13	-8
14	-14.8

4047 IC

pin	V
1	-15.8
2	-15.8
3	- 7.9
4	- 7.9
5	-15.8
6	-7.4
8	-7.4
9	-8.4
10	-8.4
14	-15.8

NE570

pin	v
1	-14.8
2	-13.9
3	-13.9
4	-15.8
5	-13.9
6	-13
7	-13.9
8	-13.9
9	-7.3
10	-9
11	-13.9
12
13	-13.9
14	-14.9

[misterc57]

My thoughts

According to schematic, 4047 pin 11 should have same V as MN3005 pin 9. Need to recheck that.

Is schematic saying 4047 pins 7,8,9,12 should be -15V? Not seeing that.

Is schematic saying 4047 pins 4,5,6,14 should be the same V? They are not.

Schematic is showing pins that do not exist on the NE570 (pins 15, 16)

Is this schematic to be trusted?

[Helmholtz]

Is schematic saying 4047 pins 7,8,9,12 should be -15V?

Yes.

Is schematic saying 4047 pins 4,5,6,14 should be the same V?

Yes.

[g1]

Is this schematic to be trusted?

Is it supposed to be the right one?
Here is another. Not sure if it's the same or not. But at least it's a real factory schematic.

[Mick Bailey]

It's worth checking the 4558 outputs to see if any are stuck to either -15v or ground, which could indicate a fault.
For signal tracing FX pedals I like to use an audio probe and signal generator through the guitar input, though any audio source would do. Start at the input and work along the signal path(s). Sometimes I print out the schematic and draw these in for convenience.

[misterc57]

Is it supposed to be the right one?
Here is another. Not sure if it's the same or not. But at least it's a real factory schematic.

I think this is the re-issue version which looks like it can be helpful as I think it is all the same components but a different PS.

[misterc57]

Yes.



Yes.

Could this imply a bad 4047?

[misterc57]

It's worth checking the 4558 outputs to see if any are stuck to either -15v or ground, which could indicate a fault.
For signal tracing FX pedals I like to use an audio probe and signal generator through the guitar input, though any audio source would do. Start at the input and work along the signal path(s). Sometimes I print out the schematic and draw these in for convenience.

I will try this. With a faulty 4558 would the pedal still pass a signal (which I am getting a dry signal to the amp)?

[misterc57]

My thoughts

Schematic is showing pins that do not exist on the NE570 (pins 15, 16)

My bad. NE570 does have 16 pins

[misterc57]

So I am going to use the schematic supplied by G1 attached here

EH deluxememoryman.pdf

Trying to understand things.

U1A is amplifying the signal in conjunction with the level pot and works regardless of the S1 position?

Is the blend pot mixing the wet and dry signal?

Thank you

[Helmholtz]

U1A is amplifying the signal in conjunction with the level pot and works regardless of the S1 position?

Is the blend pot mixing the wet and dry signal?

Yes and yes.

Pins 1,3,7 should sit at -7.5V.

[Mick Bailey]

I will try this. With a faulty 4558 would the pedal still pass a signal (which I am getting a dry signal to the amp)?

If an opamp is faulty the pedal could still pass a dry signal. For example - If U1a was working and U1b was not, you'd have a dry signal on one end of the blend pot but no signal could be passed to the wet side. The same if other opamps along the wet side weren't working.

Another fault that would block the signal is a faulty coupling cap, especially electrolytics which in old pedals can effectively go open-circuit due to very high ESR as they dry out.