Vintage Morley Power Wah Doesn't Always "Wah"

[louloomis]

Hey Everyone.

Just wanted to provide an update on this repair. Long story short, I ordered the capacitors discussed earlier in the thread, using the recommended changes in values.

I completed the replacement of the old capacitors with these new ones.....and now the pedal works perfectly!

The wah sounds loud and clear and transparent and basically like an incredible and "cosmic" sound you could only hear in some 1970s-era medium-sized concert theater. Couldn't ask for more. Fantastic!

Thanks again, everyone, for being an important contributor to this victory!

Regards,
LL

[louloomis]

Caps usually aren’t intermittent. I would try some freeze when it is in failure mode.

Thanks for the info. I'm sure you're right. I really don't know myself.

If it's any help, it was intermittent for a bit and then basically "wahs' almost inaudibly (maybe not at all - I took the pedal out of service by then).

Don't know it that helps at all.

For what it's worth, I'm kind of committed to the cap replacement at this point anyway because I already started clipping them out.

LL

[tedmich]

Quick question anyone know the specs on a power pack for these?Was just asked to cobble one together.
Thanks,
nosaj

my old one had full AC line power through the toggle at the front, this went into an internal transformer and a full wave rectifier pair making about 24VDC.

More modern versions use a Morley branded regulated 9VDC 300mA center negative with a std 5.5mm x 2.1mm thats ~12.7mm long. Its a pretty clean supply and this may be necessary.

[olddawg]

Yes, these are great pedals.

Thanks for the ideas. Here is my feedback on your comments/suggestions:
1. The shutter is working fine.
2. My successful testing of the photocell are detailed in a previous post in the thread.
3. The switch is working, as detailed in a previous post in the thread.
4. The discussion around my assembling an order for all the capacitors recommended thus far is detailed in a previous post in the thread.
5. I do not know about the potential grounds issue. It seems like the caps need to be replaced anyway, so I will start with those as the next step.

Thanks.
LL

Caps usually aren’t intermittent. I would try some freeze when it is in failure mode.

[louloomis]

Those are great classic pedals. I have owned/used a couple. Are you sure the shutter isn’t hanging up? That’s a common problem. You can actually test the photo cell and The was circuit with a small flashlight, varying the beam on the photo cell. Another thing that happens with these is switch contacts and 40 year old electrolytic caps in the signal path. Since it is intermittent, i would be checking the shutter, grounds, and switching to start.

Yes, these are great pedals.

Thanks for the ideas. Here is my feedback on your comments/suggestions:
1. The shutter is working fine.
2. My successful testing of the photocell are detailed in a previous post in the thread.
3. The switch is working, as detailed in a previous post in the thread.
4. The discussion around my assembling an order for all the capacitors recommended thus far is detailed in a previous post in the thread.
5. I do not know about the potential grounds issue. It seems like the caps need to be replaced anyway, so I will start with those as the next step.

Thanks.
LL

[nosaj]

Those are great classic pedals. I have owned/used a couple. Are you sure the shutter isn’t hanging up? That’s a common problem. You can actually test the photo cell and The was circuit with a small flashlight, varying the beam on the photo cell. Another thing that happens with these is switch contacts and 40 year old electrolytic caps in the signal path. Since it is intermittent, i would be checking the shutter, grounds, and switching to start.

Quick question anyone know the specs on a power pack for these?Was just asked to cobble one together.
Thanks,
nosaj

[olddawg]

Those are great classic pedals. I have owned/used a couple. Are you sure the shutter isn’t hanging up? That’s a common problem. You can actually test the photo cell and The was circuit with a small flashlight, varying the beam on the photo cell. Another thing that happens with these is switch contacts and 40 year old electrolytic caps in the signal path. Since it is intermittent, i would be checking the shutter, grounds, and switching to start.

[louloomis]

man what dejavu! I had a power Wah too, all those unpopulated pads Morely must have had one PCB...good times. I still have this sticker on my guitar case!
[ATTACH=CONFIG]57154[/ATTACH]
and still don't know what it means...a 0.5 entendre?
As I remember this things frequency range was ideal for maybe an 88key keyboard; it simply disappeared over most of its travel for the attached guitars frequency range.
Hope the caps do it! Good luck!

Hahaha. Yeah, a 0.5 entendre. And not 1/2 because........"You can't land on a FRACTION!" as Dennis Hopper said in "Apocalypse Now".

I think I have that sticker on a guitar case, too. You're right about the range - it's way wide. I had a Power Wah that I bought in the 1980s and sold it in the 1990s or so because of that wide sweep. Now, I just use the range of the wah that works for the guitar. It's a bit interesting to keep it in mind, but if you can just move your foot in that range, these wahs sound incredible to my ears. Very muscular tone.

LL

[tedmich]

man what dejavu! I had a power Wah too, all those unpopulated pads Morely must have had one PCB...good times. I still have this sticker on my guitar case!

and still don't know what it means...a 0.5 entendre?
As I remember this things frequency range was ideal for maybe an 88key keyboard; it simply disappeared over most of its travel for the attached guitars frequency range.
Hope the caps do it! Good luck!

[galaxiex]

Correct, the 3 blue caps are the power supply electros.

470uf 35V .... could get 50V there
and the two 47uf 50V

[louloomis]

Yes those will work.

As pointed out by dmeek the 100uf could go to 35V as it is in the power supply.
Never hurts to go a bit bigger on the voltage rating, just don't go smaller, esp with power supply caps.

May as well get the other electro power supply caps too, while you are making an order.

In case it's not obvious....
Electro caps are polarity sensitive, be sure to observe polarity when changing them.

Thanks, dmeek and galaxiex! Very helpful info.

galaxiex - what are the other electro power supply caps I should order? The big light blue ones in my picture? Sorry, I don't really know how to read a schematic.

Thanks.
LL

[galaxiex]

I am about to order parts for the this repair.

I read the markings on the sides of the whitish-yellowish capacitors (I counted 4 of them - the three pointed out by dmeek - and one other one which looks to be the same vintage and style but is located closer to the edge of the unit).

Here are the markings:
100uF 25v
10uF 16v
1uF 50v
1uF 50v

I tried to find these online so I created the order in the attached photo as a draft. Can someone confirm these are the correct "type" of capacitors I need to buy? This is from Allied Electronics (no affiliation). Thanks -LL

[ATTACH=CONFIG]57144[/ATTACH]

Yes those will work.

As pointed out by dmeek the 100uf could go to 35V as it is in the power supply.
Never hurts to go a bit bigger on the voltage rating, just don't go smaller, esp with power supply caps.

May as well get the other electro power supply caps too, while you are making an order.

In case it's not obvious....
Electro caps are polarity sensitive, be sure to observe polarity when changing them.

[dmeek]

I would use 100uF 35V. This appears to be the schematic.

https://music-electronics-forum.com/...1&d=1582723678

[louloomis]

I am about to order parts for the this repair.

I read the markings on the sides of the whitish-yellowish capacitors (I counted 4 of them - the three pointed out by dmeek - and one other one which looks to be the same vintage and style but is located closer to the edge of the unit).

Here are the markings:
100uF 25v
10uF 16v
1uF 50v
1uF 50v

I tried to find these online so I created the order in the attached photo as a draft. Can someone confirm these are the correct "type" of capacitors I need to buy? This is from Allied Electronics (no affiliation). Thanks -LL

[louloomis]

Regarding your question about the photocell position relative to the 'curtain'; as you say, it was working fine before. So if it has not been moved be careful not to move it, as they can be troublesome to get right.

Ok. Thanks for the input.

FYI - Earlier, when I received a photo from another poster above of his own unit, I noticed that my "curtain" was sitting much higher up and covering more of the photocell than the other poster's unit was. So I adjusted mine to match what was in the photo of the other poster above. I also centered mine because it was very slightly off center (which I had originally thought might have been due to slippage).

I remember where my curtain was set though because the nut position was almost at the farthest point of its travel. I hope I didn't make it all much worse by adjusting it, but I'll revisit it when I am done with the capacitor replacement as needed.

LL