Vintage Morley Power Wah Doesn't Always "Wah"

[dmeek]

They look yellowish to me, maybe they're white.

https://music-electronics-forum.com/...1&d=1582672181

[louloomis]

They look yellowish to me, maybe they're white.

https://music-electronics-forum.com/...1&d=1582672181

dmeek - I think they're supposed to be white, but they are yellowing for sure (in person; I didn't realize it was also so visible in the photograph!). Thank you for taking the time to create a photo with the arrows to point out the ones you mean. VERY helpful. I appreciate it a lot.

galaxiex - Ok. Makes sense and sounds like a good plan to me and seems like there's a consensus that these capacitors need to be replaced. Thank you for your input.

Thanks everyone!
LL

[g1]

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.

[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

[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

[dmeek]

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

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

[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.

[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]

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

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

[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!

[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

[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.

[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

[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

[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.