Danelectro Cool Cat Chorus w/ Low Volume

yazooligan

yazooligan

Well-known member
I picked up one of these seafoam green 18v models used and it's got an issue. Volume is really low, whether the pedal is on or in bypass. I've opened it up but I'm not sure what I should be looking for unless there's a trim pot in there somewhere. Does anyone have any ideas on this one? It’s definitely getting 18v. Thanks so much!


 

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Check your in and out jack tips connect correctly

I had a bbe free fuzz with low volume the out jack flexible spring part wasnt getting a good connection with the jack tip

It had been bent down and barely made a connection when the jack was inserted

Once I bent it back in place and got a nice secure connection it was as good as new

I'd noticed the out cable felt loose in comparison to the in cable and had a look in the sockets and saw the tip connection was bent downward

They were similar plastic jack sockets so hopefully it'll be the same el cheapo sockets in your case for an easy fix

Worth a quick check
 
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Mcknib said:
Check your in and out jack tips connect correctly

I had a bbe free fuzz with low volume the out jack flexible spring part wasnt getting a good connection with the jack tip

It had been bent down and barely made a connection when the jack was inserted

Once I bent it back in place and got a nice secure connection it was as good as new

I'd noticed the out cable felt loose in comparison to the in cable and had a look in the sockets and saw the tip connection was bent downward

They were similar plastic jack sockets so hopefully it'll be the same el cheapo sockets in your case for an easy fix

Worth a quick check
Click to expand...
Thank you! This has plastic jacks too so I’ll definitely check that!

It looks like there are a couple trim pots on the main board, but those aren’t for volume.

FDD9C177-2FD0-4FDA-A290-2C2E8C3E50F5.jpeg
 
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The trimmers, I believe, are for biassing the BBDs — see reply #2 by Mark Hammer's in this thread:


I'd recommend marking how they're currently set, whether you intend to adjust them or not.


Mine's packed away, and was working at the time; I might be able to find it and dig it out if necessary to compare something...

[EDIT: I guess my link just takes you to the login page instead of the intended thread, so I'll just quote Mr Hammer here, he mentions an article he wrote for Premier Guitar:

"You'll recall from the article that all BBDs have to be biased in order to pass signal. The bias voltage is derived from the supply voltage, and the bias trimmer simply divides that voltage down to the appropriate bias voltage.
Where that trimmer ought to be set, and remain set, depends on the stability of the power supplying it. If the supply voltage shifts, the bias can end up being set "wrong" even though it started out being set right, simply because it just divides the PS voltage by some set fraction, regardless of what the supply voltage is.
So where am I going with this? If it starts out working, and then craps out, but the clean signal still sounds fine, that could imply that the batteries are providing a suitable supply voltage to the non-delay audio path (so clean sounds fine), and can initially provide a suitable bias to the bbd, given how the trimmer is set, but as the batteries declare themselves a little tired after a bit, that bias becomes "wrong".

Which leads to the inevitable question: are the batteries fresh?"

Your pedal looks mint, btw.]
 
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Mcknib said:
Check your in and out jack tips connect correctly

I had a bbe free fuzz with low volume the out jack flexible spring part wasnt getting a good connection with the jack tip

It had been bent down and barely made a connection when the jack was inserted

Once I bent it back in place and got a nice secure connection it was as good as new

I'd noticed the out cable felt loose in comparison to the in cable and had a look in the sockets and saw the tip connection was bent downward

They were similar plastic jack sockets so hopefully it'll be the same el cheapo sockets in your case for an easy fix

Worth a quick check
Click to expand...
I looked inside the jacks with a flashlight and could see two contact prongs in the INPUT and STEREO OUT jacks, but only one prong in the main OUT jack.

Are there supposed to be two in there?

Signal comes out loud and clear (ie correctly) from the STEREO OUT jack, but with no chorus, obviously.
 
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Can't find a schematic for it but it's apparently a lot like an Ibanez CS505

You can download the service manual PDF for that including the schematic here

Ibanez CS505

Doing a quick comparison to your pcb you can see it's got the 10K (103) bias trimmer and the 200K (204) clock trimmer, a 4K7 going to pin 3 of the MN3007 etc so you could use the CS505 schematic as a guide

The first thing I would check are the op amps if it's not a faulty jack one will be a buffer the other the LFO

I think yours uses TL072 instead of TL022 but can't make out the labelling on the top one so I'd check output pin 1 to see what the volume is like

The buffer should have around 4.5v on pin 1 If you have an audio probe use that starting at the buffer output pin 1 and follow it along to see where you lose volume

The LFO op amp will be near the speed pot and should have fluctuating voltage on it's output pins so you'll know which is which

The in jack will be stereo so will have 2 prongs, tip and ring, out jack mono so only 1 prong if you don't get a secure connection with a jack inserted that'd indicate it may not be making a good connection

If you have chorus effect don't adjust the trimmers for now
 
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Mcknib said:
I'm confused you get no chorus effect at all? Or you get it at low volume
Click to expand...
Plugged in normally, I get chorus from the OUT, same low volume as the bypass signal.

I then plugged into the STEREO OUT jack for comparison and the volume was the same as if I were plugged right into the amp.

EDIT: Here’s a video to cut down on confusion.
 
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Right gotcha I'd audio probe from the buffer output pin 1 to the mono jack to hopefully find where it's dropping out

If you look at the CS505 schematic you'll see a few CP check points

I'd also check output pin 7 which I think should be mixed wet and dry to see how strong the signal is and the MN3007 output pins 7 and 8

Obviously assuming the CS505 is similar to your circuit maybe do a few comparisons e.g. check your buffer has a 47K input resistor to pin 2 and a 47K feedback resistor between pins 1 and 2 etc
 
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Mcknib said:
The first thing I would check are the op amps if it's not a faulty jack one will be a buffer the other the LFO

I think yours uses TL072 instead of TL022 but can't make out the labelling on the top one so I'd check output pin 1 to see what the volume is like
Click to expand...
Correct, it's a TL072 up top. I'm not sure how to set my DMM for the correct reading. Here are the readings I got for Pin 1 with a few different settings. 1576 & 71.9 & 072

I won't attempt any more readings until I know which setting I should be using.
Mcknib said:
The buffer should have around 4.5v on pin 1 If you have an audio probe use that starting at the buffer output pin 1 and follow it along to see where you lose volume

The LFO op amp will be near the speed pot and should have fluctuating voltage on it's output pins so you'll know which is which
Click to expand...
I don't see another IC near the Speed pot other than the TL072 I mentioned. Sadly I don’t own an audio probe. :( I’ve definitely ruled out the output jack being the issue though.
 
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Set it to DC voltage lowest setting usually around 20 vdc

Red probe in V volts black in COM (common or ground)

The LFO IC may not be right next to the speed pot I mentioned it so you'd know which is which buffer you'd get steady voltage readings LFO would be varying on it's output pins

The idea is to see if you can find where volume drops out

20201124_172442_copy_309x281.jpg
 
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If it were a burned out resistor or capacitor, there wouldn’t be any sound coming out at all, right?

I’m more than happy to try replacing some IC’s if they’re the most likely culprit.
 
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yazooligan said:
If it were a burned out resistor or capacitor, there wouldn’t be any sound coming out at all, right?

I’m more than happy to try replacing some IC’s if they’re the most likely culprit.
Click to expand...
I would audio probe it if there's no obvious signs of anything

If you're getting effect you want to track down where volume drops out

Its better to find your fault area rather than change anything

Do you know if the previous owner messed with it
 
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Mcknib said:
I would audio probe it if there's no obvious signs of anything

If you're getting effect you want to track down where volume drops out

Its better to find your fault area rather than change anything

Do you know if the previous owner messed with it
Click to expand...
Some of the screws are near-stripped so I’m likely not the first person to open it up.
It will be a few days before I can get back home and put a probe together, but I’m determined to get this solved and get my fifty bucks worth out of it.
 
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I'm wondering if it might be a problem with the switching set up because you get low volume in both effects and bypass mode

Unfortunately I've no idea how the switching works maybe someone knows how the 4013 is used so you could check input and output

All that flip flop logic stuff is beyond me
 
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I took a closer look at the board and found a diode that had way too much solder on the component side. When I solder sucked it, it revealed a broken leg. I removed the rest of the diode and took pics of it and the board. I’ll add them to the OP. Looks like a 1N4148
 
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