# Danelectro Cool Cat Chorus w/ Low Volume



## yazooligan (Aug 9, 2021)

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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## Mcknib (Aug 9, 2021)

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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## yazooligan (Aug 9, 2021)

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
> 
> ...


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.


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## Feral Feline (Aug 10, 2021)

The trimmers, I believe, are for biassing the BBDs — see reply #2 by Mark Hammer's in this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=118382.0
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 (Aug 10, 2021)

Just to check you do get chorus but at low volume?


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## yazooligan (Aug 10, 2021)

Mcknib said:


> Just to check you do get chorus but at low volume?


Yes I do!


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## yazooligan (Aug 10, 2021)

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
> 
> ...


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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## Mcknib (Aug 10, 2021)

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 (Aug 10, 2021)

yazooligan said:


> Signal comes out loud and clear (ie correctly) from the STEREO OUT jack, but with no chorus, obviously.



I'm confused you get no chorus effect at all? Or you get it at low volume


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## yazooligan (Aug 10, 2021)

Mcknib said:


> I'm confused you get no chorus effect at all? Or you get it at low volume


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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## Mcknib (Aug 10, 2021)

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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## yazooligan (Aug 10, 2021)

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


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


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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## Mcknib (Aug 11, 2021)

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


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## yazooligan (Aug 12, 2021)

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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## Mcknib (Aug 12, 2021)

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.


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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## yazooligan (Aug 12, 2021)

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
> 
> ...


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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## Mcknib (Aug 12, 2021)

Whats the 14 pin IC bottom right near the switch


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## yazooligan (Aug 13, 2021)

Mcknib said:


> Whats the 14 pin IC bottom right near the switch


It’s a TC4013BP


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## Mcknib (Aug 14, 2021)

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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## yazooligan (Aug 14, 2021)

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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## yazooligan (Aug 9, 2021)

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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## yazooligan (Aug 15, 2021)

Mcknib said:


> 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



I think the 1N4148 I pulled might be part of the switching system. Added the photos to the OP too.


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## Feral Feline (Aug 15, 2021)

yazooligan said:


> ...Added the photos to the OP too.


Strictly curious — why? 

You could've just added them to a new post in the thread, and kept the original OP photos. 

To reiterate, strictly curious.


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## yazooligan (Aug 15, 2021)

Feral Feline said:


> Strictly curious — why?
> 
> You could've just added them to a new post in the thread, and kept the original OP photos.
> 
> To reiterate, strictly curious.


I’ve been at a cabin all weekend with shoddy internet reception, a lot of craft IPA’s, and plenty of time on my hands. My thinking hasn’t been entirely clear at times.


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## Feral Feline (Aug 15, 2021)

Craft isopropyl alchohol, who'd have thunkered it.


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## Coda (Aug 15, 2021)

Feral Feline said:


> Craft isopropyl alchohol, who'd have thunkered it.


You get a purer tone when you clean your pcb with craft isopropyl. That’s the real secret to the Rat…not the 308.


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## yazooligan (Aug 15, 2021)

Feral Feline said:


> Strictly curious — why?


Also, never hurts to give someone new to the thread all the evidence up front, since some of us don’t care to read the entire thread before deciding whether to weigh in.


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## Feral Feline (Aug 16, 2021)

yazooligan said:


> Also, never hurts to give someone new to the thread all the evidence up front, since some of us don’t care to read the entire thread before deciding whether to weigh in.


True that, it had crossed my mind of course after I posted my question.

Right now I can't get off my mind what IPAs you've been using, ehr, consuming. 🍺


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## Mcknib (Aug 16, 2021)

Let us know what happens when you replace it 

It might be a clamping diode does it connect to the transistor next to it


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## yazooligan (Aug 17, 2021)

Mcknib said:


> Let us know what happens when you replace it
> 
> It might be a clamping diode does it connect to the transistor next to it



While the diode was out, I plugged in and got the same low volume in bypass and no sound at all when engaged. Put in a new N4148 and I'm back to where I started. It does look like it connects to the transistor next to it though.

I made an audio probe and probed around the main board and the I/O board. I could only get signal to come through in a few spots. On the bottom IC (HA17741) it sounded really loud and overdriven/distorted. In other spots closer to the jacks there was a lot of buzz with the clean signal audible in the background. I'll make a video to demonstrate where they are and add it to the OP.


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## Mcknib (Aug 17, 2021)

I used to think with components coming from power or ground and not being part of the audio path you would get no audio at those points

You can in fact get distorted audio for example on op amp power pin 8 as I discovered with a trouble shoot a while back but it's still not part of the audio path and with your effect signal sounding good in your video I'd think it may just be that


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## yazooligan (Aug 18, 2021)

Mcknib said:


> I used to think with components coming from power or ground and not being part of the audio path you would get no audio at those points
> 
> You can in fact get distorted audio for example on op amp power pin 8 as I discovered with a trouble shoot a while back but it's still not part of the audio path and with your effect signal sounding good in your video I'd think it may just be that


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## yazooligan (Aug 18, 2021)

Oof. I’m just about ready to throw this thing in the fucking trash. I’m pulling my hair out over it. That said, it was fun building my first probe.


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## Mcknib (Aug 18, 2021)

Try probing the 4013 pins

I'm not sure if you'd get audio I don't know what it does possibly acting to toggle signal from the input to 1 or the other outputs

You know it works with low volume in both effect and bypass mode so it's perhaps something common to both

I'd check that and use datasheets to check outputs on the ICs and transistors see if you can find where it goes in at a good volume but comes out lower


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## Feral Feline (Aug 18, 2021)

yazooligan said:


> Oof. I’m just about ready to throw this thing in the fucking trash. I’m pulling my hair out over it. That said, it was fun building my first probe.


Set it aside and come back to it later, if need be, but it sounds too good to give up entirely on it.



Here's a link to a thread where the OP wants to mod the mix ratio, but there's some good info there that might be relevant or at least give you a better understanding of the overall circuit:





__





						Cool Cat schematic
					

Cool Cat schematic



					www.diystompboxes.com
				




Same guy, same desire, different thread, yet clues to your puzzle seems unlikely in this thread — but it's short and you never know what may wind up being useful:




__





						mixing stereo outputs of an 18v danelectro cool cat chorus. Formula?
					

mixing stereo outputs of an 18v danelectro cool cat chorus. Formula?



					www.diystompboxes.com
				





Various Chorus schematics (alas no CC DC-1, but a great resource nonetheless):




__





						Account Suspended
					





					www.kobra.hr
				






Sometimes I get lucky searching online in another language, but apparently no Russians nor Japanese have traced the DC-1. I'll try a few other languages later...


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## yazooligan (Aug 18, 2021)

Mcknib said:


> You know it works with low volume in both effect and bypass mode so it's perhaps something common to both
> 
> I'd check that and use datasheets to check outputs on the ICs and transistors see if you can find where it goes in at a good volume but comes out lower


I thought this was a transistor, but it's an IC. MC78L12CP

According to the CS-505 schematic I think it's the last IC in the chain. There's a 1N4001 diode right next to it.









						1683-CF61-ABEB-463-B-8-CFF-0086-B6-B06-E8-E
					

Image 1683-CF61-ABEB-463-B-8-CFF-0086-B6-B06-E8-E hosted in ImgBB




					ibb.co


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## Feral Feline (Aug 19, 2021)

That's the voltage regulator.
Common to find that style of regulator in Chorus/Flanger/Delay/Reverb builds.

If you look at the lower left of the schematic, or at the block diagram, in the CS-505 service manual that Mcknib gave the link to, you'll see the regulator comes  shortly after the 18V power input, and knocks it down to 12Vcc and Vref 6v, if I understand it correctly.

I suppose if the regulator's fried/faulty and not giving enough juice that could explain the low volume. It makes me wonder though, I'd think it's okay 'cause the 4013 and the 3102 will both demand a steady solid source of power — if not your bypass (4103) would be wonky and the chorus might not happen if the clock (3102) isn't getting its due. I'm taking stabs in the dark here.

EDIT: Is the 78L12 getting unusually hot when the pedal's powered up?


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## yazooligan (Aug 19, 2021)

Feral Feline said:


> Is the 78L12 getting unusually hot when the pedal's powered up?


Not sure how to tell. Do I just touch it with my finger? It’s kind of hard to get to sandwiched between the two PCB’s.


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## yazooligan (Aug 19, 2021)

I tried the audio probe again, this time focusing on all the transistors. On most of them I could hear some of my clean signal very faintly. A few of them gave me nothing.


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## Mcknib (Aug 19, 2021)

Some transistors will be being used as switches

You're probably best just starting at the in pad through the buffer which is probably a transistor looking at the CE2 and CS505 schematics 

All you can really do is continuity check to see what connects and probe each section and hopefully find where volume drops out 

Each section will be similar to most analog choruses in that you'll have a buffer, filtering, a mixer, bbd circuit, LFO etc


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## Feral Feline (Aug 19, 2021)

yazooligan said:


> Not sure how to tell. Do I just touch it with my finger? It’s kind of hard to get to sandwiched between the two PCB’s.


You don't need to touch it; just put a finger near it — it's normal to be warm, all electronics get warm, but if it's radiating enough heat to make you wary of touching it or the parts near it (since it's hard to access)  ... 🌡️♨️ 🔥.


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## yazooligan (Aug 9, 2021)

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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## yazooligan (Aug 20, 2021)

Okay. Enough fucking around. I’m changing out the TL072’s today and if that doesn’t fix it, it’s going in the trash compactor.


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## Mcknib (Aug 20, 2021)

The old frustration creeping in? Put that hammer away!

It's gotta be something simple here's what I'd do

Use the CE2 schematic check all active device outputs in the audio path (blue ish lines), if an outputs low volume, trace it back

Most analog choruses will be similar circuit nodes if you're not sure if it's the buffer or whatever you can compare to the schematic see if yours has a 47n and a 1K going to the base or gate of transistors etc, you can ignore the switching, power supply and LFO for now and trace this basic audio path obviously yours is using TL072 dual op amps and an MA17741 single op amp instead of 4558 and TL022 for the LFO and filter/mixer

Because it works the clock, regulator, LFO etc must be ok it could well be not enough juice as @Feral Feline says but you'd need to systematically eliminate things starting at the input buffer

Because it's low volume in bypass and effect mode I thought it might be in the switching circuit but I don't know, not knowing if the 4013 is used to toggle fets or whatever I thought it had to be something common to both did you probe the 4013


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## JamieJ (Aug 20, 2021)




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## Feral Feline (Aug 20, 2021)

I'll loan you mine, then you'll be inspired to hang on to yours, get it rollin' right...


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## yazooligan (Aug 23, 2021)

While pulling one TL072, a pad or two came off with it, and now I get no chorus in bypass and even lower output. Thanks so much for the help but it’s going on Reverb for $20 for someone with more repair skills than myself. I have a Caesar chorus to build anyway.


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## Mcknib (Aug 23, 2021)

Bummer

I did the same with a Blackstar HT Modulation pedal removing a dodgy dual pot


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## yazooligan (Aug 23, 2021)

yazooligan said:


> While pulling one TL072, a pad or two came off with it, and now I get no chorus in bypass and even lower output. Thanks so much for the help but it’s going on Reverb for $20 for someone with more repair skills than myself.





Mcknib said:


> Bummer
> 
> I did the same with a Blackstar HT Modulation pedal removing a dodgy dual pot


Man I appreciate your replies so much. I’ll probably put some other 2-knob PCB in the enclosure so it doesn’t go to waste. Re-painting it in a sparkle finish might be pretty sweet. A Red Llama or DOD 250 or Tone Bender perhaps. Been meaning to build all three. Just need to figure out how to get the footswitch to work with it.


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## Feral Feline (Aug 24, 2021)

Very tempted to try taking that off your hands, but I'm no trouble-shooter.

I like the idea of recycling the enclosure. Maybe stuff an HM2 in there or a Bumble Buzz Fuzz whatever it's called (no knobs) and you can have a sleeper pedal...  Say to your band-mates: "I'm just going to kick in a subtle chorus for the bridge of the song..." .

Even better if you lend it as a chorus to a friend.


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## yazooligan (Aug 24, 2021)

Feral Feline said:


> Very tempted to try taking that off your hands, but I'm no trouble-shooter.
> 
> I like the idea of recycling the enclosure. Maybe stuff an HM2 in there or a Bumble Buzz Fuzz whatever it's called (no knobs) and you can have a sleeper pedal...  Say to your band-mates: "I'm just going to kick in a subtle chorus for the bridge of the song..." .
> 
> Even better if you lend it as a chorus to a friend.


I do have a bumble buzz PCB sitting around…


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## yazooligan (Aug 31, 2021)

Feral Feline said:


> Very tempted to try taking that off your hands, but I'm no trouble-shooter.



Well, I took another look at the spot I thought I messed up, and I was able to re-flow the joints and get chorus/bypass sound again. I changed out the other TL072 and...I'm still back at square one with the low volume issue, but at least it's not completely broken like I thought!


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