SOLVED Paradise Overdrive (Gain Pot Motorboating)

[FuzzyChicken]

Hi first time on the forums, how ya'll doin?
I've tried to solve this problem quite a few times already but to no avail, so now I'm here hoping that one of the wiz's can help me out.

So as the title suggests I have a problem with the Paradise Overdrive, mainly the gain control. At all the knobs in the 12 o'clock position everything seems fine. I can even push the volume and it seems to be okay. The gain however in the last 1/10 of a turn starts motorboating quite a bit. If i back off the gain knob a bit the motor boating goes away but seems to have a faint noise (which is what I'd expect out of a gain knob semi-cranked). The knob also seems to make a lot of noise when I touch the shaft to turn it (the same sound happens when touching the input jack terminals). I can't seem to fix the problem at all and was wondering if anyone can point me in the right direction here. On an added note I replaced C2 for a 4n7 cap, sound waaaaay less muddy!
So far I've tried:

• Replacing the gain pot for a new one.(A250)
• Replacing the IC(JRC386D)
• Cleaned most of the flux-gunk. I rewired the pots but didn't clean them yet.
• Rewired the pots.

IC measurements:
1: 1.3
2: 0
3: 0
4: 0
5: 3.94
6: 8.78
7: 4.295
8: 1.298

Thanks in advance folks!

 

[Nostradoomus]

What kind of power supply are you using?

 

[FuzzyChicken]

I tried using both a 9v battery and a isolated power supply(friedman power grid 10). Same issue with both...

 

[music6000]

Hi first time on the forums, how ya'll doin?
I've tried to solve this problem quite a few times already but to no avail, so now I'm here hoping that one of the wiz's can help me out.

So as the title suggests I have a problem with the Paradise Overdrive, mainly the gain control. At all the knobs in the 12 o'clock position everything seems fine. I can even push the volume and it seems to be okay. The gain however in the last 1/10 of a turn starts motorboating quite a bit. If i back off the gain knob a bit the motor boating goes away but seems to have a faint noise (which is what I'd expect out of a gain knob semi-cranked). The knob also seems to make a lot of noise when I touch the shaft to turn it (the same sound happens when touching the input jack terminals). I can't seem to fix the problem at all and was wondering if anyone can point me in the right direction here. On an added note I replaced C2 for a 4n7 cap, sound waaaaay less muddy!
So far I've tried:

• Replacing the gain pot for a new one.(A250)
• Replacing the IC(JRC386D)
• Cleaned most of the flux-gunk. I rewired the pots but didn't clean them yet.
• Rewired the pots.

IC measurements:
1: 1.3
2: 0
3: 0
4: 0
5: 3.94
6: 8.78
7: 4.295
8: 1.298
View attachment 3444View attachment 3443View attachment 3445
Thanks in advance folks!

I built this on my Eyelet Board around 2 years ago from Tagboard Effects Layout, where it was updated from my findings to a 4n7 Cap.
I just measured mine & there could be slight difference as I only use National Semi LM386N-3 in these type pedals.
The Battery measured 9.47v
1 : 1.347v & 8: should be exactly the same, they are Linked.
2: 0v
3: 8.8mw
4: 0v
5: 5.98v Yours seems low here!
6: 9.22v
7: 4.66v
8: 1.347v

 

[music6000]

Here is my Build, I used a 100uf for Main Power Filtering, don't know if that may help!

 

[FuzzyChicken]

I built this on my Eyelet Board around 2 years ago from Tagboard Effects Layout, where it was updated from my findings to a 4n7 Cap.
I just measured mine & there could be slight difference as I only use National Semi LM386N-3 in these type pedals.
The Battery measured 9.47v
1 : 1.347v & 8: should be exactly the same, they are Linked.
2: 0v
3: 8.8mw
4: 0v
5: 5.98v Yours seems low here!
6: 9.22v
7: 4.66v
8: 1.347v

Huh maybe I just got a bad batch of those chips. I’ll try out the lm386n-3 like you suggested, I think saw it on mouser before. Thanks for the input! While I’m ordering the ICs i’ll Try looking around pin5 and see if any joints are cold.

Ps: Your build looks awesome! Never seen anyone using eyelets for pedals before.

 

[Robert]

Someone had a similar issue a while back (before the forum existed).

If I recall, the problem was corrected by using a different version of the LM386, quite possibly the LM386N-3.

 

[FuzzyChicken]

Well I bought some from mouser and they’re on their way. Hopefully this is the problem.

 

[music6000]

Huh maybe I just got a bad batch of those chips. I’ll try out the lm386n-3 like you suggested, I think saw it on mouser before. Thanks for the input! While I’m ordering the ICs i’ll Try looking around pin5 and see if any joints are cold.

Ps: Your build looks awesome! Never seen anyone using eyelets for pedals before.

Here is how the Op Amp Socket is fixed from the Back in my Eyelet Board designs:
I made a Drilling Tempate out of 2mm Aluminium with 14 pins so I can use it for multiple sockets!

I twist the wire tightly & wind it around & down a Safety Pin & slide it on the Socket pin & Solder,
With 2 wires going to the same Socket pin, I part the insulation in the middle so there is around 6mm gap.
Twist wire & wrap around & down a Safety Pin & slide onto Socket pin.

 

[Barry]

Nice

 

[Chuck D. Bones]

Here is my Build, I used a 100uf for Main Power Filtering, don't know if that may help!

Love the finish on that box!

 

[Chuck D. Bones]

Make sure the pots and jacks are well grounded to the inside of the box. Remove paint as req'd.

 

[music6000]

Well I bought some from mouser and they’re on their way. Hopefully this is the problem.

Yes, as Chuck pointed out, Has this been tested in the Enclosure with the Pots & Jacks attached & Grounded?
We take it for granted sometimes, that's how Members test there Builds!

 

[FuzzyChicken]

I've taken the board out of the box once to apply all those fixes I tried already (pot swapping, rewiring, etc...). The recent tests were done through a breadboard set up, guess there wouldn't be much of a ground with that method. I'll try boxing it when I get the chance, should be able to do so in the next couple o' days. I appreciate everyone's input, I feel like I'm making progress now!

 

[FuzzyChicken]

I hope everyone doing alright in these troubling times, stay healthy everyone!
I got the LM386N-3 from mouser as music6000 suggested and it worked great! No more motorboating! Thanks to everyone who pitched in with ideas, I learned a lot for sure.

 

[music6000]

Awesome!
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