Can anyone fix my pedal please?

svejk · December 2016

Hi there, can anyone fix a power supply on my Rockett Lemonaid? Someone who shall remain nameless shoved a power cable in and sheared off the socket inside the pedal. Now it won't work, even with a battery. On the picture below it's on the left - you can see the barrel tip and the sheared housing. I'm sure it's fixable...I will pay all postage and any reasonable charge (a guestimate would be good if you can...). Thanks in advance! https://goo.gl/photos/AEXGjBE9YvjCr3PBA ;

Gassage · December 2016

@juansolo

ewal · December 2016

Sure someone here will help. But can also recommend Martin at www.owenelectronics.co.uk

vasselmeyer · December 2016

Try @juansolo and cleggy. They restored my Mk1 Guv'nor to it's full glory for what I felt was a very fair price indeed.

robinbowes · December 2016

Hey, I'm in York. I could have a look at it for you - should be a simple fix if the part is available. R.

svejk · December 2016

Thanks so much everybody! @robinbowes that sounds great. Let me know where and when to drop it off. No hurry on this, I'll just fit round you. Cheers!

ICBM · December 2016

It should be one of these or very similar: https://shop.pimoroni.com/products/dc-barrel-power-jack-connector?utm_medium=cpc&utm_source=googlepla&variant=7570536833&gclid=CO7ajtG7l9ECFQEz0wod8mIDAg I'm sure robinbowes knows this, but for anyone else who needs to change one, the best method on a modern though-plated board is to carefully destroy the remains of the old jack using small cutters, leaving just the three metal contacts - then they can be desoldered individually. If you try to do all three at once and get it out as a single unit you'll probably damage the board before it will come out cleanly.

robinbowes · December 2016

<blockquote class="Quote"> <div class="QuoteAuthor"><a href="/profile/70/ICBM" title="Link: /profile/70/ICBM">ICBM</a> said:</div><div class="QuoteText"> I'm sure robinbowes knows this, but for anyone else who needs to change one, the best method on a modern though-plated board is to carefully destroy the remains of the old jack using small cutters, leaving just the three metal contacts - then they can be desoldered individually. If you try to do all three at once and get it out as a single unit you'll probably damage the board before it will come out cleanly.</div> </blockquote> Yeah, been there, done that!

Good tip. R.

svejk · December 2016

Great advice and help. Should be sorted now

robinbowes · January 2017

Update: I got a replacement socket and fitted it. It wasn't quite the right part and I had to trim down the each of the terminals so they would go through the PCB holes, but the end result is fine. It appears to work when I apply power as the LED comes on when the effect is engaged, but there is little or no sound - sound passes fine when the effect is bypassed. So, it appears there is a secondary fault somewhere. I'm going to pull the pedal apart and take a look for anything obvious, but I don't suppose anyone has a schematic, or any trouble-shooting issues for this pedal (J.Rockett Lemon Aid) ? R.

ICBM · January 2017

That's odd - from simple physical damage like that you wouldn't think there was anything else - unless the force which broke the jack also twisted the PCB and cracked a joint? I would start by carefully checking that.

robinbowes · January 2017

I don't see any obvious cracks/breaks. I've checked the soldering is OK by testing continuity between each joint on the socket and a component connected to that joint - all good. Looking at the board, I don't see any obvious failures. The board looks like this: <img src="https://lh3.googleusercontent.com/3IzH2ITLP3gPW3KaWybHN3DHmkaBmdjEI4W2DN-VxfnZGp6etzpasxuy1vA-dyErKyEUSZTN0CvB4qM0D_iQyozwQwFY38ZPUSIc0YfjuILGyNI1CibN7RHRu5NTal_M7AfuGw=w1614-h1210-no?.jpg" alt="" title="Image: https://lh3.googleusercontent.com/3IzH2ITLP3gPW3KaWybHN3DHmkaBmdjEI4W2DN-VxfnZGp6etzpasxuy1vA-dyErKyEUSZTN0CvB4qM0D_iQyozwQwFY38ZPUSIc0YfjuILGyNI1CibN7RHRu5NTal_M7AfuGw=w1614-h1210-no?.jpg"> The transistors are 4 x 2n3906 and 2 x 2n5485. I guess I'll have to try and trace the signal path and work my way back from the output until I find where it stops working. R.

svejk · January 2017

Thanks for sticking with this Robin...sorry it's turned out to be much more of a pain than it looked!

ICBM · January 2017

Have you checked the new socket pins are definitely soldered to the pads on both sides of the board? If not, and the supply to the LED comes from one side while the supply to the circuit is from the other, then the LED could come on without the circuit working. (I assume the LED is D2.)

robinbowes · January 2017

Yes, both sides are apparently OK (I followed traces and checked continuity on both sides of the board). D2 is indeed the LED. I don't see any reverse polarity protection. I wonder if the power socket incident involved a centre positive supply which has fried one or more transistors? R.

svejk · January 2017

Just checked the power supply my son was using. 9v centre negative.

robinbowes · January 2017

I may have a lead... I started removing the transistors to test them out-of-circuit with my DCA55. The first one (a 2n3906) tested OK, the second (a 2n5485) came up as a "Common anode diode network" - it should identify it as a jfet. Time to see if I have spares... R.

robinbowes · January 2017

I took the other 2n5485 off and it tests correctly as "N-channel Junction FET". So, looks like I've found the problem. I'll order a replacement and get it fitted later this week. R.

robinbowes · January 2017

The replacement FET fixed the problem. All done and ready for collection now. R.

Howdy, Stranger!

Categories

In this Discussion

Become a Subscriber!

Can anyone fix my pedal please?

Comments