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Hi All,
A friend and I recently constructed our first pedal, the Tube Screaming Ultra (a troubleshooting, half-working nightmare), and for our second we decided to try the Robin Trower Version included in the Build Report.
The build itself, initially, was great, apart from the fact that it did not work at all. Fixed a few connections, and still nothing. Looking at an older build report, we switched out C10 (100uF) and C11 (47uF) for 10uF caps, as per this older build report. Testing it now, bypass works fine, but the pedal itself does not. The status LED does not turn on, and no sound is produced, in any switch configuration. Wiring is a mess, but as far as we can tell, intact and functional. Multimeter confirmed that power is running into the board, but evidently is not circulating correctly. As this is our second pedal, we are unsure exactly what to probe for further info.
A few more little details:
Whilst the older report did not include the 5819 Diode, we did not bother to remove it as we figured it would have little actual impact. Additionally, there is a high chance that C4 is broken, however looking at the circuit diagram this should not impact the pedal so severely.
I have attached a picture (sorry for the mess!).
Any suggestions on potential errors/fixes would be greatly appreciated. If any more information is required, please let me know.
Cheers.
Difficult to see
This is how it connects to the 3PDT yours obviously being modded on the in pad again its hard to see if your 3PDT lugs are horizontal like this
We’d need an image looking down on the 3PDT and pcb so that we can clearly see and trace the wiring
Thanks for the reply,
I’ve attached another image for clarity, although it is still rather messy I’m afraid. (Status LED is welded and screwed, preventing the board from being removed without desoldering.)
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Jacks are connected as per build report, sleeve to ground, tip to switch.
The lugs on the 3PDT switch are wired like this:
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Lug 1: Wire to A (top of board, as per Robin Trower version)
Lug 2: Wire to input tip
Lug 3,9: Wired to eachother (bypass)
Lug 4,5,6: Wired to S4, S5, and S6
Lug 7: Wire to output on board
Lug 8: Wire to output tip
Are you connecting your in cable to the input jack remembering input is on the left wrong way up, that’s a fairly common mistake you’d still get bypass but no effect
There are a few solder joints that look like they lack solder and are potentially dry I’d reflow any solder joints that look dull, grey, ball like or crumbly especially on your 3PDT switch
Hold your iron tip on them for around 4 seconds until you see the solder pooling making sure you get a good connection between solder pad and component pin
Set your iron to 370°C
As far as I can see all values look correct
Agreed. Maybe focus on the offboard wiring as Billy says. If the pedal recovers, well and good. If not, double-check the board for similar possible cold joints. The right hand 9V via might need a touchup for starters.
Also check that no frayed wires are shorting against each other, not completely clear from the pic. Eventually try audio probing to identify where the potential fault lies if all the above haven’t resolved the problem.
Let us know how it goes in time and fingers crossed meanwhile ????
I found this discussion comparing the 5817 to the 5819 -“<span class=”ILfuVd” lang=”en”><span class=”hgKElc”>The 1N5817 is rated at 20V, with a 450 mV drop at 1A and the 1N5819 is 40V, with a 600 mV drop at 1A. This makes the <b>1n5819 slightly inferior to the 1n5817</b>. Also to get the required voltage out you would need to make about 2% more voltage in at the same current with the 1n5819.” In the scope of a 9v circuit 2% is probably not a major deal breaker but coupled with a “broken” C4 it’s not going to help. The 3PDT switch looks like a toggle – is it an On/On, On/On/On or On/Off/On? I haven’t used a 3PDT toggle in place of a stomp so I don’t know if a different type will make any difference. Based on some problems I had several years ago you might want to use your multimeter to check continuity of the jacks themselves – I had several builds in my Box of Fail that had bad jacks.</span></span>
Chuck
Thanks for the replies,
I suspect it is likely the wiring – still getting the hang of soldering (in fact, the wiring was so dodgy in our first pedal that we needed to assemble the case using a ‘brain surgery’ technique, strumming while we compacted everything in as to not bend the wires, as they were rather unhappy).
I also made a typo in my original statement – it is D4 that is potentially broken, not C4. Since I am desoldering the wires, I may as well replace it.
Another potential point of error is C10 and C11, as we had difficulties replacing the original caps with 10uF ones, resulting in their connections to the board being far from ideal (one of the legs being effectively ‘pressed’ to the hole on the board, rather than through it). Though as it still has contact I am unsure whether this would impact the function of the pedal so severely. For future reference, any suggestions on desoldering such components efficiently and effectively, with only a soldering iron?
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Question: For future reference, any suggestions on desoldering such components efficiently and effectively, with only a soldering iron?
People use solder braid and/or a solder sucker for desoldering. I prefer the sucker myself and the trick is to deploy it with speed to avoid overheating the pad(s). So, the solder will melt as you heat it and then the vacuum action of the said sucker removes the solder. If you need more than one attempt at this, let the pad cool down a bit in between. If you manage to remove it successfully (not always straightforward), you’re good to go.
Might be worth getting a piece of Veroboard, components inserted from top as pictured here:
Underneath here:
So that you can practise soldering without the risk of damaging a PCB. Or better still, find a simple circuit and learn how to lay it out on Veroboard from the schematic. At the end, you’ll have learnt a new skill and practised soldering at the same time.Here’s an example to clarify:
An update:
After replacing and resoldering every single wire, still nothing. I then removed D7 (5819 diode) and jumped it instead, as to mimic the older build report. Now, the status LED successfully turns on, but the pedal still does not work, instead producing loud cracking/ popping sounds (shorting, I assume) when on and receiving signal. What should I probe next, and what values should I expect to see?
Looking at the board picture I would reflow the entire board.
For example, if you look closely at C4, C5, C8, and a few of the IC pads there is no solder in the pads, or at least very little. Reflow by having extra solder handy and go over each pad making sure the solder flows through the pad. Not to excess but just enough so you do not have any cold solder joints.
You may want to share a clear back of the board shot so we can more closely examine the board’s solder joints.
Here are a few suspect joints that I can see.
So that you can practise soldering without the risk of damaging a PCB. Or better still, find a simple circuit and learn how to lay it out on Veroboard from the schematic. At the end, you’ll have learnt a new skill and practised soldering at the same time.
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