Hello this is my first time posting on this forum. I have a protone haunted delay. In bypass everything is fine signal goes from guitar to amp. When engaged light goes on but no sound gets through. I took off the back cover and multimetered the dc in and it is getting 9 volts. I don’t have much in the way of trouble shooting chops and any assistance would be appreciated. I was multimetering all the components but don’t really know what I’m looking for.
Update and question: Protone haunted delay non-op Q
- Thread starter Nobigdeal
- Start date
I did some voltage testing from the top and this pic shows the values written on a few of the components…three of them are 9s, one of them is .26 and the rest are zero. Maybe this is confusion on my part but I am getting no voltage readings “0s” on the stomp button lugs and the input and output hot lugs when pedal is engaged. Could it be the stomp is bad or perhaps one of those components that tested at zero are bad? Thanks again I appreciate all the help.
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You can do it from the top as long as you can work out which resistors are giving you the 4.5V. Essentially there would normally be 2 resistors between the ground and 9V, and the point where they both join would be halfway voltage, so 4.5V for a 9V power supply. That 4.5V is used to bias the opamps so they will work properly. If they are not biased to that voltage (which they aren't if you measure them at or near 0V) then no signal will pass through those op amps. You need to work out if there is a failure to derive that 4.5V, or a broken connection that means the 4.5V does not get to the op amps.
In the seabed delay linked to above, the resistors in question are 10K (brown, black, orange) which is fairly standard. I can see you have a few on the board in the right place, so use a continuity measure on your multimeter to find the right ones. One will have one end on 9V and the other will have one end on ground, and they will be joined at the other end.
Checked continuity on the components and this pic shows the Xed out components with no continuity. I’m not quite sure how to go about identifying with the multimeter the two resistors joined at one end and tied to the 9v and ground. If you could elaborate with steps I’d be very obliged.
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@PJS maybe I just found what I was looking for. I voltaged tested again looking for the resistors that are tied together between the 9v and the ground. In this pic I wrote the values for each leg of the two resistors (brown black orange banded). They are next to each other in an L shape. The legs are: resistor one 9.29 and .26, resistor two .26 and 0. Thanks again for your help.
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I think those are the 2 resistors you are looking for alright, and that 0.26V corresponds to the bias voltage you are getting at the op amps. That 0.26V should be (with 9.29V as the input voltage) about 4.6V. It looks as if something is shorting that voltage nearly to ground. The resistor that has 0V at one end and 0.26V at the other almost certainly has a capacitor in parallel with it. It will most likely be in the range of 10uF to 100uF electrolytic. With no power to the circuit, measure the resistance of the resistor that we are talking about. It will most likely read a lot less than 10K. If so then either the resistor is shorting, the capacitor is shorting, or there is a piece of metal somewhere it shouldn't be. Electrolytic capacitors do die over time, so I would be most suspicious of that. You might be at the stage of needing to take the board out of the case, because if everything you see agrees with what I have described then the next step I would do if this was mine would be to identify the capacitor that is parallel to that resistor and desolder it. The circuit will work without it, so then I would measure those voltages again, and if they have come back to normal then I would solder a replacement in and test it.
Almost certainly not. It will be a cylinder with a metal label wrapped around it. You probably won't be able to identify the correct one without removing the board and looking at the traces. One leg of the capacitor that you are looking for will be directly connected to one end of the resistor that we have been talking about (0v one end, 0.26v other end) The other leg of the capacitor we want will be connected to the other end of that same resistor. If you are unsure, then take the board out and provide photos of the trace side and we can help out.
Got it, I removed the pcb and guidance on understanding the trace from the resistor in question and the capacitor to remove would be much appreciated. Here is a pic of the underside showing the two legs of the resistor and their voltage read (.26 and 0) and the upper side with the same resistor circled. Many thanks @PJS
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OK, I think this. If you look at the track side there is a brown wire soldered across it. In your photo the left hand end of that brown wire I am pretty sure connects to the capacitor you need. I would take some measurements of voltage on both sides of that capacitor just to make sure there is 0V on one side and 0.26V on the other. If that all checks out then whip it out. I have no idea what your experience of soldering is, but I will just say that on a single sided board like this be especially careful not to put too much heat on there for too long. You can lift the pads off the board pretty easily. That can be fixed but does make the process more complex. If in doubt stop and let it cool down and then go again. With a component like this I would heat one leg and the wiggle the component sideways to pull that lead out just a bit, then do the other leg a bit, and go from side to side until it is all the way out.
I did test voltage of that cap and it was one leg 0 and one leg .26. I removed the cap, but not as intended. Using fine tip solder iron applied heat and gave it some back and forth motion. The top of the capacitor cane off but the legs are still in the board. For a small part it is in there much more firmly than I would have thought. Any way I plugged in and the pedal still works in bypass. When engaged the pedal works as before. Very low volume and almost no dry signal. With that cap off when in bypass the pedal produces a repeating high pitch pulse tone. Hard to describe but a dolphin sound is what came to mind. I’m no worse off than before so if you have any additional al ideas I’d be obliged and happy to give it a try. Thanks again @PJS
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Bummer. The only other thing connected to that net is the op amp. If it was socketed it would be simple to pull it out and test if that sorted out the voltages. It's not though so it would need to be desoldered. That is not a simple task with 8 pins - especially if you want to avoid breaking it - just in case it is not the problem. How confident are you that you could remove that chip (and put a socket in while you are there)? If it is something you think you could do then do it, and clean up the holes and then measure the voltages on the empty pads. If you do break the IC then they are not rare or expensive, but it's better not to break it if you can avoid it.
There might be, but I can't think of any off hand. There are various ways I would think about removing that chip. One it to use small cutters to cut each pin, and then once all the pins are cut and the IC if off (but rubbish) then you can remove each pin individually. That method is guaranteed to break it. If you have a desolder pump or brain you can use it to get the solder off each pin and if you get them clean enough the IC should come out. Those products can be quite effective. The other is that you can bend a piece of copper wire into a U shape and solder it to all the pins. You can then use that wire (and moving the iron around) to spread heat to all the pins at the same time and melt all the solder at once and the iC should pull out. You will then have a big mess of solder on the pads that will need cleaning off. Before you try any method definitely watch some Youtube videos on the different processes to see how to do them.
Somebody may also chime in with other things to look at that I may not have thought about.
Somebody may also chime in with other things to look at that I may not have thought about.