Troubleshooting Glory Hole

[schnerf]

It's all together, but it's my first build (of relatively few) that hasn't worked right out of the gates.

I had dry signal when bypassed.
No sound when engaged
No LED

I switched the LED leads, so the red wire goes to A and black to K, even though I had it red to square pad and black to circle pad like I've done previously (this time, I used the pre-wired LED from lovemyswitches--I guess they used opposite wire coloring?) (The diodes are added based on the stripes, the FET/saddle are aligned with the notch toward the top, and all of the electrolytic capacitors are positive side on top (in the square pad) and stripe on the bottom -- my one worry is if the LED was reverse what I'm used to, are the electrolytics reversed as well?)

I still have dry signal on bypass
LED works!
When LED is on, all I get is a hum.

I looked for solder bridges and ran a blade between everything.
I checked for ground faults (everything that beeped looks like it should have a ground connection, except I'm not positive the right-most pin on the A100K pot. This was the only pot pin to beep. The mini toggle didn't beep anywhere.) On the 3PDT breakout, GND always beeped, IN beeped when the LED is lit, and OUT beeped when the LED wasn't lit.
I'm not getting any ground continuity beep on the surface mount transistor leads to the breakout or pads (main board or breakout). I soldered it to the 5457 side of the board and connected left pad to left pad (D), middle to middle (s) and right to right (G) with the chip side up.
I checked wiring (seems good).

I'll order an audio probe, but any ideas on what else I can test?

 

[Chuck D. Bones]

Welp, wish I had come back and read your responses first. Your assessment of me not knowing what I'm doing was correct. I ordered some JFET 2N5457's on eBay and just threw them in the pedal and still nothing. Either they are fake or something else is really wrong with my pedal. Is there any way I can test to see if they're legit without buying a socket? Also do you guys know anywhere I can get legit 5457's? Tayda doesn't have any, smallbear doesn't either. eBay had an abundance but I guess I know better now. This is becoming really aggravating. I also ordered some J201 transistors from the same guy on eBay and I'm having second thoughts about putting those anywhere near my other pedals

Doc,
I don't know what your electronics capabilities are, so I'm going to ask a few questions. It is not my intent to be insulting, so please don't take it that way.
1. Do you own a DMM?
2. If so, so you know how to use it?
3. Do you have a few clip leads?
4. Are you able to identify the S, D & G leads on a JFET?

If the answer to all of these questions is "yes", then it is a simple matter to measure Idss and Vp. That will tell you if a particular JFET is in-spec or if it's even a JFET.

There are other JFETs that SB carries which will work as subs in your Gloryhole.

 

[caiofilipini]

I've used these in my Glory Hole build and they're legit:

(*) JFET 2N5457 - Guaranteed Genuine - GuitarPCB

(1) Genuine 2N5457 JFET Transistor from my own personal collection. Hand Tested and all are in the proper range for guitar pedals.

guitarpcb.com

 

[docgerlach]

Okay. Well, I decided to play it safe and I bought some JFETs from guitarpcb.com and they seem legit and checked out when I tested them. But still no noise coming out of the pedal. I then replaced my DC jack thinking that could be a problem, still nothing. Then I tested my foot switch and found that the middle row had no continuity and I thought I’d finally found it, but surprise, still nothing after replacing it with a working one. I’ve checked over every component to the best of my ability with a DMM and everything seems to check out. And just as a precaution I re-flowed EVERY joint and checked over every wire. At this point, literally every component, wire and part has been double and triple checked. Is it at all possible that the pcb itself is just faulty or broken somehow?? I have no idea what else could be wrong. Pedal works in bypass but has no signal when on. I’m about ready to call the project a total loss but I really want to hear it work!!

 

[Chuck D. Bones]

Do you want to measure some voltages on the board? If so, we can do some systematic troubleshooting.

 

[docgerlach]

Do you want to measure some voltages on the board? If so, we can do some systematic troubleshooting.

Yes please. I’m up for anything at this point

 

[Chuck D. Bones]

With power on and no signal, measure these voltages & report back:
IC1 pins 1, 7 & 8
Q1 D & S

This will tell us if things are biasing correctly.

 

[docgerlach]

With power on and no signal, measure these voltages & report back:
IC1 pins 1, 7 & 8
Q1 D & S

This will tell us if things are biasing correctly.

Alright, here’s what I found.
For reference, I measured 9.1 V on the pcb pads.
IC1
pin 1: 0.0v
pin 7: 7.9v
pin 8: 8.8v

Q1
D: 8.2v
S: 0.3v

I also wrapped the board in a paper towel this morning to isolate it from the case and make sure nothing was grounding out. Still nothing

 

[Chuck D. Bones]

IC1 is not biasing correctly. Pins 1 & 7 should be at about 4.5V. Q1 is not biasing correctly either. Q1 S should be above 0.5V. You said you tested Q1. Did you measure Vp & Idss?

Measure IC1 pin 5, Vref. Should be 4.5V I suspect you have at least one short on the board.

Post pix of both sides of the board since you installed Q1.

 

[docgerlach]

Well, like I said I don’t really know what I’m doing here. I thought Q1 was good. How would I go about testing Vp and Idss?

Pin 5 measures at 0.6v

Sorry for the hassle and my lack of knowledge.

Here are pics with the new Q1 from guitarpcb.com

 

[Chuck D. Bones]

I can't read the top of IC1. Is it an LM833 and where did you get it?

Just to be clear, when you measure voltage, the - lead of your DMM is grounded to one of the jacks, yes?

 

[docgerlach]

Ah sorry, bad lighting. Here’s a better picture.
I’ll be darned... The bag it came out of said it was an LM833N but that is not what it says on top. I could be mistaken but this looks like the wrong IC. It came from Tayda. Is this my problem??

Also, yes I am grounding it to one of the jacks when measuring.

 

[temol]

You have wrong IC installed here. And no IC socket... If you manage to remove the chip (without damaging solder pads), install a socket.

 

[Chuck D. Bones]

You have wrong IC installed here. And no IC socket... If you manage to remove the chip (without damaging solder pads), install a socket.

Indeed. I'm not a fan of IC sockets... until it comes to troubleshooting. NB: better photos early on would have saves us all a lot of time.

Sacrifice the chip, not the board. Cut all of the IC leads, then unsolder each one individually. Use solder braid, solder sucker and/or tweezers. Minimize the heat applied to the board.

This will correct the problem with the IC, but Q1 still has a problem. Did you buy more than one 2N5457? If so, we should test the other one(s) to see why the one on the board is running so cold.

 

[docgerlach]

Indeed. I'm not a fan of IC sockets... until it comes to troubleshooting. NB: better photos early on would have saves us all a lot of time.

Sacrifice the chip, not the board. Cut all of the IC leads, then unsolder each one individually. Use solder braid, solder sucker and/or tweezers. Minimize the heat applied to the board.

This will correct the problem with the IC, but Q1 still has a problem. Did you buy more than one 2N5457? If so, we should test the other one(s) to see why the one on the board is running so cold.

I am incredibly embarrassed that I didn’t catch this sooner. I am also really sorry if this felt like a waste of time for you guys. However I have learned a lot about troubleshooting so thank you for that! I will get a new IC ordered asap. I did order 3 2N5457s so I have 2 left right now. I also have a handful from ebay but Im apprehensive about using those. What’s the best way to test them? If you don’t mind sharing

 

[Chuck D. Bones]

Measuring JFETs:
Vp
Connect drain to +9V.
Connect gate to GND.
Connect DMM between gate & source, + end at gate, measure voltage.
The voltage reading will be negative for N-channel JFETs like 2N5457. Spec for 2N5457 is -0.5V to -6.0V. Anything more negative than -3.0V will be useless in this circuit.
Idss
Connect drain to +9V.
Connect gate to source.
Connect DMM between source and ground, + end at source, measure current.
Spec for 2N5457 is 1 to 5mA.

So we don't repeat the problem we had with the IC, be sure to read the printing on the JFET and verify that it is 2N5457.

 

[Chuck D. Bones]

I am incredibly embarrassed that I didn’t catch this sooner. I am also really sorry if this felt like a waste of time for you guys.

Don't worry about it. This is a learning experience. When I start a troubleshooting task, I stick with it as long as the person I'm helping stays engaged. I appreciate it when you make my part of the job easier.

I recommend that you order extra parts, especially semiconductors, because sometimes you are going to need the spares. Whatever you don't consume in one build can be used in another.