Build Your Own Clone Message Board

I'm a rank beginner at this, so not totally surprised that it wasn't firing on all cylinders coming out of the gate. There is a definitely a massive drop off in volume when I enable the pedal. The LED comes on, and the "None" position is marginally louder than either the LED or Si clipping options.

A couple of notes about my build process:

I inadvertently melted insulation off of the battery leads and have covered these boo boos with electrical tape
I installed the two ICs backwards initially and left the battery connected and the pedal enabled for a few minutes (chips were hot to the touch)
Only one of the clipping LED's becomes illuminated when I play, and it's not a very bright illumination

I'm wondering whether there was damage to the wires going to the battery. As noted, there is a big drop off in volume, but there are some slight differences when changing the clipping type or whether it's in Norm, Thin, or Fat position. I did do the "FET mod". I also took the pedal out of the enclosure and tried reflowing as many of the components as I could; some are obstructed by the pots.

Thanks for your advice,
Victor

Some additional glamour shots...

If you initially had the dual op-amps installed backwards and applied power to the pedal it’s a safe bet that they are both toast now. If you have any spares lying around try plugging them in and see if that fixes it.

_________________
"It’s your soldering."

Definitely do what Stephen said. If you need replacement chips, you can get some from BYOC or another vendor; they're pretty inexpensive.

By the way, the behavior of the clipping LEDs sounds normal to me. They will only light up briefly when they get hit with a signal strong enough to meet their clipping threshold, which is pretty high.

_________________
Scott

My band, Austin Hollow

Thanks for your quick replies, Stephen and sjaustin.

BYOC is currently out of stock, and I understand that there is some religious fervor regarding the vendor of the 4558. The ones in my build were TI 4558P. How important is it to use the same vendor's op-amp?

Also, in the meantime, while awaiting the arrival of the parts, is there some way I can test (in circuit) the op-amps and the charge pump (which also may have been installed backwards at one point)? I found the data sheet for the op-amps - which clearly identifies pin 1 in the addendum, by the way - and would be happy to measure voltages if that would help me definitely prove that the op-amps have been damaged. https://www.ti.com/lit/ds/symlink/rc4558.pdf?ts=1598546032117&ref_url=https%253A%252F%252Fwww.google.com%252F



I would have expected both LED's to light up, not just one. If only one is lighting up, is that indicative of a problem?

I could be mistaken here, but after looking at the data sheet, here's what I (think I) learned regarding identifying the orientation of the chip, i.e. the location of pin 1:

From the TI data sheet that I provided a link to in the previous post:



For the RC4558P parts supplied with my kit, this indicates package type "P" which is shown further down into the document:



This mechanical data drawing suggests to me that the "dimple" indicates the location of pin 1. I've shown these IC's installed in their sockets on my Green Pony with these dimples next to the notches on the silkscreen on the PCB for the CHARGE PUMP and 4558 IC's. The charge pump IC does have a notch in its package that the 4558's don't have; perhaps the 4558 parts that were used when the instructions were written did have notches and these TI parts that came with my kit don't?

You've done some pretty good research there, and are correct. There are (at least) two standards for marking pin one as you have noted. The half moon cut-out indicates the end where 1 and 8 are. If a chip has the DOT, that indicates pin 1. Once in a great while, you will see a chip with both and they might contradict each other. In that case you go with the half moon cut-out.

As far as which indicator you get and how it pertains to the instructions, there isn't really anyway of knowing unless the seller has a picture of the particular chips that are shipping at that time. It boils down to the specific machine used on that manufacturing line to make chips on that day. Some manufactures are more consistent than others. Another 'most of the time' rule is that when you are looking at the chip with the markings reading from left to right, pin 1 is in the lower left.

As you have found; P refers to the plastic 8 pin package we all know and recognize as an IC.

As far as your previous question about substitutions. You can use any dual op-amp for this application such as a TL072 or variant. You indicated that you stumbled upon the religious aspect of op-amps. You can dive into that mess after you get the pedal working. For now, just call it a dual op-amp and use whatever you can get. We can talk about how the Malaysian made ones are soooo much different that the Thai made ones later. Brand doesn't even matter at this point in terms of functioning, they are electrically all the same. Different brands, fabs, dates, etc can be sonically different, but as far as the pedal working, they are all the same in a given type.

_________________
If practice makes perfect, and nobody is perfect, then why practice?

It hurts me to say this.. but.. follow me on facebook and.. instagram

The IC installation info that would have prevented your issue appears to have been inadvertently omitted from the Green Pony instructions. It is present in several other BYOC kit instruction sets and I have attached it to this post, below. As Scott (sjaustin) replied to you in another thread, he has brought this to BYOC's attention and the GP instructions have already been updated with it (see page 23): http://byocelectronics.com/greenponyinstructions.pdf

Thanks again for raising this point. Customer feedback is an important element in discovering and fixing oversights in the kit instructions.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks, duhvoodooman and spin for your replies. The diagram that duhvoodooman attached is perfect. There are a lot of details to account for in the instructions, and I'm happy to be a part of the community effort to help account for all of them.

Is there a way to test the function of my charge pump in circuit? If I need to order some op-amps, I want to make sure that I replace the charge pump if I fried that, too.

For my edification, it would be nice to be able to test and verify which of these parts has been damaged. I understand that it is more difficult to do in circuit especially if the non-function of one affects either of the other two. I bought the beginner kit with the Green Pony instead of classic overdrive, so I do have access to the DMM from that kit with which I can measure pin voltages, etc.

Thanks again for the prompt responses.

I would suggest getting pin voltages on all three IC's. Here's how to do that:

Set your multimeter to the DC voltage mode, indicated by a solid line above a dotted one. Use the 20VDC range setting if it's not an auto-ranging meter. Your power source needs to be connected and there needs to be a cable in the input jack. If the pedal is assembled into the metal enclosure, put the black probe into one of the corner screw bosses of the enclosure--this is your ground connection. If the "guts" are out of the enclosure, use the sleeve tab of the input jack for the ground connection. Then touch the red probe to each point that you want to measure. The pin numbering is per the left side of the image shown below--down one side and up the other. Please report your results here, along with the voltage of the power source that you're using.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I inserted the black probe into one of 4 the screw holes on one of the corners of the enclosure and left it there while measuring.

4558 closest to the input and output jacks
Pin 1: 8.50V Pin 8: 9.37V
Pin 2: 7.71V Pin 7: -7.18V
Pin 3: 0.16V Pin 6: 0.00V
Pin 4: -8.99V Pin 5: 0.00V

4558 closest to footswitch
Pin 1: -0.03V Pin 8: 9.34V
Pin 2: 0.01V Pin 7: -0.02V
Pin 3: 0.01V Pin 6: 0.00V
Pin 4: -8.95V Pin 5: 0.00V

Charge pump
Pin 1: 9.33V Pin 8: 9.31V
Pin 2: 5.60V Pin 7: 4.34V
Pin 3: 0.00V Pin 6: 4.80V
Pin 4: -3.56V Pin 5: -9.05V

The footswitch was in the "on" position. I'm using a 9 volt battery.

Thanks for your feedback,
Victor

The lower 4558 and the charge pump voltages look good. The upper 4558....not so much. It should be almost the same as the lower one. So I suspect that one is fried. Any 4558 should work there; AAMOF, any general purpose dual op amp should work well there. This would include the TL072, TL082, NE5532, OPA2134A, LM833, etc.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks for looking at my measurements. I opened up an old Radio Shack Electronics Learning Lab kit but the only dual op-amp doesn't seem to be rated for high enough voltage. It's a TLC272CP https://www.ti.com/lit/ds/symlink/tlc272.pdf?ts=1598651326650&ref_url=https%253A%252F%252Fwww.ti.com%252Fstore%252Fti%252Fen%252Fp%252Fproduct%252F%253Fp%253DTLC272CP%2526keyMatch%253DTLC272CP%2526tisearch%253DSearch-EN-everything%2526usecase%253DOPN.

I have a Vox Pathfinder amp and I found its schematic. It appears to have NJM4558D's https://www.profusionplc.com/images/data-sheets/njm4558d.pdfand NJM072O's in it but I would guess that these are soldered to the board rather than being in sockets. If the latter, I could take it apart and borrow one temporarily just to test out the theory while I wait for a new IC to arrive. Am I likely to find that the IC's are in sockets inside of the amp?

Thanks again for the help. To be honest, the troubleshooting is more than half the fun.

I think you're just the right kind of weirdo to go a long way in this hobby.

_________________
Scott

My band, Austin Hollow

I would very much doubt it, but, hey, you never know....

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I did take the back panel off of the Pathfinder amp to look at the circuit board. The 4558's were soldered to the board without an IC socket. Not having access to any other dual op-amps, I placed an order for the replacement TI RC4558P from Small Bear Electronics (BYOC is out of stock) and will hopefully have it in hand by the end of the week.

Dude. PM me your address. Don't have 4558's on hand but I can send you something to test with, as you wait for smallbear.

_________________
Everyone likes sausage. Nobody wants to see how it's made.