Box of Rock, only dirty: headroom problem

[marcelomd]

Looking at your pictures. In my experience the transistor sockets are not perfect. They can, and do, sometimes become loose enough to make noise, but not completely disconnect.

Maybe you have a cold solder, too. I'd clean up the board a bit. With some cleaner fluid and re check it.

[menstrel]

Looking at your pictures. In my experience the transistor sockets are not perfect. They can, and do, sometimes become loose enough to make noise, but not completely disconnect.

Maybe you have a cold solder, too. I'd clean up the board a bit. With some cleaner fluid and re check it.

12 hours ago I just removed the sockets and soldered the transistors directly on the pcb, redone some soldering and sprayed a deoxidizer, unfortunately it didn't help. To be precise, the crackle is not present from the beginning, for example I'm 20 minutes without problems and then suddenly it crackles for a few minutes and then stops but after about another 20 minutes it starts again, almost periodically even if I haven't been there anymore half an hour to test. The strange thing I noticed is that the noise seems to consist of 2 or more noises that are always the same, type A then B and finally C, and after about 20 minutes the sequence is repeated, A-->B-->C. Weird huh?!

On the cold solder, I have to say that I use solder paste and the solder is shiny only at the moment then it becomes opaque which looks cold. Which weld are you referring to?

[PRR]

> type A then B and finally C, and after about 20 minutes the sequence is repeated

Cellphone. WiFi router. Air conditioner. 'Smart' thermostat. Refrigerator. Timer on microwave oven. Police/Taxi radio on road.

A fairly steady 20 minute repeat seems unlikely for a pedal.

[menstrel]

> type A then B and finally C, and after about 20 minutes the sequence is repeated

Cellphone. WiFi router. Air conditioner. 'Smart' thermostat. Refrigerator. Timer on microwave oven. Police/Taxi radio on road.

A fairly steady 20 minute repeat seems unlikely for a pedal.

I hadn't thought of that, i'll check tomorrow.

[menstrel]

> type A then B and finally C, and after about 20 minutes the sequence is repeated

Cellphone. WiFi router. Air conditioner. 'Smart' thermostat. Refrigerator. Timer on microwave oven. Police/Taxi radio on road.

A fairly steady 20 minute repeat seems unlikely for a pedal.

Made some tests and I don't think it's due to external factors. Anyway, this is the noise it makes from time to time

https://voca.ro/1dTxeoShJ2xZ

In reality it is causal both in time and in substance, yesterday just a coincidence of repeated A...B...C bla ba bla

[menstrel]

I forgot to conclude that i re-soldered the jack and 3pdt cables and i no longer heard the noise i had described, kept it on for over 2 hours.
Great pedal, same sound texture as the original, with gradual tone from start to finish, having both BOR bass and higher treble.

[menstrel]

I'm reviving this thread because while using it I noticed a slight decrease in volume and/or sonic punch (less low frequency ? ) compared to before and I don't understand why this happened.

I tried to replace the mosfets with other 2N7000s and with BS170 but nothing changed, and the BS170 itself made me think. In fact, I know that generally the BS170 and the 2N7000 have the pinout reversed and therefore it would be enough to rotate the mosfet by 180°, but in my case I don't understand why I don't have to rotate the BS170 to work.

I had read that sometimes the BS170 is produced with a different pinout ( DGS or SGD) but with the multimeter in diode mode, it would seem that my pinout is D-G-S looking frontally in fact if I connect the red probe to the source and the black probe to the drain I read about 0.65v and by reversing the probes I find an open circuit condition.

Edit:

I mean, I knew that if I rotate the BS170 (or 2N7000), the BOR stops working but the BS170 mosfets I use have this pinout
https://www.componentsinfo.com/wp-content/uploads/2020/08/bs170-pinout-equivalent.gif

and the BOR works only if I rotate them by 180° i.e. with the sources connected to the 5.1k resistors.

How can such a thing happen?

[menstrel]

anyone ?

[bluelagoon]

Sorry can't help too much with your present conundrum, but it could be time to get yourself a component tester. Then you can know the right pinout on all your transistors with just a quick 10 second test. They are reasonably priced. Doesn't make for a quick remedy, but could do you well into the future. See them at the following links -

https://vi.aliexpress.com/item/1005005576233370.html?spm=a2g0o.productlist.main.25.47b26cc5dOjoOv&algo_pvid=51a54c43-e8c0-47c9-b3df-677439b14050&algo_exp_id=51a54c43-e8c0-47c9-b3df-677439b14050-12&pdp_npi=4%40dis%21AUD%2134.43%2114.46%21%21%2122.14%21%21%402103225216919284523703056e4e8b%2112000033640154112%21sea%21AU%21712531695%21&curPageLogUid=ATfmcJAr5Q1i

https://vi.aliexpress.com/item/1005005151807417.html?spm=a2g0o.productlist.main.59.47b26cc5dOjoOv&algo_pvid=51a54c43-e8c0-47c9-b3df-677439b14050&algo_exp_id=51a54c43-e8c0-47c9-b3df-677439b14050-29&pdp_npi=4%40dis%21AUD%2122.65%2122.65%21%21%2114.57%21%21%402103225216919284523703056e4e8b%2112000031880443943%21sea%21AU%21712531695%21&curPageLogUid=uUNoEvwbXcQy

https://www.aliexpress.com/w/wholesale-component-tester.html?SearchText=component+tester&g=y&trafficChannel=ppc

[duck_arse]

I tried to replace the mosfets with other 2N7000s and with BS170 but nothing changed, and the BS170 itself made me think. In fact, I know that generally the BS170 and the 2N7000 have the pinout reversed and therefore it would be enough to rotate the mosfet by 180°, but in my case I don't understand why I don't have to rotate the BS170 to work.

I had read that sometimes the BS170 is produced with a different pinout ( DGS or SGD) but with the multimeter in diode mode, it would seem that my pinout is D-G-S looking frontally in fact if I connect the red probe to the source and the black probe to the drain I read about 0.65v and by reversing the probes I find an open circuit condition.

Edit:

I mean, I knew that if I rotate the BS170 (or 2N7000), the BOR stops working but the BS170 mosfets I use have this pinout
https://www.componentsinfo.com/wp-content/uploads/2020/08/bs170-pinout-equivalent.gif

and the BOR works only if I rotate them by 180° i.e. with the sources connected to the 5.1k resistors.

How can such a thing happen?

the datasheet. get it, for the parts you have on the bench in front of you. look at the symbol thereon. it tells you some things, they always do, that's why engineers draw them the way they do. the gate, for instance, is drawn separate from the channel, because it is insulated from it in real life. and also see, between source and drain, the body diode, which is an intrinsic part of mosfet manufacture. so if your meter reads "diode" across two pins, you know which two pins they are. if your reversed meter then reads open, you know that is the channel, and you expect it to read open.

but most important is that the datasheet will have the pinout. if we won't trust the datasheet, what use are they? the BS pinouts are reverse of the 2N pinouts, until someone shows a datasheet to the contrary. because datasheet, there is never any need to "try it the other way".

[menstrel]

Thanks bluelagoon, I actually own one but I didn't think it also tested mosfets. With that I verified that my BS170s have inverted pinout, practically the same as the 2N7000. It also tells me the threshold voltage, for bs170 2.5v and for 2N7000 1.8v. It remains to understand why the volume is lower and has less punch.
Thank you again

[antonis]

It also tells me the threshold voltage, for bs170 2.5v and for 2N7000 1.8v.

According to my datasheets, V_GS(th) for both BS 170 and 2N7000 lies between 0.8 and 3 V (typical 2.1V), for V_GS=V_DS and I_D=1mA

https://www.acdcshop.gr/content/BS170_mmbf170.pdf
https://www.acdcshop.gr/content/2N7000-G.pdf

Now, there is a rather likely case where your particular 2N7000 exhibit a V_GS(th) higher than BS170 into respective circuit..