Build Your Own Clone Message Board

Hi all, I am having trouble with the MOSFET boost section. I tried bridging the IO and got the expected vol effect at the boost pot, So I think something is wrong with my boost section. I see that the MOSFET is installed backwards but that was called for in the instructions - as was a backwards install of both of the diodes. I was concerned that the electrolytic was the only polarity sensitive element that was NOT called out as a backwards install - and I tried reversing that just as SOP. no luck. Any ideas about what might be causing a loud 120hz hum to be the only impact of switching the boost on?

I also tried reheating the solder on all the joints to be sure they weren't cold. No change.

What kind of solder are you using? It seems awfully dull looking.

You might also want to trim the component leads down to their solder joints--you don't want them shorting against the electrolytic caps on the CJ board under the boost module.

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

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

I'm using Kester electronic silver solder. and I will trim those..

The solder joints in the top photo look cold (insufficient heat transfer while soldering) and solder starved (too little solder used).

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"It’s your soldering."

Ok. I went over all the solder joints, reheated them and added a bit to each. No change.

To correct my first assessment: there is a boosted signal coming through when the the 'boost' is engaged, it's just accompanied by a loud 120hz hum - louder that the signal. That hum can be produced with or without input by engaging the boost. It is controlled by the boost vol. And I tried the i/o bypass jumper, everything works in that situation except the boost becomes a vol control.

Thanks for thinking about this.

Thought so. Not a lot of fans of that stuff around here--it's more difficult to use and less forgiving of technique and temperature window. We strongly recommend the classical lead/tin stuff here. Still, if you've been through the joints a couple of times, that's probably not your issue here.

If I have to guess (and in lieu of actually knowing the problem, I have to!), I'd say that the MOSFET is probably bad. You can check this if you have a signal tester. Check for signal on the input to the MOSFET (middle leg) and then on its output (leg closest to the 10uf electrolytic cap). Tonally, the two should be pretty nearly identical, but the output will be considerably louder. If the MOSFET is bad, the input should still sound OK but the output will have the noise.

BTW, MOSFETs are notoriously sensitive to electrostatic discharge, so you want to be very careful (and grounded!) when you handle them.

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

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

Writing this down for posterity so that it's searchable, and may help others, but I *think* I've answered my own question (anyone, please feel free to chime in if I'm wrong):

I just started my Crown Jewel build, with the Germanium/Treble Booster module, and while following the boost module instructions, I noticed that there aren't any instructions specific to the installation of the germanium transistor, which I'm not super familiar with (how do I match the orientation? do I clip the leads? do I solder the leads? etc). The only reference to the transistor in the current revision of the instructions says: "You will lay the transistor on the board after you have placed it in the socket."

However, I did just realize the existing Germanium Boost pedal probably has pretty good instructions for installing transistors, and indeed it does. The section on installing transistors at the very bottom is really great, especially the part where it tells you, in all caps, "DON'T FREAK OUT!" Hopefully future revisions of the treble boost module will just also contain that section.

They will. Thanks for bringing that to my attention!

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The tone is in my hands?!
Email: nick@buildyourownclone.com

Nice. It's great documentation; thank you!

Back to the original poster....when you jumpered the I/O of the boost module socket, did the 120Hz noise go away?

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Yes. When I bypass the boost section, the boost control acts as a volume control and the signal is clean.

AND I took it to the gig anyway, where it sounded Great (thank you very much!) Really a cool pedal.

I tried a new mosfet. Still humming.

I just checked all the supply voltages to the boost module and they are correct.

Do you have a module other than the MOSFET?

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

I just ordered 2. I'll get them in a day or two and tell you what happens.

Ok. I just built and installed the LPB boost. Same hum. So I assume that there is a problem in the main board that only pertains to the boost section and only engages when the board is installed. Hmm. I don't have an oscilloscope. Is there another way to dog this down. To recap: the main functions all work fine and with the i/o bypass jumper in, the boost stage becomes a volume control.

I tried a new power supply and the noise is gone. The bad one was a Roland ACR-120. Since it was neg pin 9v I thought it would be fine but for some reason it causes a hum only in the boost mode. The hum is not the usual 60hz stuff which is present in the normal use of the guitar. This hum is very specifically 120hz. Anyway with a different ps I'm fine. Thanks for your help.

-B

Ok. I don't think that power supply is intended for guitar effects use.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Hi all,

I just completed building my byoc Crown Jewell with the MOSFET boost module, and I can confirm the OP's findings and solution:

With an RCA AH562 power supply plugged into my old house's outlets, the boost screeched and the drive was rather noisy. With a new Boss PSA-120S power supply, the pedal worked excellently with very minimal noise.

Thanks OP and others on this thread for helping me find this simple solution!

Best wishes,

akuster777