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PostPosted: Wed Sep 21, 2022 12:54 am 
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Hey guys, first time builder.

I’m a professional guitar tech with some basic electronics experience. My (2.0) brownface trem‘s bypass works, but when engaged the LED becomes bright, then fades to a dull glow without pulsing. This only happens with a DC power supply, the LED doesn’t come on when powered by a brand new battery. What little sound does come out when engaged, is extremely quiet. When turning the trim pots, the bias pot can cause the volume to taper off as well. The depth and rate knobs have a similar effect, at no point does it pulse as a trem should. I put the PCB together with little hassle, caught some mistakes early on and fixed them. I used a fine tip, well tinned iron, the work seems clean, no joints touching, shiny dots. I reflowed the solder as suggested in other chats, no joy. Really hoping someone has an answer, I’ve read some other chats on adjacent issues but no one seemed to have my exact problem. I’m sure it’s something simple. Thanks for your help.

Ps in the photos you might see the DC jack is disconnected, I did that to remove the PCB from the case as I opted for the internal jack. I checked many times to make sure it was properly connected when I was having my issue. It’s currently reattached out of the case.


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PostPosted: Wed Sep 21, 2022 9:40 am 
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With the exception of the 5088 mounted at the bottom right just above the Level trimpot, all six of the other transistors are mounted backwards. Their flat and rounded sides should align with the shape printed on the PCB. These transistors will all need to be desoldered and remounted in the correct orientation for the circuit to function properly.

Removing components with three (or more) leads is a bit of a tricky business and care must be taken to avoid damaging the PCB eyelets. If you want to reuse the transistors, you'll need to remove virtually all of the solder holding them in their eyelets. A combination of a solder sucker and good quality desoldering braid is strongly recommended for this purpose. Properly done, the transistor will virtually fall out of the PCB. Once the transistor has been removed, use these same items to clean up any residual solder in the eyelets to prepare them for remounting the tranny.

Alternatively, you can opt to just replace the transistors--BYOC sells both types for 70 cents apiece. In that case, you can just clip off the head of each tranny and then desolder one lead at a time, a far easier and less risky process. Clean up any residual solder in the eyelets and you're ready to install the new transistors.

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PostPosted: Thu Sep 22, 2022 3:00 pm 
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Well I’m glad it was something simple. Thank you for the quick response, I opted to try and salvage the trannys and it worked! The light pulses, the trem trems, it works. I’m not totally out of the woods yet:

No signal when engaged using a brand new battery. Bypass works, but nothing when on.

It’s very dark. I’m fortunate enough to have access to a '61 Brownface Concert (it’s actually what inspired me to build this pedal) so I’m familiar with the ideal sound, and given it’s naturally a warmer rounder effect in general, this is more like a total loss in high end, akin to rolling off my guitars tone knob. No attack. I read on another thread that there are some resistors and maybe a cap that can be swapped, but I have a feeling it’s not yet working properly.

Thanks again


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PostPosted: Thu Sep 22, 2022 3:19 pm 
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Looking good, I can tell you, the black battery wire is (-) and the red is (+) You're sending + voltage instead of -.

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PostPosted: Thu Sep 22, 2022 9:01 pm 
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Good catch, swapped them and presto, now it works with a battery, thank you.

On the other issue, I set the ‘level’ trim pot with the depth knob all the way down; that setting really captures the loss of high end, or rather a wooly low mid boost and a high roll off. Is that just the sound of the pedal? Seems like plenty of pick attack is present in the demo videos I’ve watched, it’s hard to say from my end. Thanks always


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PostPosted: Thu Sep 22, 2022 9:15 pm 
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It's hard to know from your description whether the pedal is operating as normal or if there's a flaw. It definitely is a warm/dark effect, but everyone's ears and preferences are different. Is it possible for you to upload an audio sample and share a link? I have a BFT on hand that I could use to compare it to.

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PostPosted: Fri Sep 23, 2022 9:21 am 
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sjaustin wrote:
Is it possible for you to upload an audio sample and share a link? I have a BFT on hand that I could use to compare it to.

+1. I've got a fully functional Harmonic Trem also, and an audio clip would be very useful. Needs to be good quality audio, though.

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PostPosted: Fri Sep 23, 2022 8:35 pm 
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Signal chain: Fender Starcaster--> BFT-->78 Vibro Champ (Vol 3 Treb 6 Bass 4) -->Beta 57-->Warm 73 Pre (no eq)--> Logic

I start clean, then turn the pedal on at noon and go through the maximum and minimum settings for each knob, then clean again. I tried to upload a wav but it wouldn't let me.

https://soundcloud.com/avi-dee/bft-test-wav


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PostPosted: Fri Sep 23, 2022 9:12 pm 
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Sounds noticeably darker than mine.

I noticed that you said you set the level trimpot with the depth all the way down. I'm wondering if that might be a factor here, since my understanding is that the harmonic trem effect works by splitting the incoming signal between high pass and low pass filter sections, panning back and forth between them and then mixing the two outputs back together. I would think that having the depth turned down all the way would make it hard to balance the two filtered signals, so maybe the way you have the bias set is giving short shrift to the higher frequency signal. I would recommend that you try setting the depth at the halfway point (or higher) and then adjust the two trimpots exactly as described on page 10 of the instructions and see if that gives you a better result.

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PostPosted: Mon Sep 26, 2022 11:15 am 
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Capacitor value placement is very crucial to this circuit. We can't see your cap codes in the pics, so please double check that those are correct.

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PostPosted: Fri Oct 07, 2022 9:07 pm 
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Double checked all the caps, they’re correct


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PostPosted: Fri Oct 07, 2022 9:15 pm 
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duhvoodooman wrote:
Sounds noticeably darker than mine.

I noticed that you said you set the level trimpot with the depth all the way down. I'm wondering if that might be a factor here, since my understanding is that the harmonic trem effect works by splitting the incoming signal between high pass and low pass filter sections, panning back and forth between them and then mixing the two outputs back together. I would think that having the depth turned down all the way would make it hard to balance the two filtered signals, so maybe the way you have the bias set is giving short shrift to the higher frequency signal. I would recommend that you try setting the depth at the halfway point (or higher) and then adjust the two trimpots exactly as described on page 10 of the instructions and see if that gives you a better result.


I readjusted as described, no luck :(


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PostPosted: Mon Oct 10, 2022 12:08 pm 
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Do you have a signal tester? It would be helpful if you could listen to the high pass and low pass paths seperately.

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PostPosted: Mon Oct 10, 2022 12:53 pm 
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I have one at work, which parts of the PCB should I check for the high pass/ low pass signals


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PostPosted: Tue Oct 11, 2022 11:00 am 
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Makua94 wrote:
I have one at work, which parts of the PCB should I check for the high pass/ low pass signals


You'll want to check at Q2 and Q3. These would be the two 2N5088 just to the right of the two 2N5089 located in the middle of the PCB. Q2 would be the high pass and would be more towards the top (jack side) of the PCB and Q3 would be the low pass and more towards the bottom (foot switch side) of the PCB.

First test for signal at the base of Q2 and 3. This would be the center leg of each transistor. Signal volume should be somewhat low at this point. Then check for signal at the collector of Q2 and 3. This would be the leg closest to the top side of each transistor. Signal will be a bit louder at this point.

So at Q2 you should hear the "high" part of the tremolo and the "low" part of the tremolo at Q3.

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PostPosted: Tue Oct 11, 2022 8:01 pm 
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Ok I tested the paths and there was definitely something off. Q2 base was just a ton of buzzing over the signal, Q2 collector had no discernible difference. Q3 base was also very buzzy, Q3 collector was less buzz but still some present. The high and low signals were not very evident at either position. It’s completely possible that I was testing them wrong, but I had continuity in for other components


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PostPosted: Wed Oct 12, 2022 11:44 am 
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Makua94 wrote:
Ok I tested the paths and there was definitely something off. Q2 base was just a ton of buzzing over the signal, Q2 collector had no discernible difference. Q3 base was also very buzzy, Q3 collector was less buzz but still some present. The high and low signals were not very evident at either position. It’s completely possible that I was testing them wrong, but I had continuity in for other components


Signal testers are typically very noisy as they usually don't use shielded wire. So you could have some sort of problem, but probably not. I'd say if it's not "buzzy" when you play it normally, then the problem is with the signal tester.

So you're not noticing a different in tone between the two signals? Could you at least here tremolo at Q2 and Q3?

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