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Messages - Cybercow

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31
VFE Projects / Re: Bumble bee ainít swellin. Help me Mr. Bean :D
« on: May 27, 2020, 12:20:09 PM »
JimiLee - that 2Ķ2 cap is actually C14. I was referring to C4 (0.68ĶF) - it's always connected. C5 & C4 are actuated via the toggle switch. And never mind the bit about pulling the FET or any transistors. The following should help.

Have you gone thru this part of the setup procedure (#4 from page 7)? - - - - "4) To set up the swell effect do the following: set the switch in its middle position, the MIX knob all the way counter-clockwise and all other pots to their middle position. Leave TWEAK in the center and the 20k trimmer all the way down. Now, adjust the 20k trimmer clockwise until you hear notes start to swell up in volume. Continue adjusting it until the volume of the swell matches your input. From there, you can adjust the TWEAK trimmer to  re-tune. In my build, the 20k is set at about 11 oíclock and the TWEAK trimmer pretty much in the middle."

What occurs to me is that the voltages are to be measured with the above mentioned settings. Mind you please, that this is an assumption on my part as it is not clear at what settings things should be when measuring the voltages.

So, if you're getting proper voltages on the collectors of Q6 & Q7 with the 20K trimmer turned all the way down (counter-clockwise), then you should be able to get it swell by following the instructions in #4 on page 7 as noted above.

32
VFE Projects / Re: Bumble bee ainít swellin. Help me Mr. Bean :D
« on: May 27, 2020, 09:48:13 AM »
Did you remove Q6 & Q7 (2N3904s) also? The ones with the low voltages?

And something is definitely wrong if the 100K Tweak trimmer is changing the voltage on the collectors of Q6 & Q7. C4 is supposed to isolate them from ground.

33
VFE Projects / Re: Bumble bee ainít swellin. Help me Mr. Bean :D
« on: May 27, 2020, 09:20:32 AM »
The v+ is 8.05 and the v- is -7.45.

OK, the supply seems fine. (I mis-stated the Ī15v previously, it should be closer to Ī9v like you have.)

Q5 seems to have near enough correct voltages, but Q6 & Q7 are far too low. Those 2N3904 collectors (Q6 & Q7) should be at around 5.9v. Did you set the switch in the middle position, the Mix control all the way counter-clockwise and the other controls centered?

What voltages do you get when you remove the 2N5457 & 2N3904s (Q6 & Q7) from their sockets? Please try that and report your voltages.


34
VFE Projects / Re: Bumble bee ainít swellin. Help me Mr. Bean :D
« on: May 27, 2020, 06:57:17 AM »
JimiLee - "Sorry, yes. The VGS measures 3.1. Would that stop the 3904 trannies at the top on the right and the one below it from measuring properly? Iíve got more 5457s on order. "

The FET Vgs needs to be between 1.25 and 1.5 as indicated in the build docs. But the poor FET performance should not be responsible for the incorrect voltages of the trigger sensor section BJTs (2N3904s). What are the voltage output of the switching board PCB? It should be a dual rail at Ī15v. Have you verified that?

35
General Questions / Re: Waterslide Graphics
« on: May 26, 2020, 02:05:41 PM »
In my experience with waterslides, anything bigger than 1590BB and I use the photopaper, glue-stick & ArmorAll method.

https://www.youtube.com/watch?v=25BnW3aTU9I

36
VFE Projects / Re: BOM values vs. silk-screen values
« on: May 26, 2020, 11:21:37 AM »
MadBean - Yikes! What a mess indeed!. Still, that is quite helpful. Thank you very much.

Instead of running thru all 20 projects and pulling up the Eagles with part IDs, perhaps you'd be willing to do it, (as you've done here), when someone asks. (?)

Again, thank you for this and the explanation.

37
Hmm, I haven't built this one yet and so I haven't studied it very much but the build doc talks about the trim pots being used to bias the jfets so it seems where you have the trim pots(s) set may affect those voltages that are off. Not sure, just throwing it out there

While the 20K trimpot does indeed adjust the FET (Q2) in this circuit, the off-voltages are exhibited by what appears to be the 2N3904 transistors in the detection section of the circuit (Q5, Q6 & Q7) as indicated in jimilee's posted voltage readings. There seems to be no simple tweaking for the 2N3904 transistors.

Of the 3 trimpots on this PCB, the 20K is for the rough swell adjustment; 50K for the bass adjustment; and 100K to fine tune the swell adjustment.

38
VFE Projects / Re: BOM values vs. silk-screen values
« on: May 26, 2020, 06:42:38 AM »
I've wondered about this. A genuine problem exists between the fact that the part IDs on the schematics are listed NOWHERE else in the build docs or on the PCB silkscreen. So, when looking at the schematic and trying to identify which specific Q is Q5 (when Q4, Q5, Q6 & Q7 are all 2N3904s) but are marked as "Q4", "Q5", etc only on the schematic; it makes troubleshooting a PITA because we then have to trace portions of the circuit to determine which part is which.  Or is there something I've missed for specify component identification?

39
One of the things I've noted about this (and some other VFE build docs) build document is that the PCB nor the build docs identify the part numbers - only the values. The only way to assure one is correctly referencing (correlating) any specific part between the schematic, the PCB and\or the build document images, is to do some circuit-tracing. Which a is PITA. At least the one image with the blue & red traces is helpful in that regard.

40
I don't see your measured voltages listed anywhere. However in the photo, I do see two questionable solder joints - lower-right area and mid-lower-center area. (Circled in red.)

And considering there are several socketed components, (always a good idea), have you ensured all the legs of those devices are sitting snuggly in their respective sockets? Sometimes, I have to "wrinkle" the ends of the legs a bit to get them to fit snuggly.

41
VFE Projects / Re: Bumble bee ainít swellin
« on: May 24, 2020, 04:49:53 PM »
Did you do the stock build or follow the variations found page 7 of the build document? (Opamp substitutions? Opto-Coupler used? FETs used? 20K trimmer or 22K resistor? Value of C25? (Although the C25 question is likely not part of the problem.)

I have a VFE Bumble Bee in build queue, and while I've not yet gotten to the building part, I have been researching all the info I can find on the SG-1 circuit. There is a lot of concurrence that the following parts (numbers based on the schematic of this particular build) should be closely matched:
ē R17 & R32 (4K7 Ω)
ē C20 & C21 (1ĶF)
ē D3 & D4 (1N914)
ē R33 & R34 (100k Ω)
ē Q6 & Q7 (2N3904)

What are the actual measured voltages for your 2N3904 Qs?

42
Build Reports / Re: Cheese Fuzz (Sacred Cow prototype)
« on: April 15, 2020, 11:57:17 AM »
Thanks for kind responses everyone. Been busy putting together MadBean's "Pork Barrel" & "Man-O-War Dlx" and a few other builds this past month.

43
Build Reports / Cheese Fuzz (Sacred Cow prototype)
« on: March 02, 2020, 03:32:17 PM »
MadBean was kind enough to grant me one his "Sacred Cow" prototype PCBs and I finished it. I call it "Cheese Fuzz". A gnarly fuzz with a rotary selector for different tone shaping values and compression levels. It's based on the Big Cheese / JHS Cheesball fuzz. Itís like a fuzz face wrapped in a op-amp and is capable of a high degree of compression/fuzz/ filtering. I retained the A10K volume pot instead of using MadBean's suggested A100K to better tame the output. Tried it out on a couple of solid state amps (cheese little Johnson 12 watt with a 6" speaker & a Line 6 Spider Jam 75 watt with a 12" speaker) and a tube amp (Vox MV50 AC with Marshall 4x12" cab) and it sounds great on all 3 amps. Anyway, here are some shots of the enclosure and a bit of circuit porn . . . . . .





Gut and build shots . . . .







44
Build Reports / Re: the FLUNKEE FX-25 envelope filter
« on: January 29, 2020, 10:21:44 AM »
Excellent job - inside and out! Looks great!

45
Build Reports / Re: Triiiumvirate Build Completed
« on: January 29, 2020, 10:18:54 AM »
Thank you all! The kind comments are very much appreciated.

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