LPB-1 - WTF is going on?

Started by CodeMonk, September 06, 2014, 12:17:35 AM

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CodeMonk

I don't often ask for help here (I'm a stubborn bastard and maybe part masochist)

I built an LPB-1 yesterday.
I get only unity when the volume knob is maxed.
Did visual as well as checked for continuity where there should not be as well as continuity where there needs to be continuity with my meter.
And did all the normal trouble shooting crap (shorts, backwards parts, blah, blah, blah).
Did it according to both Jack Ormans schem and the one from Beavis Audio.
Sound is a little more defined, but no boost


Christ, I can build damn near every version of a Big Muff from memory, but an LPB-1 with 2 schematics?
Maybe I should get drunk tomorrow and start from scratch.

Voltages:
Battery : 9.56
C: 4.88v
B: 4.27v
E: 0.1607v

With the voltage divider resistors (1M and 100K) I should be getting around 0.8v at Base

If I pull the transistor out, I get:
C: 9.54v
B: 0.8v
E: 0

I've tried 4 transistors (2N5088). I've checked them all with my Peak meter and all check out ok.
Same results


Bah. I need a drink. or 12


petemoore

Convention creates following, following creates convention.

toneman

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CodeMonk

#3
Quote from: toneman on September 06, 2014, 12:24:26 AM
did U use THIS pin configuration???

http://vakits.com/2n5088-npn-transistor

yup
And my peak confirms that pinout.
I got those 2N5088's from Tayda, but the pinout checks out.
(I have heard they sometimes give you weird sh*t).

Edit:
Scratch, I got them from mouser (order of 200 + 500).


CodeMonk

Quote from: Blitz Krieg on September 06, 2014, 01:40:25 AM
http://www.diystompboxes.com/smfforum/index.php?topic=104730.0

Been there.
Thats where I found out what voltages I should be looking for.
I'm still getting 4+ volts at base, but when I remove the transistor, I get 0.8v just like in post #9.


Heres the layout (skipped the LED and power filter/polarity protection stuff in the image):



Maybe there's just a really stupid mistake I'm missing.
Bright green is input
gray is ground
red is power
C2 goes to output

CodeMonk

Just breadboarded it for shits N' Grins.
Voltages looks good.
So I messed something up (obviously).
But, after about 6+  quick shots of brandy, I think I'm gonna turn off my iron and hit it again tomorrow.
A hot soldering iron and booze may not mix so well. Weed, sure, booze no.

Why the hell can I build/design 200+ layouts over the years (Some double sided, and self etched PCB's at that) 30 - 40 different fuzzes plus phasers, flangers, delays, understand CMOS switching (Thanks a ton RG,  your my hero), plus build space probes and repair space shuttle crap and god knows what else with very few or no problems but the simplest boost in history kicks my ass?


I still prefer rum.

anotherjim

#7
Weird - but the voltages you have with Q1 fitted do suggest your C is actually a B!
Edit - or you have a PNP  :icon_eek:

duck_arse

anyone who's seen one of my vero layouts knows how much I like to use colour in those diagrams. and so, your layour shows R1 and R4 bottom ends near to the grey, ground line, but the pads ain't grey. are they connected for true and proper?

cider for mine. no hot or heavy machinery after, though.
don't make me draw another line.

CodeMonk

Quote from: duck_arse on September 06, 2014, 11:20:16 AM
anyone who's seen one of my vero layouts knows how much I like to use colour in those diagrams. and so, your layour shows R1 and R4 bottom ends near to the grey, ground line, but the pads ain't grey. are they connected for true and proper?

cider for mine. no hot or heavy machinery after, though.

Yeah, R1 and R4 are grounded
R4 the Emitter, R1 Pulldown.


@anotherjim
4 2N5088's, 2 2N3904's.
Datasheets and Peak meter show EBC pinout as laid out on that layout, left to right.
For more shits and grins though, I did rotate a 2N5088 and voltages were still messed up.

I even took a few pictures of the back of the board for higher resolution to look for solder bridges. Found none, but at that point, I did have a few shots of brandy in me.
I have a few extras boards here, I may just start from scratch later tonight.

soupbone

Quote from: CodeMonk on September 06, 2014, 02:00:30 AM
Quote from: Blitz Krieg on September 06, 2014, 01:40:25 AM
http://www.diystompboxes.com/smfforum/index.php?topic=104730.0

Been there.
Thats where I found out what voltages I should be looking for.
I'm still getting 4+ volts at base, but when I remove the transistor, I get 0.8v just like in post #9.


Heres the layout (skipped the LED and power filter/polarity protection stuff in the image):



Maybe there's just a really stupid mistake I'm missing.
Bright green is input
gray is ground
red is power
C2 goes to output
Hey Rob.Is this layout one that you made?

CodeMonk

#11
Quote from: soupbone on September 07, 2014, 12:07:32 AM
Quote from: CodeMonk on September 06, 2014, 02:00:30 AM
Quote from: Blitz Krieg on September 06, 2014, 01:40:25 AM
http://www.diystompboxes.com/smfforum/index.php?topic=104730.0

Been there.
Thats where I found out what voltages I should be looking for.
I'm still getting 4+ volts at base, but when I remove the transistor, I get 0.8v just like in post #9.


Heres the layout (skipped the LED and power filter/polarity protection stuff in the image):



Maybe there's just a really stupid mistake I'm missing.
Bright green is input
gray is ground
red is power
C2 goes to output
Hey Rob.Is this layout one that you made?

Yeah
BTW, the rest of the layout looks like these : http://www.aronnelson.com/gallery/main.php/v/Small+Bear+Electronics/ as far as the filtering and LED stuff goes.
I was gonna go over it again tonight, but its been a REALLY long day and I'm beat.

soupbone

Quote from: CodeMonk on September 07, 2014, 02:35:03 AM
Quote from: soupbone on September 07, 2014, 12:07:32 AM
Quote from: CodeMonk on September 06, 2014, 02:00:30 AM
Quote from: Blitz Krieg on September 06, 2014, 01:40:25 AM
http://www.diystompboxes.com/smfforum/index.php?topic=104730.0

Been there.
Thats where I found out what voltages I should be looking for.
I'm still getting 4+ volts at base, but when I remove the transistor, I get 0.8v just like in post #9.


Heres the layout (skipped the LED and power filter/polarity protection stuff in the image):



Maybe there's just a really stupid mistake I'm missing.
Bright green is input
gray is ground
red is power
C2 goes to output
Hey Rob.Is this layout one that you made?

Yeah
BTW, the rest of the layout looks like these : http://www.aronnelson.com/gallery/main.php/v/Small+Bear+Electronics/ as far as the filtering and LED stuff goes.
I was gonna go over it again tonight, but its been a REALLY long day and I'm beat.
Cool!I'll check it out!

CodeMonk

#13
Yup, it was a REALLY stupid mistake I made.
The circuit is all fine and dandy, I just wired the DC jack backwards.

Edit:
Just did test.
Getting some clipping, but it was also hooked up to a Peavey Vypyr (Needed something with headphones) so it was probably the Vypyr clipping
Test it with my AC30 tomorrow.

anotherjim

Well, I'm slapping my head too! Since you'd pretty muchalready proved the transistors were good - reverse power is the next logical suspect!
The basic/simple errors are the last thing we suspect - human nature bites sometimes ;)

bool

Reverse power isn't really a "simple" error - when you think about it from a certain angle.

CodeMonk

Plugged the LPB-1 into my AC30.
I get unity at around 9 O'Clock.
Very responsive to picking dynamics.
If I pick lightly, I get a nice clean boost, pick hard, I get some clipping, like an OD with the gain set really low.
Sounds perfect to me.