Could I get schooled on a bit of "electrical theory", please?

[plexi12000]

hi dudes- and a salute to any vets out there, as well. 

Ok, I'm troubleshooting my "Blackfire M" build.  (PNP-BS250 trnstrs.) i started with my meter checking voltages.  I'm getting 9v's at the various "drain" resistors but i'm only 

getting a voltage drop at the last drain resistor.  That indicates there is no CURRENT flowing at those other points, right?  I have "continuity" from one end of the power supply trace to the other.  So, I am wondering how can you get voltage.....but yet no current? 

all of them are connected to the  "power rail"?  My LED indicator is lighting up.

I'm confused! -lol   I'd like to understand this before moving on to using my audio probe.  Thanks a bunch!

[mth5044]

Care to post a schematic?

[Joe]

Several months ago, I breadboarded an Obsibian, and the BS250's were way different than the ones I used back in the day.

See if you can get it to work by adjusting the gate bias voltages, as they may need to be quite different than the original values.

[PRR]

> how can you get voltage.....but yet no current?

Cold winter day. Wear your wool sweater over silk underthings, rubbing a cat, while shuffling leather shoes over a nylon carpet.

Your body will charge-up to 10,000 Volts.

No current. No excitement.

Touch the door knob. Current flows (Ouch!) as the voltage on your body drains away. Now something is happening.

If you rub/shuffle like mad, current will continue to flow. (Though in practice, you are unlikely to shuffle-up charge fast enough to feel continued current flow.)

Rather than all this silk-rub, or a mechanical carpet-shuffler, we find it convenient to use battery or battery-eliminator off a lamp circuit. We can have a fairly stable 9 Volts, with or without current flow.

> getting 9v's at the various "drain" resistors but i'm only getting a voltage drop at the last drain resistor.

Whatever these "drains" are, they are not draining.

Flood. Water comes in the basement. 9 feet of water (pressure, voltage) from top of flood to cellar floor.

Cellar drain carries it away (current). If drain actually DRAINS infinite water, the cellar has zero water. If drain does not actually drain at all, cellar water rises the full 9 feet.

In much signal processing (audio toys; audio swings both ways) we don't want full-up or full-down, we want somewhere in the middle so we can wobble it both ways. If the flood only comes in via a 4" hole, and the drain is a 4" hole, the cellar will fill about half-way. Now we put a flap in the drain, we can easily increase or decrease the drainage, water level will vary. In accordance with our flap, but able to do much more work.

Uh...

"Blackfire M" seems to be a game?? If it is electronic, post link to schematic or we'll be yammering about the wet cellar and never getting to your problem.

(Which is probably bad joints, possibly at the Sources.)

[Kipper4]

I believe the schematic can be found here.
My browsers so far out of date and support  I cant view images on this pc.


http://gr1ng0.tripod.com/Downloads/dl.html

[PRR]

> I believe the schematic can be found

PCB layouts only.

The link(s) for Blackfire actually gives you a ZIP file(s) which have PDF files inside.

Gosh, I didn't know Tripod was still alive.

[plexi12000]

Thank you PRR!  that makes perfect sense. kinda like a capacitor, i guess.  Wish i paid attention more to "electronics" when i was young! lol  i avoided it like the plague.

Well, i kinda started over.  i had some components socketed. i took those components out...and removed the board from the enclosure.

i tested EVERY trace for conductivity w/ my meter.  even tested "through" each socket and all points on each trace.  The actual board is fine.

So...??  Maybe fried transistor(s)?  Or maybe like joe said, resistor values for the "gates" need to be adjusted?  Man....i sure as hell don't know.

[plexi12000]

well, i got this thing working........kinda sorta.   i had one trace making contact where it should not have.  dumb mistake corrected.

tried it.....had nice 'output' and nice warm distortion......but with a constant squeeling.  BAH!

so, i tried what Joe suggested.......try different value resistors that regulate the voltage for the transistor "gates."  2.2m is on the schematic....i had some 3.3m which reduced the squeeling by probably "half".

the next value i have on hand is 4.7m.  put them in and nothing at all.  so i guess i'll order some values between 3.3 and 4.7m and try to zero in on what works.

hopefully thats the issue-