forum-vibe schematic or image completed board?

[bvdl]

Hi,

I'm building the forum-vibe from Cassic Amplification.
After choosing the "vintage build"'s build instructions, I saw there's a dicrepancy between transistors in the schematic and shown on a completed FV-5 board.
Several transistors have their base and emitters swapped.

Which one should I follow, the schematic or the completed FV-5 board?

Thanks!

[duck_arse]

hello and welcome to the forum, bvdl.

if you link us to the docs you are looking at, it makes things much easier for us. having said that, the first return in a popular search engine (and back one page) was this page:

http://www.classicamplification.net/fv/files/fv5_mod_07.htm

go there, klik the "BC549" link, then tell us what transistors you are using. I'll wait here for you ........

[armdnrdy]

I'll wait here for you ........

Still waiting!

[bvdl]

Hi,

For Q1 I use 2N5210 and for Q2-Q13 I use 2N5088, exactly as on the BOM found here:
http://www.classicamplification.net/fv/files/fv_vint_05.htm

This is the example of a finished FV-5 board, which is the one I'm working on, also I chose the "vintage" option, without the mods except for a trimpot on the lamp bias. This trimpot is to found on the scheme as well.

http://www.classicamplification.net/fv/files/fv_vint_06.htm

Then, when following the traces on the pcb I found almost all transistors were placed backwards when referenced to the scheme.

http://www.classicamplification.net/fv/files/fv_sch_vint.htm

But then, I also found an image to use as an instruction that follows the scheme.

http://www.classicamplification.net/fv/files/fv5_vint2n_03.htm

It must be that the transistors used in the foto example have other pinouts for c and e than my 2N5088 's.

What do you think?

The LFO is not working, (the lamp isn't flashing), so first I'm searching for errors I made on assembling.

Are the white dots representative for e?

Greetz, Benny.

[duck_arse]

the white dot does indicate emitter in this inst. I think the white blob on the transistor outline on the pcb also indicates E. that would mean the one shown here (it would have been helpfull if they had noted the transistors used in the photo build on the page):
http://www.classicamplification.net/fv/files/fv_vint_06.htm
is loaded with BC series transistors (perhaps not all of them, tho). your transistors, being the opposite orientation, should face as shown in this dia:
http://www.classicamplification.net/fv/files/fv5_vint2n_03.htm

it appears to me to be the same board in both examples. but, when in doubt, and that is always, check YOUR part against the manufacturers datasheet, then check YOUR orientation with regard to the circuit diagram.

have you read the stuff at geofex on the univibe? it may well help with the fixxing.

(all care, but no responsibillity, taken)

[bvdl]

Hi,
this link: http://www.geofex.com/Article_Folders/univibe/uvfrindx.htm
from the Geofex site you mentioned is going to give me insight in how this stuff works. Thanks a lot for that!
I hope I can find the error.

[duck_arse]

N.P.

you can find just about everything at geofex. R.G. was also having a discussion on the lamp and lamp driver section here a few months back, might be worth searching that thread.

[edit :] can we see some photos of your soldered board?

[bvdl]

Hi,

I'd love to show a picture, but my wife went on a trip with our camera for a couple of days...
I'll do it as soon as I get it back.

I also didn't find any drawings on how to connect everything... so I went for clues on the board like for example I1 I2 I3 would be for the intensity pot lugs 1 2 3, etc... I followd the circuitdiagram for bits I coulnd't find...

There are a few to many things I must guess on for my taste...
Also following all the traces and following the circuitdiagram is such a time consuming job for me...
I guess I have to go trough that anyway...

[bvdl]

Hi, I can't find how I should attach a photograph... If I click the "insert image" it inserts some code, but an option for an actual selection of the file is not displayed...

Benny.

[duck_arse]

bvdl - when you klik this button it gives you a pair on "img" tags. the thing is, your pictures need to be hosted somewhere on the web already. like imgur, which works very well indeed in all our browsers, or other places, like photobucket, or imageshack, or tinypic, or dropbox, or that googoo thing, there will be others, but no-one complains when you use imgur.

so you size your picture sensible for all us slow/narrow/limited connection users, then upload it to your hosting site of choice, and they provide you with an address for your image. you need to copy that, then paste between the img tags first mentioned. (you can do test posts in the testing section, and nobody will larf at you.)

over to you.

[bvdl]

OK, let's try...

The board has had some handling to it already, it used to look less sloppy.

[bvdl]

Q13 used to be on the screen where Q14 is printed, I moved it when folowing the schematic in an attempt to solve the issue.
I suppose I need to dig into the connections on my pots, I wired these accordingly to what I thought to read on the schematic also...

It surprised me that the lamp won't even blink 

But, if someone sees a big mistake rightaway, it'll save me a few evenings of searching I guess.
Thank you beforehand,

Benny Van De Locht.

[R.G.]

It would save you a lot of time to take a diagram of the PCB and the schematic, then by looking at the schematic and noting what part connects to what pin on the transistor, deduce which hole in the PCB diagram is the collector, which the emitter, which the base. One can only hope that all the transistor footprints on the PCB are the same pattern of E, B, and C.      But given that modest bit of luck, you only have to do one or two transistor places to figure out which pin-name (E, B, C) goes in which hole.

Once you know that, you can look at the datasheet of your chosen transistor types on line and know how to bend the leads and insert them in the PCB pattern.

Once you've done that, you can correct your transistor placements and then get on to debugging.

[bvdl]

Hi RG,

I did that once already, but maybe I made an error doing it...
I'm going for a second shot at it.

Benny.

[R.G.]

I did that once already, but maybe I made an error doing it...
I'm going for a second shot at it.

Good plan. Once you get done, let's take another look.

Did some research. Here are the pinouts:

Notice that the BC549 and 2N5088 are the same order, merely reversed in which direction the flat face of the transistor is oriented.

The right answer to your first question is to put the emitter pin where the schematic says the emitter goes. Which way the flat of the transistor package faces depends on that.

The LFO lamp not blinking is a reasonably common  problem with vibe clones. There are some conditions that can cause that. Get the transistors all checked out and we'll dig into the LFO.

[bvdl]

Thanks for helping me out, I'll have a look at it tomorrow... but I'm rather slow at it.

Benny

[bvdl]

OK, I felt like picking up this one again after being bored by it...
It seems the rectifier bridge 1:is obsolete because I have a wall wart supply providing 18V DC
                                      2:needs at least 40V to let actually something through.
So first thing to check is remove this, and see haw it goes from there.
I Also found a wiring diagram on this forum (in German):
http://musikding.rocks/wbb/index.php/Thread/417962-Forum-Vibe-Vintage-Verdrahtung/

Testing, testing.

[R.G.]

OK, I felt like picking up this one again after being bored by it...
It seems the rectifier bridge 1:is obsolete because I have a wall wart supply providing 18V DC
                                      2:needs at least 40V to let actually something through.
So first thing to check is remove this, and see haw it goes from there.
I Also found a wiring diagram on this forum (in German):

I don't follow the "forum vibe" but it sure seems like there ought to be a wiring diagram wherever you got the board. I have wiring diagrams up at geofex for the Neovibe univibe clone, and have had them there since about 1999. I don't even sell Neovibe boards, just give the PCB pattern away for free.

Be really careful about that 18Vdc wart and how you use it. It's a common mistake in univibe clones to use a DC wall wart, then try to hook the (-) side of the wart to the signal ground and get into trouble with hum and other issues caused by the offset of the wall wart (-) from signal ground by the negative side of the rectifier bridge. If you use a DC wart and want to use it for power other places, you have to remove the rectifier bridge and put in wire links. I think you're already there, but I had to mention it in case you're not.

If your bridge rectifier needed 40V to let anything through, you may well have had it installed incorrectly. No integrated bridge that is not damaged needs 40V across it to conduct. FWB losses are two diode drops, about 1.1-1.6V total.

[bvdl]

Hi R.G.,

I indeed hooked up wires from the wall wart directly into the + and - of the power regulator. But I can't even measure anything on the B+ of the 3 cicuit blocks...
It should be a DC voltage right?
I think I might have overheated some electronic component, would you think this would be likely? There are no components that look abnormal.
The connection of jacks, pots, DT3P and DT2P switche(s) and led's seem to be connected resembling different connections I found across the net regarding this project.
I wanted to start measuring all my transistor cbe values like on the last page of this online PDF (the fv-4 board should be somewhat identical to my FV-5 board according to the author) : http://basicaudio.net/univibe-ForumVibe-final.pdf
But maybe I should replace the elco's of the power regulator first to eleminate the possibility of having a broken power regulator?

On the other hand, why did I have to remove the rectifier bridge, since current will flow in the right direction regardless of operating voltage or AC/DC? I better kept it in place, since I had to destroy it to get it removed well...

Any help would serve me,

Thank you in advance.

[R.G.]

When you're getting very odd readings, question everything.

So:
1) Measure the output of the wall wart with your meter. Does it read 18V AC or DC? Or something else? What does your meter tell you about the POLARITY of the output plug? Is is what you thought?
2) Before you hook up the power supply to the circuit board, use your ohmmeter and measure the resistance from the V+ to V- pads. If this shows 0 ohms with leads swapped both ways, the board has a short which must be fixed before you can do anything else with it.

I think I might have overheated some electronic component, would you think this would be likely? There are no components that look abnormal.

If no components look abnormal, why do you think that?

The connection of jacks, pots, DT3P and DT2P switche(s) and led's seem to be connected resembling different connections I found across the net regarding this project.

Reading many different descriptions of circuit that may or may not be the one you built is a good way to get confused.

But maybe I should replace the elco's of the power regulator first to eleminate the possibility of having a broken power regulator?

What is an "elco"?

On the other hand, why did I have to remove the rectifier bridge, since current will flow in the right direction regardless of operating voltage or AC/DC?

You didn't have to, but it was good advice. If (and only if!) you have a DC power supply, the rectifier bridge will indeed cause the correct + to - connection of the DC supply. However, it will also cause the supply (-) lead to sit at one diode drop **below** signal ground, meaning you cannot connect that power supply to any other pedal or supply with signal ground. It makes a built-in trap.