LukeFRC

sorry to bother you all again...
tracked down the problem I think. The 4558 chip seems to be funny.
On the [url="http://www.tonepad.com/getFile.asp?id=97"]schematic[/url] it works as two seperate units (op amps???) IC1a seems to be fine, everything doing what it should.
Ground is ok, as is the voltage into this chip. On the IC1b part however we seem to have a wierd fuzzy loudness. input 6 is fine, the signal from the bass, the output 7 however comes out all distorted. IS there a reason it would do this or have i broken the IC somehow?

sorry to bother you all again...
tracked down the problem I think. The 4558 chip seems to be funny.
On the [url="http://www.tonepad.com/getFile.asp?id=97"]schematic[/url] it works as two seperate units (op amps???) IC1a seems to be fine, everything doing what it should.
Ground is ok, as is the voltage into this chip. On the IC1b part however we seem to have a wierd fuzzy loudness. input 6 is fine, the signal from the bass, the output 7 however comes out all distorted. IS there a reason it would do this or have i broken the IC somehow?

I got my H&K Q600 bass amp for under the trade price because it had been sitting around for a few years at the bass merchant and I think mike wanted rid of it.
This is a good thing.

so wired together in hopefully properly... and I have a pedal that amplifies and does a nice fuzz sound! with a phasing thing in the background. not what i was aiming for but progress!



EDIT:


ARRRGGHHH!!!! Whats gone wrong this time? the chorus is there in the background its just something is turning it into a fuzz pedal. Im guessing either the 4558 chip or one of the transistors??

I get to wear the bass chat dunces hat for a bit though

[quote name='escholl' post='770154' date='Mar 10 2010, 10:50 AM']0.033 nF, or 33 pF, seems awfully small for a cap in this position in the circuit -- are you sure that is the right value? If it was 0.033 uF, which is 33 nF, that would make more sense given the typical input impedance and bandwidth requirements of these types of input stages.[/quote]



yes, i think you're right! I was just following my plans which were confsing me, I've just looked up the baja version on freestompbox and it's way clearer! Oddly I had ordered the right pieces, just thought i had them wrong.... lets start again.
The good news is that I have now worked out enough of what each bit is doing that I pinpointed the 2 problems!

i built a nice clone of a catalinbread SFT which does the trick....

okay... audio probe is brilliant idea, thanks- this is what i was looking for, some way for me to test my circuit
rigged one up and it works a treat. I'm actually going to look forward to going over the sft cuircit just to see what everything does!

but I think I've found my problem....no signal is getting through the opening 0.033 nF cap. you can hear the bass in the input arm of it, but on the output one not at all, just a popping noise. why would it do that?

I'm not sure why this is happening but i guess it would be usefull to check all the correct power from the battery is getting to the right places at the right voltages. That's for tomorrow, in my testing ive managed to break the battery clip!


EDIT: sorry my moans are overtaking this thread... anyway, found a wrong cap in a place that may affect it.... also unsure it was there when i had it working.... more cap shopping tomorrow..... remember kids this is a pedal building morality leson!

thanks guys! a long time of checking coming up I think. I think i know which end of the circuit board the problem is, its just tracking it down....

oh and bypassing the 0.033 cap stopped the noise, but didn't make it work...

like this?


thing that confuses me is that it was working, abet with a fault.
i tried to fix the fault. put the right cap in the 0.033 nF slot (the first one after the in, second nearest the in on the board) and spotted the 0.01 cap on the out side wasnt there.
Fixed them and it didn't work, went back a stage or two and it still doesn't work... :S


EDIT: should add.

+v linked to battery red
pot's wired in correctly (they did work when it did work)
ground and battery black on the sleave of the in jack.
tip of jack to in
tip of out jack to out
sleeves linked

argh... something's wrong here! any tips on how to debug?

well the new caps went in and the whole thing stopped working and now more or less sounds it's pulsing...... something's gone wrong.... but figure it's me rather than the parts....

ahh the wee gap may have something to do with it... and the 33nF not 33pf at the entry too... off to maplin....

yes, lots of people saying what a great build it is and how they managed first time....

Thing is it works, just with the buzz which would make me think it could only be one or two components. I had the same problem with the SFT and found it was just one cap grounding in too early... testing time i think!

sooo... I bought the circuit board from tonepad for the small clone and stuck everyhting on (populated the board?)
wired it up to test. tip to in, out to tip, ground to sleave of in, link to sleave of out.... (that right yeah?)

and it works... but not right. something is sucking a lot of the volume and bottom end out, and there is a lot of hiss.
There is a micro pentometer on the board which you set to find the effect. The volume issue is unchanged by this but the hiss goes if the effect is off.
two problems i think.

I'm going to sit down and check everything tomorrow, does anyone have any advice of where to look?

open it up and have a look, it'll be something obvious i guess.
probe it with a multimeter if you need


also reread your initial post. it did used to work?

[quote name='7string' post='762422' date='Mar 2 2010, 11:57 PM']When I shared a flat in Glasgow one of my flatmates had a 6ft Scots flag in her room.

Not to be outdone, I bought a St George Cross the same size. I still have it as well [/quote]

imperalist bawb..... wait, i bet scottish swearwords can get through the filter!

[quote name='steve' post='762381' date='Mar 2 2010, 11:17 PM']as an englishman living in scotland, it should have a st georges cross headstock, strap, case and plectrum [/quote]

as an englishman living in [i]glasgow[/i], it should have a st georges cross headstock, strap, case and plectrum and stab-proof vest

interesting... i was playing with the SFT circuit earlier and one of the things i noticed was that it was very loud and boosted the signal a fair bit.

Now I had intended to wire the thing up

inst--> SFT ---> Big muff ----> chorus ---> out to amp

I wonder if it would make more sense to wire it up

inst--> Big muff ----> chorus ---> SFT ---> out to amp

what you think guys?

okay, next question. what do you want it for? at the moment if that cuircuit works (and I don't know enough about electronics to kknow if it does) when the input signal gets above a certain level the lights go on. There is no way of setting the level.
depending on what you want it for would [url="http://www.maplin.co.uk/Module.aspx?ModuleNo=26071"]this kit work[/url]? it may be easy to modify the mic input into a jack input.... and if it worked it would flash according to volume...

so the transistor lets through the current when it gets a signal from the guitar? to flash the lights on?
Is it compensated for a guitar level input?

eh? it's a wee bit tae english that

in fact.... i have a load of these in cream, 19mm for 6.3mm shafts


need 3/4 more knobs of some kind. anybody got any spare i could have off you? (should prob put this in the items wanted bit but think wil get more views here from ppl who build things)

I ordered a few weeks back and got worried they still existed! The guy emailed back to confirm for me!
Yeah is it £12 or more and you have to start paying VAT?

Going back to my drill dillemas, my local DIY store didn't have any cone step drill bit things. A 12 mm bit was £13! In the sale a Bosch 100 bit set of bits and screw driver heads was only £14. I bought that,used a 10mm and wiggled!

All holes drilled, painted red, all parts in way. Im just short two resistors and one cap for rigging up the power supply inside. Oh and I forgot to order knobs.