quasar v4 not working [almost solved]

[kiasyd]

hi my name is Axel and I'm an electronics engineering freshmen from Chile:
so, mi problem is that mi quasar just refuse to make any kind of sound, its not my first project (and it's actually the smaller   ),anyways, i try using my amp like some kind of prove so i can know where the sound stop, and it stop right after q1, so i replace c2 nothing happend. only use one substitution i used was 2sc945 as q1-2 and used the parts marked for the bass mod. i also have done the hole circuit twice (one by me and one by a friend) and both times happened the same
if anyone wanna help i would be very thankfull
ps: sorry about my poor English, hope you all understand

[mgwhit]

[Edit: Deleted my incorrect information about the transistor pinouts.  Sorry!]

[mgwhit]

What are your voltages at IC1:pin3, IC1:pin8 and Q1:pin1?

[mgwhit]

Wow.  Is it possible that the layout from the build doc shows the incorrect orientation of Q1 and Q2?  What I'm seeing does not match up with the datasheet for either the 2SC1815 or the 2SC945.  Try rotating your transistors.  Meanwhile I'm going to search the archives.  I would think something like this would have come up before now.

[kiasyd]

Wow.  Is it possible that the layout from the build doc shows the incorrect orientation of Q1 and Q2?  What I'm seeing does not match up with the datasheet for either the 2SC1815 or the 2SC945.  Try rotating your transistors.  Meanwhile I'm going to search the archives.  I would think something like this would have come up before now.

:S great i just used the bad version of the pedal  

What are your voltages at IC1:pin3, IC1:pin8 and Q1:pin1?

ic:
1  4.63
2  4.63
3  4.59
4  0
5  4.59
6  4.63
7  4.63
8  9.03

q1-2 [same voltages]
b  8.36
c  9.03
e  8.37

thanks for the help [VERY quik help  ]

[jkokura]

Wow.  Is it possible that the layout from the build doc shows the incorrect orientation of Q1 and Q2?  What I'm seeing does not match up with the datasheet for either the 2SC1815 or the 2SC945.  Try rotating your transistors.  Meanwhile I'm going to search the archives.  I would think something like this would have come up before now.

No, if you read the docs you'll see that Bean talks about there being strange pinouts with those parts. It looks correct to me on the layout. The collector is the middle pin, and it connects straight to +9V.

Jacob

[jkokura]

anyways, i try using my amp like some kind of prove so i can know where the sound stop, and it stop right after q1, so i replace c2 nothing happend.

Hi Axel, welcome to the forum.

It sounds to me like you're trying to use an audio probe. If so, that's great. It's probably the best tool to use.

From what you describe, I would suspect that Q1 is the problem, not C2. If you get no audio on the Emmiter of Q1, but you do on the Base, that would suggest that something is either wrong with your power, or that the Q itself is not functioning for some reason.

Looking at your photos, your soldering looks good, but I haven't had a chance to really check all your parts against each other. Try and be really clear and walk through your schematic using an audio probe. If you have sound stop at a certain place, look at the schematic and ask which part could be causing the problem.

Jacob

[kiasyd]

anyways, i try using my amp like some kind of prove so i can know where the sound stop, and it stop right after q1, so i replace c2 nothing happend.

Hi Axel, welcome to the forum.

It sounds to me like you're trying to use an audio probe. If so, that's great. It's probably the best tool to use.

From what you describe, I would suspect that Q1 is the problem, not C2. If you get no audio on the Emmiter of Q1, but you do on the Base, that would suggest that something is either wrong with your power, or that the Q itself is not functioning for some reason.

Looking at your photos, your soldering looks good, but I haven't had a chance to really check all your parts against each other. Try and be really clear and walk through your schematic using an audio probe. If you have sound stop at a certain place, look at the schematic and ask which part could be causing the problem.

Jacob

thanks for the welcome, had been lurking for a while i just don't feel too comfortable writing in english.
i also think that the Q is the problem and since i dont really have an  electronics store near i just wanna be sure before buy some  new transistors. now i`m sure that the components are right, all in their pace and the right value, i literally spent hours  checking everything was the way it should be, including checking my solders with a magnifying glass.
can you tell me if some of the voltages i posted earlier are wrong plz???

[oldhousescott]

IC1 voltage look fine. Q voltages look wrong. Collector voltage is correct since it is tied directly to +9. Base and Emitter for Q1 should be sitting around 3 volts. B and E for Q2 should be around 4.5 volts. I'd try some new transistors, if you have any.

[kiasyd]

IC1 voltage look fine. Q voltages look wrong. Collector voltage is correct since it is tied directly to +9. Base and Emitter for Q1 should be sitting around 3 volts. B and E for Q2 should be around 4.5 volts. I'd try some new transistors, if you have any.

mmm... the voltages are the same in both PCBs and i also tried replacing the transistors, i have 5 of them.
maybe they are not the correct substitution?

[mgwhit]

No, if you read the docs you'll see that Bean talks about there being strange pinouts with those parts. It looks correct to me on the layout. The collector is the middle pin, and it connects straight to +9V.

I totally agree about the middle pin being the collector, but from tracing the connections on the layout diagram it looks like the bottom pin on Q1 and the top pin on Q2 should be the base.  The bottom pin on Q1 connects to R3 and the top pin on Q2 connects to R13.  The orientation of the transistors on the layout (i.e. flat-side left for Q1, flat-side right for Q2) does not jive with the data sheets for the 2SC945 and the 2SC1815 that are linked from the build document.

[kiasyd]

No, if you read the docs you'll see that Bean talks about there being strange pinouts with those parts. It looks correct to me on the layout. The collector is the middle pin, and it connects straight to +9V.

I totally agree about the middle pin being the collector, but from tracing the connections on the layout diagram it looks like the bottom pin on Q1 and the top pin on Q2 should be the base.  The bottom pin on Q1 connects to R3 and the top pin on Q2 connects to R13.  The orientation of the transistors on the layout (i.e. flat-side left for Q1, flat-side right for Q2) does not jive with the data sheets for the 2SC945 and the 2SC1815 that are linked from the build document.

Just tried turning both Qs, didn't  notice any change in any voltage, and obviously didn't sound. Are there any part biasing the transistors???

[mgwhit]

Meh.  I must be reading the data sheets backwards.  Sorry about that.

What's the value of your R18?  Should be Blue-Grey-Black-Brown-Gold if that's a 6k8 with 1% tolerance, but both of yours look slightly off to me.  Could be the photos, could be my brain -- it's been letting me down a bit today.   

[kiasyd]

Meh.  I must be reading the data sheets backwards.  Sorry about that.

What's the value of your R18?  Should be Blue-Grey-Black-Brown-Gold if that's a 6k8 with 1% tolerance, but both of yours look slightly off to me.  Could be the photos, could be my brain -- it's been letting me down a bit today.   

it happened to me to, the datasheet shows the transistor from below, then i had to see it from abode,and the from the schematics. that isn't a good exercise after seen the same circuit all day long.
r18 is  [gold its 5% tolerance  ]

[jkokura]

Keep it up guys! If you stick with it something will turn up.

I'll say it again, from the datasheets in the build docs, and from the way I looked at the documentation, the Q's in question are oriented correctly in the build docs. I know it may look backwards, but it's correct.

As for the problem in question, what are your voltage readings at the input and ground? Also, have your checked for any incorrect continuity between either the Base or the Emitter on that Q? the extra power has to be coming from somewhere, and if it's not a bad Q (which I still suspect), then it has to be a solder bridge.

Jacob