Colorsound Power Boost 18v... Annoying ticking noise.

[bettsaj]

Hi guys, I'm hoping someone will be able to help troubleshoot this issue.

I have recently built an exact 121 clone of an early version Colorsound Power Boost. I've researched many different forums, poured over shed loads of photographs and checked the many different schematics out there. I eventually made my own PCB board, which is an exact clone of an original board, complete with board mounted pots, I then sourced as many NOS components I could (not that they sound any different, 'cos they don't... just for aesthetics really) So i used Iskra resistors, tropical fish caps, the only new components I used were the axial caps, but even there i used the exact same brand as the caps used in the new power boost reissues by Stu Castledine (Vishay)..... i got a bit anal about it, for a project.

Here's the board after etching.




Here's an image after populating with the components




And the trace side




The pedal is fantastic, very loud, and when you turn the volume up to around 80% it changes into a really nice overdrive.

However, there is an issue..... When you turn the pedal right up full you can hear a ticking noise.... If you back of the volume down to about 90% it disappears. has anybody got any ideas what could be causing this issue..... Has anybody else had this issue?

I've read on a few forums that some people have biased the pedal..... I don't see why you should have to. The production pedals aren't biased, they know the component values and stuff them in the board and it works. i'm wondering if one of my NOS components is a bit duff.

If anyone wants a copy of the PCB layout for etching let me know 

[Electric Warrior]

I've read on a few forums that some people have biased the pedal..... I don't see why you should have to. The production pedals aren't biased, they know the component values and stuff them in the board and it works. i'm wondering if one of my NOS components is a bit duff.

Of course they're biased. But they're biased using stock resistor values - which should work well fine as long as the specs of your transistors are in the right ballpark.

[bettsaj]

Blimey.... You get around a bit don't you 

Of course, you're right. I suspect that the resistors I used should be ok... I checked every one before placing it the board....... I suspect either a signal path issue, or if it is the pedal maybe I've got to change a resistor value to reduce the amount of gain....... Maybe there's just too much :-)

[Electric Warrior]

I'm everywhere.

What happens when you unplug the guitar? It may be pickung up something that the pedal brings out.

Have you checked how your voltages compare with my vintage unit?

Battery: 18.84V
Q1 C 6.43V B 3.92V E 3.54V
Q2 C 11.53V B 6.44V E 5.82V
Q3 C 10.19V B 2.77V E 2.23V

Transistors are BC184L in this one. Unfortunately I have no idea what gain range they're in. Other vintage units BC169Cs, i.e. high gainers..

[bettsaj]

Let me finish putting it in the enclosure, then we'll take it from there.... Like you say, there may be a shielding issue.

I'll get on it tonight.... Once it's in the enclosure I'll be able to rig it up properly and test it. I've not tried unplugging the guitar with it still all switched on so can't answer that question. If the ticking is still there I'll rig up a camera, and video some troubleshooting efforts, including unplugging the guitar with it all on.

[bettsaj]

Have you checked how your voltages compare with my vintage unit?

Battery: 18.84V
Q1 C 6.43V B 3.92V E 3.54V
Q2 C 11.53V B 6.44V E 5.82V
Q3 C 10.19V B 2.77V E 2.23V

Transistors are BC184L in this one. Unfortunately I have no idea what gain range they're in. Other vintage units BC169Cs, i.e. high gainers..

Right, what I can say is I've copied your pedal and used BC184L's in all 3 positions.... I don't suspect they're my issue.

I'm not using a battery, i'll be plugging in a DC adaptor.... However I can confirm the ticking is there on both battery and DC

I'll check the voltages tonight and report back

[Electric Warrior]

Some Overdrivers used transistors from the B-bucket, so I guess you can get away with lower gains. If your voltages are too far off, trying a different type may be worth a shot.

[bettsaj]

Right Mr Warrior... on to voltages 

Battery: 18.84V
Q1 C 6.43V B 3.92V E 3.54V
Q2 C 11.53V B 6.44V E 5.82V
Q3 C 10.19V B 2.77V E 2.23V

My readings are:

Battery: 18.80V
Q1 C 6.37V B 3.90V E 3.52V
Q2 C 11.36V B 6.37V E 5.74V
Q3 C 10.54V B 2.75V E 2.19V

I did all that on batteries, and not DC as I had planned to. I've not put it in the enclosure yet as I've not had time tonight.... I'll try and get it sorted over the next day or 2, as I'm away Thursday.

What is your opinion on the voltages.... l don't think they're majorly different. probably not so far out to cause any issues.... The collectors on Q2 is lower and Q3 is higher, significant??

[Electric Warrior]

That's really close. Nice! So that rules out a bias problem.

[bettsaj]

I need to get this stuffed into the enclosure, and then do some troubleshooting as I said earlier on..... It looks like I'm almost singing from the same hymn sheet as your "genuine" pedal.... so onwards and upwards. I need to let you hear the issue I think. When i say it's a ticking noise, it's clocked.... That means it's not random ticking.... Which is why i'm thinking it might be where the output is slamming the G-Force. It might be overloading it... I also need to try it through that small combo amp I mentioned.

I'll report back in a couple of days as i'm travelling to Coventry (for my sins) tonight, and spending all day there tomorrow on a training course. I might be able to wire it into the enclosure tomorrow night.. I'll see how it goes time wise.

[bettsaj]

Ok, this is aimed primarily at Electric warrior however please, if anyone has any ideas chime in as I'm desperate for a solution to this issue.

I have at last stuffed the PCB into an enclosure and the ticking noise is still there, however i may have misled you by saying ticking noise. It's more a rapid ticking... Not like a clock, definitely electronic and not anything to do with my rack system as I tested it through my sons practice amp. Check this short video,

It's annoying, and I have to fix this, any advice would be greatly appreciated.

To recap and to bring everyone else up to speed, I have checked voltages on the transistors which were

Electric Warriors voltages

Battery: 18.84V
Q1 C 6.43V B 3.92V E 3.54V
Q2 C 11.53V B 6.44V E 5.82V
Q3 C 10.19V B 2.77V E 2.23V

My voltages:

Battery: 18.80V
Q1 C 6.37V B 3.90V E 3.52V
Q2 C 11.36V B 6.37V E 5.74V
Q3 C 10.54V B 2.75V E 2.19V

This is a 121 copy of Electric Warriors power boost, using the same values on all components, and the same trannys which are BC184L's.

All electrolytics are new Vishay caps, the same as the ones used by Stu Castledine in the reissue power boosts, the resistors are NOS Iskra resistors the same as the originals in Electric warriors and also Mullard caps... Again, the same as the original.

The resistors were all checked before being soldered, and are within tolerance. I have no way of checking the capacitors.

The only differences are the board which was etched by me from a trace of an original, and the pots which are standard off the shelf pots from bitsbox. The volume is a 10k rev log, and the bass and treble are both 100k lin.

The schematic used was this one




The PCB trace used was this one, created by me



This was copied from this image, and used the schematic as a reference (I believe this board is from a Vox Power boost.. basically the same in all but name)




I've built 2 of these now, with the same issue... The other one was built using all new parts as opposed to NOS, and the resistors in the other pedal were all 1/4w carbon film resistors.

2 pedals with the same issue.. 1 with NOS and the other with brand new components.

[Electric Warrior]

What happens when you roll down the volume on the guitar?

[bettsaj]

Just done another video... Uploading as I type. i'll post it when it's finished

[bettsaj]

While i'm waiting for the video to upload, I've taken some photos of the wiring, most notably the switch wiring.

I've just done another experiment... i switched the pedal on, and touched the switch and the noise reduced. it didn't disappear, but it did reduce significantly... I'll post a video of that also once it's finished uploading



Standard true bypass wiring.

Wiring is as follows:

top left - board input
middle left - input jack

centre top - ground from LED
Centre middle - ground

Top right - board output
middle right - Output jack

The rest of the wiring is like this... not too shoddy i don't think

[Electric Warrior]

While i'm waiting for the video to upload, I've taken some photos of the wiring, most notably the switch wiring.

I've just done another experiment... i switched the pedal on, and touched the switch and the noise reduced. it didn't disappear, but it did reduce significantly... I'll post a video of that also once it's finished uploading

If you touched the strings on your guitar when you tried that, it shouldn't make a difference. If you did, you have a shielding issue and need to check if all grounds connect correctly i.e. strings with the output jack of the guitar, sleeves of the lead, the pedals' jacks' sleeve connectors as well as the board's ground with the enclosure.

[bettsaj]

Ok... 2 more videos..

In answer to your question. I have taken another very brief video showing what happens. but basically, If I touch the pedal, it reduces, if i touch just the guitar there is a very small slight reduction.. If i touch both it reduces.

i must say at this point that the guitar is well shielded, the earth to the trem, claw is good and there's copious copper shielding inside the pickup cavity... it's a Gilmour strat, home made but with the best components available. fully loaded pick guard from strat cat... I've never had an earth issue with the guitar before now, so i don't believe it's the guitar.

[Electric Warrior]

Yeah, that confirms that the problem is happening after the guitar. Once you touch the strings, the pedals should be shielded because the grounds should connect. Maybe your lead's ground is only connected on one end?

[bettsaj]

Yeah, that confirms that the problem is happening after the guitar. Once you touch the strings, the pedals should be shielded because the grounds should connect. Maybe your lead's ground is only connected on one end?

Both guitar leads are shop bought.. Not mine, my sons. Suffice to say I get the same with my home made cables

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[bettsaj]

The main issue for me is this hideous noise.... Any ideas?

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[Gus]

Do you have LED or CFL bulbs in the room? if so test again with the lights out.

Can you test it in another room, outside, another house etc.?

Do you have a portable AM radio? If so turn it on and walk around the room and tune it up and down the dial, check if it picks up the same noise
You might be detecting some EMI

Can you wire a shorted tip to sleeve 1/4 inch plug (no cable because that would be an antenna) to put in the input of the boost and then turn up the boost volume to check if it still ticks, this shorts the input to ground. This should reduce RF pickup if that is you problem

Do you have a oscilloscope to check the boost?