# Powersound Overdriver Colorsound Help



## Zduck (Feb 16, 2021)

When engaged the volume is really quiet. Bypass doesn’t seem to work at all.

Did I miss anything obvious? I used 2n5088 transistors instead of BC109 as I read they were a modern equivalent. Would that cause a problem or did I put them in backwards? The only other difference from the build instructions is I used 22u caps instead of 25u on c3 and c11. There is voltage on the IC legs and 9-14v on the diodes.

Thanks for any help! I’m fairly new to this!


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## Barry (Feb 17, 2021)

What footswitch are you using?


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## Zduck (Feb 17, 2021)

Barry said:


> What footswitch are you using?


Standard 3pdt on/off footswitch and the pedalpcb true bypass pcb.

I used an audio probe to test things and the input from the input jack has sound but the pad going to the output jack has zero signal. This is when in bypass. This makes no sense to me? The footswitch pcb is soldered on really well.. 🤔


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## Zduck (Feb 17, 2021)

3PDT Stomp Foot / Pedal Switch
					

3PDT | ON-ON | Latching | Solder Lugs | Long Lasting | High Quality




					www.taydaelectronics.com
				




This footswitch specifically


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## Mcknib (Feb 20, 2021)

The first thing I would do is probe volume middle lug 2 to see how strong the signal is coming out then probe your out pad it should be the same, that'll let you know if you're loosing signal before it gets to the out jack and 3PDT and if you have more than one problem it may just be a dry solder joint on your red out wire

You wouldn't get audio on the main pcb OUT pad when the circuits bypassed audio doesn't travel through the circuit in bypass mode you're simply sending you guitar signal IN at lug 2 along the 3PDT jumper between lugs 3 and 9 straight up to lug 8 your OUT jack to your amp (red lines) switched the other way (purple lines, effects mode) you'd send your signal in up to pcb in through the circuit to pcb out and the out jack

You should get bypassed signal regardless of a fault in the circuit

Check your 3PDT lugs with your audio probe in bypass mode and see if you get signal and it's strength on lugs 2, 3,9 and 8 from your description you should have good signal on lug 2 in jack tip so it's just a case of checking the jumper across to and the out jack tip have good connections





With no bypassed signal it has to be either incorrect jack wiring, (can't really see them clearly) faulty switch a dry solder joint somewhere or a short

At a quick check your components look correct can't see R4, 7, 9

Your 3PDT is the correct type hopefully it'll be a nice easy dry solder joint


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## Zduck (Feb 20, 2021)

Mcknib said:


> The first thing I would do is probe volume middle lug 2 to see how strong the signal is coming out then probe your out pad it should be the same, that'll let you know if you're loosing signal before it gets to the out jack and 3PDT and if you have more than one problem it may just be a dry solder joint on your red out wire
> 
> You wouldn't get audio on the main pcb OUT pad when the circuits bypassed audio doesn't travel through the circuit in bypass mode you're simply sending you guitar signal IN at lug 2 along the 3PDT jumper between lugs 3 and 9 straight up to lug 8 your OUT jack to your amp (red lines) switched the other way (purple lines, effects mode) you'd send your signal in up to pcb in through the circuit to pcb out and the out jack
> 
> ...


Thanks so much for you suggestions! As for the footswitch, the jacks are 100% soldered correctly, and the lugs on the footswitch are 100% soldered to the pcb really well (and resolded several times). I'm going to chock it up to a bad footswitch... Anyways, since I posted I removed the footswitch from the equation by soldering the jacks straight to the main pcb to try to figure out the low volume problem. Unfortunately, since I hadn't heard back from anyone I stupidly cut out the 2n5088s and resoldered another 3 of them in backwards to see if that fixed the problem. No sound came out at all. Now that you've confirmed they have the same pinout as the BC109 and match the layout of the pcb, I will cut those out and resolder in another set in the proper layout. Would the 22uf caps in c3 and c11 instead of 25uf cause such a volume loss? At full volume it's way below unity. Once I get the trannies in I will probe things and let you know what I found out..thanks!


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## Mcknib (Feb 21, 2021)

No the cap value wouldn't make a difference electrolytics have a tolerance of + or - 20% so a 22u would be fine, 25u caps were a common value when the original pedal was made these days it's 22u

I wouldn't advise removing anything until you know it's a problem you can easily damage solder pads with too much heat removing and replacing components 

Continuity check your switch with your meter to see if it's faulty you should get continuity between the lugs with the purple lines clicked one way and red the other way the 3PDT middle common row should only have continuity with either the top or bottom row

When checking make sure the middle row only has continuity with one or the other and not both

As I say if everything is connected correctly and all solder joints are good you should get bypass signal regardless of a circuit fault

Solder joints may look good but can be dry inside especially if too much solder is used

Unfortunately you appear to have a problem in the circuit and with your bypass 

Debugging can be frustrating but you're far better finding the fault rectifying it and moving to the next one

Post your transistor voltages that may indicate something


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## Zduck (Feb 22, 2021)

Mcknib said:


> No the cap value wouldn't make a difference electrolytics have a tolerance of + or - 20% so a 22u would be fine, 25u caps were a common value when the original pedal was made these days it's 22u
> 
> I wouldn't advise removing anything until you know it's a problem you can easily damage solder pads with too much heat removing and replacing components
> 
> ...


I just checked the footswitch with my meter and theres NO continuity between lugs 8 and 9! I reflowed some solder on them and still no connection. Faulty switch I guess?


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## Zduck (Feb 22, 2021)

Well you were right about replacing the transistors too many times. I think I ruined this pcb. It looks like at least one of the transistor pads has gone missing (Q2 Emitter).

Was it from using the solder sucker too many times? Or from too much heat? Can this pcb be saved? I've already wasted 6 2N5088s on this. Chalking it up as part of the learning process. I have tried transistor sockets before but I find that they dont hold the transistors very well so I stopped using them and just soldered right away.

Here are the voltages I'm getting with a 9.5v power supply plugged in right now:

Q1
E: 0.27
B: 0.08
C: 0.27

Q2
E: 0.08
B: 0.70
C: 0.08

Q3
E: 2.17
B: 2.79
C: 9.40

IC voltages in attached picture.


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## Mcknib (Feb 22, 2021)

Possibly too much heat has damaged it internally that'd account for no bypass signal

Did you get audio at volume pot lug 2 with your probe

Yes you can save the pcb simply place a wire jumper on the actual component legs from Q2 emitter to R4 side that connects to C3 +


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## Zduck (Feb 22, 2021)

I just checked with a probe and volume pot lug 2 is not getting any guitar signal

I was able to probe the guitar signal at the base of Q1 but no signal on the either outside lugs of Q1. It's coming into Q1 but not going out? I'm new-ish to electronics but shouldn't the signal come into the transistor base and go out the emitter? I had just put in a fresh Q1 transistor so it should be okay.


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## Mcknib (Feb 22, 2021)

You signal looks like it goes from Q1 collector to Q2 base your Q1 collector voltage is low so check R2 and Q1 solder joints

Reflow for around 4 seconds till you get a nice flow and a good connection between solder pad and component legs / pins

Unfortunately you can also damage transistors with too much heat hopefully that's not the case and its just not conducting correctly because of the voltage so don't heat them for too long

I'm assuming you've put your jumper on at Q2 emitter to R4

Using the schematic I'd check continuity on all transistor pins to make sure no other pads are damaged


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## Zduck (Feb 22, 2021)

Mcknib said:


> You signal looks like it goes from Q1 collector to Q2 base your Q1 collector voltage is low so check R2 and Q1 solder joints
> 
> Reflow for around 4 seconds till you get a nice flow and a good connection between solder pad and component legs / pins
> 
> ...


Just to confirm the jumper goes like this?


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## Mcknib (Feb 22, 2021)

Continuity check all pins to be 100% sure from the shop pcb image in your first post  that looks like the collector connected to the 1K8 in the schematic


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## Zduck (Feb 22, 2021)

I’m having trouble understanding how the transistors work. There is audio signal coming into the base of Q1 (I checked with an audio probe) that measures .08V. (And it goes to R5 as well). But there’s no audio or continuity to either outside lug of Q1? Do transistors need a certain voltage applied to the base and/or emitter and/or collector in order for it to “open” and the signal to come out the collector? I have .70V and .58V reading on the emitter and collector of Q1.


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## Zduck (Feb 22, 2021)

I was able to google these values for a genuine Colorsound Overdriver:

Genuine Pedal 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

Looks my Q1 voltages are way too low.


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## Mcknib (Feb 23, 2021)

Looking at the shop pcb image the 5088 pinout must be the other way around 

The BC109 in the TO92 package per the silkscreen isn't that common in every pinout I checked it's EBC same as a 5088 would be turned that way around or at least it looked that way 

But in the pcb image for Q1 the left pin definitely connects to a 100K, Q2 and 3 a 1K8 so that'd be the collector comparing it  to the schematic 

I've edited out my previous incorrect info so as not to confuse anyone else

Fair enough you may have initially put them in wrong but I'm definitely responsible for you doing it again 

I can only apologise, if you can't get the transistors out without further damage I'll get you a new pcb sent out seeing as you're a beginner who did it again because of my incorrect info

You can get transistors out without cutting the legs or damaging them I'll msg you rather than write a novel


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## Zduck (Feb 24, 2021)

Hmm so I flipped the 5088s and same voltages on all the legs as when they were the other way around. 

The collector (left leg) of Q1 is .70V and the R2+ 10k is also .70V. 

Q2 collector is .08V and the R3+ 1.8K is also .08V.

Q3 is 9.70V and R13+ 1.8K is also 9.70V.

That’s telling me that there is continuity between the collectors and the next components and the pads on the resistors haven’t been destroyed if they’re passing voltage correct?

Not getting any signal coming out of the circuit. The last place I can get signal is R5+ 150K and Q1 base. Signals going into the transistor and not coming out, too low voltage?


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## Mcknib (Feb 24, 2021)

Just to be doubly sure the Q1 pad that you pulled off is it the left or right pin as you look at the pcb

Could you provide a link to the 5088s you purchased too

What voltage do you get both sides of R2


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## Zduck (Feb 24, 2021)

Q1 right side (emitter) looks like the pad is missing. I also checked continuity between that and R6 (which looks like joined on the pcb diagram) and nothing. So maybe that where the problem lies? A jumper?









						IC 2N5088 0.625W 0.05A NPN 4PCS
					






					leeselectronic.com
				




R2 north side I get .070V bottom side I get 17.75V


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## Zduck (Feb 16, 2021)

When engaged the volume is really quiet. Bypass doesn’t seem to work at all.

Did I miss anything obvious? I used 2n5088 transistors instead of BC109 as I read they were a modern equivalent. Would that cause a problem or did I put them in backwards? The only other difference from the build instructions is I used 22u caps instead of 25u on c3 and c11. There is voltage on the IC legs and 9-14v on the diodes.

Thanks for any help! I’m fairly new to this!


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## Mcknib (Feb 24, 2021)

I'd place the jumper on the underside wiring it directly to the resistor solder joint and the transistor socket leg, the emitter connects to both R6 12K and R1 6K8 and as you can see from the schematic and pcb image so obviously check they both have continuity when you have your jumper in place

Your power isn't getting past R2 from your voltage readings so reflow the joint at the north side

Your 5088 link doesn't actually tell us much! We'll just have to assume it's standard pinout





Get yourself one of these to avoid future transistor pain etc, cheap and does the job









						Mega328 Lcr-t4 ESR Transistor Tester Diode Triode Capacitance SCR With Case for sale online | eBay
					

Find many great new & used options and get the best deals for Mega328 Lcr-t4 ESR Transistor Tester Diode Triode Capacitance SCR With Case at the best online prices at eBay! Free delivery for many products!



					www.ebay.co.uk


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## Zduck (Feb 26, 2021)

Okay, so I took a day off and came back to this thing today. I jumped the collectors of Q1 and Q2 as they had no continuity with the resistors. Now they have continuity and higher voltages. I tested on the out pad of the pcb and we have signal! This is promising. I installed a new footswitch as well that works this time. I tested the pedal and it works-ish. I feel like it’s not quite right. I took a video to help demonstrate the issues.

Volume (top left) 
Still fairly quiet overall but louder than before. It reaches unity volume only when it’s fully cranked. I heard these pedals were supposed to VERY loud so I don’t think it’s right.

Gain (top right)
Doesn’t seem to add any/much gain at all. And then when I turn it fully right (9-10 spot) the pedal gets very bassy but I can hear some gain in there.

Bass (bottom left)
Seems to work fine

Treble (bottom right)
Seems to work okay except I notice a slight volume increase when fully cranked to the right?

Also the pedal/switch has an audible “pop” when footswitch engaged. Not sure if that’s just how the original pedal works.

Any things to look for now or general thoughts? Thanks


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## Mcknib (Feb 26, 2021)

What voltages are you getting on your transistors now

Try audio probing the outputs of the transistors see if you can find where the volume drops off
Check how loud guitar signal is at the collector of Q1 base and collector Q2 and 3

The original 3 knob verson I've read did have huge volume

Switch pop can be improved using a 1M pulldown resistor immediately after the input to ground


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## Zduck (Feb 27, 2021)

The voltages I’m getting now are:

Q1 (left to right) 
2.35, 1.61, 1.05
Q2
10.98, 2.34, 1.71
Q3
9.63, 2.69, 2.06

I checked with the audio probe and the collector of Q3 is the same volume as the input jack. When I probe the “out” pad of the pcb the volume has dropped unless I crank the volume knob fully then it’s the same volume as the input and Q3.

Probing the transistors, Q1 base is same as input but Q1 collector is distorted. Q2 base and collector are distorted as well. But then Q3 base and collector are clear just like the input jack. 🤔


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## Mcknib (Feb 28, 2021)

Q1 collector is low I'd expect more voltage than that did you reflow R2, Q1 collector is connected to Q2 base so obviously having a knock on effect


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## Zduck (Feb 28, 2021)

I reflowed R2 and it’s still pretty much the same voltage. Q1 collector is 2.29, the top of R2 is 2.29 and the bottom is 17.75 (vcc). Base of Q2 is same collector of Q1 (2.29).

Curious why the collector of Q2 10.98 but the base of Q3 is only 2.69? Shouldn’t they be the same? Is it because the Q2 collector goes through the eq section and drops voltage before Q3 section brings it up again?


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## Mcknib (Mar 1, 2021)

Found some voltages from the original on DIYSB don't expect yours to be exactly the same with component tolerances etc but it'll give you an idea

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





__





						Colorsound Overdriver/Powerboost circuit "analysis"
					

Colorsound Overdriver/Powerboost circuit "analysis"



					www.diystompboxes.com
				




R2 is definitely 100K from what I can see but appears to be a problem personally I'd check R2 isn't bridged to any nearby components R5, R7 etc then lift the 2.29v side out very carefully and see if you get higher voltage on it

From your voltages VCC is all good you just appear to be dropping 3 or 4 volts too much through R2 you can see for example Q1 collector to Q2 base has the same voltage so looks like it's working just not getting the correct voltage which is what I mean by it having a knock on effect on the rest of the circuit

The voltage on the base of Q3 looks like it would come from the voltage divider R12 and 13 around 3v less a little voltage drop through the resistors



			https://ohmslawcalculator.com/voltage-divider-calculator


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## Zduck (Mar 1, 2021)

I pulled out R2 to be safe and swapped in another 100K. Afterwards I’m getting 1.5V but then I moved the pcb while reading and it jumped up to around 4V Q1 base and collector but is now down around 1.5 to 2 again. Would a loose Q1 transistor inside the socket be causing the inconsistency or maybe I need to jumper all the Q1 legs to resistors in case somethings not connecting right? Seems like there could be bad connection here.


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## Zduck (Mar 1, 2021)

I answered my own question by measuring voltage on the actual Q1 legs and they match the socket legs and the linked resistors.
I’m getting Q1 left to right:

2.2V, 1.5V, 1V


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## Mcknib (Mar 1, 2021)

Try another transistor but it seems the voltage you're getting the Q1 side of R2 is low you're getting VCC on one side and it's dropping almost all of it through the resistor did you check to see if R2 is connected to anything it shouldn't have continuity with

Without powering the circuit check resistance from D102 cathode to Q1 collector it should read around 100K ohms (R2 value)


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## Zduck (Mar 1, 2021)

I checked resistance from D102 to Q1 collector and it’s exactly 100.2K ohms.

I cleaned around the R2 resistor solders and don’t see anything that could be possibly touching it 🤔


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## Mcknib (Mar 2, 2021)

With your collector voltage changing whilst you were taking readings try holding the transistor down in the socket see if that does indeed change anything it's just weird getting VCC one side of the resistor and dropping all that voltage through it suggesting a high resistance between the pads but your 100.2K says it's fine, also try pressing R2 see if that affects voltage readings 

As you say sounds like a bad connection so prodding and pressing may reveal where it's at 

The last time I had a strange fault with a transistor in a socket one of the legs had actually sheared, the other 2 legs and the socket held it in place so when I had it wrong way up it was fine as soon as I put it the other way the leg dropped down disconnecting and it didn't work it had broken in the socket so I couldn't see it 

Are your transistors definitely all 5088s?


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## Zduck (Mar 2, 2021)

Mcknib said:


> With your collector voltage changing whilst you were taking readings try holding the transistor down in the socket see if that does indeed change anything it's just weird getting VCC one side of the resistor and dropping all that voltage through it suggesting a high resistance between the pads but your 100.2K says it's fine, also try pressing R2 see if that affects voltage readings
> 
> As you say sounds like a bad connection so prodding and pressing may reveal where it's at
> 
> ...


They are definitely all 5088s. I have a bunch and have even been switching them in now that I have the transistor sockets in there and getting pretty much the same readings.

I think the sockets may possibly be causing the Q1 issues. The Q1 collector is reading 2.2V fairly consistently but if I push the tip of the meter probe into the top of the socket and read the leg there I can get 4.4V from Q1 collector. Maybe pushing the tip into the socket pushes the transistor leg into place a bit better and makes better contact with the socket. What do you suggest I try next? Should I try and pull off the black plastic on the socket to expose the metal socket legs and solder the transistor directly to the socket legs?


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## Mcknib (Mar 3, 2021)

Those are strange sockets you could try using a cut off component leg to wedge it in better, see if that makes a difference not ideal but ok for testing purposes 

Take voltages on the underside solder joints to see if it's a constant 4.4v on Q1 collector 

I've never used those type of sockets perhaps your transistors aren't making good contact inside them


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## Zduck (Mar 3, 2021)

The underside solder joints are reading the same as the transistor legs (Q1 2.2,1.6,1.03) so they must be connecting okay?

So I figured out how I was reading 4V randomly. When I pull out the Q1 transistor and read the Q1 socket or solder joints I get 4V, 3.5V, 013V. I guess when I was pushing in the meter probe it was actually disengaging the transistor legs rather than connecting them better. Isn’t it strange that the transistor is dropping the collector and base voltage and increasing the emitter voltage? I swapped in other 5088s and get the same reading. I’m stumped.


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## Zduck (Mar 3, 2021)

btw I have tried two different sources of 2N5088s with same results


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## Mcknib (Mar 4, 2021)

R2 is what confuses me you get VCC on one side as you should then low voltage on the other side

What do you get when you remove Q1 from its socket on R2 collector side 

The only scenario I've ever had like this was a solder bridge causing a short only when the IC was in socket 

I got weird voltages with it in socket and good with it out so naturally thought the IC was toast! not so, it being an active device the same as a transistor it only connected the bridge when the IC was in socket and active in the circuit


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## Zduck (Mar 4, 2021)

If I remove Q1 I also get 4V on R2 top side and 17.3V on the bottom side of the resistor.

What’s interesting is if I remove all three transistors I get 18.13V on north side of R2 and 18.32V on south (vcc) side..

also to rule out the actual transistors even further, I had some BC109s arrive in the mail today and swapped them in and still got the same Q1 2.3V, 1.6V, 1.03V..


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## Mcknib (Mar 5, 2021)

Link the actual sockets you're using I'm not familiar with that type

Although I don't think so check the Q1 socket holes don't have any continuity with each other


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## Zduck (Mar 5, 2021)

3 Pin 2.54mm Single Row Female Pin Header
					

GTK - Get It Fast - Same Day Shipping




					www.taydaelectronics.com
				




Tayda doesn’t seem to carry the same part number I ordered (X-7260) but they look identical to the ones in the link.

I just checked and there is no continuity between the pins.


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## Zduck (Feb 16, 2021)

When engaged the volume is really quiet. Bypass doesn’t seem to work at all.

Did I miss anything obvious? I used 2n5088 transistors instead of BC109 as I read they were a modern equivalent. Would that cause a problem or did I put them in backwards? The only other difference from the build instructions is I used 22u caps instead of 25u on c3 and c11. There is voltage on the IC legs and 9-14v on the diodes.

Thanks for any help! I’m fairly new to this!


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## Zduck (Mar 5, 2021)




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## Zduck (Mar 5, 2021)

The component tester I ordered arrived today and I just tested the three transistors. They range from 311 hfe to 429 hfe. From what I understand hfe is how much gain they have. What does the Uf voltage mean? What do I look for when using this machine? Is it more to tell me if a transistor or other component is broken or out of tolerance? Thanks


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## Mcknib (Mar 6, 2021)

They're fine looks like the fwd voltage of the base emitter junction so about right for a silicon transistor at around 0.7v

Have you got your transistors pushed as far into the sockets as you can get them they're the same pitch as SIL sockets but defo much deeper I can't find a datasheet for those sockets so don't know if it's a spring type mechanism that locks them in place

From what I could find they're designed to be used with 0.1" headers which would normally lock in place as you push them in and header pins would be a lot thicker









						0.1" (2.54 mm) Female Header: Straight - Pimoroni
					

This connector is a straight female header strip designed to match 0.1" male headers.




					shop.pimoroni.com
				




Tayda part number is the A-1069 bit


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## Zduck (Mar 6, 2021)

I was really hoping it was the sockets that were the problem but I just removed the plastic socket housing and soldered the transistors directly to the socket pins and get the same result Q1 2.2,1.6,1.03  

I even continuity tested the transistor legs and the socket pins/legs and they’re definitely attached well as there’s zero resistance. 

Im stumped.. why does attaching the transistors into the circuit pull down the voltage so much.. it’s clearly way lower in Q1 than it should be. I really don’t know what could be the issue. Any other ideas before I toss this pcb out the window?!


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## Zduck (Mar 6, 2021)

Checking further resistance; Q1 collector connects to Q2 base. That’s what it should do. But when I check Q2 collector to Q3 base it shows -11 on the meter. What is negative resistance? So it is connected but there is some resistance? Is that would it should be? It’s also showing -13 and -10 on the Q3 collector and emitter when connected to Q2 collector as well... is that anything suspicious?


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## Mcknib (Mar 7, 2021)

Q2 collector and Q3 base don't directly connect there are several components between the two that would affect resistance readings

You can check resistance on your transistors by measuring from a reference point

Without any power to the circuit

For example Q3 emitter you can see it has R14 going to ground so your reference point would be ground to Q3 emitter where you would expect the value of R14 470R the accuracy of your reading would depend on your meters input impedance and whether it would load the circuit down etc

Q1 collector we've already checked referencing from a VREF point where you got just over a 100K what you'd expect so no high resistance affecting it there

All you're basically doing is measuring resistance along a path or trace you can see from the schematic what it should be but as stated there are other considerations all components will have an element of resistance, there may be paralell resistances etc

Series resistance is easy enough you simply add values paralell a little more complex and series and paralell takes a wee bit more maths

With your build all you can do is continue your checks you have made some progress

You may be getting minus meter readings because your leads are simply inverted swap them round and see

I'd personally at this stage continuity check everything around Q1 to make sure there are no bridges and good connections eg on the schematic you can see R5 connects to Q1 base and C1 with the other side going around to R4 check that then on the pcb you can see R5 is next to R2 and R6 where you dont want a connection so check there's no connection there

I'm far from an expert but as I said it does appear once Q1 is active in circuit the voltage drops it may well be something simple that's gone over my head so hopefully someone with a better knowledge than me may instantly know what's going on!


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## Zduck (Mar 7, 2021)

I checked the continuity and resistance of everything this afternoon. I went through each resistor and every one is the correct value/resistance it’s supposed to be, as well as the circuit has continuity where it’s supposed to.

I plugged in the pedal again and jammed a little bit and it does sound pretty good. The volume has to be cranked to reach unity but it does sound pretty good if you find the right gain and eq setting.

I’m sick of looking at this thing at this point and I’m gonna call it done for now unless any new info comes to light like you said. I’ll leave this post up in case anyone else has something to suggest that we both overlooked.

I want to thank you so much Mcknib for all your help and time with this. I feel like I’ve learnt a lot through this troubleshooting process that will help me a lot moving forward with my next builds. I have a stack of other pcbs I am excited to get to, fingers crossed they’re come together much more smoothly. Cheers.


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## Coda (Mar 7, 2021)

I’ve been following this, and I can’t remember if it had been said, but is the charge pump working ok? It almost sounds like the pedal is running at 9v, instead of the 18v the charge pump provides...


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## Zduck (Mar 7, 2021)

Hi Coda, I am reading 17.75 volts in the circuit at the vcc spots so I think it’s working okay?


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## Mcknib (Mar 7, 2021)

Always good to take a break and come back a little saner it can definitely get frustrating, what I'd do is give both sides of the pcb a good clean with alcohol and a toothbrush I'm starting to think if it sounds good it may well be your meter affecting voltage readings what model of DMM is it

I've been able to have a closer look at your pics and zoom in on my pcb is there a bridge at volume lug 3 and the black ground wire that'd certainly affect the volume if it is making contact


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## Zduck (Mar 7, 2021)

Here’s the meter I use. Unfortunately what you pointed out was just a little piece of metal flake or something on the pcb and wasn’t affecting anything. Brushed it off and nothing changed. I’ll try the toothbrush and achohol suggestion tomorrow!


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## Mcknib (Mar 8, 2021)

The impedance is fine so it will be pretty close to the actual voltages you've read  

I don't think you're that far away from sussing the fault 

Out of curiosity when you get the 4v reading does it increase the volume 

As you say you're better stepping away from it and coming back to it with fresh eyes I don't think cleaning it will fix it, there is a possibility it will but it's more to get a better look at it without all the gunk clogging it up


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## Zduck (Mar 8, 2021)




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## Zduck (Mar 8, 2021)

I cleaned the pcb with alcohol and a toothbrush. Didn’t fix anything unfortunately as you suspected but it’s easier to see now. Posted some more pics above, if perhaps something looks suspicious.

I can’t test the audio signal at 4V right now because I was getting the 4V with Q1 transistor unplugged from the socket, and it’s now soldered directly to the socket legs. I could unsolder it if you think it’s important to try? I will try more probing with the audio probe next.


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## Mcknib (Mar 9, 2021)

Nothing jumping out maybe a wee bit too much solder on your jumpers I'd also check if you haven't already that you have continuity with components leading off where you have your jumpers I'm taking it where you required jumpers did physically have pulled pads? did you actually solder your jumpers directly to the component legs particularly the jumper Q1 collector to R2 looks like you did but hard to see

I'm gonna have a look back through again kinda lost my way a wee bit maybe concentrating too much on Q1 collector you did say earlier volume was good up to Q3?

Good idea doing a re probe I think you've just invented a new DIY phrase haha

Re probe bate


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## Zduck (Mar 9, 2021)

Haha I like that!

So probing the audio signal, everything seems okay until Q3. Collector of Q2 is louder and more distorted than the input jack signal. But then when I probe base of Q3 there is no audible audio signal, it just pops when I touch it.. Then Q3 collector has audio signal but it’s basically the same volume and gain as the input signal. So it’s lost it’s volume and gain that it had at Q2.


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## Zduck (Mar 9, 2021)

Actually I can hear the signal on Q3 base but it’s REAL quiet.


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## Mcknib (Mar 9, 2021)

I would probe everything between Q2 and Q3 base see if you can track down where it drops out ie a component where it's loud one side quiet the other


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## Zduck (Mar 9, 2021)

Ok looking at the components in the EQ section after Q2 going into Q3, R7 is super quiet, R10 is about level with input but is distorted, R8 and R9 are super quiet like R7 (barely audible). R3 is loud and matches the collector of Q2. C5 is quiet. Is there anywhere specifically I should check?


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## Mcknib (Mar 9, 2021)

It's just a case of tracing from where the audio's ok to where it fails and finding where the signal loses volume 

So if it's good going into a component and not coming out you'd look around that area and reflow solder joints etc

Audio probing basically tells you what area your problem is in not what's causing it whether that be a short, faulty component, dry solder joint or whatever you need to investigate reflow joints see if that fixes it and so on


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## Zduck (Feb 16, 2021)

When engaged the volume is really quiet. Bypass doesn’t seem to work at all.

Did I miss anything obvious? I used 2n5088 transistors instead of BC109 as I read they were a modern equivalent. Would that cause a problem or did I put them in backwards? The only other difference from the build instructions is I used 22u caps instead of 25u on c3 and c11. There is voltage on the IC legs and 9-14v on the diodes.

Thanks for any help! I’m fairly new to this!


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## Zduck (Mar 10, 2021)

Ok thanks. I guess I’m having a hard time understanding the schematic and which component goes into the next. Q2 collector is loud, R3 is loud, but C5 is quiet. It looks like C5 is next in the path before going into the eq section. I reflowed the solder on C5 but didn’t fix the problem. I’ll keep looking.


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## Mcknib (Mar 10, 2021)

You're doing the right thing

What I normally do is print off the schematic as you have and use my probing in combination with continuity checking so I know what side of the component I'm probing e.g. C1 I'd continuity check which side is connected to in, probe it and mark with a tick on the schematic if it's ok then do the R5 side and so on marking as I go with ticks for ok and Xs for dodgy

I'll also often note the voltages on the schematic what they should be if I know and what they actually are

Basically giving you a visual of where your likely problems are

With this you do have more than one path going into the eq you can see where traces join with the dots letting you know its connected it's a baxandall set up boosting and cutting your bass and treble frequencies through Q3 I think obviously depending on the pot positions

So you will hear differences as you have at the transistor outputs depending on the pot rotation e.g. gain cranked more distortion bass CCW less low end etc

So once you find a problem ie something with little volume go back and try to pinpoint where it's lost and review your findings we know for example Q1 C voltage is more what you'd expect at 9v as @Coda said and youve got 17.7v going into R2 so you'd expect double what you're getting there

Did you ever just lift the R2 leg that connects to Q1 C out to see what voltage you got on it

Debugging although it can be a PITA and you just want to get the %^&*$# thing going does teach you a lot if you're more of a layman like me and can actually be enjoyable when you get those eureka moments where you go sh*t that's loud oh that must be an amplification stage.....I've learnt something......who's a clever boy then! 

Me, that's who gimme a $%@^&^× biscuit


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## fig (Mar 10, 2021)

i just spewed my tea ya bastard! 🤣


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