Replies to This Discussion

Permalink Reply by Ron "Oily" Sprague on January 8, 2012 at 1:20pm

Where's yer pickup? You got power, speaker out, and input jack...but no string vibration transmitter, that I can see. Doh! My bad: this is an amp. I got guitar guts on the brain. Your LED works, so you're getting power, and it looks like all the wires are in the right places, including the grounds... I assume the other one you wired up works fine?Did this thing come with a volume knob, or are you using the one on your guitar? Maybe you got a bad chip? It does happen...

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Permalink Reply by Dan Sleep on January 8, 2012 at 1:48pm

You also need to be sure you don't burn out any components when you are soldering. Using a heat sink will help.

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Permalink Reply by Ron "Oily" Sprague on January 8, 2012 at 1:49pm

Oops, the rest of my Reply didn't Save...

Was gonna ask if you could go through these steps ( maybe you've done some or all of these already...):

A) Check your wiring schematic one last time.

1) Test the circuit at all points with a Multimeter, or wire and alligator clips. I have a fair amount of trouble getting small precise solder beads, so it could be a short where you soldered to the board?
I assume the IC chip was already attached, but it is possible to burn it up accidentally by applying too much heat for too long... 2) Check the input jack to make sure the tip and sleeve lugs have been wired for the correct polarity.
3) Because you demonstrably have power, the problem is most likely at the speaker end or the input end ( although as suggested previously, a bad chip or other component might be also be the culprit)
4) Desolder everything, strip to bare wire, and try hooking up with everything just twisted / taped together.

If none of these work, send it back for a replacement.

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Permalink Reply by nates68chevelle on January 8, 2012 at 2:23pm

Oily "Strat-O'-Nine-Tales" Fool said:

Oops, the rest of my Reply didn't Save...

Was gonna ask if you could go through these steps ( maybe you've done some or all of these already...):

A) Check your wiring schematic one last time.

1) Test the circuit at all points with a Multimeter, or wire and alligator clips. I have a fair amount of trouble getting small precise solder beads, so it could be a short where you soldered to the board?
I assume the IC chip was already attached, but it is possible to burn it up accidentally by applying too much heat for too long... 2) Check the input jack to make sure the tip and sleeve lugs have been wired for the correct polarity.
3) Because you demonstrably have power, the problem is most likely at the speaker end or the input end ( although as suggested previously, a bad chip or other component might be also be the culprit)
4) Desolder everything, strip to bare wire, and try hooking up with everything just twisted / taped together.

If none of these work, send it back for a replacement.

• The boards came pre-assembled with wires for the input and outputs, so all i had to do was wire to the speaker, to the 9 volt, and to the input jack...the mono jack does have a third prong that i didn't use, but i have the tip going to the input and sleeve going to the ground on the board, so it should work.  The second board i hooked up the same way with everything just twisted together, eliminating the solder joints, but neither circuit works.  I can't imagine that i got 2 bad assemblies, but i guess it's possible.

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Permalink Reply by Ron "Oily" Sprague on January 8, 2012 at 2:58pm

Nate,

Hmmm. Ohhhh-kayyyyy...

So A is out, #2 and #4 you did...you have a 3-lug RTS input jack, wired up properly...OK, really stupid "Tech Support" question: You plugged in a guitar, turned up its volume knob, with the amp turned on, and you get nothing, in either case?

Yeah, doesn't seem likely you would get 2 bad assemblies...your wire gauges look different from those pre-wired to the board, so there's likely an impedance mismatch, but you seem to be getting enough power to at least light up the LED, so the mismatch if any is small...

Did the kit come with a schematic, and if so could you post a pic? You might need to take this over to the CBG Amp group, run it by them; pretty sure a number of people there have used this same kit. I confess to being stumped.

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Permalink Reply by nates68chevelle on January 9, 2012 at 2:20am

Oily,
Thanks for the replies. I did check it with a guitar and an iPod plugged in, but didn't get any noise with either one. I also wired in a potentiometer on the speaker side just to see if it would do anything, but still nothing. I'll admit I'm not an electronics technician and this thing is just boggling my mind. I'll head over to the specialists. Thanks again.

Oily "Strat-O'-Nine-Tales" Fool said:

Nate, Hmmm. Ohhhh-kayyyyy...

So A is out, #2 and #4 you did...you have a 3-lug RTS input jack, wired up properly...OK, really stupid "Tech Support" question: You plugged in a guitar, turned up its volume knob, with the amp turned on, and you get nothing, in either case?

Yeah, doesn't seem likely you would get 2 bad assemblies...your wire gauges look different from those pre-wired to the board, so there's likely an impedance mismatch, but you seem to be getting enough power to at least light up the LED, so the mismatch if any is small...

Did the kit come with a schematic, and if so could you post a pic? You might need to take this over to the CBG Amp group, run it by them; pretty sure a number of people there have used this same kit. I confess to being stumped.

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Permalink Reply by David L. on January 9, 2012 at 2:47am

Hi Nate,

I have made a few smokey type amp circuits using the LM386 and had one I couldn't get to work until I realised I'd put the chip in the socket the wrong way around (the half moon on the top of the chip goes at the pin 1 and 8 end on the schematic if you have one.)

On the simplified circuit of a smokey amp like this

 

Is there any possibility this could have been done on yours?

Regards

David 

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Permalink Reply by Naz Nomad on January 9, 2012 at 3:39am

Close-up, in-focus pics of BOTH sides of the PCB and all the off-board wiring would enable people to give you a better idea where you went wrong.

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Permalink Reply by Ron "Oily" Sprague on January 9, 2012 at 5:14am

Nate,

I think both Naz and David may be on to something. From looking at David's hand-drawn schematic, the location of various naughty bits, and your pic, I can see the half moon dimple indicating pins 1 and 8 on your chip. So why are the speaker leads on your board closest to pin 8? In David's diagram they are closest to pin 5. And Naz makes a good point: a pic of the other side of the PCB might help...just a thought.


Here's a pic of the same board from the Q Kit website; you can see that the dimple is toward the caps and transistors, while on yours it appears to be 180 degrees away from them:

http://store.qkits.com/images/qk17.jpg

Nope, dangit; it was just a shadow. Rats...

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Permalink Reply by nates68chevelle on January 11, 2012 at 4:18am

David,
I ordered the board pre-assembled, so if it's wired wrong, they did it at the shop.  But I ordered 2 boards and they're both assembled the same way.  I guess they're either both wrong or both have bad components.  Which seems like it would be a rare occurence, but within the realm of possibility I guess.

David Lloyd said:

Hi Nate,

I have made a few smokey type amp circuits using the LM386 and had one I couldn't get to work until I realised I'd put the chip in the socket the wrong way around (the half moon on the top of the chip goes at the pin 1 and 8 end on the schematic if you have one.)

On the simplified circuit of a smokey amp like this

 

Is there any possibility this could have been done on yours?

Regards

David 

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Permalink Reply by robert jones on January 24, 2012 at 4:46am

Everything looks to be wired correctly as far as I can tell from the photos so I'm going to ask the obvious question.

Did you turn the amplifier volume trimmer up?

I used a similar kit once that shipped with the amp volume control set to zero.

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