Piccolo Build - No sound one channel

bluenoteJML · « **on:** 12 Jul 2010, 08:42 pm »

Well, I'm back. I just finished my piccolo build, many thanks to Alan for the frontpanel express file, it looks awesome! I turned on the piccolo and get a lovely blue light and very nice sound from one speaker only. Switched cables around and still no sound. Removed piccolo from setup and sound on both speakers. So I've screwed something up, just have no idea what. I'm not (as my posts would indicate) sure how to read the schematic to find out where the voltages are not correct. Can someone give me some guidance? I have the loading set to 47K and started with the lowest gain setting. The light stays blue through all three settings on the gain.

Jon

analog97 · « **Reply #1 on:** 12 Jul 2010, 11:48 pm »

Carefully check all components for a loose solder joint. That's my guess. Also, try the gain at other positions (lower your volume first). Maybe you'll be lucky and find the bad channel has a loose gain resistor.

bluenoteJML · « **Reply #2 on:** 13 Jul 2010, 01:19 am »

Thanks. I'll go over them to see if as you suspect it's a bad solder joint. Would not surprise me at all. I started with a a silver solder from mundorf and finished with it but it's hard to flow without using too much heat. More soon I'm sure

analog97 · « **Reply #3 on:** 13 Jul 2010, 02:08 pm »

I had a similar experience when I recently built a couple Piccolos for my friends. I missed a solder connection (silver solder) on a gain resistor, so when my buddy tried the 20db gain setting, there was no sound in one channel. Easy to identify and fix. I keep a 5x magnifying glass and use a toothpick to gently wiggle the resistors. If you identify a bad joint, but already have the battery pack installed and this hides the bottom component holes, you can repair from the top side, but just make sure your tip stays away from any components. Be careful if you do this. Good luck. The Piccolo is a superb l'il machine!!

bluenoteJML · « **Reply #4 on:** 17 Jul 2010, 05:29 pm »

Hi Analog,
So here's a dumb question. I resoldered every joint on the piccolo board, hooked it back up and still no sound on one channell. Oddly though, it switched channels. Not sure why I did it but I must have had the Cornet on Mono and didn't realize it. Moved the mono switch from one side to the other and now i have perfect sound on both channels. So here's the question, before this the mono switch didn't seem to matter, why should it with the picollo in operation?

Jon

bluenoteJML · « **Reply #5 on:** 17 Jul 2010, 05:52 pm »

I must admint, this sounds awesome. I barely have the amp cracked on volume too. Listening to the new release of exile on main st. I'll take pics as soon as i've finished the box. have to cut off and install the knobs and paint the bottom of the case. I used the frontpanel express file posted in another thread about the silk screening. It looks awesome.

analog97 · « **Reply #6 on:** 17 Jul 2010, 09:40 pm »

I dunno about the mono switch question. As long as you have awesome sound in both channels you are good to go. Congratulations on your success. The Piccolo/Cornet2 is an awesome vinyl front end!! Enjoy.

poty · « **Reply #7 on:** 18 Jul 2010, 02:30 pm »

Quote from: bluenoteJML on 17 Jul 2010, 05:29 pm

I must have had the Cornet on Mono and didn't realize it. Moved the mono switch from one side to the other and now i have perfect sound on both channels. So here's the question, before this the mono switch didn't seem to matter, why should it with the picollo in operation?

It seems you NOW have the Mono switch on! As soon as it (the switch) sums both channels from input RCAs and then distribute the resulting signal to both channels of Cornet, the non-working channel of the PICCOLO hides. You can prove it by pulling one of the input cable from PICCOLO input and have either no sound at all or no changes (both channels sound) - depends on what channel is working.

analog97 · « **Reply #8 on:** 18 Jul 2010, 02:48 pm »

On the Cornet2, the stereo position is when the mono switch is set to the left.

bluenoteJML · « **Reply #9 on:** 18 Jul 2010, 03:55 pm »

Have not had a chance to test Poty's suggestion but the switch is set to pointing to the right, which Analog97 says is now Mono. So am I pushing both channels through one now? This doesn't solve the underlying issue I started with if that is true. Are there points along the pcb that i can check voltages? I see some listed in the schematic but am not sure where exactly to test on the board. I've either missed (yet again) a solder joint or I have something bad on the board.

bluenoteJML · « **Reply #10 on:** 18 Jul 2010, 09:24 pm »

If a bad solder joint is not the culprit, would most likely be? What would voltages should I expect to see and where on the board?

bluenoteJML · « **Reply #11 on:** 27 Jul 2010, 01:24 am »

I've gone over the board now several times and can't find any faulty solder joints. I've been told to compare the voltages on both sides of the board. What am I looking for? I can follow instructions pretty well but am somewhat lost when it comes to reading schematics. Can anyone point me as to where to test and what to look for?

WGH · « **Reply #12 on:** 27 Jul 2010, 02:25 am »

Quote from: bluenoteJML on 27 Jul 2010, 01:24 am

I can follow instructions pretty well but am somewhat lost when it comes to reading schematics.

This should help:
http://www.best-microcontroller-projects.com/how-to-read-schematics.html

Wayne

Theo · « **Reply #13 on:** 27 Jul 2010, 05:21 am »

Quote from: bluenoteJML on 18 Jul 2010, 09:24 pm

If a bad solder joint is not the culprit, would most likely be? What would voltages should I expect to see and where on the board?

Could it be the jfet at that channel is faulty? Jim can shine a light on that.

poty · « **Reply #14 on:** 11 Aug 2010, 12:43 pm »

Have you solve the problem? Just interesting to know what really caused this?

bluenoteJML · « **Reply #15 on:** 14 Aug 2010, 03:23 am »

Hi. Wish I had better news, but no. Still no sound on one channel. I'm a but frustrated at my inability to find the issue to be honest. Going to try again. If you have suggestions as to what I should be seeing for voltages etc and where on the board, please let me know.

bluenoteJML · « **Reply #16 on:** 14 Aug 2010, 02:33 pm »

Okay - if I have done this correctly here some voltage measurements on the caps in the following positions:

C10 - 8.75v
C11 - 3.64v
C16 - -8.26v
C17 - 3.13v
C1R - 1.39v
C1L - 3.67v

Jim- can I send you the piccolo if I can't figure this out?

Jon

poty · « **Reply #17 on:** 15 Aug 2010, 06:49 pm »

It seems not all voltagesyou measured right, but never mind.
I think you should give us the results from the following experiments. The experiments need a capacitor (about 100nF or more) with two wires soldered to it. Before the experiments you should be shure that your Corned is switched to stereo.
1. You should while playing music connect the wires from the capacitor to the center pins of both J2 (left and right channels). Do you hear both channels?
2. ... connect the wires to the C1 (the side nearer to the out connectors) of both channels. Do you hear both channels?
3. ... connect the wires to the C1 (the side nearer to the in connectors) of both channels. Do you hear both channels?
4. ... connect the wires to the R2 (try both sides) of both channels. Do you hear both channels?

Waiting to hear from you.
(If you don't have a capacitor like this, you can use just wire, but in the case you should be VERY accurate.)

hagtech · « **Reply #18 on:** 16 Aug 2010, 06:39 am »

Hmmm, some problem with right channel. Yes, you can send it in. I will look at it.

jh

bluenoteJML · « **Reply #19 on:** 19 Aug 2010, 09:22 pm »

Poty - I'll try to get you the measurements. Jim - I lifted a trace replacing a cap hoping that would sort the issue. No such luck. I'll send it in if what Poty suggests doesn't pan out.

Jon