[count123]

Stuffed the Piccolo board with all the correct parts, powered it with 18v power supply [wall wart]. Didn't work.
LED light didn't even come on. Couldn't measure any voltage anywhere.
Put it away for 6 months, got tired of trying to figure out problem.
Just brought it back out again. It didn't fix itself.
Don't know where to start looking for the problem fix.
Help!!!!

[galyons]

Try with batteries, if that works then....Test the wall wart. Test the connection from the wall wart to the Piccolo, voltage, both positive and negative continuity. Test for  +5.5v at R21.  Make sure that the diode at D4 is oriented correctly and you have about +5v on the switch side. 

If the batteries do not work...Make sure that the  switch is installed correctly. Did you change the locking ring orientation on the switch?

Check for bad solder joints on the regulator.  Do you have +9-10v at pin 8 and -5v at pin 5?  Check for correct orientation of diodes D1-3.  Approx 9v after D3? 

Test and provide results.

Good luck,
Geary

[poty]

Geary has good routine for checking.
I'd add that wall wart you are using may be reversed polarity one. Then first step - check the voltage at the wall wart connector. Center hole should be positive regarding the shell contact. If it is not so - you may the U2 (and possible C20 also) already broken.
Then - like Geary said - check voltages on the L1 (2 measurements from each end) to ground, pin 5 of U2 to ground, cathode of D4 (the point where the arrow of the diode symbol points to), R12 (both ends to ground), cathode of D2, cathode of D3, C18. Then voltahe on pin 5 of U1 and C8. If you have all the above voltages - LED should lit.

[count123]

Thanx Greary and poty for replying. Had to resolder the battery holder back on. The cheap wires broke off.
Checked the wall wart and it was putting out 18.3V. The center was + the outside was -. D4 was oriented like
the diagram. Changed the locking rings on switch. Which is the regulator?? 
D1,D2 are oriented like diagram. D3, don't know. Can't see markings. Voltage is .015V.
L1 measured .045V both sides.  Pin 5 of U2  .000V
Cathode of D4--.014V      R12---.021V      Cathode of D2--.015     Cathode of D3--.015     C18-- .013V
Pin 5 of U1--.000V     C8---.018
I don't know, maybe it's the DC jack installed incorrectly. It's on battery power now. Wall wart was disconnected.
Hope you can help.         Thanx

[BobM]

It's supposed to be 12V DC. Perhaps the 18V is overloading it? I don't think that there is a downconverter/limiter chip in there for an overpowered wall supply.

[poty]

Count123, could you say what you have done to find the problem before that? In the first message you mentioned some attempts to repair the unit.
From your measurements I can only see that the Piccolo doesn't receive the power at all. As soon as you are now powering the device from batteries let me explain what you should do to find the source of the problem.
- measure the voltage ON THE PCB where the wires from batteries come. Should be around 6V. Watch the right polarity! If not - replace the batteries or check how good you soldered the wires. There should not be any tricks.
- the DC connector for external power has a contact which interrupts battery supply when the external plug is in. Please check if the switch is closed (pull out the batteries and check continuity between the minus of battery and the ground). If not - try to figure out what causes this effect.
If both above measurements are right, you must have the battery voltage on L1 (both sides to ground). No surprise!

[count123]

Manual says from 6Vdc to 24Vdc.
When I tried to find the problem, rechecked for correct value and placement of caps and resistors on PCB.
Checked for solder bridges and dry joints. [NO JOKES]. Checked for voltages. Got none.  [Before]

Got 6.09V from batteries entering PCB.  Solid soldered wires.
There is a problem with ground continuity. Showed infinity in ohms between negative on battery wire and ground
post and outside of RCAs.
Where do I start looking for bad ground under a green skin.
Built a Cornet and it had bridge between 2 side by side copper trace under the green skin. Don't know how I
found it.

[poty]

When I tried to find the problem, rechecked for correct value and placement of caps and resistors on PCB.
Checked for solder bridges and dry joints. [NO JOKES]. Checked for voltages. Got none.  [Before]

OK, the work was impressive! But even now we have one of the voltages we didn't find earlier :

Got 6.09V from batteries entering PCB.  Solid soldered wires.

It's a good sign!

There is a problem with ground continuity. Showed infinity in ohms between negative on battery wire and ground
post and outside of RCAs.
Where do I start looking for bad ground under a green skin.
Built a Cornet and it had bridge between 2 side by side copper trace under the green skin. Don't know how I
found it.

I don't think you should start looking under the solder mask. For me - sounds like either DC power connector is bad or you managed to solder it incorrectly. I'll try to upload a piece of Piccolo PCB explaining what I mean. The negative battery circuit begins from the point marked as "Minus of the battery" and I hope you have already used the point to measure the battery voltage. Then it goes to pin 1 of the DC power connector. If nothing is inserted in the connector the pin 1 and pin 2 should be shorted (appears as zero if you check continuity). If not - you should check if you solder the connector right. For that you can check for zero resistance between the center pin of the connector to pin 3, the outer contact of the connector to pin 2. If all the above measurements are OK then you have defective connector.

[BobM]

Just a thought, but do you have the top piece screwed into the rest of the metal casing or is it outside the case and unattached? I found a ground issue trying to play it out of the case - bad hummmmm. When screwed together there was no hum, so I assume the case acts as a ground plane. It might be part of the issue.

 

[count123]

If all the above measurements are OK then you have defective connector

I don't understand the above statement?  Anyways, Nice picture of PCB and directions.
I put in new DC connector in board.  Checked solder joints.  Looked good.
Continuity between shorted pin 1&2  was  0 ohms.  Continuity between center pin and pin 3 - 0 ohms.
Continuity between outer contact and pin 2 was infinity[flipping all over the place].
With DC plug in connector, showed .1 ohms  between outer cover and pin 2.

Still have no idea.

I don't know if it's humming. Right now, it's not functioning.                Thanx

[poty]

If all the above measurements are OK then you have defective connector

It was the end of one branch of the algorithm.

I put in new DC connector in board.  Checked solder joints.  Looked good.

Could you clarify - you changed the DC connector according to the algorithm (i.e after you found out that there is no continuity between pin 1&2 AND pin 3 and pin 2 checking) or "just in case"?

Continuity between shorted pin 1&2  was  0 ohms.  Continuity between center pin and pin 3 - 0 ohms.
Continuity between outer contact and pin 2 was infinity[flipping all over the place].
With DC plug in connector, showed .1 ohms  between outer cover and pin 2.

OK! As you can see the pin 2 is directly connected to ground. Then the continuity between minus of the battery and the ground should be 0 Ohm now. If not - check continuity between "Minus of the battery" and pin 1.
If the continuity is restored - then you should have voltage on the cathode of D4 as minimum (to ground) as minimum. When you turn the S2 to any "ON" position you should have the voltages also on R12, pin 8 and so on...

[count123]

I changed the DC connector "just in case" something was touching something, and had a new one hanging around.  Everything is so close at that junction, could have had a solder bridge at one of the pins.  Put on the
magnifying glasses. Couldn't see a problem but replaced it anyway.
There was continuity with all the points you mentioned.
There was battery voltage at all the points you mentioned.
I haven't tested it, yet, to see if it works. Will try to-day.

Still have a problem, plugged in the DC power supply and tested at D4, R12 and pin 8 and am still only getting battery voltage[6.12V]  instead of power supply [18V] .   
LED light still NOT coming on.                Thanx for your time "poty".  You're a godsend.
   

[poty]

Testing battery powered device is a bit easier, because for external power supply there are several more parts (L1, C20, U2, R21, R22) involved. but as soon as you insist on checking everything I'll write further two "branches" of testing. I'm assuming that "LED light still NOT coming on" applies to both power supply options.
For battery powered device:
At the beginning of the power supply there is a voltage converter U1. The power to the converter put between pin 8 (plus) and pin 3 (minus). We have already known that there is the battery voltage at pin 8. The pin 3 is directly connected to the ground which has been restored too. From the converter you should have two voltages: on pin 5 (to ground) - "-5V", on the cathode of the D3 (to ground) - "+9V". If you don't have both voltages the LED won't light. In that case - check if you soldered U1 right (i.e. pin 1 is on the right side). Further measurements: voltage across C4 (not to the ground!!! between its legs), voltage across C5. Both should be around 5V. Check if the D3 soldered right. Having 6V on the pin 8 you should have at least 4V across C7. If you have both voltages - LED should be ON.

For wall wart powered device:
You should have the voltage across pin 3 (PLUS) and pin 2 (MINUS) from my picture I sent earlier after you plug the wall wart to the DC connector.
If not (and taking into account that you have already successfuly checked continuity between the outer part of wall wart and pin 2) - the wall wart may expect different center pin size (more thick).
If you have the voltage across pin 3 and pin 2 - check if the voltage is on L1 (both sides) to ground and across pin 4 and pin 3 of U2. Pin 2 also should have continuity to ground. After that - check the output voltage (on pin 5) - should be 5,5V - and reference voltage across R22 - should be around 1,3V. If not - I'm afraid the U2 is already dead. If all is OK - the rest should be equal to battery powered routine.

[hagtech]

It sort of sounds like what has been said already - the "ground" side of dc jack is not connecting to "ground" side of PCB.  This is done by a contact switch inside the dc jack itself.  When external wall wart is removed, the connection switches over to internal batteries.  Check this area of circuit.

jh

[count123]

Sorry for not getting back sooner. Things to do.  Anyways,  here it goes.  Battery voltage  6.21V.
U1-- P3 has continuity to GR.   Pin5  to GR.--0V.    D3  cathode to GR.--6.2V    U1 is soldered correctly according
to diagram.   According to the diagram Pin 1 of U1 is on the bottom left by the notch [ I guess it depends on how
your looking at the diagram].   Across C7--0V.    Across C4 & C5--0V.

With Wall Wort
18V across pins 2&3 of DC connector.
18V to GR. of L1. Both sides.  Pin4--18V   Pin3--18V   P2 has continuity to GR.   Pin5--18V.

Replaced U2. Made no differance.
Replaced Wall Wort connector with a better fitting one.

I wonder why I quit the 1st time?  This is a head banger.      Led light still not on.                Thanx 

[poty]

I'll resort your results for better following:

Battery voltage  6.21V.

ОК.

D3  cathode to GR.--6.2V but Across C7--0V.

BOTH are impossible! First of all - the cathode of the D3 is the same as the "plus" of C7. Minus of C7 is connected to ground. So either you measured on wrong side of D3 (and then - D3 is dead or reverse soldered) or something wrong with soldering C7.
Further thoughts greatly depends on the answer of the first. If C7 is not soldered correctly then it may be possible that you do not have enough voltage on the output and then the 6.2V on the cathode of D3 could be explained. IN another case... If U1 is not soldered correctly or broken, the voltage drop on the D2-D3 would be not less than 0,6*2=1,2V. The Battery voltage is 6.21. So the voltage on the cathode of the D3 should be no more than 5V. Which problem is your - you should test and decide. (check continuity of cathode D2 to plus of C4 and to anode D3; check continuity of the cathode of D3 to the plus of C7 and R14; check continuity of minus C7 to ground)

U1-- P3 has continuity to GR. Pin5  to GR.--0V. U1 is soldered correctly according to diagram.   According to the diagram Pin 1 of U1 is on the bottom left by the notch [ I guess it depends on how your looking at the diagram]. Across C4 & C5--0V.

The pin 1 mark of the U1 should be heading the corner of C4 and R13 on the board (goes to the square pad). It's the first place to test. The numbering of the pins:

          C4
R13__1--8
_____2--7
_____3--6
_____4--5
         
Then test the following:
U1 pin 8 - should be the battery voltage (to ground) and has continuity to the anode of D2 and plus of C3
U1 pin 3 and pin 6 - continuity to ground
U1 pin 2 - 10 Ohm to the minus of C4 and to the plus of C5
U1 pin 4 - continuity to the minus of C5
U1 pin 5 - continuity to the minus of C6 and 10 Ohm to the cathode of D1
C6 "plus" - continuity to ground
C4 "plus" - continuity to the cathode of D2 and the anode of D3
If all tests are ok, the C7 correctly wired and you still don't have LED on - U1 is dead.

With Wall Wart:
18V across pins 2&3 of DC connector.

OK if pin 3 is positive.

18V to GR. of L1. Both sides. Pin4--18V

Great.

Pin3--18V

Are you sure? Pin 3 is tied to ground! Then if you have 18V on the pin - it means there is no continuity of the pin 3 to ground (check!!!). It may have devastating influence on the U1 (full 18V goes to it, with absolute maximum = 16,5V)!! Check also continuity of pin 5 to R21 and plus of C21; pin 1 to R21 and R22; R22 to ground.
Please take into account, that if you point the leads to yourself, the pin would be numbered 1-5 from the left to the right:
-----
I O I
-----
|||||

12345

P2 has continuity to GR.   Pin5--18V.

With S2 on the OFF position you should measure +5,5V on pin 5 to ground! There is no tricks here at all.

[count123]

More problems!!  Replaced  U2, LED light & all the caps. in power supply section [just in case].  Accidentally, took  out eyelets in some of U2 pin holes.  Had to look for eyelets.

Just a question.  Why is battery -  different from  PCB - ?

OK. Here is the test.

Cathode of D3 & - of C7 is connected to ground.
Voltage at cathode of D3 is 6.33v   [all tests with battery voltage].
There is continuity of D2 to + of C4 & anode of D3.
    "     "     "            of D3 to + of C7 & R14.
    "      "       "         of C7 to ground

U1- -pin 8 is battery voltage & has continuity to anode of D2 & + of C3
        pin 3 & 6 have continuity to ground.  [at PCB]
        pin 2 - 10 ohms to - of C4 & to + of C5
        pin 4  - NO CONTINUITY - of C5
        pin 5 - continuity to - of  C6 &  3K ohms to cathode of D1.
 
Continuity of C6+  to ground
       "         of C4+  to cathode of D2 & anode of D3.

Thanx for your help, poty. Hope this ends soon. Spent way to much time on this.  To add to this, a diode fell off
my Cornet2 phono  [yes, I soldered it] ????     

[hagtech]

The battery return is separated from board ground to make sure that batteries to not get "charged" when AC adapter is plugged in.  If you are stuck, send it in.  I will make it work.

jh

[poty]

...Replaced  U2, LED light & all the caps. in power supply section [just in case].  Accidentally, took  out eyelets in some of U2 pin holes.  Had to look for eyelets.

No wonder - you've made so many "just in case" soldering!

Cathode of D3 & - of C7 is connected to ground.

Can't understand it with

    "     "     "            of D3 to + of C7 & R14.

The latter is OK, first sentence is somehow wrong.

Voltage at cathode of D3 is 6.33v   [all tests with battery voltage].

Too small yet.

There is continuity of D2 to + of C4 & anode of D3.
    "     "     "            of D3 to + of C7 & R14.
    "      "       "         of C7 to ground
U1- -pin 8 is battery voltage & has continuity to anode of D2 & + of C3
        pin 3 & 6 have continuity to ground.  [at PCB]
        pin 2 - 10 ohms to - of C4 & to + of C5
Continuity of C6+  to ground
       "         of C4+  to cathode of D2 & anode of D3.

OK

        pin 4  - NO CONTINUITY - of C5
        pin 5 - continuity to - of  C6 &  3K ohms to cathode of D1.

Here we can find 2 problems.
1. pin 4 must have connectivity to to the minus of C5 - so check solder joints, maybe (taking into account eyelets) broken traces...
2. 3kOhm from pin 5 to the cathode of D1 is also wrong. R15 is right value (10 Ohm)? Is there continuity from pin 5 to the left side (according to the schematic) of R15? ... from the right side of R15 to the cathode of D1?

  ... a diode fell off my Cornet2 phono  [yes, I soldered it] ????

Sorry, I didn't understand this!