Boss ge 7 won't turn on

[Jun1001]

Let's take it from the very first clueless beginning..

Is, by any chance, your IN plug stereo..??
(if yes, there is no connection between jack's sleeve and ring, hence no continuity for battery negative pole..)

Does Diode's cathode (the edge with stripe) make contact with battery (+)..??
(continuity test..)

Is there power (9V) on Diode's cathode (DMM's black lead on any convenient ground)..??

1.I've connected it in the order of guitar > ge-7 > amplifier, so it's not stereo.

2.If it's done according to the picture, it seems to be connected.




3.Sorry, I don't know English well, so I don't know the meaning of conventional ground. So I tried it like a picture, but 9v didn't come out.

[GibsonGM]

I cannot see in your picture if you are on + or - at the battery. 

Be sure your black probe is on battery "-".   Place the red probe on battery "+", record the voltage. This tells you the battery is good and that you are doing this correctly.

Keeping the black probe on "-", then touch the diode with the red probe. Do you have voltage?

Tell us what the battery voltage is, and if you have voltage at the diode.  The actual voltage you read is important.

[antonis]

Sorry, I don't know English well, so I don't know the meaning of conventional ground.

Neither do I but you've mistakenly understood "conventional" instead of "convenient"..
(the later meaning any 0V/GND/Battery(-) point is closer accessible..)

[Jun1001]

I cannot see in your picture if you are on + or - at the battery. 

Be sure your black probe is on battery "-".  Place the red probe on battery "+", record the voltage. This tells you the battery is good and that you are doing this correctly.

Keeping the black probe on "-", then touch the diode with the red probe. Do you have voltage?

Tell us what the battery voltage is, and if you have voltage at the diode.  The actual voltage you read is important.

Thank you for your kind teaching
This picture shows the voltage of the battery





And this is a picture of the black probe being placed in the battery's - and the red probe being touched on the diode

[GibsonGM]

Good!     You have power to the PCB. 

Next, please try to measure the voltage at the IC's again.  Keep the black probe where it is, on "-", and use the red probe.

We would like to see 9 volts on pin 8 of the ICs. Pin 4 should have no voltage.

[Jun1001]

Good!    You have power to the PCB. 

Next, please try to measure the voltage at the IC's again.  Keep the black probe where it is, on "-", and use the red probe.

We would like to see 9 volts on pin 8 of the ICs. Pin 4 should have no voltage.

is this right?

I put the black probe on the - of the battery and measured it by putting the red probe against the pin and there is 9v on all 8 pins of the 3 ICs.

[GibsonGM]

Yes, that was correct.  Ok, I do believe that means the ICs are fried. It suggests internal shorting. Perhaps an AC power supply was used on it at one time, and ruined the ICs.  Antonis will read this and confirm if I am correct     Your model appears to have 2 "SIP" (single inline package) ICs which I assume are also damaged; I am not sure if they are easy to obtain.

You will have to decide if you have the skills and time to rebuild this - it is up to you.  It may be easier for you to just buy a replacement.

If you want to try, can you get TL022 opamps, and some IC sockets? If so, I would next carefully remove the ICs and install sockets.  They are easier to get out if you clip each leg and remove the pieces one at a time.

This does not mean the other components are OK.  I would check any electrolytic caps as well.  The switching transistors are also now suspect, but that can be worked on after.

And we don't know what those two SIP's are yet, and if the are inexpensive or not...

[Slowpoke101]

Mike, has the OP confirmed that there is continuity between the "-" of the battery and pin 4 (board ground) of any of the TL022 ICs? If there isn't continuity he will see the whole board show 9V everywhere.

[Jun1001]

Yes, that was correct.  Ok, I do believe that means the ICs are fried. It suggests internal shorting. Perhaps an AC power supply was used on it at one time, and ruined the ICs.  Antonis will read this and confirm if I am correct    Your model appears to have 2 "SIP" (single inline package) ICs which I assume are also damaged; I am not sure if they are easy to obtain.

You will have to decide if you have the skills and time to rebuild this - it is up to you.  It may be easier for you to just buy a replacement.

If you want to try, can you get TL022 opamps, and some IC sockets? If so, I would next carefully remove the ICs and install sockets.  They are easier to get out if you clip each leg and remove the pieces one at a time.

This does not mean the other components are OK.  I would check any electrolytic caps as well.  The switching transistors are also now suspect, but that can be worked on after.

And we don't know what those two SIP's are yet, and if the are inexpensive or not...

I'd like to try as far as I can.

First, 022 found two types on AliExpress, one said 022D JRC, but my IC said H027B at the bottom, unlike B005B, and the other just said 022D 0058T. These two are affordable enough for me to buy and I haven't found exactly the same model as my IC.

Next, SIP IC also found the same NJM4558LD as mine on AliExpress, but the last number seems to be different as well. SIP is a bit expensive, but it's still affordable.

And the socket has a square and a circle, so what can I buy?

It will take some time to ship, but if these two ICs are compatible, I can buy them right away

[Jun1001]

Mike, has the OP confirmed that there is continuity between the "-" of the battery and pin 4 (board ground) of any of the TL022 ICs? If there isn't continuity he will see the whole board show 9V everywhere.

Yes, I'm not sure if I tested it properly, but I measured the black by putting the battery's - the red on pin 4, and I found that there was no continuity between the two. What does this mean?

[antonis]

I measured the black by putting the battery's - the red on pin 4, and I found that there was no continuity between the two. What does this mean?

It means that you have only one of the TWO prerequisite points for a working potential difference..
(electrons are willing to flow towards the pulling point but this point doesn't practically exist on board..)

You see, power supply establishes a potential difference (voltage) across its edges (battery terminals) but one of them (-) doesn't continue its predestinated route..

[Slowpoke101]

Thank you Antonis. A very accurate explanation which highlights that my previous post didn't really help the OP very much.
 
Now to investigate further. You may have a faulty external DC power socket (doubtful) or the 1/4" input jack may be faulty so to begin with why not start checking things.

Make certain that you have a mono 1/4" plug (not stereo) inserted into the input jack.

Look at the picture below and without a battery being installed. test the continuity between the points marked 3 and 4. The picture is viewing the solder side of the circuit board.

If you have no continuity, solder a small piece of wire between these points so they are connected. Install the battery and see if the pedal now powers up.

[Jun1001]

Thank you Antonis. A very accurate explanation which highlights that my previous post didn't really help the OP very much.
 
Now to investigate further. You may have a faulty external DC power socket (doubtful) or the 1/4" input jack may be faulty so to begin with why not start checking things.

Make certain that you have a mono 1/4" plug (not stereo) inserted into the input jack.

Look at the picture below and without a battery being installed. test the continuity between the points marked 3 and 4. The picture is viewing the solder side of the circuit board.

If you have no continuity, solder a small piece of wire between these points so they are connected. Install the battery and see if the pedal now powers up.

Looking at the arrangement of the ICs, it seems to be a different form from the PCB I have

[GibsonGM]

Great points!  And why I told the OP to wait for more confirmation, ha ha.  It's not easy to relate the small steps that we automatically take to debug something like this.  Especially not knowing someone's abilities and experience level.  I don't want to see him dig into replacing the ICs without being sure there isn't an open ground somewhere.

I usually clip the 'black probe' to a known good ground and go through the board, testing for ground continuity in various locations.  Then for power.  9V on all pins, I have not seen but I do believe you, Ian.  Floating grounds can do odd things, absolutely.


Yes - I posted a schematic for reference, but Antonis pointed out that your board is different. Manufacturers sometimes alter things.  You might try to find the same board on the internet using any numbers that are on it (?)

[GibsonGM]

Why don't we check continuity of ground back to the battery instead of hunting on the PCB? 

My intent on saying "You should read nothing on the grounds of the ICs" was that we'd see tiny mV readings there, which show us continuity.   Or a simple real continuity test from ground pins to battery "-".

[antonis]

it seems to be a different form from the PCB I have

No problem..

Just locate reverse polarity protection diode (the only big black power diode on your board next to 100μF electro cap) and check continuity between its Anode (leg without stripe) and Input jack Sleeve/Ring..
(with IN plug in place, of course..)

[ElectricDruid]

Jeez, two pages in and it's not clear if we've got 9V on the board yet! 

[antonis]

Jeez, two pages in and it's not clear if we've got 9V on the board yet! 

But we DO have 9V on the board, Tom..

We just haven't GND..

[GibsonGM]

Language/experience barrier.  Check continuity between grounds from board to battery '-' and sleeves of jacks.

[Jun1001]

First of all, I'm so sorry and thank you for helping me.

Going back to the very beginning, checking to see if anything went wrong and if my input cable was stereo, I discovered that my input cable was a TRS cable. I've never imagined there would be a problem because I've been using it well connected to the BOSS GT-8. I'm really ashamed and sorry for my stupidity . In conclusion, I switched the cable and it turned on.

Additionally, When I accidentally forgot to put the plastic plate between the back plate and the PCB, it didn't make any noise, so I was able to quickly remove the battery and fix the situation, but I had a slight fever in the battery. I put in the plastic plate and replaced the battery, so it works fine now, but is there anything that just happened to permanently cause problems with the device?

Once again, thank you for helping me and trying to solve the problem