Synth-DIY Yahoo! Groups Archives

korg poly 800 power problem

2010-12-23 by n8

hi list.

just joined and have a question perhaps someone can chime in on...

i have a korg poly 800 mkI here on the bench with a power issue.

when on batteries it runs fine, but will not run off the wall wart...

the wall wart works ok, i tested the voltage on the dc plug and it is spitting out 13V const. I read that at the DC jack as well...

The problem so far looks like i do not get the +5V on the connector CN06A on pin 10....is that correct?

I get the pull DC in on pin 11 so that is good!

But i need to get that 5V on pin 10 so it can be sent to the chorus board, then to the volume / switch on?

from the rough schematics i see that Q1's base and collector are tied to this rail, and its emitter is tied to the DJ jack....

Q3 is E-C is on the 5V line, and its base is tied to Q2 tranny which is tied to Q15 which is tied to gnd.

Is this correct?

I assume its one of the power switching transistors are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.

I used the standard transistor PNP tester circuit, as seen here:

http://www.kpsec.freeuk.com/trancirc.htm

It seems to work fine, I can turn the led on when the switch is closed and turn it off when its open...

So i guess its ok and i should put back LOL?

Anyone know of any other transistors to check?

I am looking at Q3 for some reason....

What steps down to voltage from the DC jack in out to the +5V?

I assume once i get the +5V i will be ok...

i just keep looking at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....

Sorry for all the questions i am noob!

Cheers,

Nate

Re: korg poly 800 power problem

2010-12-27 by zoinky420

You know you could just wire the jack, or a new jack to the battery terminals.

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:
>
> hi list.
>
> just joined and have a question perhaps someone can chime in on...
>
> i have a korg poly 800 mkI here on the bench with a power issue.
>
> when on batteries it runs fine, but will not run off the wall wart...
>
> the wall wart works ok, i tested the voltage on the dc plug and it is spitting out 13V const. I read that at the DC jack as well...
>
> The problem so far looks like i do not get the +5V on the connector CN06A on pin 10....is that correct?
>
> I get the pull DC in on pin 11 so that is good!
>
> But i need to get that 5V on pin 10 so it can be sent to the chorus board, then to the volume / switch on?
>
> from the rough schematics i see that Q1's base and collector are tied to this rail, and its emitter is tied to the DJ jack....
>
> Q3 is E-C is on the 5V line, and its base is tied to Q2 tranny which is tied to Q15 which is tied to gnd.
>
> Is this correct?
>
> I assume its one of the power switching transistors are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.
>
> I used the standard transistor PNP tester circuit, as seen here:
>
> http://www.kpsec.freeuk.com/trancirc.htm
>
> It seems to work fine, I can turn the led on when the switch is closed and turn it off when its open...
>
> So i guess its ok and i should put back LOL?
>
> Anyone know of any other transistors to check?
>
> I am looking at Q3 for some reason....
>
> What steps down to voltage from the DC jack in out to the +5V?
>
> I assume once i get the +5V i will be ok...
>
> i just keep looking at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....
>
> Sorry for all the questions i am noob!
>
> Cheers,
>
> Nate
>

Re: [korgpolyex] Re: korg poly 800 power problem

2010-12-27 by Michael Hawkins

To be frank, wiring a jack to the battery terminals if done incorrectly could cause a battery explosion or fire.

So I cannot endorse that method of repair.

From: zoinky420 <zoinky420@...>
To: korgpolyex@yahoogroups.com
Sent: Sun, December 26, 2010 9:24:32 PM
Subject: [korgpolyex] Re: korg poly 800 power problem

You know you could just wire the jack, or a new jack to the battery terminals.

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:
>
> hi list.
>
> just joined and have a question perhaps someone can chime in on...
>
> i have a korg poly 800 mkI here on the bench with a power issue.
>
> when on batteries it runs fine, but will not run off the wall wart...
>
> the wall wart works ok, i tested the voltage on the dc plug and it is spitting out 13V const. I read that at the DC jack as well...
>
> The problem so far looks like i do not get the +5V on the connector CN06A on pin 10....is that correct?
>
> I get the pull DC in on pin 11 so that is good!
>
> But i need to get that 5V on pin 10 so it can be sent to the chorus board, then to the volume / switch on?
>
> from the rough schematics i see that Q1's base and collector are tied to this rail, and its emitter is tied to the DJ jack....
>
> Q3 is E-C is on the 5V line, and its base is tied to Q2 tranny which is tied to Q15 which is tied to gnd.
>
> Is this correct?
>
> I assume its one of the power switching transistors are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.
>
> I used the standard transistor PNP tester circuit, as seen here:
>
> http://www.kpsec.freeuk.com/trancirc.htm
>
> It seems to work fine, I can turn the led on when the switch is closed and turn it off when its open...
>
> So i guess its ok and i should put back LOL?
>
> Anyone know of any other transistors to check?
>
> I am looking at Q3 for some reason....
>
> What steps down to voltage from the DC jack in out to the +5V?
>
> I assume once i get the +5V i will be ok...
>
> i just keep looking at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....
>
> Sorry for all the questions i am noob!
>
> Cheers,
>
> Nate
>

Re: korg poly 800 power problem

2010-12-27 by korgpolyex800

The wall wart should be providing a consistent 9V DC output.

If you're seeing 13 volts at the input of the Poly 800 then you need to get a 9V DC wall wart. 13 volts will overload the on board power supply control circuits.

Mike

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:
>
> hi list.
>
> just joined and have a question perhaps someone can chime in on...
>
> i have a korg poly 800 mkI here on the bench with a power issue.
>
> when on batteries it runs fine, but will not run off the wall wart...
>
> the wall wart works ok, i tested the voltage on the dc plug and it is spitting out 13V const. I read that at the DC jack as well...
>
> The problem so far looks like i do not get the +5V on the connector CN06A on pin 10....is that correct?
>
> I get the pull DC in on pin 11 so that is good!
>
> But i need to get that 5V on pin 10 so it can be sent to the chorus board, then to the volume / switch on?
>
> from the rough schematics i see that Q1's base and collector are tied to this rail, and its emitter is tied to the DJ jack....
>
> Q3 is E-C is on the 5V line, and its base is tied to Q2 tranny which is tied to Q15 which is tied to gnd.
>
> Is this correct?
>
> I assume its one of the power switching transistors are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.
>
> I used the standard transistor PNP tester circuit, as seen here:
>
> http://www.kpsec.freeuk.com/trancirc.htm
>
> It seems to work fine, I can turn the led on when the switch is closed and turn it off when its open...
>
> So i guess its ok and i should put back LOL?
>
> Anyone know of any other transistors to check?
>
> I am looking at Q3 for some reason....
>
> What steps down to voltage from the DC jack in out to the +5V?
>
> I assume once i get the +5V i will be ok...
>
> i just keep looking at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....
>
> Sorry for all the questions i am noob!
>
> Cheers,
>
> Nate
>

RE: [korgpolyex] Re: korg poly 800 power problem

2010-12-27 by backshall1 (dsl)

A newer switching supply wall wart will give you a consistent 9vdc regardless of current flow, but an older one with a big transformer will be 12-13 volts when there isn't much power being used, and drop to 9v when you are using the rated current. I've used ones that measure 12-13 volts without any problems.

Don B.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of korgpolyex800
Sent: Sunday, December 26, 2010 9:58 PM
To: korgpolyex@yahoogroups.com
Subject: [korgpolyex] Re: korg poly 800 power problem

The wall wart should be providing a consistent 9V DC output.

If you're seeing 13 volts at the input of the Poly 800 then you need to get a 9V DC wall wart. 13 volts will overload the on board power supply control circuits.

Mike

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:

>
> hi list.
>
> just

joined and have a question perhaps someone can chime in on...

>
> i

have a korg poly 800 mkI here on the bench with a power issue.

>
>

when on batteries it runs fine, but will not run off the wall wart...

>
> the wall wart works ok, i tested the voltage on the dc plug and it is

spitting out 13V const. I read that at the DC jack as well...

>
>

The problem so far looks like i do not get the +5V on the connector CN06A on pin 10....is that correct?

>
> I get the pull DC in on pin 11 so that

is good!

>
> But i need to get that 5V on pin 10 so it can be sent

to the chorus board, then to the volume / switch on?

>
> from the

rough schematics i see that Q1's base and collector are tied to this rail, and its emitter is tied to the DJ jack....

>
> Q3 is E-C is on the 5V

line, and its base is tied to Q2 tranny which is tied to Q15 which is tied to gnd.

>
> Is this correct?
>
> I assume its one of the

power switching transistors are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.

>
> I used the standard transistor

PNP tester circuit, as seen here:

>
>

href="http://www.kpsec.freeuk.com/trancirc.htm">http://www.kpsec.freeuk.com/trancirc.htm

>
> It seems to work fine, I can turn the led on when the switch is closed

and turn it off when its open...

>
> So i guess its ok and i should

put back LOL?

>
> Anyone know of any other transistors to

check?

>
> I am looking at Q3 for some reason....
>
>

What steps down to voltage from the DC jack in out to the +5V?

>
>

I assume once i get the +5V i will be ok...

>
> i just keep looking

at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....

>
> Sorry for all the questions i am noob!
>
> Cheers,
>
> Nate
>

Re: korg poly 800 power problem

2010-12-27 by zoinky420

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:

>
> To be frank, wiring a jack to the battery terminals if done incorrectly could
> cause a battery explosion or fire.
>

Well a wall-wart is a more stable power source than batteries. What do you mean by 'incorrectly'?

Re: korg poly 800 power problem

2010-12-27 by zoinky420

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:

>

> So I cannot endorse that method of repair.

And what do you mean by 'endorse'? It wasn't a Hawk question, so perhaps a better word to use would have been 'recommend'.

Re: [korgpolyex] Re: korg poly 800 power problem

2010-12-27 by Michael Hawkins

the original email said that the voltage was still 13 volts while plugged in to the Poly.

From: backshall1 (dsl) <backshall1@...>
To: korgpolyex@yahoogroups.com
Sent: Sun, December 26, 2010 10:24:41 PM
Subject: RE: [korgpolyex] Re: korg poly 800 power problem

A newer switching supply wall wart will give you a consistent 9vdc regardless of current flow, but an older one with a big transformer will be 12-13 volts when there isn't much power being used, and drop to 9v when you are using the rated current. I've used ones that measure 12-13 volts without any problems.

Don B.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of korgpolyex800
Sent: Sunday, December 26, 2010 9:58 PM
To: korgpolyex@yahoogroups.com
Subject: [korgpolyex] Re: korg poly 800 power problem

The wall wart should be providing a consistent 9V DC output.

If you're seeing 13 volts at the input of the Poly 800 then you need to get a 9V DC wall wart. 13 volts will overload the on board power supply control circuits.

Mike

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:

>
> hi list.
>
> just

joined and have a question perhaps someone can chime in on...

>
> i

have a korg poly 800 mkI here on the bench with a power issue.

>
>

when on batteries it runs fine, but will not run off the wall wart...

>
> the wall wart works ok, i tested the voltage on the dc plug and it is

spitting out 13V const. I read that at the DC jack as well...

>
>

The problem so far looks like i do not get the +5V on the connector CN06A on pin 10....is that correct?

>
> I get the pull DC in on pin 11 so that

is good!

>
> But i need to get that 5V on pin 10 so it can be sent

to the chorus board, then to the volume / switch on?

>
> from the

rough schematics i see that Q1's base and collector are tied to this rail, and its emitter is tied to the DJ jack....

>
> Q3 is E-C is on the 5V

line, and its base is tied to Q2 tranny which is tied to Q15 which is tied to gnd.

>
> Is this correct?
>
> I assume its one of the

power switching transistors are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.

>
> I used the standard transistor

PNP tester circuit, as seen here:

>
> http://www.kpsec.freeuk.com/trancirc.htm
>
> It seems to work fine, I can turn the led on when the switch is closed

and turn it off when its open...

>
> So i guess its ok and i should

put back LOL?

>
> Anyone know of any other transistors to

check?

>
> I am looking at Q3 for some reason....
>
>

What steps down to voltage from the DC jack in out to the +5V?

>
>

I assume once i get the +5V i will be ok...

>
> i just keep looking

at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....

>
> Sorry for all the questions i am noob!
>
> Cheers,
>
> Nate
>

RE: [korgpolyex] Re: korg poly 800 power problem

2010-12-27 by backshall1 (dsl)

I think what Mike means here is that if you had batteries installed, and wired the A/C adapter directly to the same circuit, the higher voltage would feed back into the batteries, like an unregulated charger, and you can definitely cause a fire trying to charge non-rechargeable batteries.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of zoinky420
Sent: Monday, December 27, 2010 1:04 AM
To: korgpolyex@yahoogroups.com
Subject: [korgpolyex] Re: korg poly 800 power problem

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:

>
> To be frank,

wiring a jack to the battery terminals if done incorrectly could

> cause

a battery explosion or fire.

>

Well a wall-wart is a more stable power source than batteries. What do you mean by 'incorrectly'?

RE: [korgpolyex] Re: korg poly 800 power problem

2010-12-27 by backshall1 (dsl)

Yes, it should be lower than that if the 5V regulator section was working, so that's a pretty good indication that no power is getting through at least one of the power transistors. I'm digging out the schematic now.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of Michael Hawkins
Sent: Monday, December 27, 2010 9:36 AM
To: korgpolyex@yahoogroups.com
Subject: Re: [korgpolyex] Re: korg poly 800 power problem

the original email said that the voltage was still 13 volts while plugged in to the Poly.

From: backshall1 (dsl) <backshall1@...>
To: korgpolyex@yahoogroups.com
Sent: Sun, December 26, 2010 10:24:41 PM
Subject: RE: [korgpolyex] Re: korg poly 800 power problem

A newer switching supply wall wart will give you a consistent 9vdc regardless of current flow, but an older one with a big transformer will be 12-13 volts when there isn't much power being used, and drop to 9v when you are using the rated current. I've used ones that measure 12-13 volts without any problems.

Don B.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of korgpolyex800
Sent: Sunday, December 26, 2010 9:58 PM
To: korgpolyex@yahoogroups.com
Subject: [korgpolyex] Re: korg poly 800 power problem

The wall wart should be providing a consistent 9V DC output.

If you're seeing 13 volts at the input of the Poly 800 then you need to get a 9V DC wall wart. 13 volts will overload the on board power supply control circuits.

Mike

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:

>
> hi list.
>
>

just joined and have a question perhaps someone can chime in on...

>
> i have a korg poly 800 mkI here on the bench with a power

issue.

>
> when on batteries it runs fine, but will not run off the

wall wart...

>
> the wall wart works ok, i tested the voltage on

the dc plug and it is spitting out 13V const. I read that at the DC jack as well...

>
> The problem so far looks like i do not get the +5V on

the connector CN06A on pin 10....is that correct?

>
> I get the

pull DC in on pin 11 so that is good!

>
> But i need to get that 5V

on pin 10 so it can be sent to the chorus board, then to the volume / switch on?

>
> from the rough schematics i see that Q1's base and

collector are tied to this rail, and its emitter is tied to the DJ jack....

>
> Q3 is E-C is on the 5V line, and its base is tied to

Q2 tranny which is tied to Q15 which is tied to gnd.

>
> Is this

correct?

>
> I assume its one of the power switching transistors

are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.

>
> I used the standard transistor PNP tester circuit,

as seen here:

>
>

href="http://www.kpsec.freeuk.com/trancirc.htm" target=_blank>http://www.kpsec.freeuk.com/trancirc.htm

>
> It seems to work fine, I can turn the led on when the switch is closed

and turn it off when its open...

>
> So i guess its ok and i should

put back LOL?

>
> Anyone know of any other transistors to

check?

>
> I am looking at Q3 for some reason....
>
>

What steps down to voltage from the DC jack in out to the +5V?

>
>

I assume once i get the +5V i will be ok...

>
> i just keep looking

at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....

>
> Sorry for all the questions i am noob!
>
> Cheers,
>
>

Nate

>

RE: [korgpolyex] Re: korg poly 800 power problem

2010-12-27 by backshall1 (dsl)

Okay, time to dive into this overly-complicated 5V regulator circuit. Yes, it's a very good candidate for just unsoldering most of it and replacing it with a 7805, but somehow that just seems like cheating....

1) It's important to note that we are dealing with two different "ground" levels here. The ground from the wall wart supply is on the collector of Q1, while the ground from the batteries (also the ground for the 5V output) is on the emitter of Q1. If you can run it with batteries but not from an A/C adapter, there is a good chance that Q1 is not switching on to allow current through it. It's the negative return path for the power supply current.

2) The only thing between 6-11A and 6-10A is the power switch on the volume knob, so they should both be 12 or 13 volts when the power is switched on, using the negative terminal of the A/C adapter or collector of Q1 as a ground reference. You should get 12 volts all the way over to the emitter of Q3. On the collector of Q3 (also on 6-6A) is where the +5V should be, using the collector of Q1 or 6-7A as the ground reference.

3) The thing that switches Q1 on is the 12 volts which needs to get through D4 to the base of Q1. D4 is a 10 volt zener, so if you don't get at least 10 volts across it, it will be starved and Q1 will never switch on. If you've got 10 volts across the zener, and 13 volts from 6-10A to the collector of Q1, then it should turn on and you will only have about 1 volt across collector to emitter of Q1 (collector is the negative side). If you've got more like 13 volts from collector to emitter of Q1, then Q1 didn't turn on and is most likely bad.

4) If you don't have 13V on 6-10A then you probably forgot to turn the synth on.

5) Q18 is part of the -5V supply and it does get faily warm. The unregulated 13V is used to drive Q17 and Q18 which form an oscillator to convert it back into AC. This AC signal is stepped down through the transformer into a full-wave bridge rectifier (D8,9,10,11), then to a zener diode D7. If you have -5V at 6-8A, then Q18 is probably okay. If not, maybe Q18 is switched permanently on, or shorted inside. If you have an oscilloscope, try checking across the transformer to see if the AC signal is there. If not, try the AC range of your voltmeter across it.

Get some more voltage readings and we'll see where to go from there. If you've got a diode checker on you meter, take a look at D2 and make sure it looks good (Turn synth OFF first). Or just use the ohm-meter setting and make sure it's almost nothing in one direction and really high in the other (with the power switched off of course).

Don Backshall

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of backshall1 (dsl)
Sent: Monday, December 27, 2010 9:44 AM
To: korgpolyex@yahoogroups.com
Subject: RE: [korgpolyex] Re: korg poly 800 power problem

I think what Mike means here is that if you had batteries installed, and wired the A/C adapter directly to the same circuit, the higher voltage would feed back into the batteries, like an unregulated charger, and you can definitely cause a fire trying to charge non-rechargeable batteries.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of zoinky420
Sent: Monday, December 27, 2010 1:04 AM
To: korgpolyex@yahoogroups.com
Subject: [korgpolyex] Re: korg poly 800 power problem

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:

>
> To be frank,

wiring a jack to the battery terminals if done incorrectly could

> cause

a battery explosion or fire.

>

Well a wall-wart is a more stable power source than batteries. What do you mean by 'incorrectly'?

Re: korg poly 800 power problem

2010-12-28 by n8

Hi Mike,

Even the Korg Poly 800 OEM adapter gives out 12 volts...

Looking at the adapter, its shows it as 9V neg center 700mA 15W @ input. But when I measure the voltage it gives out 12V! But this works fine with my other Korg Poly 800. So I doubt its the power supply adapter. As long as the polarity is correct (which even if its not the D2 diode will protect the circuit from wrong polarity).
Its not the supply (though I agree seems rather high for a 9V).

One odd thing is the other wall wart supply I have, with the correct voltage and polarity, it started to heat up very hot!

Did not start a fire thank god but it too is rated at 9V, 500mA and gives out 13V!

Whats the deal with 9V giving out ~12-13V?!

I swapped out the D2 diode (not sure it was bad, my diode checker is kaput! LOL)

Found an electronics shop that has Q1, Q3 and Q16 gonna swap those out and remeasure voltages.

Right Now I am getting around 3.7 volts across EC on Q1...10V across D4 and .4V at pin 6!

aaaggggh!

Re: korg poly 800 power problem

2010-12-28 by n8

I agree Don. The power supply should be fine...thoguh something was up with the other adapter I used (one of those 7, 9 ,12 volt swtichable) with he polarity reversal switch.

At 500mA I thought it was close enough to the original 700mA one but I guess not. It became very HOT and smelled on burnt plastic! I guess something was pulling on it! Hungry machine! xp

Re: korg poly 800 power problem

2010-12-28 by n8

That is correct. 13V even when plugged into the keyboard and switched on...

It does seem to drop to 9V even when everything is connected like in normal operation....

Cheers,

Nate

Re: korg poly 800 power problem

2010-12-28 by n8

Hi Don!

I am gonna swap out Q1 and will remeasure everything to see what is happening...

You mentioned pulling stuff and swapping for a 7805?! How is that done (read backup plan here!)?

Thanks for the info...I never thought a power switched DC-DC converter circuit would be such a pain!

Re: [korgpolyex] Re: korg poly 800 power problem

2010-12-28 by Gordon JC Pearce

On Tue, 2010-12-28 at 03:46 +0000, n8 wrote:

> Hi Mike,
>
> Even the Korg Poly 800 OEM adapter gives out 12 volts...
>
> Looking at the adapter, its shows it as 9V neg center 700mA 15W @ input. But when I measure the voltage it gives out 12V! But this works fine with my other Korg Poly 800. So I doubt its the power supply adapter. As long as the polarity is correct (which even if its not the D2 diode will protect the circuit from wrong polarity).
> Its not the supply (though I agree seems rather high for a 9V).
>
> One odd thing is the other wall wart supply I have, with the correct voltage and polarity, it started to heat up very hot!
> Did not start a fire thank god but it too is rated at 9V, 500mA and gives out 13V!

That should *not* overheat when driving the Poly 800, unless there's
some horrible fault.

> Whats the deal with 9V giving out ~12-13V?!

9*sqrt(2) = 12.7V - you're reading peak not RMS voltage ;-) Under load
it will sag a bit.

> I swapped out the D2 diode (not sure it was bad, my diode checker is kaput! LOL)

And you were careful to put D2 the "wrong way", with the cathode to
positive?

> Found an electronics shop that has Q1, Q3 and Q16 gonna swap those out and remeasure voltages.
>
> Right Now I am getting around 3.7 volts across EC on Q1...10V across D4 and .4V at pin 6!

I'm not sure what you mean by "pin 6". 3.7V across Q1 emitter/collector
sounds about right. You should see roughly 9-10V across C4 and whatever
your supply voltage is across C1. If you've got 10V across D4 that
sounds about right. Q1 may be faulty.

Leave Q2 and Q16 alone - if it works off batteries there's *nothing*
wrong with the 5V supply. Don't touch it until you get the 9V regulator
working.

Gordon MM0YEQ

Re: korg poly 800 power problem

2010-12-28 by n8

"I'm not sure what you mean by "pin 6". 3.7V across Q1 emitter/collector"

On CN6A, isn't pin 6 supposed to be measured to have V>5V?

I thought that was the +5V logic?

Cheers,

Nate

Re: [korgpolyex] Re: korg poly 800 power problem

2010-12-28 by Gordon JC Pearce

On Tue, 2010-12-28 at 14:29 +0000, n8 wrote:

> "I'm not sure what you mean by "pin 6". 3.7V across Q1 emitter/collector"
>
> On CN6A, isn't pin 6 supposed to be measured to have V>5V?
>
> I thought that was the +5V logic?
>
> Cheers,
>
> Nate

No idea, I can't see that on the diagram.

Have you got the board plugged into the rest of the synth?

Gordon MM0YEQ

RE: korg poly 800 power problem

2013-12-23 by <aaron3900@...>

I don't know if the OP got an answer to his question two years ago, but does anyone know what the most common reasons are why a Poly 800 won't power up? I notice that they sell Q1, the power-supply transistor, at Syntaur, so I'm assuming that's a part that goes bad often.

I'm asking because I have a couple of Polys that won't power up.

If anyone has any insight, I'd appreciate it.

Thanks and Happy Holidays!

Aaron

Re: [korgpolyex] RE: korg poly 800 power problem

2013-12-23 by <backshall1@...>

The number one reason for not powering up is using the wrong AC adapter. It needs to be center pin negative, not center pin positive. The number two reason is probably a blown Q1 due to using the wrong AC adapter. The large diode near it (D2) is also a common problem.

Don B.

From: aaron3900@...

Sent: Monday, December 23, 2013 2:10 PM

To: korgpolyex@yahoogroups.com

Subject: [korgpolyex] RE: korg poly 800 power problem

I don't know if the OP got an answer to his question two years ago, but does anyone know what the most common reasons are why a Poly 800 won't power up? I notice that they sell Q1, the power-supply transistor, at Syntaur, so I'm assuming that's a part that goes bad often.

I'm asking because I have a couple of Polys that won't power up.

If anyone has any insight, I'd appreciate it.

Thanks and Happy Holidays!

Aaron