Yorkville AP3000 Power Amp

[opacheco]

Hi again!

In my repair process I have found some burned parts that I have  replaced but I read in the manual this note:

"If the wave form is distorted or non- existent, or there
is DC OFFSET, do not attempt to connect any M1002 module to the M1011 or you will immediately destroy
the new or repaired M1002 and will also cause more damage to the rest of the amplifier."

SEE THE SERVICE MANUAL HERE:

https://www.nodevice.com/service-manuals/audio/yorkville/ap3000-1/454806

I have measured the TEST POINT 5 Voltage (referred to ground) and TEST POINT 6 Voltage (referred to ground) in the M1011 Preamp Output Board and I got a 105 VDC in both places. This look like OFFSET VOLTAGE to me but I am not sure if I am doing something wrong with my measurements because I have disconnected the M1002 Power Amp Board only without any  "PATCH PLUGS" !!......by the way what this means??

My question is: if the LDRV and RDRV output coming from the M1011 boards  coming from a COMPLEMENTARY TRANSISTORS SYMMETRY PAIR; What Voltage must be hope to get there in the "quiescent point" without any applied AC  signal to the input connectors??

Thanks anticipated for any help!
opacheco.

 

[JohnRoberts]

If I am reading the schematic correctly test point 5 should be around -15V  (but image is not very clear).

Test point 6 maybe +55V??

The rail voltage is 100V so you shouldn't get 105 in either place.

Have you confirmed that none of the top NPN power devices MJ15022 (Q13, Q15, Q17, Q19) are shorted collector to emitter?

JR

 

[opacheco]

If I am reading the schematic correctly test point 5 should be around -15V  (but image is not very clear).

Test point 6 maybe +55V??

The rail voltage is 100V so you shouldn't get 105 in either place.

Have you confirmed that none of the top NPN power devices MJ15022 (Q13, Q15, Q17, Q19) are shorted collector to emitter?

JR

Dear JR,

I did several check for that transistors (the power transistors on the M1002 board !) and they look like ok!....But remember I have DISCONNECTED THE M1002 POWER OUTPUT BOARDS. I have connected the M1011 PREAMP BOARD ONLY. By the way I checked the Transistors on the M1011 too (Q12, Q13, Q14, Q15, Q16, Q17, Q18, Q19) and they are ok. Be sure the I am talking about the transistors on the PREAMP BOARD M1011.

Please if you read the note in the lower center of the M1011 schematic you find a note for TO TEST THIS M1011 PCB WITHOUT THE M1002 POWER OUTPUT MODULES BOARDS CONNECTED; but I don't understand so well.

Do I need to  install a "PATCH PLUGS" first in order to get a really real or correct voltage in TESTS 5 and 6 Points??.....By the way, what "PATCH PLUGS" means exactelly?

Please download the schematic for HI RES pdf image in the link or send me your email in a PM in order to sen it to you directly.

Thanks again for your help!
opacheco.

 

[opacheco]

Someone have an idea?

opacheco.

 

[scott2000]

Is there a specific reason you trying to operate or test it without everything connected?

Seems like you have to be extra careful when trying to test things separately???

 

[opacheco]

Is there a specific reason you trying to operate or test it without everything connected?

Seems like you have to be extra careful when trying to test things separately???

Scott2000,
Thabks fpr your notes.

Yes , the principal reason is the power amps sections were burned and I bought this unit in order to repair. I changed all the burned parts(a lots parts by the way!) and I don’t want to damage the parts again according to the aclaración in the  preamp schematic :

"If the wave form is distorted or non- existent, or there
is DC OFFSET, do not attempt to connect any M1002 module to the M1011 or you will immediately destroy
the new or repaired M1002 and will also cause more damage to the rest of the amplifier."

This is the procedure in order to check the preamp Q point in order to be sure about its state without damage the power amps sections.

The parts aren’t cheap parts and this will be the final of this happens again!

opacheco.

 

[scott2000]

Right...

I think it seems riskier to try doing things like powering up without  the M1002 boards when you aren't sure of how that is done by making sure to connect the patches correctly.... But I understand.... You want to make sure....


It is extremely important that you never power up an AP3000 with the interconnecting cables between the circuit
boards not connected.
Time and possible further damage will be reduced if you test M1011 and M1002 boards separately. To do this you
must use the M1011 and M1002 test connecters. These are shown in figures #5 and #6. These can be made if the
Molex connector parts are available or order them from the Yorkville Service Parts Dept. With the test connectors
connected to every board, slowly variac up the line AC voltage.
NOTE: It may be simplier to remove the power supply connections to M1002 boards not being troubleshooted to
reduce the possibility of further damage. With the M1011 test connector connected, a sinewave can be passed
through the board and be seen on test points 5 and 6. With the M1002 test connector installed, static DC
measurements can be made. A slight DC offset may be present on the board?s output as there will not be any DC
correcting feedback.


It says Figure 5 in the manual has the test connector drawing for the two different boards..... Maybe it'll help make more sense when you look at that???

 

[opacheco]

Right...

I think it seems riskier to try doing things like powering up without  the M1002 boards when you aren't sure of how that is done by making sure to connect the patches correctly.... But I understand.... You want to make sure....


It is extremely important that you never power up an AP3000 with the interconnecting cables between the circuit
boards not connected.
Time and possible further damage will be reduced if you test M1011 and M1002 boards separately. To do this you
must use the M1011 and M1002 test connecters. These are shown in figures #5 and #6. These can be made if the
Molex connector parts are available or order them from the Yorkville Service Parts Dept. With the test connectors
connected to every board, slowly variac up the line AC voltage.
NOTE: It may be simplier to remove the power supply connections to M1002 boards not being troubleshooted to
reduce the possibility of further damage. With the M1011 test connector connected, a sinewave can be passed
through the board and be seen on test points 5 and 6. With the M1002 test connector installed, static DC
measurements can be made. A slight DC offset may be present on the board?s output as there will not be any DC
correcting feedback.


It says Figure 5 in the manual has the test connector drawing for the two different boards..... Maybe it'll help make more sense when you look at that???

Scott2000,
Great!.....Let me to test following these notes(crossing fingers!) but remember: I am looking for DC OFFSET in these 5 and 6 test points in the preamp board because the DC OFFSET can damage the power amp section at all.

The millions question is, What must be the correct DC voltage in these points (5 and 6) when the "PATCH PLUGS" are conected??...I won't able to connect the power amp sections without be sure of that!

Thanks a lot,
opacheco.

 

[scott2000]

it mentions a sine wave at 5 and 6????

I'm guessing it's saying no dc offset is good????

 

[opacheco]

it mentions a sine wave at 5 and 6????

I'm guessing it's saying no dc offset is good????

I think so but I would like to Ben sure of this......I suppose the complementary pair Q18 and Q19 allow any dc voltage in the 5 and 6 tests points  BUT I AM NOT SURE AT ALL!!

opacheco

 

[scott2000]

Me neither yet.... It seems like you're wanting to get readings from one board before connecting the other but, the readings you seem to want are only possible once you connect the other......???

Sorry for not being able to help more....

The very first section in the manual has a quick operation detail that may be helpful to understand how the boards interact????

 

[opacheco]

Me neither yet.... It seems like you're wanting to get readings from one board before connecting the other but, the readings you seem to want are only possible once you connect the other......???

Sorry for not being able to help more....

The very first section in the manual has a quick operation detail that may be helpful to understand how the boards interact????

The first of the manual is very instructive but unfortunately don’t say the info that I am look for !

Thanks anyway

 

[scott2000]

What are you looking for and what is the set up you are using?

I'm thinking that, depending on how you have the unit connected up in pieces, you can't expect certain readings to be available.

So, you have to definitely follow the manual for these steps or possibly create some more problems...

 

[opacheco]

What are you looking for and what is the set up you are using?

I'm thinking that, depending on how you have the unit connected up in pieces, you can't expect certain readings to be available.

So, you have to definitely follow the manual for these steps or possibly create some more problems...

That simple!!....I am looking for DC Quiest Points  Test(verification  voltage!) Voltages, in order to verify the state of the stage amp sections for don’t  damage the other sections with bad DC polarization voltages.

opacheco