Need Help with this Circuit Please

[keeney123]

Re: Need Help with this Circuit Please

Sounds like the disconnect relays at the speaker would the the easiest way. Or maybe if the unit has a switch to go from internal to external speakers one could just switch it before turning off. However, the safest way would be to figure out why the reverb board is causing the problem. It would almost be worth it to build a circuit that turns on the individual board and plug-ins in a certain sequence. You can also put a fuse inline with the speakers to make sure the current will not exceed its rated value. That way the output circuits will be protected.

[tfs2015]

Re: Need Help with this Circuit Please

Ok, there are no protection relays connected to the speaker outputs on this unit. I disconnected CN6 which is the input from the mixer board to the power amp section and guess what, no squeal or pop coming from the speakers so what does that mean?

[budm]

Re: Need Help with this Circuit Please

Ok, there are no protection relays connected to the speaker outputs on this unit. I disconnected CN6 which is the input from the mixer board to the power amp section and guess what, no squeal or pop coming from the speakers so what does that mean?

OK, I am confused, in post 114:"Ok when I turn the power switch on both the mixer and the power amp receive power at the same time,"
How did you turn OFF the power switch to the MIXER, the Mixer board with CN6 has its own Power switch? And how about the Reverb unit, is it an Outboard Reverb unit?
May be you draw up the signal chains on how you have all the equipment hooked up.

[ben7]

Re: Need Help with this Circuit Please

I know I'm responding to an old post, (well from a few months ago) but this is the reason why you DON'T depend circuits from the internet, especially if the source is questionable.

I've previously done a whole explanation/rant of how bad the circuits can be, especially on
"electronics-diy.com"
and
"circuitdiagram.net"
(There are more as well)

The circuits are poorly designed, and are even poorly drawn (sometimes hand drawn with a computer mouse ... ugh!).
Don't be fooled thinking that you can get off easy with a "simple" circuit, as these "simple" circuits aren't as simple as you may think

-Ben

[keeney123]

Re: Need Help with this Circuit Please

Ok, there are no protection relays connected to the speaker outputs on this unit. I disconnected CN6 which is the input from the mixer board to the power amp section and guess what, no squeal or pop coming from the speakers so what does that mean?

So one could put in protections relays to the speakers I believe. And Yes, do as BudM said to draw how the amp is connected to the instruments/devices and what are the settings.

[budm]

Re: Need Help with this Circuit Please

There are many speaker protection board on EBAY.
http://www.ebay.com/itm/2-8-ohm-2-ch...8AAOSw9mFWHgvk

Or you can build one.
https://cdn.badcaps-static.com/pdfs/...1120d30991.pdf

[tfs2015]

Re: Need Help with this Circuit Please

the SMPS on this unit supplies power to the mixer circuit board, amp circuit board and the reverb circuit board. The SMPS turns on when you turn the power switch on. If you unplug CN6 from the amp board which is the input from the mixer board there would be no input from the mixer to the power amp board. The mixer also sends line level signals to the SEND outputs of the PA system. Please see this manual from a better explanation.

[budm]

Re: Need Help with this Circuit Please

the SMPS on this unit supplies power to the mixer circuit board, amp circuit board and the reverb circuit board. The SMPS turns on when you turn the power switch on. If you unplug CN6 from the amp board which is the input from the mixer board there would be no input from the mixer to the power amp board. The mixer also sends line level signals to the SEND outputs of the PA system. Please see this manual from a better explanation.

Well what you said here about power switch on the mixer, which mixer are you talking about and where is that POWER SWITCH for the mixer, you make it sound like there are TWO POWER SWITCHES!

Manual does not show separate power switch for the mxier section and the power amp section.
Your post 114:"Ok when I turn the power switch on both the mixer and the power amp receive power at the same time,"

[keeney123]

Re: Need Help with this Circuit Please

the SMPS on this unit supplies power to the mixer circuit board, amp circuit board and the reverb circuit board. The SMPS turns on when you turn the power switch on. If you unplug CN6 from the amp board which is the input from the mixer board there would be no input from the mixer to the power amp board. The mixer also sends line level signals to the SEND outputs of the PA system. Please see this manual from a better explanation.

We need a simple block diagram of the set up with the setting of the switches in each case and a brief description of what you are doing in reference to your diagram. You can do this with the paint program on windows and save it as a picture. You can hand draw the diagram and scan your drawing with a scanner/copier and save it as a picture or PFD. Then just upload the image.

[tfs2015]

Re: Need Help with this Circuit Please

Look at the manual it shows the block diagram, and a schematic for each section of the PA System

[tfs2015]

Re: Need Help with this Circuit Please

One power switch....the main one. The Mixer section is a board that contains all of the controls for the PA System its self. The power amp is another board that is part of the system as well. It is physically mounted to the heat sink as well as the power supply. Now back to the power switch. It has line voltage 115 VAC going thought it. When you turn that switch on the SMPS turns on and sends 15 VDC to the mixer to power the op amps and reverb board. 51vdc is sent to the Amplifier section to power it.

[budm]

Re: Need Help with this Circuit Please

OK, I re-read you post 114 again and understand what you said now, I was confused and the thread is getting long.
I look at the service manual looking to see if the unit does have some kind of MUTING control, sure enough in the Theory of operation on page 6, there is MUTING FET Q201.
So you need to read that page and check out that MUTING circuit.

[keeney123]

Re: Need Help with this Circuit Please

Thanks for the help BudM.
tsf2015 when one does not have the device right in front of them it is hard to visualize. It is often best to picture yourself as not having seen anything of the set up and going by online schematics that are broken up page by page. Put yourself in that position and then ask yourself how can I understand what is going on. So, your last post was very direct and clear and BudM gave you a direct clear answer. You need to check out the muting circuit and see if it is working properly as described in the Theory of Operation.

[tfs2015]

Re: Need Help with this Circuit Please

OK, I re-read you post 114 again and understand what you said now, I was confused and the thread is getting long.
I look at the service manual looking to see if the unit does have some kind of MUTING control, sure enough in the Theory of operation on page 6, there is MUTING FET Q201.
So you need to read that page and check out that MUTING circuit.

How do I check out this muting circuit? Thank you for your help and I apologize if you were confused by that previous post. I am still kind of new at posting my exact problem(s) on this forum.

Thanks
Tom S.

[keeney123]

Re: Need Help with this Circuit Please

I guess I would first check if these values are in your board. This is on page 7 of manual.
Stereo Power Amplifier circuit values for Z201, and R206 have been changed from 4.7V to 6.8V and 10K to 1K
respectively after the first 100 sets production. These changes improve turn off transient pop noise. Please update
early sets if returned for service.
Digital Reverb circuit value for VR401 is a fixed resistor with a value of 18K. This resistor controls the reverberation

[tfs2015]

Re: Need Help with this Circuit Please

Z201 was installed when I first got this unit over a year ago, and I have already replaced R206. Should I disconnect one end of Z201 to see if that helps? I am reading about to 3vdc through the speaker outputs (speakers disconnected of course).

Thanks
Tom

[keeney123]

Re: Need Help with this Circuit Please

Z201 was installed when I first got this unit over a year ago, and I have already replaced R206. Should I disconnect one end of Z201 to see if that helps? I am reading about to 3vdc through the speaker outputs (speakers disconnected of course).

Thanks
Tom

So lets stay focused on the mute circuit on power up and power down. You most likely do not have and O-scope with storage. We need to start to measure components related to this circuit. I think BudM wanted you to ohm out this circuit. It would be interesting to take a measurement on the zener diode in this circuit to seen if it is dropping 6.8 volts DC across it, you can do this after it is turned on. There is also a 1uf cap that can also get measure. This cap needs to be out of the circuit to measure it. If you had a storage O-scope you could connect to the output of the FET and turn on the power then measure when it is being turned on, that is in reference to time. I will look up the FET to try and figure the best way to test it out. Most likely it is working otherwise the unit would not be on.

[tfs2015]

Re: Need Help with this Circuit Please

the 112Jfet's are working because they are brand new I just put them in a couple weeks ago.

[keeney123]

Re: Need Help with this Circuit Please

I can not find Z201 on the schematic can you ohm this out to find what it is connected to?

[tfs2015]

Re: Need Help with this Circuit Please

I can not find Z201 on the schematic can you ohm this out to find what it is connected to?

You are right it is not in the schematic just in the parts list. One end connects to R206 the other end connects to q209