Peavey Valve King Schematic question.

[served]

Hi.

I am currently looking at Peavey Valve King schematic. Its available here: http://dl.dropbox.com/u/15231310/Valveking112%20Schematic.pdf

I have the same amp. And A problem.

On the schematic Relay S103 is not turning off and is always on.

First I thought that there is something wrong. But now if I saw the schematic, then it seems to me that there was a problem from the beginning.

Could some one please take a look at the schematic and tell me what do you think about it.
The section is on the 9th page. Where the Remote switch breakaway is.

If I measure the voltage then i get 20V on the SK103. Its all pretty weird. As there is nothing that would disconnect power from SK103.

Any ideas how this system has to work?

I would really appreciate if some one would take a look.

A.

[Johan]

I only had a quick look, but it appear the footswiches for Channel and gain boost only work when the front panel switches are in a certain position. I'm guessing the "in" position, but thats just a guess.
what exactly is your problem?..
J

[served]

The problem is that if I connect the Footswitch the Led Stays ON. No matter what I press. And Boost Volume switch doesn't have any effect. I made some measurements and the switch seems to be working. But the relay will not make a switch. If I measured the voltage on Relay. I got constant 20V reading. No matter what switch I press or unpress.

[served]

So the problem is. Why the Relay is always powered on?

Its On from the moment I turn on the Amp and turns Off if I power the Amp off.

And, I cant seem to understand. What should turn it on or off?

From the Scheme:  S102(8,7,9) will not affect Relay. The + is always on relays legs (for 101 102,103) The - for 101 and 102 is controlled By CH switch.
But for 103 the - is always present. No matter what I switch.

That is really irritating. I hope I got it all wrong.

[Govmnt_Lacky]

I have this amp. I do not know about the Peavey footswitch however, I built my own 2 stomp footswitch a long time ago. As I remember it, one of the stomps would not work UNLESS the switch was activated on the amp itself. You might have to experiment but I think it is designed this way.

[Govmnt_Lacky]

This is a cut and paste directly from the Valveking 100/112/212 users manual:

"FOOTSWITCH JACK
Provided for the connection of the optional footswitch (item #00579720). The footswitch is used to select
the Lead or Clean channels and to activate/defeat the BOOST SWITCHES (#8 & #9) within the Lead
channel. LED's on the footswitch illuminate to indicate current settings. The footswitch turns on and
off either one or both Boost functions (Gain and Volume) as selected by the front panel switches. If no
switch is depressed in the Boost section, the Boost footswitch does not function. When using the footswitch,
always insert the plug fully (second click) into the FOOTSWITCH JACK to ensure proper operation."

[served]

I will describe the problem

I have a ValveKing VK100. If I press down Channel Select Switch from the front panel. I get no sound. Then I have to press Gain switch A little bit, but not to the end and I get distorted sound. If I press GAIN to the bottom, I get no change in sound.

So why doesn't it make a sound when I press CH switch. Why do I have to press the Gain switch to get any sound.

Boost Volume switch doesn't have any effect. And I am not talking about footswitches here.

I can assume that the Bushbutton switches are broken, but I measured them and they seems to be working.

I will desolder the switch and have a closer look.


The part why I asked about footswithes and stuff was that I could not understand how the relay 103 is controlled. So I am sorry if I confused you.

[served]

So I took the switch off the board. And it works, no problem there. But where could the problem be then?
I allready replaced the relay. The old one was a bit weird. It held contacts connected too long. It took about 2 sec to release the contacts, with new relay it doesn't take time.

I was thinking maybe there is a problem with MAC97 of Q101. But if Mac is faulty, then other relays wont work either.

Its pretty confusing.

The Switch I desoldered is S102

I am starting to think that maybe other relays are not working. So I will make some measurements.

[Johan]

does the switches work when no footswitch is attached?....
..whenever there is multiple faults developing at once, look for what they have in common...it could be something like the ground to the footswitch jack, or the cable going to the footswitch jack from the main PCB.

[served]

It doesnt work with the footswitch and without.

I realized that the problem is present if I connected the footswitch and Boost LED was always on. No matter what I did.

[Johan]

It doesnt work with the footswitch and without.

then I would look around the footswitch jack and break away pcb.  the jack is a switch jack shorting the tip and ring to ground when nothing is pluggen in. if the solder joints to the jack is bad: no switching. if the caples going to the break waya pcb is bad: no switching.  if the jack itself is bad: no switching..either of those faults would seem more likely to me than three different relays going bad at the same time
J

[served]

I checked SK101 SK102 Off the board and tested them. Also tested S101. They are Ok and working.
I replaced the Footswitch Jack with New one.

I will check the cables and other stuff. Hope to find something.

[served]

What is the purpose of R170 on the remote board, if the jack is connected with the chasis?

[served]

Still no results.

But some notes.

If I turn the Amp on and all the switches are off.

I press down Bright: no change in sound.
I press down CH switch: Volume is controlled By the Clean Channel Volume knob, but it should be controlled by Lead Channel Knob. (sound is quieter than be fore)
I touch a bit Gain switch not to the bottom, And it goes Gainy and distorted.
I push down the button and no change.
Vol boost works as it should.

Now I disengage CH switch and it takes time, about 3 sec to slowly fade to clean channel.
If i de press the Gain, I hear silent distorted playing on the background.

I re checked the Footswitch firing and so on. Its good. With this experiment, no external devices was used, only the amp itself.

I have a feeling that SK103 is getting its power somewhere, so it doesnt have a OFF state, its some where between and then ON.

Any ideas?


ADD: If no buttons are pressed, I get a reading on SK103, its 4.7V. This should not be happening. With Gain pushed, I will get 15.6V

[Johan]

the way I see it is the Relay's allways get +14volt on the top side(pin-1). the other end of the relay coil gets switched between "ground" and "no ground" state. with no footswitch in the jack, the switchjack provides the ground through R170 and you use the panel switches for the switching. with footswitch in the jack the tip and ring should be "grounded" or "not-grounded" by the footswiches and you should be able to read 14volt or 0volt on the respective tip and ring connector when pushing the footswiches. however, the front panel switches override the functions of the footswitch...it would be soo much easier if I had a tubeking here to measure on myself, but I still think the problem is somewhere around the break away pcb or the jack

[PRR]

The SK103 circuit goes round and round. But it does not go through any switches. It DOES go through the jack and pedal.



With no pedal, SK103 SHOULD be ON all the time.

Get a bare-naked stereo (tip ring sleeve) plug. Or a 1/4 wood stick. Shove it in the pedal jack. SK103 should clack OFF.

Possible faults:

Damaged switch-contacts inside switch jack: high abuse area.

Short in breakaway jumper P302 P312.

Other shorts to ground near jumper or jack.

> What is the purpose of R170

Breaks-up ground loop which might add audible hum/buzz/radio. May blow-open in massive mis-connect. No real effect on pedal. Your observations prove R170 is not blown-open, so not a problem.

[served]

Now I looked at it differently, as I become to understand it more and more. Thanks to you guys!


I insereted stereo 3.5mm to 6.3mm adaptpr to footswitch jack. Readings are measured on SK103

With jack inserter, I get 0V reading on Relay. BUT: romiving the adaptor (3.55to6.3) gives 5.01V reading.

With Jack and Gain pushed I get 12.9V reading. BUT: adaptor disconnected, I get 16V reading.

So Its goot that the area has closed in to one relay and focused on small part of the schematic. I will have a look, what I can find.

ADD: If I measure resistance. Adaptor connected to footswitch socet. I get reading from Relay - leg to R170, its 1.13k
If footswitch jack is not mounted I get 0 resitance. So this chain should be ok? Or 1.13k reading is still too small and I should get infinite reading?

And another funny thing is that if I measure the resistance between Relay + leg to the same spot on R170. I get smaller reading (ca 400 Ohm) and that is not acceptable.

[served]

So. Still, no go. Just cant understand what is going on. Its just frustrating.

Would TR105 have something to do with it?

SK103 is still getting ca5V when it should actually be OFF. If Remote Switch socket has the 6.3mm stereo plug inserted, SK103 will engage if I press the Gain button, but it should actually stay OFF, because no GND should be present. So I am starting to think that there is something seriously wrong with the amp. Relays are working. Switches are working but not controlling the damn thing correctly.

[Johan]

follow PRR's drawing above...pin 1 should ALWAYS be at 14volts. pin 8 should ALWAYS be at 0 volt if nothing is plugged into the footswitch jack, and alternating between 14 and 0 volt when you use/ push the footswitch

do you have 14 volt at pin 1?...is it fluctuating?.
what pin is at 5volt sometimes and 15 sometimes?...

[Ice-9]

The texture control looks interesting, from a quick look at the schematic that "texture" control looks to me as if its changing the balance of the phase splitter. could it be changing the symmetry of the signal ?