Build Your Own Clone Message Board

Kieth gave ma some suggestions about resistor values r28 r29 and r34
As well as the 2 closest caps. The resistor values all tested correctly with
A meter and I checked the color bands under a microscope. Removed the
the mids pot to reflow the solder on all the parts he said to check and
Re soldered the mids pot but I still have the near dead spot. Has anyone
Else experienced this? Any suggestions on where and what to check next
Would be appreciated.

When you say dead spot, do you mean the pot has no effect in that range, or that the mids go dead in that range?

_________________
Scott

My band, Austin Hollow

It's not uncommon for tone controls to have "dead spot" near the midpoint where the pot has little apparent effect (the Tube Sceamer circuit is infamous for this), but I have no idea if the CJ mids control would behave this way. I'll leave that one to Keith or Nick to answer....

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

The signal all but dies between 1 and 3 o'clock. I don't get strong signal
Again until it's fully turned clockwise or from 12 o'clock down.

That sounds like a bad pot. When the pot is dialed to that dead spot, try measuring the resistance between the middle leg and each of the other legs, and also between the middle leg and ground.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I'll try that thanks

I get about 90 Kohms at the dead spot between middle and right
leg with the pedal upside down. When I take the reading while strumming
the signal gets strong when I touch the legs with the multi meter
probes. I get 14 Kohms between center and left leg.

You need to check resistance with the pedal power off. If the pedal has power on, it will interfere with the ohmmeter function in the multimeter.

its still tests at 90 Kohms and about 14 Kohms on the other leg. The pot gets readings across it's entire range
that go incrementally up as you turn from zero to the other end fully clockwise. I'm kind of at a loss. If it was
the pot I would have expected some sort of drop out at the 1-3 o'clock range.

Strange. I'll ask Keith to weigh in on this.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

It sounds like you are saying that the whole guitar signal goes away, not just the midrange, is that right?

Other than the problem around the "dead spot" does the midrange tone control seem to work as it should? The frequency pot changes the frequency and the Q switch changes the bandwidth of the midrange EQ?

Perhaps there is a partial short inside the pot from the wiper to the pot case, which is grounded when the pot is installed in the case. If that were a happening, it could short out some of the signals going in and out of IC5a when you hit the dead spot area.

The Q switch works the frequency pot works but now that you put it that way its hard to say. Most of the travel on the pot above the 12 o'clock position kills the signal so tough to tell for sure. Para metric eq's usually produce fairly dramatic differences in tone and I can't say that I've heard dramatic differences.

If might help if you could describe in different words what "kills the signal" means. Does it mean that all sound goes way down in volume? or only the midrange frequencies? Something else?

I'm trying to understand if it the problem is only affecting frequencies the tone control should be adjusting, or if it affects all frequencies. It kind of sounds like "kills the signal" is intended to mean that all frequencies, not just midrange frequencies drop in volume?

However, to avoid further delays talking about the signal, it might be useful to turn the pot with the power off, and measure from the wiper to ground. if the resistance to ground drops a lot in the "kills the signal" part of pot rotation, the pot must have an internal short circuit to its case. At least, that would seem to be suggested.

This is exactly what I was getting at with my request to check for resistance/continuity between ground and the pot wiper when the pot is in this dead zone.


This is certainly true of the CJ when it's working correctly. The Mids pot has a huge effect on the mid-range content of the output.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Keith isn't available today but will check in on this tomorrow...

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Sorry I should have answered better in my last post the volume drops down to almost not audible so yes I guess that would mean all frequencies.
When I test the wiper to ground should I just ground to the negative power lead?

Ground one lead of your multimeter to the Crown Jewel case and touch the other lead the pot wiper (middle lug). Nine volt power to the Crown Jewel should be disconnected while you measure resistance.

Ok I get 108 Kohms middle wiper to case. Check tracings going into
IC 5 A all had continuity. Frequency selector is definitely changing
Frequencies. Question about the mids control is 12 o'clock the neutral
Position meaning anything clockwise is going to increase the selected
Frequency and anything counter clockwise decrease the volume of the
selected frequency?

Yes.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Pics please.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

this pic was taken after I remove and re soldered the mid pot

Here's the rest of the board hard to get good shots of it the first pic was done with a the microscope
camera I used to verify the resistors before building. Let me know if I should take some with the case off and
the module out.

Most mutimeters use a pretty low voltage to measure resistance in order to avoid biasing on any semiconductor junctions in the circuit. If you look at the CJ schematic around the pot, there is no DC path to ground as the pot is only connected to capacitors and and op-amps. You should get a very high reading unless perhaps you have a leaky or still charged up electrolytic capacitor. If the resistance reading were affected by a charged capacitor, reversing the meter leads should show a different reading, perhaps creeping up or down. Also, if the pot is intermittently shorted to the case, as you turn the wiper the resistance to ground should change noticeably as the wiper passes through the area where the sound goes dead. So, it would be helpful to have resistance readings from each end of the pot to ground, and from the wiper to ground as the pot is turned. If the pot wiper is in an area where the sound doesn't go dead, the resistance to ground should be pretty high, higher than 108k.

Also, from your photos its not clear how far the pot leads are sticking out of the circuit board. It's good to have the pot body with good clearance from the circuit board so that the case can't accidentally touch any part of the board.

In addition, to avoid a lot of further head scratching it might be worth just changing the pot to see what happens.

It is possible to make troubleshooting into a science project using your sound card as an oscilloscope, but most problems can be solved without resorting to that. Its more something to consider doing if you are interested in learning how to troubleshoot that way.

I've ordered a new pot for the price it's the simplest way to start.
I'm hoping that's all it is. I've ordered a signal tester as well.

Center Sweep leg goes from 108 Kohms to 110 when grounded to the case.
Right leg looking at the pedal upside down 109Kohms to 152
Left leg looking at the pedal upside down 109 Kohms to 200 at the
Center point then Jumps to .8 M ohms. Not sure what that means
but it doesn't sound normal.