18Watt.com

I have a 36W prototype of a Tremolo TMB Xtra on my bench, so I used that for the following comparison. All tests are with the probe ground connected to the output jack ground wire.

Scope direct to AWG: Input jack (004): V2P2 (005): .0047 to 56k and 220uF in tone stack (007): Treble P2 / Volume P1 (009): Volume P2 (008): PI P1 (anode): Output jack:

foreverstrung wrote: ↑

Fri 01/06/23 2:10 pm

Also, set your bandwidth limit on the channel you are using to 20M.

How do I do this?
Thx

Anything to do with adjusting a channel, you click the channel button, and look at the options that pop up on the screen. Bandwidth should be one of them. It probably says "BW Limit" - set that to 20M.

IDK what "probe direct to AWG is". Please advise.
I set BW to 20M max
With my MM and amp still off, input jack securely in place, I get 72 ohms resistance at the input jack tip.
I've got the ground on the probe always to the output jack ground bar onl
The following screenshots have all the knobs up to 50% except for Reverb which is at 0
Input V2P2
0047 to 56k/220uF @ TS Treb P2/Vol P1 Vol P2 PI(V4) P1
Output

foreverstrung wrote: ↑

Fri 01/06/23 3:18 pm

IDK what "probe direct to AWG is". Please advise.
I set BW to 20M max
With my MM and amp still off, input jack securely in place, I get 72 ohms resistance at the input jack tip.
I've got the ground on the probe always to the output jack ground bar onl
The following screenshots have all the knobs up to 50% except for Reverb which is at 0

AWG = Arbitrary Waveform Generator. The Signal Generator.

You're connecting ground to your input jack, not your output jack. This is from the image you sent me:

You're connecting ground to your input jack, not your output jack. This is from the image you sent me

No. I'm not. That pic is from a couple days ago. Then, yes I did, but you directed me to use the ground on the output jack today, which I did for everyone of those last screenshots

foreverstrung wrote: ↑

Fri 01/06/23 4:55 pm

You're connecting ground to your input jack, not your output jack. This is from the image you sent me

No. I'm not. That pic is from a couple days ago. Then, yes I did, but you directed me to use the ground on the output jack today, which I did for everyone of those last screenshots

Ok, cool. Measure the resistance of the resistor on the input jack. It should be 1M.

Measure the resistance of the resistor on the input jack. It should be 1M.

Yes. 1.003 M resistance

Ok then. I have no idea what you've got going on at your input jack that you can't probe there. It looks like it's grounded out. But if you probe at V1P2, it looks normal, correct? V2P2 is the only one that really looks normal.

Hit your Measure button and get us some info on there. RMS, pk to pk, etc.

It looks like it's grounded out. But if you probe at V1P2, it looks normal, correct?

No. It does not look good. It looks the same as directly at the input jack.

V2P2 is the only one that really looks normal.

Yes. That is correct

I have no idea what you've got going on at your input jack that you can't probe there. It looks like it's grounded out.

Agreed. IDK what's up with this input jack. I've redone it now totally 3 times. All new components everytime. This appears to be biggest hurdle for me getting this thing dialed in.

Hit your Measure button and get us some info on there. RMS, pk to pk, etc.

Please clarify what your asking me here. I understand hitting the measure and getting a screen shot. Just what of please.

foreverstrung wrote: ↑

Fri 01/06/23 6:56 pm

Agreed. IDK what's up with this input jack. I've redone it now totally 3 times. All new components everytime. This appears to be biggest hurdle for me getting this thing dialed in.

Post a photo of your input jack from multiple angles. Remove it from the chassis first so it can be seen clearly. Then reinstall it, and take some photos where it can be seen, hopefully also with the wire to ground.

I doubt this input jack thing is related to your reverb thing, but we'll see what happens as we move through the circuit.

Also make sure all your pots are tightly fastened to the chassis.

That's about as good as I can get these pics. Open to suggestions for better pic taking and posting

Hit your Measure button and get us some info on there. RMS, pk to pk, etc.

Please clarify what your asking me here. I understand hitting the measure and getting a screen shot. What and where would you like me to get screen shots with measurements?
Thx

These pics might be better. Shows ground wires in the background

foreverstrung wrote: ↑

Fri 01/06/23 7:21 pm

That's about as good as I can get these pics. Open to suggestions for better pic taking and posting

Hit your Measure button and get us some info on there. RMS, pk to pk, etc.

Please clarify what your asking me here. I understand hitting the measure and getting a screen shot. What and where would you like me to get screen shots with measurements?
Thx

You press the Print button to make screenshots. The Measure button adds information to the screen. To a look at this clip for an example of what I mean: https://youtu.be/HI7DGjgl2tw?t=103

When you press the Measure button, select the following (and make sure you're selecting it for your active channel): Pk-Pk, Ampl, RMS, Mean. If trying by my description doesn't work, please refer to the instruction manual.

Try removing V1, and probing at the jack again. Make sure the signal generator is active. Try 300mA amplitude on the generator. The amp doesn't need to be on for this jack test.

Thanks,
Josh

You press the Print button to make screenshots. The Measure button adds information to the screen. To a look at this clip for an example of what I mean: https://youtu.be/HI7DGjgl2tw?t=103

Yes. I understand this. My question is, where am I "probing" when I hit the measure button?

When you press the Measure button, select the following (and make sure you're selecting it for your active channel): Pk-Pk, Ampl, RMS, Mean. If trying by my description doesn't work, please refer to the instruction manual.

At every one of the 7 screenshots/points I posted earlier or just the input jack?

OK. So here's a couple scope screenshots. Both have the V1 tube removed. Probe ground is on the output jack busbar/ground. (not input jack). The amp is off. I set the audio generator to 300mV. (I switched to #1 port, probe is set to 10x, not 1x) Here is the measurement page Should I post screenshots of the measurements of all the points we've gone through tonight?

foreverstrung wrote: ↑

Fri 01/06/23 10:39 pm

OK. So here's a couple scope screenshots. Both have the V1 tube removed. Probe ground is on the output jack busbar/ground. (not input jack). The amp is off. I set the audio generator to 300mV. (I switched to #1 port, probe is set to 10x, not 1x)
SDS00029.png
Here is the measurement page
SDS00030.png
Should I post screenshots of the measurements of all the points we've gone through tonight?

No, let's focus on the jack first. Also, change your Measure settings so it shows just the ones I mentioned at the bottom. You need to hit the back button after pressing autoset for it to show everything correctly.

I wonder if there's something wonky with your shielded input wire. Try raising it off the chassis, and see if that changes anything. If not, disconnect it from the terminal strip, and connect the probe to it while floating.

OK. Power is still off. V1 is still removed. Probe is in the exact same points. Audio gen is set just as it was, so is the scope, but I'm not even getting close to the same reading on the scope I specifically chose PK-PK, Ampl, Mean and RMS in the measurement page. This scope reading as I just described above is wonky, active. I took 2 screenshots of the measurements as they were changing quickly as this reading was active I hope I'm being thorough. I'm doing my best to post the info as I get it as accurately as possible. I don't want to waste anyones time.
I moved the shielding wire. No change. I disconnected the terminal strip with no change at all.

Post high resolution photos of your build. Also post photos of your testing setup with the amp off, but the scope and signal generator active. Post a photo of the signal generator screen as well.

OK, so here's a pic of the signal generator. Plugged into and on channel 2 This is the wave pattern on the scope And then this is the set up. Probe ground is on input jack busbar ground. Probe itself is on the input jack. (I get the exact wave pattern at the shielded wire @ the terminal strip, (Connected and disconnected from chassis. Same both ways). In the background we can see the AWG and scope.