TESORO GOLDEN SABRE

[simonbaker]

Ultimate_Haze:

Thanks for pics.

1. Are you triggering on TX only, or both signals of dual trace? It is important to trigger on TX only so we can see phase relationship.

2. Would you please provide descriptions for each picture, what each trace is and what volts/div for each trace is?

There should be four pictures, outputs of U101a, U101b, U102a, U102b. Each one should also have TX signal as one trace.


The trace with all the jaggies looks like output of U101b. But the phase does not make sense to me, unless you are triggering on both input signals.

Is it possible you connected the TX signal to the + (non-inverting) input of U101b (disc op amp) instead of the - (inverting) input by mistake? That might also explain it.

-SB

[porkluvr]

If that jittery waveform is from the LF353 pin-7, you should probably use a lower value of feedback resistance in the DISC circuit. Remember that the original TGS had a 10k notch pot in parallel with DISC. (That is, 10k according to the only schematic I have available, right or wrong.) Higher feedback resistance increases the chance of amplifier instability, and makes it more noticeable when it does occur. Removing the parallel notch pot without adding a "filler" increases that resistance from the original design value.

Another possibility is to add a small value capacitor in parallel with the feedback. It will have some affect on the overall phase relationship setup, but you might not notice and be able to ignore it. Look at the Bandito schematic to see what I mean.

If you have instability that just won't go away, try using lower feedback resistance AND adding about 5~10pF.

Changing the DISC pot to 10k (or adding a 10k parallel resistor (will have neglegable effect on the range of the DISC pot, however the slope of the control may be different, judging from my virtual testing.

[Ultimate_Haze]

TX -5V/div in all pic.s
1.TX_VS_U101 pin1/5V
2.U101 pin1 only
3.TX_VS_U101 pin7/0.1V
4.U101 pin7 only
5.TX_VS_U102 pin1/2V
6.U102 pin1 only
7.TX_VS_U103 pin7/2V
8.U102 pin7 only

[Ultimate_Haze]

I have check all several times.Couldn't find mistake.Measure all that I could.
And everything seams to be ok.
So this morning I have found that when bought 10p and 15p caps the seller have give me 10n and 15n.Damn stupid guy.
Now after replacing I have both chanels working.And sens increce.Still too low.But this is maybe up to coil.
Now I will clean PCB again and will try to make new coil.
I wonder could this mismatch made some harm to other components?


p.s. porkluvr the schematic and PCB are working OK.I were searching for mistake the I have made!Anyway thanks for attention.

[simonbaker]

I have check all several times.Couldn't find mistake.Measure all that I could.
And everything seams to be ok.
So this morning I have found that when bought 10p and 15p caps the seller have give me 10n and 15n.Damn stupid guy.
Now after replacing I have both chanels working.And sens increce.Still too low.But this is maybe up to coil.
Now I will clean PCB again and will try to make new coil.
I wonder could this mismatch made some harm to other components?


p.s. porkluvr the schematic and PCB are working OK.I were searching for mistake the I have made!Anyway thanks for attention.

That is good you found capacitor errors. Would you make new picture of TX signal vs output of U101a pin 7 (RX preamp) with corrected capacitor? The other outputs probably not affected, although all-metal JFet gate signal would be fixed too.

Can you tell us the model of your oscilloscope and maybe a link to specs or manual? Just to make sure you are triggering on TX only? I think you probably are, but need to make sure.

The disc signal with all the oscillations looks bad but even Molzar's original TGS had some of that, so I don't know how important it is to clean up -- I do it anyway in my circuits using a different circuit than porkluvr. But I think many people have good TGSL even with such oscillations!

I agree at this point the coil is probably the important factor. Those pesky coils....!

-SB

[simonbaker]

Ultimate_Haze:

It does take persistence to find subtle problems. If anyone thinks this is thread clutter, we can start a new thread for troubleshooting individual's MD problems.

I suggested new pictures of U101 pin 7 because that would be affected by wrong capacitors you discovered.

However, if oscilloscope was set wrong (trigger or vertical mode), you can take new pictures of other outputs also. As we discussed, I recommend trigger on TX channel, and use ALT mode.

Here are some more oscilloscope traces that would be useful -- each compared to the TX signal as before (dual trace):

1a. gate of JFet TR4 (disc detector) ,disc mode, with disc pot to left.

1b. gate of JFet TR4 (disc detector), disc mode, with disc pot to right.

1c. gate of JFet TR4 (disc detector), all metal mode, GB pot to left.(if signal disappears, back off a little)

1d. gate of JFet TR4 (disc detector), all metal mode, GB pot to right.(if signal disappears, back off a little)

2a. gate of JFet TR5 (GB detector) with GB pot to left. (if signal disappears, back off a little)

2b. gate of JFet TR5 (GB detector) with GB pot to right. (if signal disappears, back off a little)

Regards,

-SB

P.S. If you have more than one TGSL circuit, it is very helpful for troubleshooting to compare them.

[simonbaker]

Ultimate_Haze: What kind of digital camera do you have? It may be better to take a little further away for better focus -- and/or use tripod for steadier pictures, to make sharper. And/or use "close-up / macro" setting if you have one.

Regards,

-SB

[Ultimate_Haze]

Sorry that it took me so long.Hope this pictures are better.
Yes I have other device that is almost OK.
You want me to scope same points?

[simonbaker]

Pictures are much better. Will take a little while to study.

TX signal missing on some. Was it there when you took picture but camera shutter missed sweep?

You can compare phase differences of your good circuit with the troubled one using same traces as in pictures. They should be about the same. If not, then we look further.

I assume coil works much better on the other circuit?

Regards,

-SB

[Ultimate_Haze]

Hello,
Simonbaker.
TX signal missing on some. Was it there when you took picture but camera shutter missed sweep?
No just took another extra picture only for wave on ch2.To be seen more clear.
You can compare phase differences of your good circuit with the troubled one using same traces as in pictures. They should be about the same. If not, then we look further.
I have looked some they are not the same.Unles from what I saw.
I assume coil works much better on the other circuit?
Yes almost double sens for same coin.

[Ultimate_Haze]

Here is the rest.
Now I will make pictures of the other device.

[erolunall]

Hello


Coil calibration video on youtube for tesoro

http://www.youtube.com/watch?v=eay0HUSB26M

Best Wishes
Erol

[simonbaker]

Here is the rest.
Now I will make pictures of the other device.

Pictures are good. TX frequency looks OK.

Now we need to compare with same signals on "good" PCB -- let us know what is different. I am trying to find time to compare with my circuits. I hope others can help too.

Regards,

-SB

[Pompey]

Hello,everybody!I made TGSL -Complete details by Qiaozhi.I have a question : What voltage must be there at the ends of TX ,measured with multimeter in AC range?

[simonbaker]

Hello,everybody!I made TGSL -Complete details by Qiaozhi.I have a question : What voltage must be there at the ends of TX ,measured with multimeter in AC range?

Multimeters are all different when measuring AC at different frequencies. Some are rated to 400 Hz, some to 5000 Hz, some to 15000 Hz, etc. Oscilloscope is most reliable for measuring voltage at TX frequency (approx 14.5 kHz).

TX voltage across leads to coil should be around 12 to 16 volts peak-to-peak I would say. Some circuits have a JFet in the oscillator circuit for feedback control; the TX voltage is less usually, maybe 8 to 12 volts PP.

-SB