Barracuda Legend Kit Problems

[Old cart]

ok i have just tried an air test with a gold ring and i get a positive 6" BEEP then after that it is faint but i still cannot move it around, i have the delay trim set at 10k ohms and the delay trim pot at full (10k ohm)

old cart i do not have a 1uf cap that i can solder to pins 7 and 14

Actually I meant .1 uF. Do you have any caps laying around? .1 -22 uF will do.
Monitor the same two test points decrease the delay pot ( the one set to full)until the signals ( pulse part not the spurious signal) changes shape or gets smaller, then retest in air.

[Old cart]

can i buy one of yours it works better

Just what I was going to suggest. It appears KT315 has used some caps to eliminate noise that causes the spurious signals we talked about. Also he may have a better layout. I do not know if he sells kits though.

[Impulse]

ok i have a 4.7uF 40v cap i can take off an old board i have in front of me will that do?

[raygdunn]

Baracuda 40106 glitches

ok i have CUT the link and put the 10k pot in its place

here [ATTACH]35414[/ATTACH]

Hi Impulse,

Wow that did the trick and now your trace looks like mine. I thought mine was faulty, with those extra glitches, but there they are again.


I've tried Old cart's suggestion of a 104 capacitor between the power pins to no avail and then confirmed all power lines looks stable. I've actually ordered more chips on the basis that I've damaged the chip and there is some internal cross feed... Noew I'm not so sure. :-)

Ray

[Old cart]

ok i have a 4.7uF 40v cap i can take off an old board i have in front of me will that do?

mismit polarized (does it have +/-"marks) if so put measure the voltage acros pins 14 and 7. Connect the plus side of cap to the MORE positive voltage . If it is not polarized either way is ok. Either way keep the leads short.

[Impulse]

Hi Impulse,

Wow that did the trick and now your trace looks like mine. I thought mine was faulty, with those extra glitches, but there they are again.
[ATTACH]35416[/ATTACH]

I've tried Old cart's suggestion of a 104 capacitor between the power pins to no avail and then confirmed all power lines looks stable. I've actually ordered more chips on the basis that I've damaged the chip and there is some internal cross feed... Noew I'm not so sure. :-)

Ray

I thought i was the only ONE! Do you have the movement issue?

[Impulse]

mismit polarized (does it have +/-"marks) if so put measure the voltage acros pins 14 and 7. Connect the plus side of cap to the MORE positive voltage . If it is not polarized either way is ok. Either way keep the leads short.

Old cart it is polerized i will try it and see what happens.

[raygdunn]

I thought i was the only ONE! Do you have the movement issue?

Hi Impulse,

If you refer to adjusting the Delay on the sampling pulse, that work fine for me. (I have the extra 10K pot to play with, but that just makes fine tuning easier)

I am finding real problems getting my coil far enough away from metal and other interference. It causes that rising decay slope to move to the right (so delay needs adjusting). It disappears completely off the 'scope scale, when an inch from desk metal. Never seen that before. It appears to be purely coil orientation rather than wires from PCB. Hmm remind me the PI-1 was detecting the metal log fireplace three feet away. Perhaps it was there and I didn't monitor it.

Ray

[Impulse]

no i mean i cannot physically move it around if i move it BEEPBEEPBEEP i do not understand why? what wire are you using between the coil and board? i have a dual core foil covered + sheilded cable.

[Old cart]

Ray for big metal these things need to be feet away to not be affected. Many PI's are so sensitive to metal and electrical interference that they can no be accurately tested indoors. I try to keep my coils at least three feet away from everything when testing. I also find that slight changes in the location of the coil can make a big difference. Beak in mind that at least here in the US floors are often constructed with nails or rebar. Both are iron and PI's are VERY sensitive to iron.

Let us know how your 40106 change out experience goes. Are you using real 40106s or Chinese knock offs?

There are several things that could cause crosstalk:

1. Defective chips
2. Flux on board
3. Capacitive coupling due to poor trace routing.
4. Inductive coupling due to poor trace or wiring routing.
5. Power supply bypassing due to inadequate decoupling caps on the board

Figuring which one or ones is causing the problems is sometime tough. You just have to attack them one at a time.
Replacing chips is easy as is cleaning the board.
Power supply bypassing is easy to check you just look for low noise on the individual supply pins. This can hard to do, particularly using cheap scopes and probes which are often noisy.

The coupling ones are perhaps the hardest to find and resolve. Sometimes reroute get wiring can help , sometimes the board must be relaid out.
It does appear the KT315 has this sorted.

[Old cart]

All 5? or the last one?

also the delay trim has a slight affect in terms of amplitude not relative time or position

and by calibrator signal you mean the scope signal?

here [ATTACH]35377[/ATTACH]

you should run scope cal, one of the traces is not the right amplitude.

[Old cart]

Hey guys sorry I haven't replied for a while my laptop has died (blue screen off death) I am using my phone for now so I cannot use my oscope till its fixed I am going to shorten the lead it is just over 1m it is a dual core shielded cable with a foil wrap should I swap it for coax?

on second thought this dual core coax probably has high capacitance. Swap it for coax as soon as you can.

[Old cart]

Maybe something like this
http://www.parts-express.com/visaton...6-ohm--292-540
These are Chinese, you should be able to get them in UK.

Impulse you might try disconnecting the buzzer. Maybe it is causing interference. Then repeat the pin 2-4 test.

[Old cart]

5534 pin6 [ATTACH]35412[/ATTACH]

try adjusting you offset. The trace marker for ch1 should align
With the flat part of the waveform.

[Old cart]

ok i have resurrected the old board and it has the same issue with a different coil? 11.4v batt volts. i will go back to the board that we have been working on and desolder the 330ohm balance resistor then take 5534 pin 3 and 6

here
[ATTACH]35392[/ATTACH]
[ATTACH]35393[/ATTACH]

impulse were these taken with the old or new board?