Help with mpp rev d

[Ogoun]

Hy, ordered the complete mpp package and im stuck now. Everything worked fine but now i get strange readings at tp3. Im at step 7. had a bad solder at r10 if this caused the error. But rechecked and resoldered everything
http://i68.tinypic.com/2ujqkgl.jpg

[geoscash1]

Can you post a pic, just used the advanced feature and attach to the post. the link you posted does not work without users registering.

[raygdunn]

Hi Ogoun,

You will need to Click on 'Go Advanced' after clicking on 'Reply'. This then gives you the option to add attachments.

Ray

[Ogoun]

Sorry.
Hope it works now.

[geoscash1]

post a pic of the board, close up and clear, both sides. Also, a bit better pic of the scope settings. Cant read what the settings are in the pic posted.

[Ogoun]

Wrong coil connection. Guess i fixed it. But cant hear any coil ringing with earplugs.
timing photos will follow shortly

top view
bot view
dampening resistor div .2 / 50us / x10

tp3 div.2 / 10 us / x10

[Ogoun]

tp1 and u2-pin2

u2 probe top .5 ampdiv / .1 timediv
tp1 bot .5 / .1
both x10
line is channel b

should be diffrent.

[geoscash1]

What are the 3 wires going to the power (red/blk/wht)? should be only batt+ to middle pin and - or batt neg to one or the other outer solder lugs. Also (sounds like you may have found or fixed it already) the coil wiring doesn't look right in the pic.

Also, Looks like R13 and R14 need to be re-soldered, along with D3 and the dampening resistor, the solder pads don't look like they have a good meld to them.

Try setting your scope to 2v div and 20us with probe on x1. Use the x10 when scoping the dampening resistor for the flyback test (350v+) so make sure to use the x10 for that.

Look and read through some of the posts in these 2 threads (links below), they may help you out. I am a rookie but after messing with this board twice, then trouble shooting and fixing, this board has become a very good learning tool. there is plenty of helpful comments and scope shots in both threads below to help.

My second go around with minipulse plus
http://www.geotech1.com/forums/showt...uild-2-Started

KRinAZ's thread (good info)
http://www.geotech1.com/forums/showt...-build-the-MPP

[Ogoun]

Thx for the tipps.
Read both threads and now everything to step 5 looks great.
Sodacan gives me nice voltage drop.
Im pretty sure i messed up the whole search coil thingy.
Followed the instructions in the chance coil thread and connected it via double shielded coax cable (3€ / m wtf!)
Pics will follow soonish.
Im happy

[Ogoun]

Its alive!
Just finished my mpp and works like a charme.
still need some fine tuning and better coil.
12cm for 4cm metal plate

[geoscash1]

Awesome, nice job. Glad the links were a bit of help. What is the inductance of your coil? Its a bit hard to see in the pic but it looks like it may need a few more winds to reach the correct inductance, you should try for 300uH or just above, seems to be the best performing wise (between 300 and 350).

Anyway, glad to see you got it working.

[Ogoun]

The links Helped a lot. Cant measure inductance at The Moment.
its Build like described in chance Pi coil thread. Modified windings to fit my .5mm coated wire. Teflon coated 700v is on its way

[Ogoun]

Finally i finished my mpp.

coil is 320uh at 2ohm.
Put a trimmer in series and its just above ringing.
delay is set to 14us.
but the detection depth ....
like 10cm with a golden ring.
exspexted a little more.
Ill get my teflon wire next week. Was the last time i ordered from china
any suggestions how to increase the depth?

[baum7154]

Hi Ogoun,
Your trimmer should not be in series with the coil but should be across it in parallel. 10 cm is definitely not enough for a gold ring and an 8" 3DSS coil.

Regards,

Dan

[Ogoun]

Tx ...Rx....Grnd
|____| ......|
|...............|
|--trimmer--|
|................|
| ...............|
to coil To coil


this way?

Some idea what went wrong? broken ic?
will post some pics of TP measurements tonight.
thx in advance