Wanted Please. Decant PI board to replace the One in This enclosure.

[kt315]

i told many times modern chinese 1N4148 do not keep 100mA current. in DP they stay in power line. i changed them in my design on 1N4004.

[keith777]

dbanner.

.

[keith777]

dbanner said....This is easy fix. Or send board to me.

well if you are serious about it and willing to. then i will take you up on it........

[kt315]

In your case, replacing chips is easy, just remove them from sockets. No problem.

i got a board in repair. whole board was in sockets. i found THREE chips bad. so sockets do not give nothing.

[dbanner]

i got a board in repair. whole board was in sockets. i found THREE chips bad. so sockets do not give nothing.

My geotechenglish is bad. It is easy to change/replace chips when sockets are installed on PCB. There, that should suffice.

[dbanner]

well if you are serious about it and willing to. then i will take you up on it........

I was not really serious. You can fix this board easily. Believe in yourself. You do not need scope or LC meter, just a regular multimeter would suffice. Step by step, methodically. Check semiconductors(diodes and transistors) easy to check, no problem. Then check integrity of solder joints, correct parts placement, hookup wires etc. Then remove and replace all chips, one by one. See what I mean. Logical and methodical. Do what kt315 said, replace 1N4148 diodes. Build correct coil. I am sure it will work.

[dbanner]

From what you stated earlier, you were getting poor detection depth. That's good news because it means that the thing is alive and kicking. Try replacing preamp chip, then work your way down the signal path, changing out the chips. I suspect your preamp chip is the culprit. That LF357 has many fake chips on the market.

[dbanner]

One would think that the seller should at least have the boards tested before shipping. Whatever happened to quality control?

[dbanner]

Have a look at my Delta board. It's crazy, but it works. It was a labour of love. Never again will my love be so strong

[kt315]

i think there is a control. but those people do not want to learn the forum. there are nuances i told 1000th times about.
for example look on pics of dp in #11 post. the pots are not shielded. etcetera etcetera.... the people are like blind squireel - they look on pics but do not notice nothing.

[dbanner]

You can know very little about electronics, and build any project you want. Think of Japanese lady on assembly line in old time Sony TV factory. She probably didn't even know ohms law but she had the skills with hands. Skills are just as important as knowledge, one for builders the other for designers.

[dbanner]

Yes, you must pay close attention to details. Look and observe closely, the answers can be found without asking many questions but by "seeing". The devil is in the details.

[dbanner]

I just remembered, make damping tool so you can vary value of damping resistance. It can be found here on forum. Very simple to construct. This will help you adjust the coil to optimize performance.

[kt315]

i do albums not for mine just i do not need in the albums. i do for beginners. this pic shows sure how to shield the pots.

http://www.geotech1.com/forums/album...chmentid=40275

[dbanner]

Yes, very good. Although the outer casing of pot is isolated from internals, they should be shielded I think, connected to virtual ground? Or battery? Not sure, will have to look at schematic.