[x] Welcome at THunting.com!

A fun place to talk about Metal Detecting, Treasure Hunting & Prospecting. Here you can share finds and experience with thousands of members from all over the world

Join us and Register Now - Its FREE & EASY

THunting.com
Treasure Hunting & Metal Detecting Community
   
Advanced Search
*
Welcome, Guest! Please login or register HERE - It is FREE and easy.
Only registered users can post and view images on our message boards.
Did you miss your activation email?

Login with email, password and session length
Or Login Using Social Network Account
2
News:
Pages: 1    Go Down
Print
Share this topic on FacebookShare this topic on Del.icio.usShare this topic on DiggShare this topic on RedditShare this topic on Twitter
Tags:
0 Members and 1 Guest are viewing this topic.
Offline DAVIDNJTopic starter
Pull Tab
*

Join Date: Apr, 2011
Thank you0

Activity
0%

United States
Posts: 6
Referrals: 0

25.00 Gold
View Inventory

Awards

compass goldstar200, liberty150,homebrew BFO
« on: April 28, 2011, 11:27:47 am »
Go Up Go Down
 [wise]First let me thank everyone for a warm welcome to a new member! I can't even begin to troubleshoot my defective LF930D with the entire circuit board encased with a hard rubbery resin on both sides , it would take forever trying to peel it off with a razor knife.Should I trying to soften it with a hair dryer or just forget the thing? Even if I do get the board clean I still lack a schematic but with only 3 ic's&5 transistors it would be possible.The coil checks ok ,at least with a meter ,the tuner just won't work. Thanks for any help.
       DAVIDNJ

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg166714.html#msg166714

Logged
Offline Eugene52
M.D. Electronic Builders Club
Moderator
Gold Member
*****

Mood:Happy
Happy

M.D. Electronic Builders Club
Join Date: Dec, 2008
Thank you398

Activity
0%
Male
United States
Posts: 2630
Referrals: 0

17957.00 Gold
View Inventory

Awards

Teknetics , Fisher , Discovery3300 and TIANXUN 19 kHz VLF Metal Detector
« Reply #1 on: April 28, 2011, 01:06:48 pm »
Go Up Go Down
Quote:Posted by DAVIDNJ
[wise]First let me thank everyone for a warm welcome to a new member! I can't even begin to troubleshoot my defective LF930D with the entire circuit board encased with a hard rubbery resin on both sides , it would take forever trying to peel it off with a razor knife.Should I trying to soften it with a hair dryer or just forget the thing? Even if I do get the board clean I still lack a schematic but with only 3 ic's&5 transistors it would be possible.The coil checks ok ,at least with a meter ,the tuner just won't work. Thanks for any help.
       DAVIDNJ


Not an easy task , but it can be done if your careful . One method is using a heat gun [200 F. maximum]
And the other method is research a chemical called Dynasolve . Jasco makes a epoxy and paint thinner . 3M has something out also .

Years ago I removed a hard blue epoxy from a video decoder box by just carefully chipping away with an exact-o knife after heating it up . Just try not to get the circuit board too hot , and also be extremely careful with chemicals [keep good ventilation in your work area "Fans running" ] . I have done both black and blue epoxy removal with good success . You will be successful , if you take your time .

Others are welcome to comment here on this topic !!

Regards.........Eugene

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg166741.html#msg166741


There are 1 attachment(s) in this post which you can not view or download

Please register for viewing them.

Jasco paste.jpg

« Last Edit: April 28, 2011, 01:18:06 pm by Eugene52 » 		Logged
Let's Talk Treasure right here on Thunting.com
Offline DAVIDNJTopic starter
Pull Tab
*

Join Date: Apr, 2011
Thank you0

Activity
0%

United States
Posts: 6
Referrals: 0

25.00 Gold
View Inventory

Awards

compass goldstar200, liberty150,homebrew BFO
« Reply #2 on: April 28, 2011, 04:55:04 pm »
Go Up Go Down
EUGENE: Thanks for the advice, I will try the heating method if that doesn't work I have other detectors to waste time on.
       Best regards....DAVIDNJ

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg166791.html#msg166791

Logged
Offline Eugene52
M.D. Electronic Builders Club
Moderator
Gold Member
*****

Mood:Happy
Happy

M.D. Electronic Builders Club
Join Date: Dec, 2008
Thank you398

Activity
0%
Male
United States
Posts: 2630
Referrals: 0

17957.00 Gold
View Inventory

Awards

Teknetics , Fisher , Discovery3300 and TIANXUN 19 kHz VLF Metal Detector
« Reply #3 on: May 10, 2011, 04:17:43 pm »
Go Up Go Down
Quote:Posted by DAVIDNJ
EUGENE: Thanks for the advice, I will try the heating method if that doesn't work I have other detectors to waste time on.
       Best regards....DAVIDNJ


Hello David . Keep us posted on your progress !! After you break the epoxy off , post a pcb "circuit board" photo if you can . The low frequency [VLF] Fisher metal detectors are definitely becoming a collectors item now , information is becoming scarce . The Vintage metal detector site may have something on the LF930D but I have not checked yet .
I also posted some old Fisher schematics in the Download area today . The Fisher LF990D is the closest schematic I can find to yours . You might check to see if there are similarities to your LF930D model .

HH................Eugene

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg170543.html#msg170543

Logged
Let's Talk Treasure right here on Thunting.com
Offline DAVIDNJTopic starter
Pull Tab
*

Join Date: Apr, 2011
Thank you0

Activity
0%

United States
Posts: 6
Referrals: 0

25.00 Gold
View Inventory

Awards

compass goldstar200, liberty150,homebrew BFO
« Reply #4 on: May 11, 2011, 05:36:14 pm »
Go Up Go Down
HI EUGENE: Had no luck removing the mess from the board,just made it a little softer and the board so hot I didn't want to continue lest I destroy whatever chips and caps are underneath. I may use the case for a Classic 3 that I may build from scratch using the Greek schematic on GEOTECH from Kardista.Parts and Whites coil should be around $200 and I hope it beats my Compass Liberty150 that air tests a dime at 9" and the same if I bury it in the yard,the only mods. done were more transmit power via lower collector resistor and a few chip changes. I just turned 68 and this will probably be my last major project....radio,audio and md,ing. Will keep you posted on my progress!
 REGARDS.....DAVIDNJ

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg170895.html#msg170895

Logged
Offline Eugene52
M.D. Electronic Builders Club
Moderator
Gold Member
*****

Mood:Happy
Happy

M.D. Electronic Builders Club
Join Date: Dec, 2008
Thank you398

Activity
0%
Male
United States
Posts: 2630
Referrals: 0

17957.00 Gold
View Inventory

Awards

Teknetics , Fisher , Discovery3300 and TIANXUN 19 kHz VLF Metal Detector
« Reply #5 on: May 19, 2011, 09:34:52 am »
Go Up Go Down
Quote:Posted by DAVIDNJ
HI EUGENE: Had no luck removing the mess from the board,just made it a little softer and the board so hot I didn't want to continue lest I destroy whatever chips and caps are underneath. I may use the case for a Classic 3 that I may build from scratch using the Greek schematic on GEOTECH from Kardista.Parts and Whites coil should be around $200 and I hope it beats my Compass Liberty150 that air tests a dime at 9" and the same if I bury it in the yard,the only mods. done were more transmit power via lower collector resistor and a few chip changes. I just turned 68 and this will probably be my last major project....radio,audio and md,ing. Will keep you posted on my progress!
 REGARDS.....DAVIDNJ


Hello David . I will look for the Geotech posting from Kardista . I do not remember that schematic off hand ? For $200 in parts , it better be a great machine !!
When your 80 years old you will tell us your on your last project !!! 

Best Regards...........Eugene

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg174662.html#msg174662

Logged
Let's Talk Treasure right here on Thunting.com
Offline DAVIDNJTopic starter
Pull Tab
*

Join Date: Apr, 2011
Thank you0

Activity
0%

United States
Posts: 6
Referrals: 0

25.00 Gold
View Inventory

Awards

compass goldstar200, liberty150,homebrew BFO
« Reply #6 on: May 19, 2011, 03:38:20 pm »
Go Up Go Down
HI EUGENE: As you know I gave up trying to get the board cleaned of epoxy to troubleshoot,but I did find the coil is operating at 19.5khz and is center tapped rx & tx.Looking at a lot of schematics the old Bounty Hunter 840 uses the same configuration and was a very hot machine,I may breadboard the ckt. and let it operate around 20khz and try to get discriminate to operate in GEB . Another thought would be to build the Silver sabre ckt. per the Geo forum and try my Compass coil on it (13.77khz.)
 I go from ham radio to building tube audio amp. and back to hacking md's.WhenI was last involved with detectors there was no internet,you got most of your info from treasure mags.,needless to say I am overwelmed with information...so much so that I may just build the Mytey myte and forget all this other stuff ,just kidding even though that cheap detector went deep. Life is GREAT!
                                        BEST REGARDS..DAVIDNJ

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg174795.html#msg174795

Logged
Offline gambol1
Silver Member
*

At first we were all hunters
Join Date: Jan, 2010
Thank you0

Activity
0%
Male
United States
Posts: 919
Referrals: 0

4800.00 Gold
View Inventory

Awards

Garrett 150, 250,Fisher F75S, Tesoro sand shark
« Reply #7 on: May 19, 2011, 07:37:27 pm »
Go Up Go Down
DavidNJ, You got that board cleaned yet? There is something called M-Pyrol that dissolves epoxy. Soak your board in it for an hour and if it is epoxy it will soften it enough you can cut it off with a knife. Soak it too long and it will dissolve the chip cases too.
What I do when I have a difficult problem like that is get out the old dremel tool with a thin cut off blade and a small screwdriver. I make cross hatch cuts over the surface and then stick the point of the screwdriver in the cuts and chip out the pieces. This will get the big stuff if its hard plastic. Dremel tools are good for so many things. gambol

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,23235.msg174899.html#msg174899

Logged
Print
Pages: 1    Go Up
Jump to:  

Powered by SMF 1.1.19 | SMF © 2005, Simple Machines | Sitemap
Copyright THunting.com