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Non-working Compass Yukon 71B

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Non-working Compass Yukon 71B

James31
I have an old non-working Compass Yukon 71B that I just picked up.  When I turn it on it just gives a steady tone and the needle pegs all the way over to the right.  Adjusting the coarse tuning does nothing.  Battery check works properly.

I opened it up and I checked for broken wires etc. and it looks OK.  I suspect a problem with the board.

Does anyone have a schematic for the Compass 71B?

The IC's on the board inside have the numbers filed off.  There are 2 8 pin DIPs and 2 8-pin can ICs.  Typical 70's copy protection.

I have a schematic for a Compass 77B and it is probably similar to the 71B.  The 77B schematic that I have is hand-drawn and it is hard to read.  According to the schematic, it looks like IC1 is a 741, IC3 and IC4 are 1458's.  I can't tell what IC2 is.  It looks like 1?8?.  This is the schematic that was on the Geotech forum.  Geotech seems to be down, 404 not found.

Can anyone help with a 71B schematic or help with identifying the ICs in the 71B?
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Re: Non-working Compass Yukon 71B

Joe Ranger
..............JAMES ...............THE SMALL METERS SEEM TO HANG UP A LOT ................I have a RM6  ................................sorry don't have a copy of the schematics for the 71B............These detectors seem to be notorius for having problems due to the batteries or the battery holders or connections!!.............................JOE
COMPASS: COIN MAGNUM, JUDGE 2, XP-PRO, TESORO: TOLTEC II, BANDIDO, GARRETT: SIDEWINDER, original HUNTER, DEEPSEEKER, GROUNDHOG, GOLD HUNTER, WILSON: ATD, RANGAR.....
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Re: Non-working Compass Yukon 71B

James31
I managed to fix the problem.  The connection from the tuning control to the circuit board was bad.  It looks like something spilled on that area at some time and the socket had green corrosion on it.  I cleaned that up & sprayed some contact cleaner into the socket and it is OK now.

I replaced 2 of the battery connection wires because the 9v style connectors were worn out.  I also replaced 2 of the battery holders.  I need to find a couple of those plastic clips for the battery cover because they are broken.

I would still like to find out what the ICs are if anyone can help with that.  I traced some of the circuit and it is pretty similar to the 77B except the tuning circuit is different.  The date on the circuit board is 1973.

I have some nail-infested spots to check as soon as the snow melts, hopefully next week.
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Re: Non-working Compass Yukon 71B

Joe Ranger
...................Also these detectors are relatively cheap right now..................In fact, I just received a Compass Coin Hustler which was given to me.................I just had to pay for the shipping!!.............The Coin Hustler is very similiar to the 71B.................The Coin Hustler is a more stripped down version.............................No Meter and only one knob..............which makes it very easy and simple to use plus light weight!!............................JOE
COMPASS: COIN MAGNUM, JUDGE 2, XP-PRO, TESORO: TOLTEC II, BANDIDO, GARRETT: SIDEWINDER, original HUNTER, DEEPSEEKER, GROUNDHOG, GOLD HUNTER, WILSON: ATD, RANGAR.....
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Re: Non-working Compass Yukon 71B

tucando
In reply to this post by James31
Merry Christmas
First thing to do is change loops if you if you have another loop. It  could be that the loop has shifted and out of tune.  You can't always go by whats the number is on the IC. Compass had many  IC made and they were bogus  # so the competition would use the wrong IC and it would not work properly.
The person to have that information would be Steve Goss in Forest Grove at Compass repair. He can fix them. So you might contact him.
Hope this helps.    Merry Christmas All!
Allan Cannon
ALLAN C.
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