charic Posted May 14, 2008 Share Posted May 14, 2008 Just been to fit my new pre-amp. The aguilar OBP-2 into my samick 6'er. I connected it as such: Pickup 1 - Volume 1 Pickup 2 - Volume 2 Jack socket - Wire coming from bridge area which I presumed was for grounding. Now im confused coz everytime i hit a note it just buzzes. So i split the wire joining to the bridge and now it continually buzzes. Can someone PLEASE help me with this as I am now confused as hell. Im not new to electronics so i figured this would be easy enough (as it seemed) so wot the hell? Thx in advance, Rik Quote Link to comment Share on other sites More sharing options...
BigRedX Posted May 14, 2008 Share Posted May 14, 2008 I'm assuming you're using the 2 volume circuit as described on the last page of [url="http://www.aguilaramp.com/pdf/support_wiring_obp2.pdf"]this PDF from the Aguilar site[/url] Did this bass have an active circuit in before? If not you'll need a stereo jack socket so that the battery is disconnected when the bass is unplugged. Failing that can you post a clear photo of what your wiring looks like at the moment? Quote Link to comment Share on other sites More sharing options...
bass_ferret Posted May 14, 2008 Share Posted May 14, 2008 Thats why I pay someone who knows what they are doing to do it for me. Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 The stereo jack socket is supplied. I can take a pic later. Im wondering if resistors are supplied in the volume pots now :S Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 Oh and yes it was active before hand. Yep the 2 vol circuit as shown Quote Link to comment Share on other sites More sharing options...
BOD2 Posted May 15, 2008 Share Posted May 15, 2008 Always a bit tricky to debug these things. Apologies if these questions sound condescending at all..... 1. Check all the earths. The Aguilar diagram doesn't show the earth wires on the pickups themselves. These wires should go to a common earth somewhere. Note also the bass and treble controls are NOT earthed in the normal fashion (i.e. by connecting the pot shell to earth). 2. I installed an OBP-3 and found that that wiring colours on the unit were slightly different to those described in the circuit diagram. Recheck the circuit diagram to check that the coding is correct (I think I had a pink/black wire instead of a red/black wire or something like that). 3. Check the battery is ok - it probably is but never forget that check first. Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 hold on... pickup earths? :S + common earth? where should these be.. omg i think your my saviour mr penguin! Quote Link to comment Share on other sites More sharing options...
BOD2 Posted May 15, 2008 Share Posted May 15, 2008 Ok.... There should be two wires from each pickup - a "hot" and an "earth". The Aguilar diagram shows the "hot" wire connections that go to the centre contacts on each voume pot but leaves out the "earth" connections. The other wire from each pickup should be earthed. They should earth to the same point as the barrel of the jack plug socket (shown on the diagram where the black wire from the preamp goes). In practice I found it difficult to attach so many wires to a single solder tag on the jack plug so I soldered a ring ( a small metal washer really) to a piece of wire. I attached that wire to the earth of the jack socket then wrapped all the earths around the washer and soldered them together. Then wrapped the lot in insulating tape to prevent any shorts. Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 Ok then new problem.. only one wire from each pickup! Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 Oh and theyve added a wire to the jack for earthing now Quote Link to comment Share on other sites More sharing options...
BOD2 Posted May 15, 2008 Share Posted May 15, 2008 [quote name='charic' post='199485' date='May 15 2008, 12:33 PM']Ok then new problem.. only one wire from each pickup![/quote] I think we've found the problem ! You need two wires for a pickup to work. Does the pickup wire have a braided shield ? If so that may be working as the earth. What kind of pickups are they ? If you remove the pickup cover can you see two small solder blobs where the fine winding wire of the pickup coil comes out ? If so the hookup wires are usually soldered on to these points (be careful not to break the fine colil wire at this point). Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 You cant get into the pickups theyre a sealed unit and have no brand name on them. Researching samicks seems impossible. Yes they have a braided shield. Ah I see, however i still have to work out where to earth too. Would this by why i was getting no actually bass sound either out of interest? Quote Link to comment Share on other sites More sharing options...
BOD2 Posted May 15, 2008 Share Posted May 15, 2008 [quote name='charic' post='199500' date='May 15 2008, 12:44 PM']You cant get into the pickups theyre a sealed unit and have no brand name on them. Researching samicks seems impossible. Yes they have a braided shield. Ah I see, however i still have to work out where to earth too. Would this by why i was getting no actually bass sound either out of interest?[/quote] OK - it sounds like the braided shield is being used as the earth for the pickups. With passive pickups it's common practice just to solder the earth wire (braided shield in this case) to the metal casing of the volume control for the pickup so that would explain the use of the braiding. The pot shells are all wired together and they become the common earthing point for everything. Simple but can get a bit messy. In this case, however, the pot shells aren't earthed. So you need to connect the braided shield on both pickups to the same point as the barrel from the jack plug. Also make sure the braiding can't touch any of the contacts on the pots when you put it all back together or it might short everything out and prevent anything from working. Insulating tape will prevent this. Yes, this would probably explain the lack of bass sound too ! Quote Link to comment Share on other sites More sharing options...
charic Posted May 15, 2008 Author Share Posted May 15, 2008 Oh thankyou sir penguin ill let u know how i get on once ive done the work. Broke the d string on the bass last night purely out of frustration! Quote Link to comment Share on other sites More sharing options...
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