Post Number: 190
|Posted on Monday, March 05, 2007 - 12:47 pm: |
I "seem" to have 2 small (in my opinion) problems with my 1976 Series 1.
1st--The middle hum canceller seems to be loose if I turn the bass over. Can I do a simple "fix it" without opening her up surgically.
How would I know if the Canceller works or doesn't work??
Does it make any sort of sound if it is Tapped with a metal object, just like a pick-up??
If I use my bass on the neck p/u at the 0 db setting, then, between what would be the equivalent of 9--10 on a normal control, I seem to hear a small "static/electrical" type of sound on going beyond and back from this position. It seems to deteriorate when I go 6 db & 9 db, but this may just be wishfull thinking. Don't get me wrong, I would never have heard this unless I was not fiddling about at rehearsals with the volume turned fully off and then acting like a 10 year old with new birthday presents. It does not affect ANYTHING about the sound of the bass!
I have upgraded electronics in this bass--------were there when I bought it 7 years ago ie. it has the board with the 5 microchips as opposed to the earlier stuff. It is all Alembic marked if I remember correctly, and looks identical to all other later Series insruments. The 1 thing I did though was to Change the P/u selector so that I went directly to the bridge p/u at first turn so the wiring may be round the other way------but hell that's what makes alembics so good.
The "tone " control for this filter "seems" to have the same prob as the volume control, which may suggest a "chip problem" on the board?
As I said earlier, the bass sound as it should!---perfect---Maybe I'm hearing more than I should, BUT---the Bridge p/u doesn't do this.,
I'm unemployed at the moment, so can't rub 2 cents together,but all assistance is SO valuable.
This may be a question for Ron/Mica/David Fung/Dave Houck, but all help will be REALLY appreciated.
Thanks in anticipation
Post Number: 4212
|Posted on Monday, March 05, 2007 - 1:11 pm: |
If the humcanceller is loose, then the adhesive holding it in place has failed. If it doesn't come out all the way, a cheap way to keep it from rattling around is to wedge a bit of foldied paper in the gap between the pickup and the edge of the routing and then wait for the rest of hte adhesive to fail before worrying about it.
For the static sound while moving the pot, you probably just need to clean it a bit with some repetivite rotations. Try 20-30 at first, and then try more if it doesn't clear up. These pots are rated for something like a million rotations, so they aren't going to wear out from this. Just take the pot through the entire rotation, from end to end, without being rough at the stops to be nice to the bass. Perform this on any of the pots that are exhibiting this symptom. It will likely clear up the trouble.
Let me know your results.
Post Number: 231
|Posted on Tuesday, March 06, 2007 - 10:14 am: |
I'd try rotating the pot to see if there's dirt in there first as well, but if you turn the knob down slightly and the unusual noise stays constant without you moving the knob, it's also possible that you're suffering from a dirty/high impedence connection. It's sometimes caused by a cold solder joint (which exhibits high resistance), but in the case of an Alembic, it's more likely to be be oxidation on the molex connectors between the circuit board and the pickups, etc.
It can be a little tricky to fix this. The most effective way is probably to get a Caig Labs DeOxit pen. The pen has a red contact cleaning liquid in it which is very effective, but what really makes this useful is that it has a sort of fiber tip which is saturated with the liquid after you prime the pen. The combination of the contact cleaner and the fiber tip really helps clean things up to a much greater extent than a Q-Tip or other swab. You unplug the connectors to the PC board, then wipe down the pins firmly with the pen. This doesn't directly solve the problem if the oxidation is on the plug end (pretty much inaccessible without replacing the plug), but I won't tell anybody if you push the plug on while the contact cleaner is still wet. The Molex plugs are also self-wiping, that is, they will clean themselves up if you connect and reconnect repeatedly, but they are NOT rated for hundreds of repetitions, so this isn't the best way to do this.
All that it takes is for somebody to handle the pins with their bare hands to contaminate the contacts before they're mated. The oxidation that results can increase the resistance of the connection, which can sometimes cause oscillations and electrical noise as you describe.
The humcanceller is the coil of one of the pickups without the magnets, so it won't make any noise if you tap it with a metallic object.
The best way to test if it's working is to measure it's resistance with an ohmmeter. I don't know what the proper value will be, but it should be very close to the values of the pickup coils as well.
I hope this helps,
Post Number: 191
|Posted on Wednesday, March 07, 2007 - 3:07 am: |
Thanks a million Mica & David for a fast response.
I'll try rotating the pots over the next few days and let you know the results.
If that fails, then it means I need to open her up and have a little look. This makes me VERY nervous, as I'm not great on the tech side.
Will keep you posted and thanks again!
Post Number: 1082
|Posted on Wednesday, March 07, 2007 - 4:16 am: |
Tell you what George. If cleaning fails to solve the problem I'll take her off your hands for no extra charge ;-)
Post Number: 193
|Posted on Saturday, March 10, 2007 - 2:09 am: |
How did I gues that I would receive a note from you Graeme, saying just that!!
Post Number: 185
|Posted on Sunday, March 11, 2007 - 1:53 am: |
George, an easy, "non-tech" way to check your hum canceller is working is to play your bass near someone operating a dimmer switch! My old strat was unplayable in a room with an operating dimmer switch.
Post Number: 194
|Posted on Sunday, March 11, 2007 - 2:08 am: |
I'm sure it's working OK, as I don't get interference from most things, plus, there is a difference if I adjust the 2 screws that control it in the back of the guitar.
Nice Further by the way-------and in Britain too!!
Post Number: 196
|Posted on Wednesday, March 14, 2007 - 7:51 am: |
Things seem to be getting better the more I use the bass!
Can you believe that I don't use this baby very often!!---Too scared to damage her!
Will play her everyday at home from now on and I'm sure she will just get better and better.
My buddy is up to see me from Birmingham(England). He has a Spoiler--1985. He reckons that every tone he wants is just there in my Series---He loves it to bits---NOT for sale!
Thanks to David ( in my opinion, the best Alembic tech outside of Alembic----with of course Moder dave!!) for his great help, and to Mica (great video!!) for help. I think we have solved the "problems", but will keep everyone posted as to the outcome
Post Number: 1091
|Posted on Wednesday, March 14, 2007 - 8:06 am: |
You should get your mate to join the forum. i got my epic in brum.
Post Number: 197
|Posted on Friday, March 16, 2007 - 1:07 am: |
will certainly try Graeme. He has just had the full works for stomach cancer but seems to be pulling through ok. Let's hope so!