help me find the loose connection on my sterling

[green]

hi

i bought an used '94 musicman sterling 4 and it has a problem:

when i have the switch in bridge position (parallel coils), sometimes it occurs all of a sudden while playing, that the signal get's weaker. the sound changes, and i hear hum.
this happens by itself.
the same in the middle position (single coil) or bridge position (parallel).
it doesn't have to do with using the switch.

but most of the time when i switch to serial mode, i have a very weak signal right after switching, and the sound is muffled and lacks the high end.
switching to another mode, and switching back to serial doesn't change this.
but when i hit the bass on the side (is it called RIB ?), the loudness comes up, and it sounds like everything is right again.

now, i don't know where the loose connection is.
maybe it's inside the pickup, but that seems odd to me...
maybe it's somewhere else, and when i hit the bass the problem disappears.

i opened the electronics compartment and looked inside.
everything seemed fine.
but since i can't take out the circuit board without using an soldering iron, i couldn't look beneath it.

please help me find out why the sterling does what it does !

(i hope you could understand what i wrote. i guess it's hard to describe and sounds confusing. please ask if something is unclear)

[OutToPlayJazz]

That's a tough one - You really need to get it to a technician who knows their preamps and pickups very well. I know it's an obvious one, but did you try changing the battery? A failing 9v can do strange things to your bass's output.

The other thing I thought of was that the series/single coil/parallel switch could have a bad connection, or your pickup may be on it's way out.

Also, check how good the jack socket is - They can wear out very quickly on underside mountings at times.

It's so difficult to tell & you really need an expert to have a look at it.

Edited February 26, 2010 by OutToPlayJazz

[artisan]

just a thought,are the connections in the battery compartment in good clean condition,a bit of corrosion could be the problem.

[JTUK]

hmm..don't want to hijack a thread, but how long should a duracell last in a 9v pre?

[obbm]

Green, where are you?

[green]

i'm in germany.

battery is ok, switch is ok, jack is ok. checked them all.

the problem is:
when the sound gets weaker, i also get a little bit of hum in serial and paralled mode. which means, that there is only one coil running. in parallel mode, when it occurs, you can hear very clearly that the sound changes from the snappy parallel sound, to a more crowly single coil sound plus hum.
i guess, there must be something with the pickup, but how can it break ???

[obbm]

[quote name='green' post='758924' date='Feb 27 2010, 10:33 AM']i'm in germany.

battery is ok, switch is ok, jack is ok. checked them all.

the problem is:
when the sound gets weaker, i also get a little bit of hum in serial and paralled mode. which means, that there is only one coil running. in parallel mode, when it occurs, you can hear very clearly that the sound changes from the snappy parallel sound, to a more crowly single coil sound plus hum.
i guess, there must be something with the pickup, but how can it break ???[/quote]

The Sterling pre-amp is almost the same as the SR5. I've spent a lot of time with these and the input circuitry is quite complex as the signal is routed backwards and forwards between the selector switch and the circuit board. It may be something as simple as a wire coming off the switch. I suspect that to get it properly resolved you will need to get it to a Musicman specialist to have a look, someone who fully understands the pre-amp.

[green]

well, there are only 2 music stores with technicians here in my area. one doesn't even sell basses, just pianos.
the other one i guess is a bunch of guys making big money but they don't have a clue. i got some really bad advice there before, so i never would give my bass away to them....

that's why i need to find the problem myself.
i soldered electronics before. i'm not a pro, but i have some experience nevertheless.

i'm just trying to find out what it could be.
it really sounds like there is only one coil running. when i hit the bass, all coils come back again. does that mean it's the pickup ?
or could it be outside of the pickup ?

[obbm]

[quote name='green' post='759064' date='Feb 27 2010, 01:18 PM']well, there are only 2 music stores with technicians here in my area. one doesn't even sell basses, just pianos.
the other one i guess is a bunch of guys making big money but they don't have a clue. i got some really bad advice there before, so i never would give my bass away to them....

that's why i need to find the problem myself.
i soldered electronics before. i'm not a pro, but i have some experience nevertheless.

i'm just trying to find out what it could be.
it really sounds like there is only one coil running. when i hit the bass, all coils come back again. does that mean it's the pickup ?
or could it be outside of the pickup ?[/quote]

Could be a bad soldered joint. Check both ends of the wires that connect the board to the switch and check the the joints where the 5 pick-up wires are soldered onto the board. Be very careful with the board as the pads that the wires connect to are small and too much heat will lift them.

[green]

ok, will do !
how should i check them ? just carefully joggle the wires and see if it makes cracking sounds ?

[green]

ok, checked the wires between board and switch, and also the wires between pickup and board.
everything was just fine.

so, still didn't find what the problem is.

what else could it be ?


by the way:
the previous owner says, he didn't have that problem.
well, if he's not lying, that means that that must have happened during shipping.
maybe that helps a bit...

Edited March 18, 2010 by green

[throwoff]

are you sure its not the amp?

Or possibly something in the room? do you have your mobile phone in your pocket when you play?

[Paul_C]

[quote name='green' post='759369' date='Feb 27 2010, 07:38 PM']ok, will do !
how should i check them ? just carefully joggle the wires and see if it makes cracking sounds ?[/quote]

if it's a dry solder joint (much more likely, imho, with the new lead-free *spit* solder) then it's best to re-flow them with a soldering iron (and some old tin/lead solder if you have some )

[green]

it's not the amp, or the cell phone.

paul, you mean i should resolder it ?

how do i know if there is lead in the solder or not ?

[AlanP2008]

[quote name='green' post='779587' date='Mar 19 2010, 11:25 AM']it's not the amp, or the cell phone.

paul, you mean i should resolder it ?

how do i know if there is lead in the solder or not ?[/quote]

I have a Strat pickup that exhibits exactly the same symptom. It is an SCN (noiseless - so some kind of humbucker), and it will go "quiet" and a bit more subject to hum etc. on odd occasions. I can often fix it with a tap on the top of the cover, but it isn't a permanenet cure. Clearly it is some kind of bad joint inside the pickup, between the coils somehow, and (one of these days) I'll get round to taking it apart, and reflow each of the visible solder joints inside, to see if that fixes it... (or I'll replace it...)

Edited March 19, 2010 by AlanP2008

[throwoff]

I didn't even think it could be the pickup, if its a wiring issue inside the p/up it could be a right git to fix.

Anyone know if they are wax potted on a sterling?

[AlanP2008]

[quote name='throwoff' post='779767' date='Mar 19 2010, 01:51 PM']I didn't even think it could be the pickup, if its a wiring issue inside the p/up it could be a right git to fix.

Anyone know if they are wax potted on a sterling?[/quote]

I don't know whether they are potted, but the winding wire is a lot thinner than typical lead-out wire - so there must certainly be a joint somewhere...

[fatback]

I was in UK last week. Had a great time. Spent so much a good time I thought I had a loose connection on my sterling an all.

[JackLondon]

what about the switch itself? maybe this is the fault that happened during transport? try getting a new switch, should be no more than €5!

[obbm]

[quote name='JackLondon' post='780606' date='Mar 20 2010, 10:52 AM']what about the switch itself? maybe this is the fault that happened during transport? try getting a new switch, should be no more than €5![/quote]


£20 would be a bit closer. You can only get them from an EBMM dealer/distributor.

[green]

AlanP, i'm glad to hear that you understand my problem.
until now, nearly everyone just said i should bring it to a repair guy, that's all ;-)

no, it's not the switch. i checked the soldering.
plus, the switch can't just shut down one coil. it can only switch between presets that are given, and there is serial, single coil, and parallel.

[JackLondon]

But have you seen the inside of the switch? soldering is the small part in they way the switch works, remember it's a mechanical, moving part which can be prone to wear on particular parts!

[green]

i haven't seen the interior, but i don't think that it is possible.

the switch can't shut down just one coil. it just switches between serial, single coil, and parallel.
all of them are hum free (bogard) ;-)

if there is hum, there is a coil that's grounded, the switch itself can't do that.

am i right ?