# Tone capacitors...is this one shot?



## smorgdonkey (Jun 23, 2008)

Is there a way to test a tone cap to see if it is still functional? 

I've got a few different ones that I could just swap out but if that is not the problem I don't want to do a swap for one that is also potentially shot and then still be trying to figure out the issue with this guitar's wiring?

I have a multi-meter but from what I have been reading via the www there isn't a way to test it with a normal one (needs one with the 'uf' settings?).


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## mhammer (Nov 30, 2007)

Meters that can measure a reasonable range of capacitance arenot all that costly these days. Twenty bucks can often get you something that will read diodes, transistors, and caps, in addition to ohms and volts.

Do yourself a favour and get one. It can come in VERY handy for sussing out issues with gear.

And yes, you can measure the functionality of a cap with one. It won't be able to tell you all the fancy little details about the cap (leakage, etc.) that designers and engineers might be interested in (that's a costlier affair), but it can certainly tell you how close it is to spec, and equally important, what the value is _after_ the numbers and legending have rubbed off.


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## Wild Bill (May 3, 2006)

smorgdonkey said:


> Is there a way to test a tone cap to see if it is still functional?
> 
> I've got a few different ones that I could just swap out but if that is not the problem I don't want to do a swap for one that is also potentially shot and then still be trying to figure out the issue with this guitar's wiring?
> 
> I have a multi-meter but from what I have been reading via the www there isn't a way to test it with a normal one (needs one with the 'uf' settings?).


Caps rarely fail and when they do they tend to either short or blow up! Any multi-meter can test for a short. Blown up caps tend to show ugly signs!

They can open, but in my experience that is very rare and in a tone circuit things would tend to be obvious.

They also rarely drift in value. They are made very differently from resistors. The physics of their contruction is such that the value tends to be stable. Certainly, the value would have to drift a LOT before the tone circuit would stop working.

Why are you worried about it? What is going on with your amp and what makes you think a tone cap is a problem?

Wild Bill/Busen Amps


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## greco (Jul 15, 2007)

Wild Bill said:


> What is going on with your amp and what makes you think a tone cap is a problem?
> 
> Wild Bill/Busen Amps





smorgdonkey said:


> I don't want to do a swap for one that is also potentially shot and then still be trying to figure out the issue with this *guitar's* wiring?


Wild Bill ...I was assuming that the cap in question is in a guitar.

smorgdonkey...why not just buy a new cap, put it in... and trust that is OK?

Cheers

Dave


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## smorgdonkey (Jun 23, 2008)

Yes, sorry Wild Bill...the cap is a guitar tone cap. I didn't see any technical/repair area for guitar so I threw the thread up in here.

This is an H/S/S strat and it just has me perplexed. The wiring was not touched from factory and the neck pickup is thin & nasally, until you back off the lower tone control and it acts like a volume knob on the neck pickup. 

I have checked it over and over with wiring diagrams and find no problem. I did switch the cap today and it is still doing the same thing. I can't find any issue with the wiring at all and it is a real frustrating one. The pickups still have good resistance readings - I just can't figure out the problem.



Here is a curiosity for me...I have heard of many people who have problems with Fender factory wiring whenever there is supposed to be anything 'different', particularly on H/S/S (this one is supposed to have auto phase reverse in position 2) and a lot of negative stuff on the S-1 switching but people are always pounding Gibson's Quality Control and rarely harp on Fender for theirs...yet I see these wiring problems more than sharp fret ends and broken headstocks on Gibsons.


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## Wild Bill (May 3, 2006)

smorgdonkey said:


> Yes, sorry Wild Bill...the cap is a guitar tone cap. I didn't see any technical/repair area for guitar so I threw the thread up in here.
> 
> This is an H/S/S strat and it just has me perplexed. The wiring was not touched from factory and the neck pickup is thin & nasally, until you back off the lower tone control and it acts like a volume knob on the neck pickup.
> 
> ...


Now things make a bit more sense!

Well, there's no way voltage could ever blow a tone cap in a guitar! It's possible that you got the "one in a zillion" that got past quality control and was bad from the factory but that's like winning the lottery a few times in a row.

You mentioned occasional problems with factory wiring. This might be a clue.

A tone control in a guitar is almost always just a simple treble cut. A cap is put in series with a pot and wired across a pickup(s). The cap bypasses high frequencies - how much and how aggressively is determined by the value of the cap. The pot is just a resistance in the line. At 0 it puts the cap totally across the load for maximum bypass cut. At 10 there is enough resistance in the line to effectively block the cap from having any effect on the circuit.

I can't help but wonder if somehow the cap and pot are miss-wired. If the cap were in series with NO pot then whatever pickup was trying to deliver a signal THRU the cap would have its bass and mid frequencies blocked, with only the highs getting through. The tone would be "thin and nasally", just as you describe.

If the tone pot were just wired up across a pickup(s) it would act like a volume control. At 10 it would just load the line a little bit. A 0 it would short out the pickup. In between we would see a range from nothing to a lot - just like a volume control.

I'm seeing more and more factory wiring screwups these days. Unless they make an obvious fault they seem to get through all the way to the store floor. We should remember that at the factory likely NONE of those Chinese workers actually PLAY guitar!sigiifa 

The only manufacturer I ever knew that was chock full of players was Traynor/Yorkville. I would not be surprised to find that even their receptionist plays guitar!

Wild Bill/Busen Amps


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## smorgdonkey (Jun 23, 2008)

This guitar is MIM FSR Strat. I am awfully glad that I didn't sell it to a member here because I am sure that he would have got the guitar and feel 100% ripped off with the guitar performing like this. 

Anyway, the wiring all looks like it is supposed to by looking at the wiring diagrams - I just have top find the issue and correct it.


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## J S Moore (Feb 18, 2006)

Can you post a picture? Sometimes a fresh set of eyes can see things. I've wired up Strats and had the tone act like a volume. Took me a while to see that I had wired the cap wrong and was running the signal to ground. How you describe the thin sound thickening up makes me think of a phase issue but that would only happen with conjunction with another pickup. Maybe a bad pot.


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## smorgdonkey (Jun 23, 2008)

I had read a few times that a bad pot would do nothing but you have had pots act anything like this before?

I was wondering as far as phase and so on is concerned that as you say 'only in conjuction with another pickup' but the only issue is when it is 'neck only'.


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## Wild Bill (May 3, 2006)

Got this schematic from here:

GuitarNuts.com - Stock Stratocaster Wiring

This is an incredible site with the best version of grounding inside a guitar I have seen anywhere!

Wild Bill/Busen Amps


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## nonreverb (Sep 19, 2006)

Hate to be the fly in the ointment Bill, but some coupling caps drift ALOT! In my world, a healthy portion of the equipment I work on was built prior to 1964. Most of it uses the infernal wax caps which drift by large amounts and cause all kind of problems in filtering circuits etc. There are many early '60's guitar amps which used them as well as oil caps found in many Japanese amps of the '60's and '70's which are also a PITA.




Wild Bill said:


> Caps rarely fail and when they do they tend to either short or blow up! Any multi-meter can test for a short. Blown up caps tend to show ugly signs!
> 
> They can open, but in my experience that is very rare and in a tone circuit things would tend to be obvious.
> 
> ...


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## Wild Bill (May 3, 2006)

nonreverb said:


> Hate to be the fly in the ointment Bill, but some coupling caps drift ALOT! In my world, a healthy portion of the equipment I work on was built prior to 1964. Most of it uses the infernal wax caps which drift by large amounts and cause all kind of problems in filtering circuits etc. There are many early '60's guitar amps which used them as well as oil caps found in many Japanese amps of the '60's and '70's which are also a PITA.


Wax caps? Man, we are talking early 50's vintage and older here, NR!kksjur

I agree, caps that old can drift a bunch but as couplers I still don't think its all that critical. You need a 10x change in a coupling cap before the human ear can really notice. 

The issue is moot anyway, since I doubt if anyone stuffs a wax cap into a guitar anymore, if they ever did!

Why don't you like those Japanese oil caps? I've never had a problem with one, knock on wood.

The worst caps I've ever known are those "bumblebees". I still have a service bulletin from Zenith Radio Corp in the 50's advising any tech who comes across one to replace it with a good type of cap and bury the bumblebee under a stump by a crossroads, in the light of a full moon, with a stake through it, etc!kkjuw

Wild Bill/Busen Amps


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## bcmatt (Aug 25, 2007)

I had a friend who got a cheaper Gretsch with some funky electronics and similar types of problems, I was convinced something was wired wrong or a bad component. If I recall, what fixed it in the end was just reflowing some solder on all the connections. I think it was a bad solder connection that was really not at all visible.
I would try that first on yours. Make sure you have a powerful enough iron. I think at least 35 Watts would be sufficient. They have them for cheap at Canadian Tire for like $25. Has a pistol grip, but is for electronics and is 35 watts. Their other (25 watt) soldering irons would be a real exercise in frustration and likely make things worse. 
...oh and solder with lead in it too!


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## J S Moore (Feb 18, 2006)

smorgdonkey said:


> I had read a few times that a bad pot would do nothing but you have had pots act anything like this before?
> 
> I was wondering as far as phase and so on is concerned that as you say 'only in conjuction with another pickup' but the only issue is when it is 'neck only'.


The tone pots look good. The pot may be fried but I would re-flow the solder joints as suggested earlier with a good iron. Actually I would be tempted to use either a solder pump or wick to clean off the solder and just re-solder all of them. Is that a split coil with the humbucker on the other side? I see the green going to the right side and the black/white to the left side but I can't see where that red wire has gone.


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## loudtubeamps (Feb 2, 2012)

bcmatt said:


> I had a friend who got a cheaper Gretsch with some funky electronics and similar types of problems, I was convinced something was wired wrong or a bad component. If I recall, what fixed it in the end was just reflowing some solder on all the connections. I think it was a bad solder connection that was really not at all visible.
> I would try that first on yours. Make sure you have a powerful enough iron. I think at least 35 Watts would be sufficient. They have them for cheap at Canadian Tire for like $25. Has a pistol grip, but is for electronics and is 35 watts. Their other (25 watt) soldering irons would be a real exercise in frustration and likely make things worse.
> ...oh and solder with lead in it too!


very good suggestion............. 
As well I have had the odd case where wiring hookup looks correct, soldering points are solid and discovered a broken wire within the insulation.
If U have the means to check continuity of the hot leads from end to end or at least give a gentle pull on hot leads and see if one feels wimpy or it may even s t r e t c h a bit also for signs of a lead that may look a bit thin in one small section.


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## nonreverb (Sep 19, 2006)

Not so Bill, Hammond organs used wax caps up to and in some cases including 1964. Therefore, there are many B3's, C3's A100's in service today with them.
After that they began using a red mylar type Good-All brand and the problem was solved....even to this day those caps are rock-solid.
In the case of the tone generator, the caps were hand matched to a coil which was used as a filter to eliminate crosstalk frequencies. It's quite precise. WHen those caps drift (and they drift by over 100% in some cases), it makes a substantial difference in the way the organ sounds. It becomes dull with noticeabe crosstalk.
As for oil caps, the Elk brand amps come to mind. Once I had to replace every one of those oil caps in one. Most were off spec and a few were actually acting like high value resistors to DC. Who knows, maybe a bad batch? All I know is that's not the first amp I had to change those type caps in and it probably won't be the last....



Wild Bill said:


> Wax caps? Man, we are talking early 50's vintage and older here, NR!kksjur
> 
> I agree, caps that old can drift a bunch but as couplers I still don't think its all that critical. You need a 10x change in a coupling cap before the human ear can really notice.
> 
> ...


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## epis (Feb 25, 2012)

Check out one more time your pickups, this guy is describing a problem with symptoms very similar to yours.

T Top with sound and NO reading... An explanation?


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## jb welder (Sep 14, 2010)

Nice catch Epis! I had read the same post and was thinking the symptoms were the same: thin or nasally sound, tone control acts as volume = open pickup coil. Suggest smorgdonkey measure pickup resistance again, with pickup disconnected from circuit.


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## Wild Bill (May 3, 2006)

nonreverb said:


> Not so Bill, Hammond organs used wax caps up to and in some cases including 1964. Therefore, there are many B3's, C3's A100's in service today with them.
> After that they began using a red mylar type Good-All brand and the problem was solved....even to this day those caps are rock-solid.
> In the case of the tone generator, the caps were hand matched to a coil which was used as a filter to eliminate crosstalk frequencies. It's quite precise. WHen those caps drift (and they drift by over 100% in some cases), it makes a substantial difference in the way the organ sounds. It becomes dull with noticeabe crosstalk.
> As for oil caps, the Elk brand amps come to mind. Once I had to replace every one of those oil caps in one. Most were off spec and a few were actually acting like high value resistors to DC. Who knows, maybe a bad batch? All I know is that's not the first amp I had to change those type caps in and it probably won't be the last....


Thank you, NR! I learned something! I can understand how a tone generator application would be much more critical about caps and once again I am impressed with how those old guys worked around such problems to make such a fabulous instrument as a Hammond Organ!

Often wished I had the money to spare for a Hammond, not a B of course but maybe an M or L, as long as it had the percussion. I get a lot of eczema type skin cracking on my hands and fingers nowadays, especially in winter. This has really hurt my guitar playing. Is 60 too old for learning some keyboard?sigiifa

Wild Bill/Busen Amps


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## smorgdonkey (Jun 23, 2008)

It ended up being the neck pickup. It was showing fine on the meter and I tested it multiple times. It also had output when plugged in but when I went in to change that pot, I was going over different connections testing continuity and retesting the pickups resistance, I could not get any reading on it whatsoever.

I replaced it and now it is fine.

Thanks for the suggestions guys!


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## nonreverb (Sep 19, 2006)

Never too old Bill! Heck, I haven't started playing key's yet myself. An M or L can be had for a song these days and there's always one or two available on kijiji.:food-smiley-004:



Wild Bill said:


> Thank you, NR! I learned something! I can understand how a tone generator application would be much more critical about caps and once again I am impressed with how those old guys worked around such problems to make such a fabulous instrument as a Hammond Organ!
> 
> Often wished I had the money to spare for a Hammond, not a B of course but maybe an M or L, as long as it had the percussion. I get a lot of eczema type skin cracking on my hands and fingers nowadays, especially in winter. This has really hurt my guitar playing. Is 60 too old for learning some keyboard?sigiifa
> 
> Wild Bill/Busen Amps


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## Wild Bill (May 3, 2006)

smorgdonkey said:


> It ended up being the neck pickup. It was showing fine on the meter and I tested it multiple times. It also had output when plugged in but when I went in to change that pot, I was going over different connections testing continuity and retesting the pickups resistance, I could not get any reading on it whatsoever.
> 
> I replaced it and now it is fine.
> 
> Thanks for the suggestions guys!


Smorg, when you checked it first was it wired in circuit? You may have been seeing the resistance of a pot across the pickup and that fooled you. The only way to tell for sure is to disconnect on end of a pickup so that your meter doesn' see anything else.

Wild Bill/Busen Amps


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## smorgdonkey (Jun 23, 2008)

Wild Bill said:


> Smorg, when you checked it first was it wired in circuit? You may have been seeing the resistance of a pot across the pickup and that fooled you. The only way to tell for sure is to disconnect on end of a pickup so that your meter doesn' see anything else.
> 
> Wild Bill/Busen Amps


I was checking while it was still wired in but the tricky part is two-fold: 

1. it still had output when plugged in and on 'neck only'
2. it wouldn't read anything the last time when I checked it in the same manner(s)...so what I mean is 'if it read pot resistance once or twice, why would it not continue to read pot resistance?'.

I would die a young man if I were a guitar tech. It seems that I never have issues with Les Pauls or LP style guitars but pickguard loaded strats...f'n shoot me!!


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## loudtubeamps (Feb 2, 2012)

If your pup is wired to the switch first then............
If U read the resistance of the suspect pickup where the lead hits the switch and the switch is not positioned to contact that pup, then u should be able to get an accurate reading without lifting any leads. An intemittent set of readings might lead U back to my earlier suggestion.
Cheers, d


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