# What is this part?



## guitar69freak (Jul 29, 2019)

This is obviously why I’m having issues with this combo amp. What is this part that is leakin? Is this the capacitor and what do I replace it with?


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## player99 (Sep 5, 2019)

It's a capacitor. Two of them. Take the numbers off the side and google.

edit: 25v 2200uF but don't take my word for it.


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## guitar69freak (Jul 29, 2019)

player99 said:


> It's a capacitor. Two of them. Take the numbers off the side and google.
> 
> edit: 25v 2200uF but don't take my word for it.


found this exact same capacitor on eBay, thanks a bunch!


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## dtsaudio (Apr 15, 2009)

Do not buy your capacitors off of eBay. The chances of them being cheap fake parts are very high. 
Also it might be a good idea to find out why they failed before you replace them.


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## greco (Jul 15, 2007)

dtsaudio said:


> Also it might be a good idea to find out why they failed before you replace them.


Pay attention to this advice. Dan is a professional.
If the amp is worth it, take it to a tech.

It feels like we are going in circles here.
What are some causes of feedback?


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## Milkman (Feb 2, 2006)

I like the idea of taking it to a tech.

I spent my spare time one winter a few years back, building tube amps from kits.

I was able to follow the diagrams and have decent soldering skills so the amps worked.

BUT, honestly I had and still have very limited understanding of what the individual components do and what to look for if anything went wrong.

I learned some things in the process, but I'm now taking one of these project amps to a skilled technician so he can ensure it's safe and fully functional.


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## guitar69freak (Jul 29, 2019)

dtsaudio said:


> Do not buy your capacitors off of eBay. The chances of them being cheap fake parts are very high.
> Also it might be a good idea to find out why they failed before you replace them.



Where is a good place to buy capacitors and other electrical parts?


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## knight_yyz (Mar 14, 2015)

Digitech or Mouser


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## jb welder (Sep 14, 2010)

That is glue holding down those caps. If they were bad enough to leak, they would be domed on top.
You can see that the goo goes up the side of the cap, leakage won't do that.


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## KapnKrunch (Jul 13, 2016)

jb welder said:


> That is glue holding down those caps. If they were bad enough to leak, they would be domed on top.
> You can see that the goo goes up the side of the cap, leakage won't do that.


Lol. Technically, it's not a technical thread until JB checks in.


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## greco (Jul 15, 2007)

jb welder said:


> That is glue holding down those caps. If they were bad enough to leak, they would be domed on top.
> You can see that the goo goes up the side of the cap, leakage won't do that.


Visual assistance for educational purposes.
Reminder to self..Fluids don't often flow uphill.

BTW...Are we still going in circles re: feedback...cause and solution?


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## davetcan (Feb 27, 2006)

Well the board could be mounted upside down ....................


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## greco (Jul 15, 2007)

davetcan said:


> Well the board could be mounted upside down ....................


This is exactly why they pay you the big bucks.


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## jimsz (Apr 17, 2009)

Looks like glue to me. Don't see any corrosion on the board. Can they be tested?


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## dtsaudio (Apr 15, 2009)

JB is probably correct. Looks like glue. One thing i do see though is the jacket on the cap nearest the rectifier is deformed around the middle a bit. That may be glue as well and just a visual issue. But i would check just in case.


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## Doug_M (Apr 29, 2019)

Doubtful that is glue. Components are soldered to the board, not glued. Looks like the cap on the right leaked from the bottom. If a circuit board is relatively roomy (like the one in the picture is), replacing capacitors is pretty easy. But you need a decent soldering iron. Lot’s of good videos on YouTube showing how it’s done. I brought an original Xbox back to life earlier this year by replacing 5 or 6 bad caps. Wasn’t hard. Just took a bit of time, the right replacement caps of course, de-soldering braid, and as I said earlier a decent soldering iron. 


Sent from my iPad using Tapatalk Pro


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## dtsaudio (Apr 15, 2009)

Actually it could very well be glue. The Chinese are notorious for throwing tons of adhesive on boards to hold parts down, especially with suspect build quality and/or substandard parts. However they still need to be checked.
One quick way is - is it hard. If it is leakage oil it won't be dry, and will be quite soft.


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## jb welder (Sep 14, 2010)

Yes, I wasn't saying they glue the parts instead of soldering them. 
Heavier parts (especially top-heavy) will stress the solder joints and they can eventually fracture. More so with MI gear because it gets moved around a lot. So they secure some parts to the board with various adhesives, glue, hot melt glue, RTV etc. Behringer is notorious for putting too much hot glue in their mixers, they may have changed that but not sure as everyone now avoids working on their stuff (often not economical to repair).
There are lots of Yamaha SPX90's out there that went bad because the glue securing the components went conductive after some 20 years. All kinds of weird faults that could be solved by removing the old glue.


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## jimsz (Apr 17, 2009)

greco said:


> Visual assistance for educational purposes.
> Reminder to self..Fluids don't often flow uphill.
> 
> BTW...Are we still going in circles re: feedback...cause and solution?
> View attachment 284510


The first picture in the OP is a little hard to see and does look like the glue on chinese boards, but this close up pic sure looks more like leaking electrolyte and the cap on the right has some slight venting on the top.


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## Doug_M (Apr 29, 2019)

I’ve never seen glue on a board, but my experience is with ham radios and vintage computers. I’m going to have to buy something cheap and Chinese just to have a look! Lol


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## oldjoat (Apr 4, 2019)

ok ... just 2 caps to swap out ( and cheap $ ) ... never hurts 
fixed ? then you're done 

if not , move on with the inspection / probing


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## nonreverb (Sep 19, 2006)

Let's take this conversation in a different direction....What are the symptoms with your amp? Once we establish that, we can start looking at the areas that could be responsible for said failure. FYI the folks on here that have stated that the caps are merely glued in place are correct. It's merely component glue to secure them to the board.


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## jimsz (Apr 17, 2009)

Doug_M said:


> I’ve never seen glue on a board, but my experience is with ham radios and vintage computers. I’m going to have to buy something cheap and Chinese just to have a look! Lol
> 
> 
> Sent from my iPad using Tapatalk Pro


Often, its the glue used to laminate the board and although it should be heat resistant, chinese boards have cheap glue and they tend to look just like the pics above when they get overheated. I found this pic that looks somewhat similar...

https://cdn.instructables.com/FI9/S08W/JEOIS4EV/FI9S08WJEOIS4EV.LARGE.jpg?auto=webp&fit=bounds


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## nonreverb (Sep 19, 2006)

jimsz said:


> Often, its the glue used to laminate the board and although it should be heat resistant, chinese boards have cheap glue and they tend to look just like the pics above when they get overheated. I found this pic that looks somewhat similar...
> 
> https://cdn.instructables.com/FI9/S08W/JEOIS4EV/FI9S08WJEOIS4EV.LARGE.jpg?auto=webp&fit=bounds


For it to have overheated THAT much, the cap would look like a ballon and would have probably blown it's lid or launched itself off the board before that happened.


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## jimsz (Apr 17, 2009)

nonreverb said:


> For it to be overheated THAT much, the cap would look like a ballon and would have probably blown it's lid or launched itself off the board before that happened.


 I would tend to agree, that's why I then thought it was the caps that were leaking electrolyte instead as there seems to only be a bit of venting from one of the caps in the pic above.


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## nonreverb (Sep 19, 2006)

That doesn't look like typical electrolyte ooze. It looks like two or three drops of glue...Nice round and uniform. They've even glued them together so they anchor each other. Typical factory gluing procedure....Could a cap have failed without it showing itself? It's a possibility...However without a detailed description of the fault, dwelling on theses caps is a red herring. I'll bet the problem resides elsewhere.


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## Granny Gremlin (Jun 3, 2016)

jb welder said:


> That is glue holding down those caps. If they were bad enough to leak, they would be domed on top.
> You can see that the goo goes up the side of the cap, leakage won't do that.


I was about to say.


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## jimsz (Apr 17, 2009)

Heres a pic of a leaking cap showing no bulging or venting...

https://i.stack.imgur.com/N22ph.jpg


nonreverb said:


> Could a cap have failed without it showing itself? It's a possibility...


I was involved in a project in which we replaced hundreds of leaking caps on the two main switches line cards widely used in BC; the DMS-100 and 5-ESS. These line cards were in service for decades and the caps were in various stages of decay, many showing no signs of bulging or venting, yet leaking out the bottom.


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## nonreverb (Sep 19, 2006)

jimsz said:


> Heres a pic of a leaking cap showing no bulging or venting...
> 
> https://i.stack.imgur.com/N22ph.jpg
> 
> ...


Yes, ancient caps are a liability...and bad batches can wreak havoc on equipment. Same goes with locating electrolytic caps near sources of constant heat. I too was in the industry for many years doing component lever repair on CRT based computer monitors...I've seen it all where bad component design and bad batches are involved. Having said that, I still want to know what the fault is with this piece of equipment...without that, it's a shot in the dark guessing game and nothing more.


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## nonreverb (Sep 19, 2006)

If this thread is an extension of the OP's other post regarding a feedback question, I doubt those caps are the source of his problem....


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## jimsz (Apr 17, 2009)

nonreverb said:


> Having said that, I still want to know what the fault is with this piece of equipment...without that, it's a shot in the dark guessing game and nothing more.


I agree, but to write off others as red herrings is perhaps not appropriate considering a red herring is an _intentional_ form of misleading or distracting, which does not appear to be the case with anyone here. We're all just trying to understand if its glue or leakage, which is kind of hard to tell from the pics. If you're right and it is glue, that still doesn't mean the problem is not with caps, it could be or it could be elsewhere. To my knowledge, the problem has not been described as yet, still waiting for that.


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## nonreverb (Sep 19, 2006)

jimsz said:


> I agree, but to write off others as red herrings is perhaps not appropriate considering a red herring is an _intentional_ form of misleading or distracting, which does not appear to be the case with anyone here. We're all just trying to understand if its glue or leakage, which is kind of hard to tell from the pics. If you're right and it is glue, that still doesn't mean the problem is not with caps, it could be or it could be elsewhere. To my knowledge, the problem has not been described as yet, still waiting for that.


It's definitely not leakage. I've seen enough leakage and cap glue to be certain it's not the former. That of course is just my opinion.....As I stated: Could it be bad and not shown itself? Sure it could however, the fact that everyone's debating about whether it's glue or discharge has hijacked the real issue which is what's the symptom....I'm actually surprised that question hasn't been raised already. Having gone back and looked at the OP's other posts immediately prior to this suggests that this post is related to them. I'm going with that until I hear differently. As for red herring, yes probably not the proper use of the term...I take it back.


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## jimsz (Apr 17, 2009)

nonreverb said:


> As for red herring, yes probably not the proper use of the term...I take it back.


No problem. Cheers.


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## jb welder (Sep 14, 2010)

I don't think we've flogged this one enough yet.  All in the interest of education though, so no offence intended to anyone including the OP.



jimsz said:


> Heres a pic of a leaking cap showing no bulging or venting...
> 
> https://i.stack.imgur.com/N22ph.jpg


Actually that is also seems to be glue. Please read the whole thread that pic came from here: Choosing and replace capacitors for audio amplifier
And a few more glue examples Are these caps leaking?
How to tell if glue or electrolyte leak from old capacitors?
(this one the most obvious) Capacitor Leak On The Board? | Electronics Repair And Technology News

I'm not doubting your experience with caps leaking that have not bulged or vented @jimsz . I have seen it too. But it is usually not uniform, causes a lot of corrosion, and either is liquid when fresh, or evaporates leaving mostly a powdery residue or crud like in these pics:



















As far as the unit in question, it was discussed in another thread like @nonreverb mentioned. The OP is hoping to fix his amps by visual inspection which sometimes works, but you can end up throwing parts at things which is a waste of your time and money.
Both Dan @dtsaudio and myself have tried to steer him away from wasting money (in the other case a transformer which is big bucks) but have been basically ignored.
So I'll sit out for the rest of this round, though I don't really expect to see a response from him anyway.


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## nonreverb (Sep 19, 2006)

jb welder said:


> I don't think we've flogged this one enough yet.  All in the interest of education though, so no offence intended to anyone including the OP.
> 
> 
> Actually that is also seems to be glue. Please read the whole thread that pic came from here: Choosing and replace capacitors for audio amplifier
> ...


 I tend to agree with your assessment of the original poster's intentions jb welder. On line repair advice is almost always a dead end unless one is very familiar with the product. In this case the product being a Behringer amp which for all intents and purposes, is throw away. No offense to the OP but I suspect none of the tech's here including myself would even look at a Behringer amp if it came into the shop....it's a money loser. So why would I want to try and diagnose it on line?


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## jimsz (Apr 17, 2009)

jb welder said:


> I'm not doubting your experience with caps leaking that have not bulged or vented @jimsz . I have seen it too. But it is usually not uniform, causes a lot of corrosion, and either is liquid when fresh, or evaporates leaving mostly a powdery residue or crud


I totally get that, allow me to explain the situation of the project I was involved. The switches I referred earlier are very large pieces of network bay equipment. Each line card had 8 ports, a port representing a telephone line of any given customer. There were tens of thousands of customers in many central offices which represented thousands of these line cards causing the equipment to generate massive amounts of heat, 24/7-365, non-stop. Huge HVAC systems were installed on the roofs of these buildings, their job was to try and keep the temperature cool while fans dissipated the heat to the outside. Fast forward several decades, the HVAC systems got old and started to break down on a regular basis causing the temperatures to rise dramatically.

While this presents a huge problem, sometimes the problem was intensified when the temperature outdoors in mid summer goes over 30 degrees. It was this heat coupled with heat generated by the switches that tended to damage the caps causing them to leak, especially after being in use for several decades. As opposed to caps that leak as a result of their own degradation, the caps I saw leaked under a different set of criteria and sure enough did pool around the cap just like the ones in the pics above that look like glue. It's also why they rarely bulged or vented.

Clearly, the caps above in the Behringer are probably glued as I originally suspected considering their degradation would most likely result in your description of being non uniform, causing corrosion and leaving the residue. But, when I saw the close up pic, it reminded me exactly of the caps I saw in the switches.


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## greco (Jul 15, 2007)

WOW! 35 posts containing so much valuable educational material and discussion!
@guitar69freak Are you reading any of this? Any comment from you?


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## guitar69freak (Jul 29, 2019)

This ampler turns on and plays but only if I have the overdrive button pressed. It does appear that these caps are glued in place and there are not any signs they have overheated but the rest of the circuit board is very clean and nothing looks burnt. 

The volume pot on this amp doesn’t do a thing. There are roughly 20 resistors and other components on the circuit board and everything looks super clean. 

I’m getting lots of feedback, the volume pot doesn’t do shit and the amp only plays sound if I have the overdrive button pressed. I figured the cause would be the caps leaking/overheating/decaying, if anything.


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## oldjoat (Apr 4, 2019)

or the vol pot is defective = no signal passed to the rest of the circuit .
still just shooting in the dark with out seeing the board

to break out the scope and injector, you're at 80 for the diagnosis ... 
plus a couple of parts and another hr labour for the repair ... is it really worth it ? 

jumper the input signal ( with a small cap ) to the middle lug of the vol pot and see if you get anything
then do the same with the other lugs , one at a time 
the cap should pass the signal but block any dc voltages .


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## guitar69freak (Jul 29, 2019)

oldjoat said:


> or the vol pot is defective = no signal passed to the rest of the circuit .
> still just shooting in the dark with out seeing the board
> 
> to break out the scope and injector, you're at 80 for the diagnosis ...
> ...



Here is a couple photos of the circuit board. Nothing here seems to have burnt but that’s not to say much. I can’t think of any other issue but the caps. What are the chances that the caps are decomposing and not showing signs of wear? Doesn’t this circuit board look clean?


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## greco (Jul 15, 2007)

What is the model of this Behringer amp?


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## guitar69freak (Jul 29, 2019)




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## greco (Jul 15, 2007)

Do these look like your amp? 


















D


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## oldjoat (Apr 4, 2019)

ouch ....
ok , flip the board over and take a magnifying glass to the input jack and its solder joints . 
especially at the board pads . wiggle the jack and look closely for broken jacks
then do the same with the vol control and the board pads.


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## guitar69freak (Jul 29, 2019)

greco said:


> Do these look like your amp?
> 
> 
> 
> ...


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## guitar69freak (Jul 29, 2019)

oldjoat said:


> ouch ....
> ok , flip the board over and take a magnifying glass to the input jack and its solder joints .
> especially at the board pads . wiggle the jack and look closely for broken jacks
> then do the same with the vol control and the board pads.


I’ve taken a look and I have no broken cold solders on this board. My next move was to deoxidize the pot using Deoxit D5 contact cleaner which I use often cleaning HIFI equipment.


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## oldjoat (Apr 4, 2019)

the plastic jacks are also known for breaking ...
figure out which pad is the input to the circuit ( near the jack )
plug it in and touch that pad and see if you get a hum ( 60 cycle) ... use a screwdriver or piece of wire to do it ( should be low voltage )
hum and noise = bad solder joint , broken pad/track, or bad jack somewhere.
no changes = possibly a bad "chip" and the cost of repairs > value of amp in most cases.


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## greco (Jul 15, 2007)

Thanks for letting us know the specific model...









Is this your only amp? If so, it must be very frustrating not to have anything to plug your guitar into.

Please keep us updated. I certainly admire your determination.


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## davetcan (Feb 27, 2006)

Interestingly enough I have my Renegade in at the docs right now, I'm getting all of the cheap ass Chinese Caps replaced as we speak. This one was leaking nicely onto the circuit board.


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