Hello from NY,

[chasenblues]

New member from Long Island NY,Checking in to say hello.
Hoping to get some advice/information/tips on getting a Gibson G10 SS amp back up and running hum free. I saw and read a thread(http://el34world.com/Forum/index.php?topic=7494.0 ) from 2009 regarding the amp thats answered most of my questions(I hope ). I'm looking for advice about finding a replacement the 2000uF filter cap can, Can someone point me to the proper sub-forum to ask for help?

Thanks.

[sluckey]

Mouser will have that cap.

[EL34]

What voltage do you need
I don't stock many higher uf value solid state type caps but I do have a couple types of 4700uf/16v caps
Axial and radial

It probably would not hurt to have a higher uf value
Not sure if you can use those or not?

They are on this page
http://hoffmanamps.com/MyStore/catalog/parts4.htm

[chasenblues]

What voltage do you need
I don't stock many higher uf value solid state type caps but I do have a couple types of 4700uf/16v caps
Axial and radial

It probably would not hurt to have a higher uf value
Not sure if you can use those or not?

They are on this page
http://hoffmanamps.com/MyStore/catalog/parts4.htm

Thank you for your response, This is the Cap i'm looking to replace.



I guessing from reading it will be impossible to find a direct replacement for it,
So would 2-1000 uf 50v radial Caps wired in parallel do the job?

I will also be removing the "death cap" and replacing the 2 wire ungrounded plug for a 3 prong grounded one.


Otherwise the Amp is in pretty good shape for its age.

http://i108.photobucket.com/albums/n20/chasenblues/IMG_0183_zps81cd9aa9.jpg

[sluckey]

This is the Cap i'm looking to replace.

That ain't even close to what you asked for originally. Just get three 470µF @ 50V from almost anywhere.

[EL34]

yeah, that looks like 3 x 500uf caps in one package.

As Steve said, get 3 x 470uf caps x 50volts

[chasenblues]

This is the Cap i'm looking to replace.

That ain't even close to what you asked for originally. Just get three 470µF @ 50V from almost anywhere.

How so?
I asked about finding a replacement a 2000 uf capacitor can as its listed on the schematic.

[sluckey]

This is the Cap i'm looking to replace.

That ain't even close to what you asked for originally. Just get three 470µF @ 50V from almost anywhere.

How so?
I asked about finding a replacement a 2000 uf capacitor can as its listed on the schematic.

You did ask about a 2000µF cap in your first post. But in your second post you said "This is the Cap i'm looking to replace." and also posted a pic of the cap. Well, the pic clearly shows a multi cap that contains 3 each 500µF caps. That's what my comment is about.

So, do you want to replace the cap in your pic or do you want to replace a 2000µF cap? You don't think the cap in the pic is a 2000µF cap, do you?

[chasenblues]

This is the Cap i'm looking to replace.

That ain't even close to what you asked for originally. Just get three 470µF @ 50V from almost anywhere.

How so?
I asked about finding a replacement a 2000 uf capacitor can as its listed on the schematic.

You did ask about a 2000µF cap in your first post. But in your second post you said "This is the Cap i'm looking to replace." and also posted a pic of the cap. Well, the pic clearly shows a multi cap that contains 3 each 500µF caps. That's what my comment is about.

So, do you want to replace the cap in your pic or do you want to replace a 2000µF cap? You don't think the cap in the pic is a 2000µF cap, do you?

No,I don't.
my question was based on what was printed on the schematics and parts list.
Tbh i was questioning in my mind the difference between what was said to be there on the schematic
and what i was actually seeing.
 
Why i asked about using 2-1000uf 50v caps in parallel, Wouldn't that
accomplish the same thing as using 3-470 uf 50v with less connections?
 




Guess i'm asking the wrong questions the wrong way.

[sluckey]

Guess i'm asking the wrong questions the wrong way.

We just haven't quite connected with the communications yet. But I think I understand finally.

No,I don't.

The pic has nothing to do with the cap you really want to replace. It was just a confusion factor to me.

So would 2-1000 uf 50v radial Caps wired in parallel do the job?

Absolutely. An alternative is to use a single 2200µF @ 50V. Readily available, even at Radio Shack. If space is limited, a single 2200 would be the preferred cap.

[Willabe]

Is the picture you posted your amp?

There's 2 different things being shown here, 1 a picture and 2 a schematic and parts list. The 2 have different value caps.

If so your really should replace all 3 of the caps that are in that multy cap can. 


            Brad     

[chasenblues]

Is the picture you posted your amp?

There's 2 different things being shown here, 1 a picture and 2 a schematic and parts list. The 2 have different value caps.

If so your really should replace all 3 of the caps that are in that multy cap can.  


            Brad    

Yes the pictures of the internal shot of the amp and the Cap are from the amp i'm trying to fix, Not from the internet.
The pictures of the schematics and parts list are from the net but match the ones that are attached to the back panel of the amp.
Thats why i said in the previous post that what's listed on the parts list is not what's actually in the amp.

Parts list, C15 says.(For G10-G20 models)



This is the Multi Cap thats in the amp (500+500+500=1500 uf)


 
A previous poster mentioned that the parts SHOULD be readily available from Radio Shack,The store that is local to me is a joke. Unless your looking for something to do with cell phones or overpriced plans the staff is useless and their inventory frustrating.

As a PS to the above, I got a better look at the circuit board and saw this Cap. I'm guessing from the bulge that this one has to be replaced also.

[Willabe]

I would replace ALL the electrolytic caps.

It looks like in the picture the 3x500uF caps are in parallel, if so you can get a single 1500uF @ 40v or go ahead and get a single 2000uF @ 40v it'll work fine. Since Doug doesn't stock those values, try Mouser.   

          Brad      

[chasenblues]

Updating my post,

Amp is now running Hum free after replacing bad caps.
Replaced 2wire power cord with 3wire grounded cord.

I have a possible issue with the trem circuit.

With the trem "intensity" knob in the off position the amp sounds normal and loud when turned up
and the rest of the amps settings function as normal.

When turning the pot to increase the "intensity" of the trem,
the output gets to a certain level but towards the very end of pots range sweep(close to maximum) then the volume drops quite low.
Back the intensity down just a little the volume cranks back up.
 
The trem actually sounds pretty good,The speed control seems to be working as it should.
 
The thread i referenced in my first post had some info in it but it seems to have been purged from the site.
Any troubleshooting suggestions?

Schematic of trem circuit,


 

[PRR]

Carefully adjust the "FET Bias" trimmer. You want the FET to be "barely on", not "FULL on".

But the droop at full Inten is "normal" for this simple circuit, you won't be able to cure it.

[chasenblues]

Ok thank you,

I see the trimmer on the schematic,
There appears to be two trimmer attached to the board which one would be the FET Bias?







Thank you for your help.

[HotBluePlates]

I see the trimmer on the schematic,
There appears to be two trimmer attached to the board which one would be the FET Bias?

Well, we don't have the amp in front of us, or have a complete schematic. So you're asking a lot of us to know the details of your amp. 

Here's my best guess, which could be wrong:
Look at the schematic fragment you posted for the trem circuit. R30 is connected to the wiper of the FET bias trimmer, and your parts list says R30 is 220kΩ. I see a 220kΩ resistor just above the upper trimmer in your picture, so I'd guess that trimmer is the FET bias.

Notice that your parts list has 2 trimmers mentioned, R13 (100kΩ, FET bias) and R29 (2.5kΩ). If you can measure resistance of any part of the trimmers, the one which is 100kΩ should be pretty obvious.