Capacitor identification

[lasse]

Hello,

Below is a link to a thread about my attempt to bring back my old H/K Citation 11 back to opeative status.

http://techtalk.parts-express.com/showthread.php?240968-Recapping-and-more

Now, I have come a bit further and would like you to help me in identifying a few capacitor-types found inside.

See attached pictures:



My short question is: What types are they (type 1, 2 and 3) and should they be replaced?

And what about the flat round yellowish type? They are said to be horrible in audio circuits but very stable? Can you assume that the H/K designers knew what they did and picked the right type for the application or should I (amateur as I am...) override this and replace them with something else?

Best regards//lasse

[lasse]

Re: Capacitor identification

Hello again,

By the way, what do you think of little white dots, showing up on disc-caps?

Regards again,//lasse

[Ron_E]

Re: Capacitor identification

#1 is polystyrene, #2 looks like mica, and #3 is most likely some kind of film capacitor. I believe all three types are stable over time and polystyrene caps are very good audio caps. I'm sure someone will correct me if I'm wrong.

Ron

[rone]

Re: Capacitor identification

#1 is polystyrene, #2 looks like mica, and #3 is most likely some kind of film capacitor. I believe all three types are stable over time and polystyrene caps are very good audio caps. I'm sure someone will correct me if I'm wrong.

I'm not 100% sure #1 is polystyrene, but it could be - the board stencil looks like it says 6800, which is rather large unless it is in nanofarads. 2 and 3 appear to be film types that you don't need to worry about. I would focus on the silver and black and blue "can" caps in the upper of the two boards in that picture, and the black ones in the lower board.

[Ron_E]

Re: Capacitor identification

I'm not 100% sure #1 is polystyrene, but it could be - the board stencil looks like it says 6800, which is rather large unless it is in nanofarads.

It's definitely polystyrene. I have an assortment of Mallory polystyrene's in their original boxes with values up to .056uf (56000pf on the box). The 6800 value is in picofarads. I have some assorted surplus 6800pf polystyrene's and some even have the MIAL logo like the cap in the picture.



Ron

[Pete Basel]

Re: Capacitor identification

I think #2 is a paper cap and you probably should replace it with
a mylar or poly film type also with a 5% or better tolerance.
#2 looks like the old Sprague "Orange Drop" type but obviously
it is not orange.

Polystyrenes are excellent capacitors but they do not handle heat
well, not an issue in that application but be careful when soldering
them. I would not replace them.

Edit: I'm not positive about #2, I have seen many of them in very old
equipment and they might be polyester (mylar) but I'm not sure - ask
around. I probably have one in the junk box and can cut it open if
you want to know.

[lasse]

Re: Capacitor identification

Hi

thanks for all the feedback on the more strange types of caps in my old unit. I will follow your advice and replace "nr 2" which it is represented in a few more spots in the unit!

For the moment, I´m struggling with the decision on which brand/type of electrolytic to switch to in the unit. I´m leaning towards Panasonic FC. Comments on that? (This will probably never end- A novice has let himself under the hood of a amplifier.....)

Regards and thanks for your patience//lasse

[lasse]

Re: Capacitor identification

I think #2 is a paper cap and you probably should replace it with
a mylar or poly film type also with a 5% or better tolerance.
#2 looks like the old Sprague "Orange Drop" type but obviously
it is not orange.

Polystyrenes are excellent capacitors but they do not handle heat
well, not an issue in that application but be careful when soldering
them. I would not replace them.

Edit: I'm not positive about #2, I have seen many of them in very old
equipment and they might be polyester (mylar) but I'm not sure - ask
around. I probably have one in the junk box and can cut it open if
you want to know.

Hello,

The H/K Tech manuals component list states "Mylar" on that type but it looks a bit "burned" on the upper part.
I Think that the general rule is to not replace Mylars?

Regards//lasse

By the way, this morning (Swedish time-night in the populated areas of the globe...) i traced down all of the resistors of the PS and the main preamp board-I will start with those two, apart from electrolytics in the whole machine.

Some of the installed resistors differ from the schematics-I suppose that I should replace with the installed value.

//l

[Pete Basel]

Re: Capacitor identification

Right I would not replace mylars unless you suspect a problem with them.

[Pete Basel]

Re: Capacitor identification

Have you seen this very old article about picking capacitors?

http://waltjung.org/PDFs/Picking_Capacitors_1.pdf

Part 2:

http://waltjung.org/PDFs/Picking_Capacitors_2.pdf

[lasse]

Re: Capacitor identification

Have you seen this very old article about picking capacitors?

http://waltjung.org/PDFs/Picking_Capacitors_1.pdf

Part 2:
http://waltjung.org/PDFs/Picking_Capacitors_2.pdf

Hello and thanks Pete!

A quick glance shows that the topologies described in the texts are directly applicable in my vintage preamp!

Best regards//lasse

[clydethecat]

Re: Capacitor identification

Edit: I'm not positive about #2, I have seen many of them in very old
equipment and they might be polyester (mylar) but I'm not sure - ask
around. I probably have one in the junk box and can cut it open if
you want to know.

I'm pretty sure the brown caps are polyester, they're CDE's product to compete directly with the Sprague Orange Drop.

I imagine the white boxes are polyester too.

[Pete Basel]

Re: Capacitor identification

Thanks, yes, CDE was the brand I was trying to remember.

lasse, I changed the coupling caps in the line stage to inexpensive (not boutique)
polypropylene caps just because of their durability and they are considered to
sound best - though I doubt in blind tests that anyone would hear a difference.

People make all sorts of claims but when put to a blind test caps do not usually
make a difference.

If you go to the trouble of changing the mylars you might as well use low cost
polypropylene types if you can find them at reasonable prices in your country.

[robertcottiers]

Re: Capacitor identification

I certainly recommend that after changing most of the caps and resistors in that pre-amp some testing would be in order,at the very least a frequency sweep in the audio band to make sure that you have not introduced any frequency response deviations with all of the new components.

Bob

[Pete Basel]

Re: Capacitor identification

Yes, and do the work in phases.
Coupling caps, test
PSU caps, test
Phono caps, test
Line Resistors, test
Phono resistors, test
Check resistor values with and ohm meter as you remove them,
and as you install new ones. Just in case you mis-read something.