Replacing ceramic disc caps with silver mica caps?

G · 17th November 2002, 11:43 AM

I started refurbishing a Citation 16 that I got for a song because it was in bad shape. I removed the driver boards and cleaned them and then started looking through the circuit diagram. These boards use a lot of ceramic disk caps. Could these ceramic disk caps be replaced with silver mica caps? Also I think that all of the 1/8 watt resistors on the boards are carbon film resistors. Would replacing these with metal film resistors be acceptable or would it compromise that warm HK sound?

G

BrianL · 18th November 2002, 12:41 AM

So, you want to replace bad capacitors with
not-quite-so-bad capacitors.

May I suggest Polypropylene. Also, if you
can get the needed voltage rating and
capacitance, you can try C0G ceramics.
(not other types of ceramic)

My preference is metal film resistors. Start
with the most significant ones -- feedback loop
and anything else directly connected to the inputs
and outputs. Though if you're going to go to the
trouble, you might as well do them all!

peranders · 18th November 2002, 09:21 AM

Nelson Pass had this amp "boosted"

http://www.passdiy.com/pdf/citation.pdf

When the design is a little bit poor and the semiconductors are tired (compared to new devises), the use of changing resistors is little. Sorry. If you still want to change into metal film, it can't hurt.

djk · 18th November 2002, 09:33 AM

If there is a µA739 14 pin dip opamp on that circuit board I think you are wasting your time and money.

Elso Kwak · 18th November 2002, 12:32 PM

Hi,
Just look here what the Bongoman does:

http://groups.yahoo.com/group/SAE_Talk/message/4647
(Replaces all ceramics by dipped silver mica's)

G · 18th November 2002, 02:02 PM

Hi All,

I plan to totally stripping the driver board and replacing all of the components. Including the UA739. So you see I have my choice of resistors and caps . The new BJT's will be MJE182s and 172s and MJE350s and 40s. There are a couple of general purpose BJT's in there but I'm waiting on the service manual before I decide what to use in their place.

G

17th November 2002, 11:43 AM	#1
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Replacing ceramic disc caps with silver mica caps? I started refurbishing a Citation 16 that I got for a song because it was in bad shape. I removed the driver boards and cleaned them and then started looking through the circuit diagram. These boards use a lot of ceramic disk caps. Could these ceramic disk caps be replaced with silver mica caps? Also I think that all of the 1/8 watt resistors on the boards are carbon film resistors. Would replacing these with metal film resistors be acceptable or would it compromise that warm HK sound? G __________________ Gavin

18th November 2002, 12:41 AM	#2
BrianL diyAudio Member Join Date: Mar 2002 Location: USA	So, you want to replace bad capacitors with not-quite-so-bad capacitors. May I suggest Polypropylene. Also, if you can get the needed voltage rating and capacitance, you can try C0G ceramics. (not other types of ceramic) My preference is metal film resistors. Start with the most significant ones -- feedback loop and anything else directly connected to the inputs and outputs. Though if you're going to go to the trouble, you might as well do them all! __________________ bel

18th November 2002, 09:21 AM	#3
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Nelson Pass had this amp "boosted" http://www.passdiy.com/pdf/citation.pdf When the design is a little bit poor and the semiconductors are tired (compared to new devises), the use of changing resistors is little. Sorry. If you still want to change into metal film, it can't hurt. __________________ /Per-Anders (my first name) or P-A as my friends call me

18th November 2002, 12:32 PM	#5
Elso Kwak Banned Join Date: Dec 2001 Location: Zamboanga, City of Flowers, Mindanao	Ceramic vs. Silver Mica caps Hi, Just look here what the Bongoman does: http://groups.yahoo.com/group/SAE_Talk/message/4647 (Replaces all ceramics by dipped silver mica's)

18th November 2002, 02:02 PM	#6
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Hi All, I plan to totally stripping the driver board and replacing all of the components. Including the UA739. So you see I have my choice of resistors and caps . The new BJT's will be MJE182s and 172s and MJE350s and 40s. There are a couple of general purpose BJT's in there but I'm waiting on the service manual before I decide what to use in their place. G __________________ Gavin


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18th November 2002, 09:33 AM	#4
djk diyAudio Member Join Date: Feb 2001 Location: USA	If there is a µA739 14 pin dip opamp on that circuit board I think you are wasting your time and money.

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