Capacitor brand/type for NAD amp?

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

My NAD 3125 may need new caps (it is 20 years old). All original caps
look fine, and are ELNA brand, either RE or CE series. I cannot find
ELNA online, although I may check a local store. I've been told
Panasonic FC series are good. Are they a suitable replacement for the
originals? They are "low impedance" - is this the important criteria
for audio? ELNA appears to be well respected in the audio world from a
bit of searching I've done, so I don't want to lose any of the
original NAD sound by using the wrong caps.

The one problem my amp has (see earlier post) seems to be isolated to
the left channel infrasonic filter section. Assuming I can resolve this
be replacing the caps in that section, should I just quit there?

Many people have said to just replace all caps on a 20 year old amp,
but the Panasonic spec sheets show that 20-30 years is a reasonable
lifespan for caps at near room temps. The 1000-2000 hrs ratings seem to
be at the max operating temps. Replacing all the caps seems like a
fair bit of trouble, especially if the result is a possible loss of
sound quality if the new caps are inferior to the originals, in terms
of audio quality. Any insight is appreciated!

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

"TDWesty" <vwdiesels@gmail.com> wrote in message
news:1118983405.653035.211470@g47g2000cwa.googlegroups.com...
> My NAD 3125 may need new caps (it is 20 years old). All original caps
> look fine, and are ELNA brand, either RE or CE series. I cannot find
> ELNA online, although I may check a local store. I've been told
> Panasonic FC series are good. Are they a suitable replacement for the
> originals? They are "low impedance" - is this the important criteria
> for audio? ELNA appears to be well respected in the audio world from a
> bit of searching I've done, so I don't want to lose any of the
> original NAD sound by using the wrong caps.
>
> The one problem my amp has (see earlier post) seems to be isolated to
> the left channel infrasonic filter section. Assuming I can resolve this
> be replacing the caps in that section, should I just quit there?
>
> Many people have said to just replace all caps on a 20 year old amp,
> but the Panasonic spec sheets show that 20-30 years is a reasonable
> lifespan for caps at near room temps. The 1000-2000 hrs ratings seem to
> be at the max operating temps. Replacing all the caps seems like a
> fair bit of trouble, especially if the result is a possible loss of
> sound quality if the new caps are inferior to the originals, in terms
> of audio quality. Any insight is appreciated!

Panasonic FC capacitors are electrolytics. The high-value electrolytics you
mentioned (50v 4700uF and 1000uF) will be used in the power supply section,
which is working fine in your amplifier (I think you said your amplifier is
working fine with CD and DVD inputs, but not with tuner and VCR inputs.)

For the problem you have - weak signal on left channel when using tuner or
VCR inputs - you need to establish the cause. I'd guess it's a defective
switch or connection somewhere.

It could be a very minor fault, but may take an engineer several hours to
track down.

Tim

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

In article <1118983405.653035.211470@g47g2000cwa.googlegroups.com>,
TDWesty <vwdiesels@gmail.com> wrote:
> Many people have said to just replace all caps on a 20 year old amp,

I've got a '71 Quad system still working fine. The AM tuner has had a few
sets of valves, and I've cleaned or replaced a few pots and switches. But
not one cap...

--
*42.7% of statistics are made up. Sorry, that should read 47.2% *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

I've sprayed all the switches & pots with contact cleaner, and the
resistance across the terminals off all the input switches are the same
- about 0.5 ohms. It is a bank of 4 switches (tape, cd, tuner, phono)
soldered directly to the board, so without a desoldering tool, removal
looks to be fairly tricky. Tape works fine, CD & tuner are bad in the
left channel.

I may try to replace the transistor for the infrasonic filter, which is
apparently bypassed for the tape input. I need to find one, it is not a
common one - C1845.

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

Hello,

Well, that transistor is a 2SC1845, and is really common.

--Tim


TDWesty wrote:
>
> I've sprayed all the switches & pots with contact cleaner, and the
> resistance across the terminals off all the input switches are the same
> - about 0.5 ohms. It is a bank of 4 switches (tape, cd, tuner, phono)
> soldered directly to the board, so without a desoldering tool, removal
> looks to be fairly tricky. Tape works fine, CD & tuner are bad in the
> left channel.
>
> I may try to replace the transistor for the infrasonic filter, which is
> apparently bypassed for the tape input. I need to find one, it is not a
> common one - C1845.

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

In article <d99bb1lm89qs8rulckpdtecdcqq2dulg2c@4ax.com>,
Laurence Payne <lp@laurenceNOSPAMpayne.freeserve.co.uk> wrote:
> If you're not equipped for desoldering a switch, are you sure you
> should be contemplating a recap?

I'd normally remove a multipole switch by clipping the contacts etc to
minimise damage to the pcb. Many are a pretty tight mechanical fit.

And I do have a desolder station.

--
*If a pig loses its voice, is it disgruntled? *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

Archived from groups: sci.electronics.repair,rec.audio.tech (More info?)

In sci.electronics.repair TDWesty <vwdiesels@gmail.com> wrote:

: The one problem my amp has (see earlier post) seems to be isolated to
: the left channel infrasonic filter section. Assuming I can resolve this
: be replacing the caps in that section, should I just quit there?

I'd suggest finding the source of the problem vs. shotgunning parts that
are likely not to fix the problem. The "low impedence" capacitor is probably
a low ESR capacitor. Impedance is a result of the value of the capacitor
which is intrinsic, plus the inductive reactance of the leads/foils.

Most stereo equipment is "step and repeated" in their PC board designs.
You have one working side and one with low signal. Compare (using an
oscilloscope) the working side components vs. the nonworking side.
It's helpful to have a schematic to see where the positions of the
components are but a skilled technician/engineer can often follow the
signal paths by the physical layout.

I have repaired electronic equipment for decades and have never seen a
need to brute-force "every electrolytic capacitor" in any piece of
equipment. It just seems foolish to me. Especially if the equipment
has been in use (electrolytic capacitors do fail by "reversed polarity"

B.