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Help to identify capacitors and diodes

E

Eugen T

Jan 1, 1970
0
Hi all,

I have schematic with a couple of capacitors that that I don't know the
value - I don't have access to capacitance meter right now :(

Caps are pretty small, about the size of 1/4 Watt resistors - most probably
in pico-farads. Here is what I found written on some of them:
K5U 334M, K5R 43K, 221 ???, FC2 9916, 104 K5X
I think I'll just replace them with similar size/look caps, but it would be
nice to know their exact values.


Also, can somebody tell me how to figure out if the diode in schematics is
Zener or just a diode? There is no schematic available for the thing that I
am working on (propriatary stuff) - one little red diode/zener is blown
apart - I can't even read what's written on it (well, there is starting 1N -
but 1N series include both - zener and 'normal' diodes). Diode is in series
with (resistor parallel to capacitor) on negative end and, I believe,
capacitor on the other (positive). I think it's just a diode, because 1). I
am 99% sure it's in path of small signal (unamplified sound to power amp)
and 2). It looks like 3 other similar looking diodes (NOTHING WRITTEN ON
THEM - only line in the middle - direction can be figured out by line drawn
on PCB).
 
T

The Real Andy

Jan 1, 1970
0
Hi all,

I have schematic with a couple of capacitors that that I don't know the
value - I don't have access to capacitance meter right now :(

Caps are pretty small, about the size of 1/4 Watt resistors - most probably
in pico-farads. Here is what I found written on some of them:
K5U 334M,
0.33uF

K5R 43K,

43pf perhaps. The K could be a temp coefficient, a working voltage or
multiplier. Hard to say.
221 ???,
220pf


FC2 9916,
no idea
104 K5X 0.1uF


I think I'll just replace them with similar size/look caps, but it would be
nice to know their exact values.

The K5R, K5U and K5X sound like different types of dielectric.
Also, can somebody tell me how to figure out if the diode in schematics is
Zener or just a diode? There is no schematic available for the thing that I
am working on (propriatary stuff) - one little red diode/zener is blown
apart - I can't even read what's written on it (well, there is starting 1N -
but 1N series include both - zener and 'normal' diodes). Diode is in series
with (resistor parallel to capacitor) on negative end and, I believe,
capacitor on the other (positive). I think it's just a diode, because 1). I
am 99% sure it's in path of small signal (unamplified sound to power amp)
and 2). It looks like 3 other similar looking diodes (NOTHING WRITTEN ON
THEM - only line in the middle - direction can be figured out by line drawn
on PCB).

Can you provide us with some pictures? Sounds like they could be
1N4148's or 1N914s. Are they encapsulated in glass?
 
E

Eugen T

Jan 1, 1970
0
The Real Andy said:
43pf perhaps. The K could be a temp coefficient, a working voltage or
multiplier. Hard to say.

no idea


The K5R, K5U and K5X sound like different types of dielectric.


Can you provide us with some pictures? Sounds like they could be
1N4148's or 1N914s. Are they encapsulated in glass?
Hi Andy,

Wow, thanks so much for identifying these caps. If it's not a secret, what
manual did you use to id them?

I will definitely make pictures of diodes, post them and then post links
here a bit later.
The diodes are encapsulated in glass - I found a couple of diodes in exactly
same configuration on the board (parallel with resistor) - one of them is
totally blown away, second is 1N 4150.

The second set of diodes (4, the ones that I mentioned in previous post) are
all the same, red in color, encapsulated in glass, very small. The one
that's blown may not be the same one after all, but I'll post pictures -
three diodes are in the same direction, fourth is in the opposite direction
from them - they are all lined up on PCB - one thing I found on this broken
diode - last number of model is 4.
 
A

Asimov

Jan 1, 1970
0
"Eugen T" bravely wrote to "All" (09 Jun 04 18:47:40)
--- on the heady topic of "Help to identify capacitors and diodes"

ET> From: "Eugen T" <[email protected]>

ET> Hi all,

ET> I have schematic with a couple of capacitors that that I don't know
ET> the value - I don't have access to capacitance meter right now :(

ET> Caps are pretty small, about the size of 1/4 Watt resistors - most
ET> probably in pico-farads. Here is what I found written on some of them:
ET> K5U 334M, K5R 43K, 221 ???, FC2 9916, 104 K5X
ET> I think I'll just replace them with similar size/look caps, but it
ET> would be nice to know their exact values.

Capacitors have a manufacturing code for their type, using numbers
and letter such as NP0, Y5U etc. It often refers to the temperature
coefficient (tempco). The value is usually in pF indicated by a 2
digit number followed by the multiplier and a letter for precision. So
your first above example K5U 334M might indicatea K5U tempco
characteristic of value 330,000 pF or 330nF with M or 20% precision.
The next one would be only 43pF with 10% precision etc. Look up the
capacitor codes FAQ for a complete listing.


ET> Also, can somebody tell me how to figure out if the diode in
ET> schematics is Zener or just a diode? There is no schematic available
ET> for the thing that I am working on (propriatary stuff) - one little red
ET> diode/zener is blown apart - I can't even read what's written on it
ET> (well, there is starting 1N - but 1N series include both - zener and
ET> 'normal' diodes). Diode is in series with (resistor parallel to
ET> capacitor) on negative end and, I believe, capacitor on the other
ET> (positive). I think it's just a diode, because 1). I am 99% sure it's
ET> in path of small signal (unamplified sound to power amp) and 2). It
ET> looks like 3 other similar looking diodes (NOTHING WRITTEN ON THEM -
ET> only line in the middle - direction can be figured out by line drawn on
ET> PCB).

The Zener diode symbol has little angled dashes added in opposite
sides onto the diode cathode dash. Something like this:
|
/-|-/
/ \
~|~
|

Find the electronic component symbols FAQ for more info. Anyways the
silkscreen will usually label a zener with a prefix ZDxxx instead of
Dxxx for a diode. So that's another way to tell. But you can be pretty
sure the diode is not a zener because audio amplifiers rarely use
them.

These diodes might be just regular diodes but the red body colour is
sometimes found on temperature reference diodes used for biasing the
output power transistors. These are designed to exhibit the same
temperature/voltage curve as power transistors so as to keep the bias
idle current constant as they heat up. These reference diodes are
often in contact with the heatsink but perhaps not in your amp.
But since you say it is in the signal path it's not sure what it is.

A*s*i*m*o*v

.... I worked hard to attach the electrodes to it.
 
E

Eugen T

Jan 1, 1970
0
A couple of dead caps read:
KAQ 136 and K2A "104" - I believe it's 104 - it's pretty burned from heat of
another component burning beside it.

I'm still working on getting macro lens for my digital camera to take
pictures of these suckers :(
 
T

The Real Andy

Jan 1, 1970
0
On Thursday, 10 Jun 2004 09:55:06 -500, "Asimov"

Capacitors have a manufacturing code for their type, using numbers
and letter such as NP0, Y5U etc. It often refers to the temperature
coefficient (tempco). The value is usually in pF indicated by a 2
digit number followed by the multiplier and a letter for precision. So
your first above example K5U 334M might indicatea K5U tempco
characteristic of value 330,000 pF or 330nF with M or 20% precision.
The next one would be only 43pF with 10% precision etc. Look up the
capacitor codes FAQ for a complete listing.

http://www.wescalkorea.com/product/kemet/C315_C350.pdf shows a data
sheet for a series of capacitors. It gives some detail on the package
marking at the end of the pdf. Just to add to Asimov's post, the K5U
is actually the type of dielectric used. This does effect temp
stability, but will also affect working voltages among other things.

These diodes might be just regular diodes but the red body colour is
sometimes found on temperature reference diodes used for biasing the
output power transistors. These are designed to exhibit the same
temperature/voltage curve as power transistors so as to keep the bias
idle current constant as they heat up. These reference diodes are
often in contact with the heatsink but perhaps not in your amp.
But since you say it is in the signal path it's not sure what it is.

Diodes that measure temp are normally just standard diodes or
transistors. The junction voltage varies around 2mv/degC from memory.
This method is fairly standard
 
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