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Old 17th April 2009, 07:18 PM   #1
Stream is offline Stream  Russian Federation
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Default Resistor instead of Cap in HK347

Hello. I need Your help. Today I disassambled friend's HK AVR 347 Reciever to prepare it for some tweaks, which was planned for tomorrow.
When I satrted to search all the caps I should change, I was Stunned - I saw some resistors in place where service manual describes capacitors!

Here is scheme and that "caps":

Click the image to open in full size.

So how it was:
1. I'm reading service manual, seing "c507 - 330pF ceram. capacitor"
2. Searching c507 on board.
3. See marking "c507" on board, but it is resistor there!
4. Closed my eyes and try again, but FAIL again!

So, PLEASE explain me, whats happening. I haven't repaired or tweaked solid state amp before, so maybe I just didn't realize something and this is normal...

I haven't photos now, I will share them tommorow.
But it's VERY important to have answer as fast as posible...

Thank You.
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Old 17th April 2009, 07:37 PM   #2
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They are small capacitors looking like resistors. Don't worry.
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Old 17th April 2009, 08:42 PM   #3
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Thanks. I though about this, but they looks like resistors, so I was very shocked.

Then, If it's ok, I would like to disscuss on this scheme at all.

I'm planning next replacing:
C637, C632 to Panasonic FC 220uf
c562 Elna silmic II 100uF
c607 - Silver Mica

I'm intersed on purpose of next caps (If it worth changing on some better cap):
c507 - if it just cap to remove some RF noise?
c572 - ?
c567 - just for Mute operation and not important for SQ, right?
c682 - ?

P.s. I'm also will be pleased with some another advices on tweaking this scheme.
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Old 17th April 2009, 10:08 PM   #4
mjf is online now mjf  Austria
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hello.
the numbers in the schematic are not easy to read........
input c507 attenuates rf
c 572 compensation against oscillations - sensible part
c 567 for muting,not in the signal path
c 682 looks like a part of a protection circuit.
if the electrolytics 10 years old and more perhaps you can change them all ..........panasonic fc/fm and so are a good choice i think.......
for the cap in the feedback leg (c 142?) i would use a nonpolar elcap.................
greetings............
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Old 18th April 2009, 04:27 AM   #5
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Sorry, here is larger image:
Click the image to open in full size.

I think c562 is feedback cap.
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Old 18th April 2009, 05:20 AM   #6
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And here is photo:
Click the image to open in full size.
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Old 18th April 2009, 08:01 AM   #7
mjf is online now mjf  Austria
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thank you,now i can read the numbers...........
c 562 is the number of the feedback cap.
foto: c507 (yellow-green) looks like an axial ceramic cap....o.k.
if you like to experiment with sound: input elcap c502 can be changed to a 10uf high quality elcap......or you can bypass it with a foilcap.............
greetings...............
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Old 18th April 2009, 06:19 PM   #8
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Yep those green resistor lookalikes are really ceramic capacitors. I guess they use these because they are easy for pick-and-place machines to handle.

If you really wish to swap, change them for silver mica or polystyrene
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Old 22nd April 2009, 02:42 AM   #9
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I concur: yes, they look like 1/8W resistors, but are in fact capacitors. I have seen this before in the most unlikely place: a super Nintendo cartridge. The silkscreen said "C__" not "R__".
Maybe someday they will make ICs that look like resistors, too.
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Old 22nd April 2009, 12:48 PM   #10
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Thank You All! Harman is successfilly recaped and now sounds better

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