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Harman Kardon 430 Crackling Issue

robz2000

robz2000

New Member
Hi,
I'm trying to do a restore on a harman Kardon 430. should be simple enough. But I've come across an issue i cannot track down. There is a crackle at all volumes. not a hum, but crackle. It occurs through headphones & the speakers. in both channels.
it has to be the pre amp i would think .I've recapped the tone board, and nothing. i didn't touch the transistors on the tone board, as I've rarely seen issues there on any other amp, including HKs.
other observations...
no change with any controls, volume, bass, treble, balance etc.
no extra crackle on pushing volume knob.

touching the wires behind both the volume and the selector switch, seem to either increase or decrease the crackle, but not much at all. but i think i hear a little more/less if those wires are moved.
all controls have been treated with deoxit 3x at this point, including the push buttons.

i am shying away from the amp board, and big transistors and caps as the issue is happening in the headphones as well as the speakers, but i'm obviously missing something here!!

any suggestions would be much appreciated.
ty
Rob
 
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robz2000 said:
touching the wires behind both the volume and the selector switch, seem to either increase or decrease the crackle, but not much at all. but i think i hear a little more/less if those wires are moved.
all controls have been treated with deoxit 3x at this point, including the push buttons.
Click to expand...
Check solder connections..
 
Last edited:
Both channels -- only thing in common is the AC power on/off switch - fuse FU8/fuse holder or the input power selector ( if equipped).. Do the lamps flicker ?

Power on/off switch could be arcing. Fuse clips could be loose or oxidated.
 
Last edited:
Yeah. Both channels. I have looked and looked and tapped and tapped. Haven't found that loose connection yet either
 
Will check on lamps flickering. But I don't think they were. Will check that fuse too. Thanks for the info avionic
 
Does this unit have a voltage selector on the rear panel or internally.
 
I think it might. Turned the lights out for the eve. I will be back at this one in the am
Thanks again avionic, you've given me a few things to go over here.
 
robz2000 said:
There is a crackle at all volumes. not a hum, but crackle. It occurs through headphones & the speakers. in both channels.
it has to be the pre amp i would think .I've recapped the tone board, and nothing. i didn't touch the transistors on the tone board, as I've rarely seen issues there on any other amp, including HKs.
other observations...
no change with any controls, volume, bass, treble, balance etc.
no extra crackle on pushing volume knob.
Click to expand...

The crackling you're describing sounds a lot like the "popcorn popping", "snap crackle pop", or "very erratic, loud static" common when older small signal transistors "go noisy".

We've got a thread listing all the common, "known to go noisy" transistors... and some of the replacements for them here: https://www.audiokarma.org/forums/i...ilure-prone-whatever-and-replacements.731653/

The HK 430 and HK 330C are nearly identical, other than the power supply, so here are the transistors to consider replacing (in the 330C, so you'll have to translate to the 430):

Board Component Model
Power supply Q1 2SD414 Q or R TO-126 package KSB546YTU
Power supply Q601 2SA844 E TO-92 package KSA1220AYS
EQ amp Q101,Q102 2SC1344 E Replace with KSC1845F
Main amp Q421,Q422 2SC458 B Replace with KSC1845F
EQ amp Q013,Q104 2SA844 E Replace with KSA1015 GR
EQ amp Q101,Q102 2SC1344 E or 2SC1775 E Replace with KSC1845 F
Main amp Q417-Q420 2SD476A Replace with MJE15032
Main amp Q607,Q408,Q415,Q416 2SC1509 (S or R)
Main amp Q409,Q410,Q413,Q414 2SA777 (S or R)
Main amp Q401-Q406 2SC1345 (f) Closest is KSC1845 but Ic max exceeded
 
thanks DLUCY. i am hesitant on these, as the noise happens on all inputs, volume turned down ,and via headphones. would any of the transistors above cause such a widespread noise? that said, i have not repalced any transistors yet, so it's a def possibility. i'm going to go over FU08 and the power switch and rule that out first, then i'll see what looks common above. thanks again (BTW, your write up here on the HK 730 is spectacular!)
 
dlucy said:
The crackling you're describing sounds a lot like the "popcorn popping", "snap crackle pop", or "very erratic, loud static" common when older small signal transistors "go noisy".

We've got a thread listing all the common, "known to go noisy" transistors... and some of the replacements for them here: https://www.audiokarma.org/forums/i...ilure-prone-whatever-and-replacements.731653/

The HK 430 and HK 330C are nearly identical, other than the power supply, so here are the transistors to consider replacing (in the 330C, so you'll have to translate to the 430):

Board Component Model
Power supply Q1 2SD414 Q or R TO-126 package KSB546YTU
Power supply Q601 2SA844 E TO-92 package KSA1220AYS
EQ amp Q101,Q102 2SC1344 E Replace with KSC1845F
Main amp Q421,Q422 2SC458 B Replace with KSC1845F
EQ amp Q013,Q104 2SA844 E Replace with KSA1015 GR
EQ amp Q101,Q102 2SC1344 E or 2SC1775 E Replace with KSC1845 F
Main amp Q417-Q420 2SD476A Replace with MJE15032
Main amp Q607,Q408,Q415,Q416 2SC1509 (S or R)
Main amp Q409,Q410,Q413,Q414 2SA777 (S or R)
Main amp Q401-Q406 2SC1345 (f) Closest is KSC1845 but Ic max exceeded
Click to expand...

I just checked Digi-Key and the KSA1220AYS is obsolete. What would be a good replacement?!
 
robz2000 said:
thanks DLUCY. i am hesitant on these, as the noise happens on all inputs, volume turned down ,and via headphones. would any of the transistors above cause such a widespread noise? that said, i have not repalced any transistors yet, so it's a def possibility. i'm going to go over FU08 and the power switch and rule that out first, then i'll see what looks common above. thanks again (BTW, your write up here on the HK 730 is spectacular!)
Click to expand...

a noisy transistor in the preamp, tone control or power amp could behave like this.
 
thanks again everyone. i've ordered a few of the transistors on the tone board and power board, and we'll see if that does the trick here. if not i'll prob sell as is an move on. jsut can't afford to spend more time that that on this particular device. And i thought it was going to be an easy 90 restoration!!!! that's how it goes sometimes i guess! thanks again everyone.
 
Before replacing capacitors and transistors wall to wall in your receiver, there are a few steps to do.

First of all, make sure the power transistors are secured to the heat sink. The collector of the power transistors is electrically connected to the board by the mounting screws. Tighten these screws.

If the above step does not cure the problem, short the input pin (IN) to the ground (adjacent E) pin on the power amplifier board, with a short wire. Do that for both channels. If there is no change in the noise, the problem is within the power amplifier section. If the amp is quiet with the inputs of the power amplifier shorted to ground, the problem comes from the preceding stage(s).
 
All of the transistors on the preamp / tone board are known to go noisy, so these are likely to be causing some amount of the noise:

  • Q501,Q502 2sc1344 -> KSC1845F
  • Q503-Q506 2sc1344 -> KSC1845F

Similarly, some of the small signal transistors on the main amp board are known to go noisy:

  • Q401-Q406 2sc1345 -> KSC1845F

Some of those on the main amp board are very, very highly likely to go noisy and should be replaced on sight:

  • Q421,Q422 2sc458 -> KSC1845F

There are a few more small signal transistors on the main amp that are not notoriuos for "going noisy", so I would wait until after replacing the above before swapping these for modern, lower-noise, higher-performance ones:

  • Q407,Q410,Q415,Q416 2sc1509
  • Q408,Q409,Q413,Q414 2sa777
 
ecluser said:
Before replacing capacitors and transistors wall to wall in your receiver, there are a few steps to do.

First of all, make sure the power transistors are secured to the heat sink. The collector of the power transistors is electrically connected to the board by the mounting screws. Tighten these screws.

If the above step does not cure the problem, short the input pin (IN) to the ground (adjacent E) pin on the power amplifier board, with a short wire. Do that for both channels. If there is no change in the noise, the problem is within the power amplifier section. If the amp is quiet with the inputs of the power amplifier shorted to ground, the problem comes from the preceding stage(s).
Click to expand...
My HK430 has a similar issue as robz2000, except mine crackles on the right channel regardless of input (FM, AUX, PHONO). I shorted the pins on the power amp, and the amp is quiet when shorted. Thus, based on your suggestion, meaning that the problem is probably located in the tone/preamp board. I replaced the six troublesome 2SC1344s (Q501-Q506) in the tone/preamp board with KSC1845s. This didn't fix the issue. The crackling continues on the right channel only. What would you suggest I do next?
 
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