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Old 27th February 2015, 10:33 PM   #21
Zen Mod is offline Zen Mod  Serbia
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caps as caps ........ matter of taste

if you have place - put some 4u7 block caps there

if not , 10uF Elna Silmics , bypassed with 220nF (and up) block cap

I prefer polycarbonats (MKC by Philips coding)
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Old 27th February 2015, 10:59 PM   #22
RS232 is offline RS232  United Kingdom
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Your right, caps are a matter of taste
I do have some 4.7 and 10uf nichicon Muse caps, some Standart Elna ones
For now going to leave it like it is maybe put some bypass caps on the power supply diodes and main capacitors ( 0,1uf MKT ) just to see if I can lower the "noise" I ear when close to the speaker.

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Ric
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Old 28th February 2015, 04:53 AM   #23
Nelson Pass is offline Nelson Pass  United States
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Another happy ending thanks to ZM.

Thank you Sasha.

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Old 28th February 2015, 05:52 AM   #24
AMV8 is offline AMV8  United Kingdom
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RS232
Good to hear that you have repaired the KL amp. I am a big fan of the amplifier and I hope you enjoy yours.

On my KL amplifiers the tantalum caps were only used to filter the power supply to each section of the amplifier being placed between the power supply rails and earth. I have never seen KL use a tantalum cap in line before. On all my amplifiers the in line capacitors are all plastic.

If I want more bass from the KL intergrated I normally assist the bass by partnering the amplifier with a Sony active subwoofer. This does not alter the KL amplifier output but just adds a little extra at the low end. The sony active sub woofers can normally be picked up on ebay for not much cash.

Don
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Old 28th February 2015, 12:34 PM   #25
Zen Mod is offline Zen Mod  Serbia
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having full schm would help in solving minor bass issues .....
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Old 28th February 2015, 04:25 PM   #26
RS232 is offline RS232  United Kingdom
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Thanks to all specially to might Zen
I know a schematic/service manual would be nice but... were to get one
I still have that "noise" from the power supply
What do you guys ( Zen Mod ? ) think about small MKT caps on the rectifiers and main caps I know it doesn't hurt but not an easy task to do in this amp.
There is an other issue I would like to fix but one thing at a time...
And look at this a visit from papa himself, I'm honored

Ric
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Old 28th February 2015, 04:57 PM   #27
Zen Mod is offline Zen Mod  Serbia
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frankly , without schematic , there is slight possibility to point on culprit ..... is PSU or circuit itself prone to noise generating

usually , any snubbing (caps across diodes ) can be just cherry on top , not cure

anyway - if there is any sort of reg , try to change active/passive parts , to cure noise

if it remains the same ..... then circuit itself is to blame

on the other hand - counting that noise is same in both channels , it can be both - due to flaw in common PSU , or inherent to circuit construction

what's happening with noise level when you exclude pre-stage , as in test with CD ditto to pot ........ as I understood - pot is in usual place , between pre stage and , say, power amp ?

to be more precise - if noise is same in both min and max pot position , then culprit is after pot ..... so - look for common things between channels ....
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Old 28th February 2015, 08:28 PM   #28
RS232 is offline RS232  United Kingdom
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Only the supply for the phono/input stage is regulated with 78L15/79L15 with one 200uf 100v cap and 2 10uf + 2 100nf near the regs ground is floating.
Noise is present with or without phono/input stage connected to volume pot.
Power supply is very simple: transfomer - rectifiers (8 of them) - main caps with 40000uf no snubbers anywhere.
The amp design is not the very best it still uses germanium transistores ( AC127/AC128 )and I think the rest of them (8 in total) are ZTX ones
And yes the noise doesn't change with pot position and the only common thing to both channels is the power supply.
I'm going to live with this noise for this weekend right now trying to fix a beautifull Marantz CD73.

Ric

Last edited by RS232; 28th February 2015 at 08:37 PM.
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Old 28th February 2015, 09:04 PM   #29
AMV8 is offline AMV8  United Kingdom
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Your KL amp probably has a seperate power supply for each channel; 4 rectifers per channel and 10 000uf per rail from a common transformer.

The ztx transistors are normal for KL. The ac127/8 I have never seen in a KL amp. The ztx transistors are usually in the vas or driver part of the circuit with a high quality transistor in the amplifier input; which is usually set up as an LTP.

Is it possible that someone changed some transistors sometime and put in the ac127/8 which could be the source of general background noise especially if in the amp input.
Don
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Old 1st March 2015, 12:16 PM   #30
RS232 is offline RS232  United Kingdom
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Hi AMV8
I don't think so, when I bought this amp it was faulty 2 of the rectifiers were shorted
I got that fixed and it worked fine untill a couple of weeks ago.
The board was unmolested all the solder points were original appart from the ones on the rectifiers that I replaced.
From what I could understand from the position of the transistor on the board the AC127/128 are the drivers for the power transistors (I didn't traced the tracks) but they are the last ones before the power stage.
Right now going to leave it as it is because I need to fix a vintage Marantz Cd73 for a friend and is starting to go on my nerves
I'm thinking in copy the board/schematic and post it here but like I sayed I need to fix the CD73 first.

Ric
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