Can an amateur refurb and update a KA-7100?

[neevo]

The volume has moved even further and I keen to get some thoughts from those in the know to see if it's normal or I have a problem.

We had a house sitter round last night looking after the kids. They thought they would play some music but couldn't get the settings right to play anything. However the amp was left at full volume but on a setting where no music would play (Tape).

Today it seems like the volume is no where near as sensitive as it used to be. Before 1/4 was regular listening volume, however now it appears that it's more like 1/3.

I don't think I have ever turned the volume up to full with the amp turned on after the recap so maybe the action of unloading the volume pot has done something internal... but I'm not sure.

Is this normal?

Sound is exactly the same. Volume knob just needs to be turned more. It's actually better as I have more variable volume from 0 to 1/3 turn. Just want to make sure it's not a sign of something worrying.

Is it worth checking the bias and voltage?

 

[jheu02]

Is the Muting switch "on", that would account for having to turn the volume knob more. Some actually do this on purpose for just the reason you're stating...get to use a different part of the volume knob for normal listening.

 

[neevo]

No, its not the mute switch (I use that for dropping the needle sometimes). I'm not overly worried about it as the amp seems to play fine. It just seems like the action of using all of the volume potentiometer somehow reset the action of the volume potentiometer. Like I mentioned above, the placement now for normal listening is much better and I actually get better lower volume control as each click on the volume pot is a smaller increment of db now.

Is it worth rechecking bias and centre voltage or would those not have any impact on output volume?

 

[jheu02]

Probably wouldn't affect it. Just thought of another possibility, could a ground wire have come loose or broken? That can sometimes lead to volume issues.

 

[neevo]

Interesting you mention that. I do have a floating ground on the TT at the moment as it has a banana connector and I need to remove it to put it back on the amp ground post (hadn't yet as the hum isn't really noticeable and my tube preamp should be back on soon). Let me take the banana connector off, put the wire back on the amp and report back.

 

[jheu02]

I was actually thinking of the ground wires on the volume pot, but if you've only been listening to albums, perhaps that's part of it. Any other sources you could try?

 

[neevo]

Only have a baseline of where the vol pot should be as before yesterday it was a 100% vinyl only amp. Added a SONOS connect to as a source yesterday which I have no idea how that should sound and where it should be on the dial.

 

[philster]

My two cents: When it comes to ordering parts, don't rely completely on service manuals or someone else's parts list. Do your own careful visual inspection of every board and see what is actually in your unit, "on the ground." You may find different part values and marking errors on boards. Generally, go with what's actually installed instead of what's on the parts list.

Plus, a thorough inspection can reveal damaged components, evidence of prior repairs, bad solder joints, heat damage, possible fit problems with new parts, etc. And you get to know your new toy this way.

Very good idea. I found Nikko amps to have stated values on the schematics and something different in the circuit.

 

[God_Of_Hi-fi]

[QUOTE = "turboyam, post: 9596922, üye: 17610"] C.coyle'ın dediği gibi, parça listelerine güvenmeyin, bazen amfinizde bazen farklı sürümler ve farklı bileşenler olabilir.
Ben de bir acemiyim ve zaten 5 amfi ve tuneri sorunsuz bir şekilde yeniden kapladım. Acele etmeyin ve her seferinde bir tahta yapın, sonuçları test edin
her pano arasında yeniden başlık yaparsınız. Sipariş verirken polarize olmayan kapaklara da dikkat edin!. [/ QUOTE]



Your opinion is very correct .. For example, a friend of mine would buy a Technics Amplificator, but I could not be with him that day. He said that the capacitors had changed and he said that he gave up buying. He thought that the capacitors of this Amplifier were blue and not in their original state.the capacitors of the same model profucedin the first half of the year are colored black... The capacitors of the same model produced in the second half of the year are also colored blue .. Sometimes you may make very wrong decisions because you do not know them. By the way, the first place to look when buying a Kenwood Ka-7100 is the Cap Transistors inside the huge Ic block. written colored red Toshiba .. Just like Sansui 9090db series .. Sometimes, instead of these transistors, Senken or different brands are used Because the outputs are blown .. Pay special attention to this, The other parts do not matter much. ...