Knight KN-928 Amplifier

[harmontt]

Hello Everyone!  I recently found an old Knight KN 928 Tube Amplifier while looking through my dad's old stuff.  It works, but crackles and is very dirty.  I'd like to clean it internally and externally, but I don't want to damage it or the tubes.  Is there any special way I should do this? Any tips on cleaning, operation, or price would be greatly appreciated.  Thanks in advance!

[EmoRarity]

Those tubs look soldered on, good luck replacing them.

[harmontt]

They aren't.  They're socketed and I don't need to replace them.

[creatip123]

Dirty as in the sound, or dirty physically (because it's very dirty in the picture too)?

 

Crackling, dirty, clippings, and volume can't get loud are symptoms of broken tube(s). Might want to consider changing them, if you deem it worth the money. 

[ShearMe]

lots of rubbing alcohol

[harmontt]

Both dirty sound and physically.  Do I have to replace all the Tubes or just some of them, and if just some, then how do I tell which?

[creatip123]

Both dirty sound and physically.  Do I have to replace all the Tubes or just some of them, and if just some, then how do I tell which?

 

That is the hard part. Best way is to use a tube tester, but those aren't consumer electronics. Check for visible defects? The thing with tubes, defects aren't always visible. I dropped my Genalex once, no visible defects, but it's still broken. 

 

And it seems like it's a full tube, not hybrid. Meaning tubes are used in both the power part and the pre-amp part. Perhaps try getting a replacement for the pre-amp tubes first? It's usually the smaller tubes. Just get cheap tubes, if just for testing. 

[harmontt]

Okay.  Would it be possible to take it into a shop to test the tubes?  Also, what should I look for in terms of defects?

[EmoRarity]

That is the hard part. Best way is to use a tube tester, but those aren't consumer electronics. Check for visible defects? The thing with tubes, defects aren't always visible. I dropped my Genalex once, no visible defects, but it's still broken. 

 

And it seems like it's a full tube, not hybrid. Meaning tubes are used in both the power part and the pre-amp part. Perhaps try getting a replacement for the pre-amp tubes first? It's usually the smaller tubes. Just get cheap tubes, if just for testing. 

Voltmeter yo, test for continuity and impedance 

[harmontt]

Voltmeter yo, test for continuity and impedance 

Are there any guides for doing that that you recommend?

[EmoRarity]

Are there any guides for doing that that you recommend?

Youtube, I went to college for it, both will get you to the same place. 

[harmontt]

Youtube, I went to college for it, both will get you to the same place. 

Alright.  My English teacher is into this stuff so I'm going to take it to him to look at.  Thanks for all of your help everyone!

[EmoRarity]

Alright.  My English teacher is into this stuff so I'm going to take it to him to look at.  Thanks for all of your help everyone!

Solid, hope you get it working, would be bitchin. 

[harmontt]

I'll be sure to post more pictures if I get it working.

[harmontt]

So it turns out that it was just the headphone jack was corroded and the speaker outputs work fine.  Sound is very clean, except when adjusting volume, so that's what the problem was if anyone was still wondering.

[Nup]

Man nice find, love old tech like this. Hope the restoration goes well, kudos!

[creatip123]

So it turns out that it was just the headphone jack was corroded and the speaker outputs work fine.  Sound is very clean, except when adjusting volume, so that's what the problem was if anyone was still wondering.

 

As in dust, or rust? Try using cotton buds dipped in alcohol. If it's dust, it'll work like a charm. If it's rust, then no other way than to replace the jack.