Knight 40 watt amplifier help

medosmas

Member
I recently picked up a knight 40 watt tube amplifier, but i know it was modified by some one. one channel sounds great with a slight hum, but works. the other channel is very faint but there is sound coming out, i have found no schematics online. does any body have a photo of the underside? particularly the power section, and the level pot control. there was a unsoldered gray cable. Again schematics would be great but a photo is better as i'm new to trying to reads schematics. thank you in advance for any info that can be thrown my way. :sigh
knight40wattamplifier012.jpg
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Is the + side of that 22uf cap shorting out to the back side of that pot? Hard to tell for sure in the pic.
 
Almost looks like on the board end of the grey cable, the shield and center connection are shorted or going to the same place. They should not. The center should probably go to the pad where it currently is, and the outer braid should go to the large ground foil next to it where the number 9 is visible. That may not be the case, but its just a guess based on what I see.

I also see a wire poking out between the red cable and the twisted yellows. Not sure if thats just a long lead that needs trimming or what.

I don't care for the flying lead on the black cap in the second picture. At a minimum, I'd insulate that connection with some electrical tape or something. Heat shrink would be better. I'd like to see that supported somehow. It looks to be hanging by the wire only. Even a zip tie or a blob of hot glue or something to keep it from moving would help.


Do you have a model number for this amp, or even a couple top side pictures and the tube numbers ?
 
Is it the Knight-Kit Y-774J? If so, there is a review with some close up pics in the June 1960 Hifi/Stereo Review.
 
That's interesting because someone that I used to go to church with had given me an old Knight Kit console that he had built when he was still in High School back in 1961 and I believe the amplifier that the console had was the same exact amplifier that is being posted about in this thread, the sad part is that the amplifier in that console was a dud after sitting in this guy's garage for over 20 years, the power transformer was shot so I had to gut the tubes out of it and scrap the amplifier. :( the tuner and the turn table were still good in it yet but I ended up having to salvage the tubes out of the tuner and scrap that as well and the I also scrapped the record player and the speakers as well. but I kept the cabinet and I'm currently using it as a stand for my LCD Video Projector and VCR, DVD Player and Stereo Receiver that the projector uses for its audio output.
 
Hi dandy,
thank you for your quick response.
the 22 Uf cap is connected to ground then pin #8 on the mullard GZ34
 
Gadget 73,
Yes the gray cable is connected to the pad 9 and the other lead to, well i post the photo. actually i added a small peace of wire cus it was too short. and the wire behind the yellow wire was a long lead. i see a 47 uf from the strip to another strip below? don't know it's purpose, it looks never so it stands out.
 
As asked previously - can you identify the model number of this amp - perhaps from the faceplate or chassis? That might help to locate schematics or other info. (If you already advised it, I missed it...)
 
That's interesting because someone that I used to go to church with had given me an old Knight Kit console that he had built when he was still in High School back in 1961 and I believe the amplifier that the console had was the same exact amplifier that is being posted about in this thread, the sad part is that the amplifier in that console was a dud after sitting in this guy's garage for over 20 years, the power transformer was shot so I had to gut the tubes out of it and scrap the amplifier. :( the tuner and the turn table were still good in it yet but I ended up having to salvage the tubes out of the tuner and scrap that as well and the I also scrapped the record player and the speakers as well. but I kept the cabinet and I'm currently using it as a stand for my LCD Video Projector and VCR, DVD Player and Stereo Receiver that the projector uses for its audio output.

Power transformers are generally pretty easy to replace. Good OPTs, not so much.
 
If I am not mistaken, this is perhaps the KA-55 with 6973 output tubes? If so, there is a SAMs available
 
Yes 6973 output tubes and there is no model number what so ever. i tried clicking on the schematics on the other thread but didn't work.
 
Did you try www.samswebsite.com? (no affiliation)

If you do a search for SAMS # 1119-SED it will list several items including Item # 91537 for Knight model/chassis 83YU774. If you click on 91537 that should have the schematic.
 
From a post in DIY Audio: "Knight schematics are among the HARDEST to find - but fortunately, this one is covered in Sams 1139-SED. It will be a schematic only, not the usual folder with parts list and photos. You may be able to get it from Walt at infotronix.us or Bob at findatube.com."
 
Can't seem to be be able to download the schematics, do i need to resister to buy it? only login option.
 
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