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Marantz 1200

May give this one a go, it has the diameter and pitch for both:
https://www.amazon.com/dp/B07K7W3NQQ/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B07K7W3NQQ&pd_rd_w=J5Exi

81ARP0YUhVL._SL1500_.jpg


EDIT: Changed my mind, this one does coarse and fine threads, the one above doesn't.
https://www.amazon.com/dp/B06X15YV6X/ref=twister_B01N49J16B?_encoding=UTF8&psc=1

715V6ot6k-L._AC_SL1000_.jpg
 
Well let's see if we target a "well known" screw say on a 1200, I'll let you know what I read and you check as well. Next thing will be finding a good source for the screws.
 
Sounds good. The screws that hold the phono, tone, and other daughter board in, are really tight pitch and a thinner diameter, there's only three of these screws in mine, almost 100% certain they're stock. Curious to see if you have those too.
 
The A7 Power Supply board, and A8 Relay board are mounted like the above, but the Phono, X10, and Tone boards are held in to the Interconnect board with these plastic blocks:
udMChgV.jpg


It's these three blocks that have a different screw on mine. The screw that holds in the A2 Phono board, must be that screw, or it will put too much pressure on the IC board, and break the Balance pot (in my case).
 
I am looking at the schematics and the X10 and Phono amp are similar to the 33 preamp including those TO-105 package. I got a bunch of what I think are equivalents and TO-105. All differentials are repleaceble with BC550C just like the 1120.
 
In wonder if Q503 is the darlington - the 240 uses MPSA65 I hope that is equivalent to SPS1952. It is just odd that it doesn't have a 5pf Miller compensation capacitor:

240:

upload_2021-4-1_17-53-0.png

1200A:

upload_2021-4-1_17-57-15.png
 
I replaced as few semi components as possible, only two MSPS1928's on the Tone board because Q405 was blown when I got it. Wanted to retain that original tone if possible.

The Service Bulletins for the 250 and the 3300 are worth checking out, the flyback diodes is one of them for the 250, and then there's a section on the output transistors, and the gain codes painted on them (if stock).

pnVIiod.jpg


pgou13d.jpg


I was glad to not have to replace the stock outputs in mine; even though my 1200 is early, the service bulletin upgrade was done on this one.
 
I can understand. I thought the passive components especially caps would dictate the tone.
I did the flybacks myself, mine was all stock.
 
That's another great point, I've read that some thought that the Vishay axial caps didn't sound as good as stock, or that they are not audio grade caps. All I can say is that IME, the Vishay axial's tightened up the entire frequency spectrum, all ranges became more precise, the sliders and preset knobs became more focused, and useful. I tested this with the same headphones (Beyerdynamic DT 770 80 ohms), and listening/testing songs, before and after. I have this 1200 hooked up to Klipsch HII's, also. Out of 8 receivers, this one gets used.
 
I had a lot of head scratching when working on my 33. That one I didn't want to mess up. So I went with Silmic IIs for the preamp boards and Vishays for the power supply if nothing else because radials wouldn't fit. I have to say the 33-240 pairing is excellent.
I replaced the outputs on the 240 because their hFE was too far apart from the specs. I also went through a bunch of options for the drivers until I settled on a couple of high frequency ones with very close hFE. Same reason, drivers were very far apart.

I may consider exotics like Mundorfs for specific audio paths but I didn't go there yet. Some people change them and do A/B comparisons, I am not sure I have such accurate ears LOL
 
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