One little sick puppy, Nippon made Sony x Tek 2465

[Fractal]

Hi there!

Today I'm coming with a bargain 2465 found at a local rando electronics dealer here in Taiwan

That puppy seemed well used but appeared to still have some life in it, so I took it home

It did turn on and sorta work, but showed a bunch of small issues; dim screen (that I thought were only due to the dirty plastic screens), non functional leds, wonky pots...

Well I got to it then...

-Opened her up - Notice the Sony/Tek slap on the tube shield; looks like those were made under license by Sony in Japan; just a short hop to Taiwan then. serial 301356. M.Sugizaki if you're reading this  (Pic.2)

-Replaced the Rifas, blown and sketchy high side caps... (Pic.3)

-Had really crusty BNCs so I pulled them out for cleanup, needing to remove out the attenuator board; incredible pieces of tech those ceramic substrate boards...what are all those different color coatings even?! (Pic.4)

-While at it I thought I might just as well balance the cooling impeller (it's one of those with the closed loop, temp-controlled brushless motor what!) (Pic.5)

-Aaand did a little retrobrite on the most browned-out knobs; just left them hanging outside around noon in a transparent bag with a mix of hydrogen peroxide, vinegar and oxy-action; looks like that ended up melting the bag? but at least not before having done enough work (Pic removed in favor of final result)

-And there I had a good base to work on; with cleaned pots and switches and all power rails tested OK


And yet the problems didn't resolve...


1- Dim screen

I refuse to believe the CRT might be bad; I've never seen one 

I have followed the first steps of the CRT adjustment in the service manual, adjusting the grid bias, but no beans; it was spot on.

Couldn't find the reason and don't have the equipment to go probing about the HV side, What I did notice however, and you may too in the 1st pic, is black dust all around the anode wire; it should be red but everywhere on and around it's path seems covered in black dust...could the crt be arcing on the chassis at some point?

2- verticals -- and horizontals completely off

I don't remember seeing it before the teardown, but the channels have gone wildly bad;

-Ch1 vertical is off, and the calibration 1kHz signal shows super attenuated - need to go to max vertical scale to even see it, and it looks more like a sawtooth -- I'll make a video when I get back to it
-Ch2 is so off I only get one div of it at full adjustment. Also horizontal completely bonkers, as if changing the scale changes nothing between a certain range
-Ch3 and 4 seem just about ok but not quite...

I'm thinking the BNC recovery may not have salvaged them and they're just making poor contact hard to tell

3- Leds not responding

The right side of my front panel leds seem unresponsive; off. Makes it hard to know which trig source and coupling it's on. And yet when I unplug/replug the connector, they do light up for a second. It seems like the front panel has its own IC and talks to the main board over serial? Is this a known issue?



I'd be curious to know your thoughts on how can I best proceed getting it back in top condition


Cheers!

[Fractal]

As promised here's a little video detailing the issues; hope it helps!

https://youtu.be/9LH8yJj_d2I