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#81
There are five Aluminum electrolytics in the 465 supply.  Three have their negative side to GND.
Theses are C1513, C1552 and C1542.  The original Mallory cans are the "-" side of the capacitor. Here, I'm using radial caps thus need to be creative.

C1512 and C1562 both have potential across the leads.  For C1512 about 65VDC and for C1562 it's about 13VDC.  Some thought is required to properly ground the entire supply. 

I've added jumpers to enable the proper grounding of circuit.  Rather than attempt to fill the large plated holes with solder I used terminal connections and screws. 

TEK_power_supply_1.jpg
#82
This was the ripple voltage of the +5VDC rail.  Clearly the rail capacitor is toast.  Vertical scale is 1VDC/division.  Ripple should be <5mV.  DC coupling.

OUCH!!!

TEK00018.PNG
#83
My 465 I've had since early 1980s gave up, the +5VDC regulated power supply rail gave up.  Pretty clear it was a shot filter capacitor, ripple voltage in excess on 600mV on the rail (should be <2mV).  Just putting a healthy 3000uF in parallel across the cap in question confirmed the diagnosis a broken to perfect trace immediately. 

These are an absolute bitch to remove without risking damaging the board traces.  Requires a desolder unit with vacuum activated trigger and a second iron in your hand to soften the other side of the joint.  You must use them both, simultaneously to remove the solder.  The good news is the caps had adequate clearance to get an iron at the top side of the joint.

Trigger board that must be removed.
sweep_trigger_board_2.jpg

Caps exposed with trigger board removed.
sweep_trigger_board_removed.jpg

Caps removed, no trace damage.
caps_out_2.jpg

Caps to be replaced.
caps_out_3.jpg
#84
Installed a 10-position terminals strip.  Each cap is 39uF/250V.
#85
Scott 350B tuner required a complete rebuild of rail supplies, replaced selenium rectifier with silicon.

DSC_6845.JPG 
#86
%THD v. power dissipated into 8Ohm NI resistor, 1000Hz, CHA&B.  Tubes are EL84M SOVTEK.

%THD_L&amp;R_1kHz.jpg
#87
Going to give these a go in the 222C.   From Russia, no supply chain issues.

EL84M

IMG-2234.JPG

IMG-2235.JPG 
#88
Passive Networks / Re: North Reading Engineering ...
Last post by nre - May 30, 2023, 05:42 AM
I would prefer to see the autoformer GND tap have a single lead going to a dedicated location on the network board where the amplifier negative terminal and the shunt resistor negative lead attach directly.  The shunt resistor could then be mounted off the autoformer.     

I sent quick disconnects for the autoformer which will allow experimenting with the attenuation levels.

Also, you can just and drop photos into the post, you don't need third parties, fwiw.

IMG_8722.jpg
#89
Passive Networks / Re: North Reading Engineering ...
Last post by deafbykhorns - May 29, 2023, 03:00 PM
How does this look for layout?
https://photos.app.goo.gl/KqQqoJtSEMrKmRKa8

#90
Horn Loaded Systems / Re: B&C DCM50 w/Selenium HM359...
Last post by nre - May 29, 2023, 11:14 AM
Stretching grille cloth has a satisfying effect.  A good pneumatic stapler helps to do this right (for me anyway).

Insert_with_grille_1.png

Insert_with_grille_2.png