MX-113 To Do's

The soldered cap pins (top oval) and large `spring-clip´ (bottom oval) seem to be what's supporting the entire RIGHT end of the PCB in John's pic:

View attachment 1394042

Maybe John can look it over again and report if that's the case, or there's another bracket under there somewhere.


-Greg
Yeah, the Mallory cap and bracket hold up the other side, but we can add a small L on the sub chassis.
 
Yeah, the Mallory cap and bracket hold up the other side, but we can add a small L on the sub chassis.
Ok fine and good idea, here's the situation.

The MX113 Power Supply PCB (PS PCB) has two mounting brackets, one on the LEFT in photo below, and C204 (the Mallory can) on the RIGHT.

mx113_PSPCB_Cap.jpg


Close-up of bracket on LEFT side.

mx113_PSPCB_bracket.jpg


RIGHT side of MX113 PS PCB

According to the schematic, there's a bracket hole in the lower-right corner of the PS PCB. Only a bracket, a couple screws and drill hole are needed.

PCB_044576.jpg


C204A and C204B, which John already has, can be soldered directly to the PCB.

The other cap-can will be restuffed and potted, and that horrible red marker removed!


-Greg
 
Update on MX113.

John had me over today to remove the can caps.. desolder C204 and cut wires on C210.

C204 BEFORE pic..
MX113_C204_before.jpg


AFTER
MX113_C204_pads.jpg

Two of the cap lugs were bent over against the PCB (upper-left and lower right lugs, with the latter being the worst to remove).


END view of C210.

Notice clockwise from upper right, are TWO red wires, a red/white wire, a violet wire, and orange wire.
MX113_C210_before.jpg


The two caps removed..

MX113_cans_removed.jpg

C204 will be discarded and Nichicon radials soldered to PCB.

C210 will be RESTUFFED with Nichicon radial caps potted in place.


This is a simplified schematic of C210 A, B, C, D.

C210_A-B-C-D_simple.png


John will be gutting C210 can soon.


-Greg
 
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I would drill out the two rivets holding the c210 cap clamps and build a small circuit board with standoffs threaded into the rivet holes.

Toss the old c210 away and save the mess and fuss for a non cosmetic cap. I would add some added high frequency filtering to the PS while redesigning it.
 
I would drill out the two rivets holding the c210 cap clamps and build a small circuit board with standoffs threaded into the rivet holes.

Toss the old c210 away and save the mess and fuss for a non cosmetic cap. I would add some added high frequency filtering to the PS while redesigning it.

Thank you but no sir. The plan is to stuff the can with Nichicon lytics, butt-solder existing wires with heatshrink, pot it with goop, and snap the can back into the clamps. Someone else can adulterate it with a hobby board.

This will be a NEW experiment in restuffing Mc cans.


-Greg
 
A new L-bracket will be needed to secure the end of the MX113 PCB that was supported by C204 and its spring clamp.

Back side of PCB

L_bracket_backside.jpg


Front side of PCB with sketch of L-bracket to chassis

L_bracket_needed_enh.png
Not to scale..

A new clearance hole will be needed in the chassis.


-Greg
 
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Good time with Greg pulling the old caps out today. The Sprague 066-128 was piece of cake. The Mallory was a pain due to how two of the spades were bent through the board. Took quite a bit of solder wick and patience.

Our unfortunate news was the HP 1206a scope I got was not fully functional. Have to figure that out.
 

Today's activities on the MX113 power supply restoration



C204 replaced with Nichicon VR radial (solder side). No photo taken of component side apparently.

MX113_C204_solders.jpg

Notice original `spring clamp´ and new 220uF cap on top.


C210 can preparation

John took the advice of removing the `tab ring´ so the FOUR new caps could be inserted in a bundle, see below.

MX113_can_prep.jpg



Cap core assembled into a bundle and `tagged´ for joining to original wires

MX113_C210_core.jpg

All negative leads (white stripes) soldered around a center AWG 20 copper pigtail and dipstick.


Cap bundle test-fitted inside can

MX113_C210_core_in _can.jpg

Caps are all in the lower half of the can with plenty of room to hide them


Looks like it's going to come out great!


-Greg
 
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@Gregory great work yesterday. The extra time put in thinking through the arrangement of the caps in the can was crucial to a clean install. We spent more "tech time" figuring out how to bundle and gang those together than what I have into the unit!

Here's the other side of the board where the Mallory can was located

IMG_3409.jpg and another from the board side. Notice the clean soldering. The can left large holes

IMG_3408.jpg
 
Today's activities on the MX113 power supply restoration


C204 replaced with Nichicon VR radial (solder side). No photo taken of component side apparently.

View attachment 1408720

Notice original `spring clamp´ and new 220uF cap on top.


C210 can preparation

John took the advice of removing the `tab ring´ so the FOUR new caps could be inserted in a bundle, see below.

View attachment 1408723



Cap core assembled into a bundle and `tagged´ for joining to original wires

View attachment 1408725

All negative leads (white stripes) soldered around a center AWG 20 copper pigtail and dipstick.


Cap bundle test-fitted inside can

View attachment 1408728

Caps are all in the lower half of the can with plenty of room.. to hide them


Looks like it's going to come out great!


-Greg
Ready to install the re-stuffed Sprague cap, but have a question. The Sprague cap was wrapped in plastic. I removed the plastic to clean out the material. Is the plastic necessary to ground the cap on the chassis separate from the ground lugs? Thanks
 
The cap-can should be grounded because the Power Transformer RED/YEL wire was soldered to the can lug (see below, top of pic).

close-up_c210.jpg

At the bottom on can (just out of focus at bottom) is a can lug with a `snipped´ wire end. Below that is a solder lug riveted to the chassis (ground).


Here's the MX113 PS schematic with GREEN lines drawn to represent `virtual´ RED/YEL transformer center-tap wire.

MX113_PS_schematic.png


All these lines need to be grounded. However C210 cap-can was insulated with a transparent plastic wrap or cover.

Looks like someone CUT a ground wire or a ground lug...

C210_brackets_wire.jpg

and cocked the can bracket. (chop chop!):rflmao:


-Greg
 
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More progress today on the MS113 cap-can restuff.

Got the wires soldered to the `cap cluster´ with heat shrink tubing today, but not after confusing the cap values. Had to check schematic THREE times until both John and I agreed everything was correct.


The original wires soldered to caps with heat shrink over top. I forgot to bring over heat gun! Rrrr

C210_wires_54.jpg



Side view with `copper pigtail´ straightened, it becomes a `copper tail´ which will be attached to a ground post with a ring terminal.

C210_wires_64.jpg



This view with cap bundle, heat shrink on ground bundle (center), and ground post.

C210_wires_68.jpg


Soon the original can will be mounted back on the spring clamps and the cap cluster stuffed inside.


-Greg
 
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Very good news....buttoned up for now. @Gregory will post pics and voltage measurements. Nevertheless, its dead quiet hooked back into MC2100 and Neat Iota speakers in my office. Smooth and crisp. Very good soundstage for mini system.

Of course there is more to do.... @Longfellowe indicated the MPX lamp could be Q405/6 short. Measured the voltage expecting 40v but = 0. Not sure what kind of heat sink there. And the signal meter is caput....IMG_3416.jpg
 
Another 2-1/2 hrs over at JBs workshop.. which is the furnace room and toasty warm.


Below are the four cap leads and the ground bundle with heat shrink applied.

heat_shrink_on.jpg

The copper tail is to the LEFT, and the power transformer center-tap wire (YELLOW stripes) was soldered to the GROUND bundle.

Remembered to bring the heat gun today to `shrink the tubing´ on the C210 cap cluster.


Here is the cap cluster test fitted into original C210 can (gutted).

can_test_fit.jpg


Next the can is reinstalled into the spring brackets and cap cluster gently stuffed inside.

can_reinstalled.jpg

Have to say I like the way it came out.


The copper tail from the ground bundle is now connected to the transformer mounting study with a bare ring lug.

PS_Ground.jpg


All work was checked and double-checked for correctness.. and then power applied.

idle_power.jpg

16 watts idle power seems low compared to my MR77 which draws 40-45 watts.


Voltage check of the primary power supply section looked GOOD.

MX113_voltages.jpg


John says he connected it to the system in his study and the hum/noise were GONE. I have an idea the PS ground wasn't right, and of course the old clunker cans needed to be replaced.

How many hours do we have into it JB? 30? since last spring? One of these days we'll have to get a pizza. :thumbsup:


-Greg
 
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