Resolved Macintosh Plus overloads the power breaker

Enric

macrumors newbie
Original poster
Jul 30, 2013
19
2
Geneva, Switzerland
Hello,

I have a nice Mac Plus supplied with a Radius Accelerator 16. It boots fine and display a stable image. Everything seems ok, but after a few minutes the circuit breaker shut down the power in the room. Once the circuit breaker reset, the Mac boots fine again and the process is repeated.
Any idea on what to investigate ?
 

Gav2k

macrumors G3
Jul 24, 2009
9,217
1,586
Have you tried moving it to another room on a different breaker ?
 

MacTech68

macrumors 68020
Mar 16, 2008
2,195
154
Australia, Perth
You might want to try the Class X 0.1uF capacitor. It's C38 on a 120v board. Also there are two Class Y 4700pf capacitors at C33 and C37.

However, if you have a 230volt board, the Class X 0.47Uf is at C37 and the two Class Y 4700pf capacitors at C33 and C36.

IMPORTANT NOTE - These capacitors must be the appropriate "Class" for their purpose. "Class X" must be replaced by "Class X" and "Class Y" must be replaced by "Class Y".

The originals may be termed as "self - healing" but at this age, many are beginning to reach the end of their workable life, causing momentary shorts across the mains input.

Class Y are supposed to 'fail safely' (since they are designed for line to chassis) but who knows what happens when they reach their end of life as they age. Class X will short across the line and can cause fast breakers to trip.

When purchasing, I would HIGHLY recommend getting them from a reputable dealer and not from cheap ebay sellers. These are a safety rated component for good reason. Also, you'll be looking for Class "X2" or "Y2" - the most common for household electronics filtering.

Both should be rated at 250Volts AC or 275 Volts AC, and will be marked with all sorts of safety & compliance bodies.

LATE EDIT - Make sure to get ones that have the correct lead spacing and size for the board.

Analog 110v ClassX & Y.jpg


Analog 230v ClassX & Y.jpg
 
Last edited:

MacTech68

macrumors 68020
Mar 16, 2008
2,195
154
Australia, Perth
Just remembered that if you're getting the potted type (which is most common) you'd need to check the spacing of the center of the solder pads since they come in fixed lead spacings. Sorry to mention that now that you've already ordered them. :(

Hopefully you already took that into account.
 

Enric

macrumors newbie
Original poster
Jul 30, 2013
19
2
Geneva, Switzerland
So, worked perfectly, the mac is powered for more that one hour now. Thanks so much!

The 0.47uf was a bit tricky to set in place because its body is slightly larger than the original one. But this was overall a straightforward job!
The two 4700pf are of both X and Y class (I ordered them as Y2 caps, but it is both mentionned 250-Y2 and 300-X1 on their body)

Now I am wondering how long the remaining old caps will last...


IMAG0195.jpg
 
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MacTech68

macrumors 68020
Mar 16, 2008
2,195
154
Australia, Perth
The Y2 caps can be "Y2/X1" combined - the main concern is that they are rated Class Y since they are fitted AC Line to Chassis.

As for the other Caps, some say "replace them all". However, if you're not seeing any other problems right now, You could leave it at that.

If you decide to replace them all, usually it's only the Electrolytics that need replacing. However, there is one that should be replaced using a Metalized Polyester cap - Some boards already have this done, depending on how recently the board was exchanged via Apple. It's one of the two large caps on the top edge of the board.
 

Zelf

macrumors newbie
Oct 24, 2019
2
0
Montreal, Canada
You might want to try the Class X 0.1uF capacitor. It's C38 on a 120v board. Also there are two Class Y 4700pf capacitors at C33 and C37.

However, if you have a 230volt board, the Class X 0.47Uf is at C37 and the two Class Y 4700pf capacitors at C33 and C36.

IMPORTANT NOTE - These capacitors must be the appropriate "Class" for their purpose. "Class X" must be replaced by "Class X" and "Class Y" must be replaced by "Class Y".

The originals may be termed as "self - healing" but at this age, many are beginning to reach the end of their workable life, causing momentary shorts across the mains input.

Class Y are supposed to 'fail safely' (since they are designed for line to chassis) but who knows what happens when they reach their end of life as they age. Class X will short across the line and can cause fast breakers to trip.

When purchasing, I would HIGHLY recommend getting them from a reputable dealer and not from cheap ebay sellers. These are a safety rated component for good reason. Also, you'll be looking for Class "X2" or "Y2" - the most common for household electronics filtering.

Both should be rated at 250Volts AC or 275 Volts AC, and will be marked with all sorts of safety & compliance bodies.

LATE EDIT - Make sure to get ones that have the correct lead spacing and size for the board.

View attachment 607886

View attachment 607887
Hi @MacTech68 !
Ok so i have a 120v board. I received has a gift a mac plus 1986 that i am restoring to a pristine state.

The 3 rfi filter caps (C33, C37 & C38) are cracked and i am having a hard time finding the precise models links on Mouser.ca website.

Experienced in soldering just need the links to the 1 x Type X 0.1uF (Lead spacing 20mm) & 2 x Type Y 4700pf (Lead Spacing 10mm) for the 120v board, cause i saw on another thread the kemet parts number only for 240v board you advised but not 120v. wich i need advices on it.

Thank you
75247367_951124048584875_7608507493685133312_o.jpg
 
Last edited:

MacTech68

macrumors 68020
Mar 16, 2008
2,195
154
Australia, Perth
Hi @MacTech68 !
Ok so i have a 120v board. I received has a gift a mac plus 1986 that i am restoring to a pristine state.
I take it you're in Canada ?

If so, try Newark (linked) OR plug the bolded part numbers into mouser.ca

0.1uf:
PME271M610MR30

4700pf:
PME271Y447MR30
 
Last edited:
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Zelf

macrumors newbie
Oct 24, 2019
2
0
Montreal, Canada
Yes in Quebec.
Thank you really much ordering them right away!

EDIT : 6.75$CAD for 3 components, 20$ shipping, 6ish bucks taxes... Total : $30.50 CAD :eek:
Bought them anyway, have no choices.
 
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