Macintosh 128k 240v Analog Board Component Identification

[nvdeynde]

The 'Classic Mac Repair Notes' describe C1 as 'the capacitor that often dies'. A visual inspection of the Capacitor tells me that it is fine, but should I replace it as a precaution?
Would this be a suitable replacement? http://tinyurl.com/qyw57b6

On the board itself I've noticed there is no +/- for the polarity of C1. Will it work any way?

Yes the Panasonic ECW-F2395JA is the right replacement for C1: it's a bi-polar, high frequency Film capacitor. They don't exist in radial electrolyte version like the original one anymore as far as I know. Since this capacitor is Bi-polar it doesn't matter how you mount it on the PCB ( +/- ).

However I do recommend to replace all capacitors instead of just this one and the filter caps. Do the whole board if you want it to last in the long term.

Visable inspection often doesn't tell much with capacitors unless they are clearly leaking or bulging as they can be open, shorted, out of specs, dried out,... without any visable signs.

 

[sadmanonatrain]

Good evening,

However I do recommend to replace all capacitors instead of just this one and the filter caps. Do the whole board if you want it to last in the long term.

I have sourced most of the replacement capacitors but I am not sure about the following ones: 10uf 160v, 470uf 10v *2 and 100uf 200v*4.

Is there anything special about the 10uf 160v and 470uf 10v caps? Low ESR etc. Their different colour jacket makes me think this. Could I replace them with a standard cap?

I'm having a difficult time finding the four large 100uf 200v capacitors. Are they still made anymore? What would be a recommended replacement?

Thank you

 

[sadmanonatrain]

Good evening,

Sorry with the questions but could somebody please tell me if this would be a suitable replacement for C1? http://tinyurl.com/ndzup92

It's a 3.9uf 250v axial capacitor. It looks the same as a capacitor on the analog board of my SE/30.

RS Components want to charge a fortune for the Panasonic part! Especially since that is the only thing I am buying from them!

I'll try to get the parts ordered today so they will arrive in the middle of next week.

Any help is much appreciated!

 

[td75]

I also bought from same eBay seller and had payment refunded! I also ended up buying from UK from here: http://www.electronicrepair.org.uk/webstore/index.php?main_page=product_info&cPath=47_22&products_id=58

Noticed on the back of Q10 there was a bit of plastic that ended up crumbling.. is Q10 supposed to be insulated from the heatsink?

 

[sadmanonatrain]

td75,

Noticed on the back of Q10 there was a bit of plastic that ended up crumbling.. is Q10 supposed to be insulated from the heatsink?

When I look at the heatsink then Q10 I see:

Heatsink --> A transparent plastic sticker --> Thermal compound --> Q10

Therefore I think that Q10 should be insulated from the heatsink.

I hope this helps!

 

[sadmanonatrain]

The replacement capacitors and 2SC3260 arrived today and have been soldered onto the analog board.

I'm still not sure about the four 100uf 200v capacitors but I will leave them in for the meantime.

Capacitors have replaced with ones of the same value but the sizes have shrunk dramatically!

I will replace C1 tomorrow then proceed to turn on and test the Macintosh.

I hope it does not blow up!

td75: Has your replacement Q10 worked for you?

 

[td75]

Replacing the Q10 has stopped the speaker clicking noise so I'm sure it was faulty, but still doesn't turn on I'm not even sure the logic board or CRT is fully working. Still lots more testing. I bought a step down converter so going to try with a 110v analog board to make sure the rest of the machine is actually working.

 

[sadmanonatrain]

Good evening,

I have replaced most of the capacitors on the analog board; these include:

R uf V

C1 3.9 25 with 3.9uf 250v axial

C2 4700 16

C3 220 16

C24 2200 16

C27 2200 10

C28 1000 16

C30 2200 10

C31 220 16

C32 2200 16

C45 470 10

C42 470 10

I have not replaced C11: 10uf 160uf or the four large capacitors in the middle of the board: 100uf 200v.

Also the two components that failed, 2SC3260 and a RIFA metallised film capacitor, have been replaced.

For the first time in a while I reassembled the Macintosh and turned it on. Nothing, no chime or any indication that the Mac was alive. Nothing happens when the brightness knob is turned.

I have tested voltages on the floppy port and they all read under 1.00v.

I've compiled a list of capacitors on a spreadsheet which I will try to upload to the forums.

I really don't know where to start to solve this next problem? Any ideas would be much appreciated!

 

[sadmanonatrain]

Good evening,

I think the problems I am currently facing outgrow the purpose of this topic.

Therefore I will start a new topic to discuss these new problems.

Thank you to anybody who helped me source replacement components!

If anybody else needs a component identified feel free to 'hijack' this topic!