68kMLA Classic Interface

This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.

Click here to select a new forum.
Help Identifying Capacitor
Posted by: superpete on 2017-04-11 17:05:57
I was trying to pull out the analog board from an LC 575 (whose case sadly arrived quite broken via the post) and pulled a capacitor leg out in the process (doh!).

I'm trying to find a replacement but struggling to decode the capacitor details (see attached). As near as I can tell its an MKT (Metallized polyester film capacitor) 33nF 400V (DC?) with a 5% tolerance.

Are there any other details I need to know? Or if someone can send a link to an exact part it'd be much appreciated.

Edit: Attachment Attached!

IMG_20170409_105211104.jpg
Posted by: 360alaska on 2017-04-11 17:29:29
<Nothing is attached>
Posted by: superpete on 2017-04-11 17:36:50
Oops! I had selected the file but forgot to hit the upload button. It's there now.
Posted by: CharlesT on 2017-04-11 20:36:39
Unfortunately, given there's no detailed documentation for that board out in the wild (that I can find), you've got the best available source right there. The part itself. Do Google searches on the numbers that could be part numbers, should hit on a spec sheet. Then find that or an equivalent at Digikey.  Or find someone with a component tester to measure yours, but it looks like you've already got the essentials.
Posted by: trag on 2017-04-11 20:55:10
Are you certain that's a capacitor? I ask only because the bottom number seems to have two letters trailing, the last of which is an 'H', suggesting henries and an inductor. How was the position on the circuit board labeled? It seems awfully large for a cap in the nanofarads.
Posted by: superpete on 2017-04-11 22:36:18
I'm fairly certain it's a cap based on the code. Attached is the location of the cap, it's not actually that big at all.

IMG_20170409_102815266-2.jpg
Posted by: 360alaska on 2017-04-12 03:13:10
You need to remove it completely and see if there is a capacitor symbols on the board itself. It is I likely a capacitor and while I'm not sure what the 33nj means I would try to get one that says 33nj.
Posted by: trag on 2017-04-12 08:28:48
I wonder if anyone ever specifies capacitors by energy storage instead of capacitance. That would make 'nj' nano-joules. E = 1/2 * C * V^2. However, using 400 for V and 33 X 10^-9 for E and solving for C gives an evev tinier C.
Posted by: CharlesT on 2017-04-12 14:42:41
Google is your friend. The top number on the side is the date code, below that is the voltage rating, below that the part number, MKT HO 370 PH,

which comes back with a bunch of hits, including the following: Metallized polyester film capacitors MKT 370/371/372/373 - Farnell
Posted by: superpete on 2017-04-12 15:56:06
Thanks Charles.

So I think my original suggestion of a 400V 33nF @ 5% (based on the J) was correct. That pdf though means the original part number would have been one of the following (depending on what lead length and packaging apple went for originally):

222237052333

222237056333

222237059333

222237066333

That said, I think any poly film capacitor meeting the original spec should be fine, which is just as well as I haven't been able to find anywhere that'll sell me the original part in quantities less than 2000!

I need to make a list of the rest of the electrolytic caps on the AB before I place an order. I'll post the list once done and some links.
Posted by: CharlesT on 2017-04-12 16:31:51
I just recently did mine, my list is on my Digikey account, I'll retrieve that and send it to you. As most others have done I uprated where I could to 105C parts and higher voltage levels to reduce the parts variety a little.

Charlie
1