Thread
Mac Plus turns off after short time
I did post links from Mouser earlier in this topic where you can still buy the identical film capacitor. I think Digikey offers them as well.
Replace them and you're good to go for another 15 years
Yes, but I was thinking maybe I should change all of them before they started exploding/leaking. I have the international 230v board and I have had some problems finding replacements for every part because they seems to differ from the cap lists people have made in other replacement threads. So I need to sit down and find other types with the same properties, because it seems hard to find the exact same capI did post links from Mouser earlier in this topic where you can still buy the identical film capacitor. I think Digikey offers them as well.Replace them and you're good to go for another 15 years
My Macs are also International 230 volts versions. I have already recapped all of them in the last years ( so logic, analog, PSU ).
Finding exact replacements is often not that easy if you want to make it look right as for example a 100uf 200v capacitor from 25 years old is much larger than one with identical specs today.
So I measured all the original one's and looked for replacements that where about the same size so they look right on the Analog board.
The solution was choosing for the same capacitance but higher voltage and going for the more expensive 5000 or 7000 hours caps.
I made an inventary of each board in Excell including the part number of the replacement caps.
To avoid trouble: I replaced all the film and axials capacitors as well as you can see in this discussion: they can brake down too.
PM me what you need and I will send you the file.
Well, a few capacitors I was awaiting arrived this morning and I quickly soldered them in.
Success so far- I have left the Plus turned on now for over an hour with no issues. Works fine now.
Here is a picture of what I have replaced on the Analog board (in addition to those in the previous picture).
I certainly haven't replaced all the capacitors (C1 included because I haven't got them yet) but this seems enough to get going again.
Away with work now for another four days but on the weekend I will have a go at just replacing those two cracked filter caps and see if it makes a difference.
By the way, they are 240v boards I am playing with.
I was also wondering- can faulty diodes give similar problems? I haven't replaced any but they are probably getting pretty old too.
Oh, and for Loom- I ordered those filter caps locally through Element 14 but they actually came from the UK to me.
Success so far- I have left the Plus turned on now for over an hour with no issues. Works fine now.
Here is a picture of what I have replaced on the Analog board (in addition to those in the previous picture).
I certainly haven't replaced all the capacitors (C1 included because I haven't got them yet) but this seems enough to get going again.
Away with work now for another four days but on the weekend I will have a go at just replacing those two cracked filter caps and see if it makes a difference.
By the way, they are 240v boards I am playing with.
I was also wondering- can faulty diodes give similar problems? I haven't replaced any but they are probably getting pretty old too.
Oh, and for Loom- I ordered those filter caps locally through Element 14 but they actually came from the UK to me.
Chances are very thin that a faulty diode would cause problems like yours. Then the diode must make contact to the ground from the Mains, which is very unlikely.
Anyway: test the diodes, a cheap DMM can do this without desoldering them from the PCB.
Definately replace the C1 capacitor as well.
As some have mentioned, it's fairly common for these to fail, sometimes rather spectacularly. As long as the replacements are X2 rated, of equal or greater voltage rating, and similar capacitance they will work. You don't need to find exact replacements although it's nice when you do.
As a temporary test it's fine to remove them. It will likely cause interference on nearby AM radios but few people listen to AM radio anymore anyway.
As a temporary test it's fine to remove them. It will likely cause interference on nearby AM radios but few people listen to AM radio anymore anyway.
I listen to WJR 760 all the time
Or WSGW(online) (but they are news radio 790 in bay city), for Coast to Coast
Alex Jones is on (online) Shortwave and AM and FM. - Huge Audience. 3+ million
Rush Limbaugh has a Massive audience, over 20 million listeners.
I'm 33 and i'm starting to feel slightly old
Anyways, that makes sense, your home wiring would essentially turn into a big RF antenna
(with out proper filtering)I wonder if the Tempest macs can withstand and EMP?
re AM interference -
Yesterday I was booting up my IIsi with a SVGA LCD monitor. Another PC nearby was attached to an external audio amplifier. During the IIsi boot period, I was getting a clear signal from a local AM station showing up on the PC-attached audio. When the IIsi display stabilised on the SVGA monitor, the signal disappeared. I'm guessing that the VGA cable was acting as some kind of retransmitter, with the length of that cable coincidentally matching the AM station bandwidth. Strange that there was no connection between the Mac and the PC, but the signal was retransmitted.
Rick
Yesterday I was booting up my IIsi with a SVGA LCD monitor. Another PC nearby was attached to an external audio amplifier. During the IIsi boot period, I was getting a clear signal from a local AM station showing up on the PC-attached audio. When the IIsi display stabilised on the SVGA monitor, the signal disappeared. I'm guessing that the VGA cable was acting as some kind of retransmitter, with the length of that cable coincidentally matching the AM station bandwidth. Strange that there was no connection between the Mac and the PC, but the signal was retransmitted.
Rick
It's a fairly common problem. It's likely just a poorly shielded VGA cable and one of the signals is close to a multiple of the frequency you were tuned to.
I was recently playing with a FPGA board and found that it emits quite a lot of RF leakage, stomping over my reception of the 128.000 MHz AM aircraft band which happens to be 4x the 32 MHz master clock on the FPGA. I loaded a Commodore SID implementation into the FPGA and could then hear the SID tunes loud and clear on the scanner. Last year I was messing around with a small Tesla coil I had built, and we discovered it was stomping all over one of the local AM talk stations. My friend tuned it in his truck and could hear the Tesla coil down the street. RF is nifty stuff but keeping it just where you want it can be a real pain.
To clarify, there *are* people who still listen to AM, but they are certainly in the minority. Dozens of unfiltered computers buzzing away in the neighborhood could cause some problems, but running one vintage machine occasionally for a couple weeks while you wait for new caps to show up is unlikely to cause any harm. If it's interfering with something you're trying to listen to, just shut it off.
I was recently playing with a FPGA board and found that it emits quite a lot of RF leakage, stomping over my reception of the 128.000 MHz AM aircraft band which happens to be 4x the 32 MHz master clock on the FPGA. I loaded a Commodore SID implementation into the FPGA and could then hear the SID tunes loud and clear on the scanner. Last year I was messing around with a small Tesla coil I had built, and we discovered it was stomping all over one of the local AM talk stations. My friend tuned it in his truck and could hear the Tesla coil down the street. RF is nifty stuff but keeping it just where you want it can be a real pain.
To clarify, there *are* people who still listen to AM, but they are certainly in the minority. Dozens of unfiltered computers buzzing away in the neighborhood could cause some problems, but running one vintage machine occasionally for a couple weeks while you wait for new caps to show up is unlikely to cause any harm. If it's interfering with something you're trying to listen to, just shut it off.
I took the analog board out of another Plus today and replaced just the two 4700pF 250v filter caps.
It's been an hour now and it's still running!
Haven't replaced any C1's yet as that order still hasn't arrived.
By the way, I noticed some C1's are 3.9uF and others are 6.8uF. Would it make a difference if I swapped them over?
And, one more- should I bother with a hot glue gun (which I haven't got) to keep the caps I have replaced in one place? Would it really matter if I didn't bother?
Thanks
Tim
It need to be a 3,9Uf High Frequency Bi-Polar capacitor of at least 100 volts.
As far as I know the only alternate on the market is the Panasonic ECW-F2395JA film capacitor.
I used it in my all recaps and works perfect, fitting is just a bit of an issue.
No glue need: I actually remove all the old silicone from the original PCB.
I'll just stick in my 2c here. I have a 240V mac plus that behaved exactly this way when I first got it. It would boot up and after a short time would trip the residual current device at the fuse box. A quick peek inside revealed the likely culprit, X and Y rated caps in the mains filter were all cracked open. After I recapped the entire board this problem went away but I'm about 95% certain that the RCD trip was caused by these.
I replaced them with these which fit perfectly -
http://uk.farnell.com/jsp/search/productdetail.jsp?CMP=i-ddd7-00001003&sku=1006064
and this -
http://uk.mouser.com/ProductDetail/WIMA/MPX21W3470FK00MYSD/?qs=%2fha2pyFaduj0ApMVe66xmIlWTZwkT1%252btsdp6MlIXDNJF3KG5WmKzuXlIXCj2njBP
This one was a shade bigger than the original due it's rounded case and I had to temporarily remove the transformer to fit it, the pin spacing was not quite perfect either. Otherwise these parts were an exact match for what came out of the european power board in positions C33, C36 and C37.
I replaced them with these which fit perfectly -
http://uk.farnell.com/jsp/search/productdetail.jsp?CMP=i-ddd7-00001003&sku=1006064
and this -
http://uk.mouser.com/ProductDetail/WIMA/MPX21W3470FK00MYSD/?qs=%2fha2pyFaduj0ApMVe66xmIlWTZwkT1%252btsdp6MlIXDNJF3KG5WmKzuXlIXCj2njBP
This one was a shade bigger than the original due it's rounded case and I had to temporarily remove the transformer to fit it, the pin spacing was not quite perfect either. Otherwise these parts were an exact match for what came out of the european power board in positions C33, C36 and C37.
II also have this issue with all three of my Pluses (which never gave issues until now), and recall a similar issue surfacing with one of my 512K's nearly 15 years ago. Never bothered to deal with it back then, but now that ALL my pluses are giving me problems I decided to google the symptoms and lo and behold there is a thread on 68k! 
Might pull the analog board out of my original Plus which I partially recapped in around 2003 and see how i go.
Might pull the analog board out of my original Plus which I partially recapped in around 2003 and see how i go.
Yep. I have replaced these in all my classic compact Macs (not just Plus's) and haven't had a recurrence. It's fairly obvious when they start to crack.
i like when they blow and make clouds of smoke.
And it stinks. The PSU in my TRS80 Model III made the whole office lobby stink for a few days when it blew two of them.
The funniest thing is the computer still works once these blow.
pop, Bang, Smoke billows out, the computer is still on no problem… haha
pop, Bang, Smoke billows out, the computer is still on no problem… haha
Those are either X1 or X2 rated safety capacitors, replace them with equivalents of that type.
I remember when the big electrolytic caps on one of my Plus A-boards went... big cloud of smoke and they bloody stunk to high heaven. Like burnt peanut butter mixed with flaming M&M's... No I wont go into how I know what they smell like! :lol:
Left a foul stench in my room for a couple of days anyway. :-/
Left a foul stench in my room for a couple of days anyway. :-/