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Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.
Warning! Exploding Maxell PRAM Batteries
- Thread starter MacGyver
- Start date
Brett B.
Well-known member
I haven't specifically seen a Maxell battery blow up, but I've dealt with several other brands. Don't remember which. Really, it doesn't matter, they can all leak.
IMO there is zero reason to even have a PRAM battery in any old Mac that you are not using on a daily basis that doesn't require it to boot. It's just too risky and there's no reason to damage your equipment with a battery that explodes.
IMO there is zero reason to even have a PRAM battery in any old Mac that you are not using on a daily basis that doesn't require it to boot. It's just too risky and there's no reason to damage your equipment with a battery that explodes.
genie_mac
Well-known member
Another one bites the dust...or should I say has bitten the dust:
Picked up an LC with monitor for a tenner today and was told it wasn't working. When I got home and spotted all the rust on the backpanel I got suspicious...more rust than usual....this couldn't be, could it???
Looks like a Maxell alright. Mind you I also have an unexploded Maxell from 1992 but the plot thickens....
I didn't know caps could turn into mushrooms either....
Ah well at least the harddrive, floppy and PSU are still OK...now can I use that floppy in my SE?
Picked up an LC with monitor for a tenner today and was told it wasn't working. When I got home and spotted all the rust on the backpanel I got suspicious...more rust than usual....this couldn't be, could it???
Looks like a Maxell alright. Mind you I also have an unexploded Maxell from 1992 but the plot thickens....
I didn't know caps could turn into mushrooms either....
Ah well at least the harddrive, floppy and PSU are still OK...now can I use that floppy in my SE?
onlyonemac
Well-known member
It's probably the result of a reaction between the capacitors and the battery acid.
genie_mac
Well-known member
Yeah looks pretty cool alright, not if you're a poor LC though.
Have decided to try and get it going again; have scrubbed it down pretty well and it doesn't look too bad. Have to replace the caps alright and not sure if the pads are gone...also have to resolder some pins of the 68020 which have come loose...very strange. The only major problem is one of the socketed chips (what are they?) where there is major corrosion. If I take it out, I'll probably loose half the legs
Well I'm away for a few weeks so this will have to wait...might start a new thread once I have something to report.
Laters.
PS: Thanks markyb86, will try that; my SE works with a FDHD alright so that's great.
Have decided to try and get it going again; have scrubbed it down pretty well and it doesn't look too bad. Have to replace the caps alright and not sure if the pads are gone...also have to resolder some pins of the 68020 which have come loose...very strange. The only major problem is one of the socketed chips (what are they?) where there is major corrosion. If I take it out, I'll probably loose half the legs
Well I'm away for a few weeks so this will have to wait...might start a new thread once I have something to report.
Laters.
PS: Thanks markyb86, will try that; my SE works with a FDHD alright so that's great.
maceffects
Well-known member
Another one...
uniserver
Well-known member
It still bugs the crap outta me as to why they use that big honkin 2200uf cap, where a normal 47uf 16v cap normally is.
i just kinda wanna know why is all.
With my LC, I clipped that big cap off and just installed a normal SMT 47uf 16v cap and it works fine.
wash up that board buddy real good maybe it might still work?
i just kinda wanna know why is all.
With my LC, I clipped that big cap off and just installed a normal SMT 47uf 16v cap and it works fine.
wash up that board buddy real good maybe it might still work?
maceffects
Well-known member
Yet, another bites the dust... Mac SE FDHD... Carnage below.
onlyonemac
Well-known member
Yeah, that one doesn't look too bad surprisingly!
Schmoburger
Well-known member
Oooooookay after reading this thread I am most definitely goin to make a concerted effort to unbury all of my stack and pull out PRAM batteries like a madman... I know a few had Tadiran cells but there were a lot with Maxell ones.Might be time for a trip out to the farm this afternoon for sure. 8-o
Schmoburger
Well-known member
UPDATE:
OK so after I'd read this threead over the weekend I quickly set about digging into my collection to inspect machines or pulled boards for damage and remove all batteries. I have gotten through 18 units so far... 2 SE's, 2 CC's, 3 IIgs's, a IIci, a IIsi, 4 LC's, 2 early and 1 late LCIII, a Performa 400 (LCII), and an LC475... plus a few pulled boards (Classic, 475, PM5200, PM7xxx) This is the results of the sweep so far... news is good but not great. :-/
Firstly I checked out dad's SE and found an intact Tadiran battery with 88 date code which I promptly removed. Then it was time to go through mine...
Before I had even started sifting through the stack, I found 3 Classic logic boards... the first had clearly had a battery explode already, which I could no longer find any viable trace of to discern a brand... only the aftermath below. I'd call this a parts board now at best...
The second one had not been demolished so impressively but nonetheless had a badly degraded Maxell that had leaked and started to corrode the caps, a couple of diodes, an I/C and a rectifier in the immediate vicinity. The finger contacts are also damaged as well as some corrosion on the bottom of the board, but i believe this may be due to it's proximity to the exploded battery, which was on the board beneath it in a stack.
The third one that was on top, as well as the RAM stacker and SIMMS connected to it, and the other stacker sitting on top of it, were luckily unharmed. Incidentally, this third board had a different battery of German origin, blue in colour, that appeared fine. I have found a few of these in the machines I've investigated so far...
Next victim was this LC475 board I pulled from a machine years ago. This one however was not recently exploded... This corrosion was present when I got the machine nearly 10 years ago hence it's non-functional state. Thus far most of the LC475's Ive had from memory have had Maxell batteries.
After that, was time to get into the complete computers... First in line were my trio of IIgs's. The first two were fine, with no signs of leakage. I believe one had a Tadiran and one a blue . Then I opened the Limited Edition (which has the PRAM battery soldered to the board on legs underneat the PSU), and found a Tadiran that was obviously original and in a very sad state. the casing was deformed, it had clearly been leaking and there was corrosion beginning on one of the feet. After I snipped it off, I found the lower surface of the battery casing to be very poorly. I'll be pulling this board out over the coming days and washing it just to be safe and make sure no trace of goop remains...
The CC's both checked out fine, as did the IIci, IIsi, LC's, LCIII, and Performa 400... No real signs of serious degradation in the assortment of blues and Tadirans aside from very minor specks of corrosion beginning on the endcaps of a few of the 80's and early 90's coded ones. There was one Maxell in the lot that seemed ok at a glance aside from similar endcap corrosion...
Then I got the the last of the pizzaboxes, my only remaining operational LC475, and was saddened to find my first real irrecoverable Maxell victim...
I guess I don't have a functioning LC475 any longer. It looks like there must have been a decent amount of heat going on in there when it happened, and it looks to have been a pretty violent reaction too... the stuff reached all the way to the very rear of the case, and seems to have eaten away at the actual locking tab even as it snapped like a cracker-biscuit when i began to open the case as you can see, as well as rusting one localised corner of the PSU case and destroying everything in it's path on the logic board... and even the fan copped a little!
I've now written this one off as junk and stripped it... luckily there was nothing in the PDS and the RAM and VRAM modules on the board seem to have miraculously escaped unharmed. The HDD was luckily shielded pretty well by it's own SCSI cable and the FDD was far enough out of the way to escape without injury. I'm going to pull the PSU apart before I use it to make sure no stuff has not gotten in and began eating away the internals. Ah well... guess I'm on the prowl for a new LC475. I don't even have a spare case anymore, as I threw most of em from the ones I stripped out to make room for working stuff and kept only the best one, which is now junk. Ah well...
ANyway, after that devestaing blow I investigated one of the prides of my collection expecting the worst But interestingly, upon opening my nearly mint SE Superdrive, I was not only pleasantly surprised to find an unharmed logic board and analogue board with caps that look as good as brand new, and not a single silver and black cap in sight, but also this Varta battery... also soldered on feet like the IIgs LE, and a date code on it that would indicate it is the original 25 year old item. It looks like new too, and from memory this machine actually still kept reasonable time after 25 years. My dad's SE FDHD even had only lost a few hours in the last 7 years with the original Tadiran.
Anyway... after the devestation I found in my 475 I'll be continuing my investigations post-hast, as I suspect at the very least my working Classics all have Maxell batteries onboard still, as well as the SE/30 and there is a good chance I may find some in the LC 5xx and early Powermacs, and the IIvx and other IIsi that I havent checked yet.
As an aside, these machines were all sold in AUstralia, and as such, many came from the Singapore factory... Incidentally, most of the machines of Singapore origin do NOT have the Maxell battery onboard, and the ones that do have it have all seemingly been manufactured in the USA?
OK so after I'd read this threead over the weekend I quickly set about digging into my collection to inspect machines or pulled boards for damage and remove all batteries. I have gotten through 18 units so far... 2 SE's, 2 CC's, 3 IIgs's, a IIci, a IIsi, 4 LC's, 2 early and 1 late LCIII, a Performa 400 (LCII), and an LC475... plus a few pulled boards (Classic, 475, PM5200, PM7xxx) This is the results of the sweep so far... news is good but not great. :-/
Firstly I checked out dad's SE and found an intact Tadiran battery with 88 date code which I promptly removed. Then it was time to go through mine...
Before I had even started sifting through the stack, I found 3 Classic logic boards... the first had clearly had a battery explode already, which I could no longer find any viable trace of to discern a brand... only the aftermath below. I'd call this a parts board now at best...
The second one had not been demolished so impressively but nonetheless had a badly degraded Maxell that had leaked and started to corrode the caps, a couple of diodes, an I/C and a rectifier in the immediate vicinity. The finger contacts are also damaged as well as some corrosion on the bottom of the board, but i believe this may be due to it's proximity to the exploded battery, which was on the board beneath it in a stack.
The third one that was on top, as well as the RAM stacker and SIMMS connected to it, and the other stacker sitting on top of it, were luckily unharmed. Incidentally, this third board had a different battery of German origin, blue in colour, that appeared fine. I have found a few of these in the machines I've investigated so far...
Next victim was this LC475 board I pulled from a machine years ago. This one however was not recently exploded... This corrosion was present when I got the machine nearly 10 years ago hence it's non-functional state. Thus far most of the LC475's Ive had from memory have had Maxell batteries.
After that, was time to get into the complete computers... First in line were my trio of IIgs's. The first two were fine, with no signs of leakage. I believe one had a Tadiran and one a blue . Then I opened the Limited Edition (which has the PRAM battery soldered to the board on legs underneat the PSU), and found a Tadiran that was obviously original and in a very sad state. the casing was deformed, it had clearly been leaking and there was corrosion beginning on one of the feet. After I snipped it off, I found the lower surface of the battery casing to be very poorly. I'll be pulling this board out over the coming days and washing it just to be safe and make sure no trace of goop remains...
The CC's both checked out fine, as did the IIci, IIsi, LC's, LCIII, and Performa 400... No real signs of serious degradation in the assortment of blues and Tadirans aside from very minor specks of corrosion beginning on the endcaps of a few of the 80's and early 90's coded ones. There was one Maxell in the lot that seemed ok at a glance aside from similar endcap corrosion...
Then I got the the last of the pizzaboxes, my only remaining operational LC475, and was saddened to find my first real irrecoverable Maxell victim...
I guess I don't have a functioning LC475 any longer.
It looks like there must have been a decent amount of heat going on in there when it happened, and it looks to have been a pretty violent reaction too... the stuff reached all the way to the very rear of the case, and seems to have eaten away at the actual locking tab even as it snapped like a cracker-biscuit when i began to open the case as you can see, as well as rusting one localised corner of the PSU case and destroying everything in it's path on the logic board... and even the fan copped a little!I've now written this one off as junk and stripped it... luckily there was nothing in the PDS and the RAM and VRAM modules on the board seem to have miraculously escaped unharmed. The HDD was luckily shielded pretty well by it's own SCSI cable and the FDD was far enough out of the way to escape without injury. I'm going to pull the PSU apart before I use it to make sure no stuff has not gotten in and began eating away the internals. Ah well... guess I'm on the prowl for a new LC475. I don't even have a spare case anymore, as I threw most of em from the ones I stripped out to make room for working stuff and kept only the best one, which is now junk. Ah well...
ANyway, after that devestaing blow I investigated one of the prides of my collection expecting the worst But interestingly, upon opening my nearly mint SE Superdrive, I was not only pleasantly surprised to find an unharmed logic board and analogue board with caps that look as good as brand new, and not a single silver and black cap in sight, but also this Varta battery... also soldered on feet like the IIgs LE, and a date code on it that would indicate it is the original 25 year old item. It looks like new too, and from memory this machine actually still kept reasonable time after 25 years. My dad's SE FDHD even had only lost a few hours in the last 7 years with the original Tadiran.
Anyway... after the devestation I found in my 475 I'll be continuing my investigations post-hast, as I suspect at the very least my working Classics all have Maxell batteries onboard still, as well as the SE/30 and there is a good chance I may find some in the LC 5xx and early Powermacs, and the IIvx and other IIsi that I havent checked yet.
As an aside, these machines were all sold in AUstralia, and as such, many came from the Singapore factory... Incidentally, most of the machines of Singapore origin do NOT have the Maxell battery onboard, and the ones that do have it have all seemingly been manufactured in the USA?
techknight
Well-known member
yaoowwwch.
Well at least the ones that did survive, you removed all the batteries. All my batteries are gone as well. Even the coin batteries in my powerbooks.
Well at least the ones that did survive, you removed all the batteries. All my batteries are gone as well. Even the coin batteries in my powerbooks.
Schmoburger
Well-known member
Yep... any of the oldworld stuff I'm just pulling em all out. Any that look remotely dodgy, are stupedously old, or are a Maxell in any condition have been already thrown in a pile to be disposed of. The ones that are left have been put in a seperate pile away from anything important for in the event i need one. They will probably be tossed as well however, as for what its worth, I have plenty of new-world stuff to pull much newer batteries out of, or I can buy them new cheaply enough off ebay anyway.
Schmoburger
Well-known member
WHilst I think about it... has anybody ever had issues with the cube PRAM batteries used on the PM5500 and some other later Powermac logic boards that are velcroed in place? Wondering if I should pull them too... they are somewhat harder to get replacements for.
techknight
Well-known member
I havent seen one leak, but i DONT take chances. I pulled them, cut the pigtales and tossed them. Kept the pigtails in case I want to patch a new battery in place, via a battery holder.
Even the powerbooks, have the little rechargeable coin cells, I pull them too. they are starting to leak. and they are positioned in such a way it will leak all over the logicboard.
Even the powerbooks, have the little rechargeable coin cells, I pull them too. they are starting to leak. and they are positioned in such a way it will leak all over the logicboard.
