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View Full Version : Tantalum capacitors on Tandon TM-100-2A



SunDown79
July 1st, 2017, 01:13 AM
So I had one of the tantalum capacitors on a Tandon TM-100-2A explode on me (it was quite a spectacle).
But I was just wondering if anyone knows the value's of these ?

Think they are 4,7uF at 16V, can someone verify ?

ldkraemer
July 1st, 2017, 05:27 AM
At grid location H5 (SAMS Photofacts) there is a Tantalum on the Logic Board and that is C30.

C30 is a 4.7uF 16V shown in their parts list.


Larry

glitch
July 1st, 2017, 06:25 AM
explode on me (it was quite a spectacle).

Gets your attention, eh? :)

SunDown79
July 1st, 2017, 09:32 AM
Gets your attention, eh? :)

It certainly does! See the picture ;)
And thanks Larry for the confirmation!

https://farm5.staticflickr.com/4238/35653018035_4a75848819.jpg
https://flic.kr/p/Wjx38v

bobba84
July 2nd, 2017, 02:56 PM
Gets your attention, eh? :)

I really hate it when that happens haha. Sure wakes you up!

Chuck(G)
July 2nd, 2017, 03:57 PM
Try a Sprague "Vitamin Q" steel-jacketed glass-sealed cap blowing up. I was working on a chassis, when one let go--the shrapnel embedded itself in the ceiling tiles and narrowly missed my face. Left my ears ringing:

Exempli gratia (http://www.ebay.com/itm/RARE-022-200V-196P-Sprague-Vitamin-Q-Capacitor-PIO-022uf-/322174114886)

Great low-drift caps sought after by the tube audio people, but it's obvious why they're not made any longer.

ibmapc
July 2nd, 2017, 05:37 PM
I had what I think was an Electrolytic Cap go off in an EL-Cheapo power supply in a clone pc tower. It sounded like a 22 caliber pistol going off and when I later opened the power supply, there was an exploded can loose in there and a bunch or what looked like Mylar foil all unraveled all over the place. I was glad the power supply cover was in place when it let go!!

Great Hierophant
July 2nd, 2017, 09:56 PM
I have a question about lifespan of Tantalums, are they good until they explode or do they deteriorate over time like electrolytics?

Malc
July 2nd, 2017, 10:16 PM
I've found tants can deteriorate over time, More so if not used for long periods of time, Just last week i had one go pop on an old cga card i hadn't used for a long time, They don't always go pop, They can go short and still look brand new.

NeXT
July 2nd, 2017, 10:27 PM
The just destabilize as they get older. I've had them work on one power cycle but go dead short on the next. IF you find one that falls below spec I can assure it's going to fail very, very soon.

bobba84
July 2nd, 2017, 10:50 PM
Maybe we should call them tantrum capacitors?

NeXT
July 2nd, 2017, 10:58 PM
They already have that nickname. ;)

Chuck(G)
July 2nd, 2017, 11:00 PM
The bottom line is that there's no such thing as a free lunch.

If you want something that will last pretty much forever, consider a Leyden Jar. You'll need a heckuva bank of the things to get a 4.7 uF cap, however.

Everything else has various failure modes; in particular tantalum caps are vulnerable to moisture--and surface-mount ones, since they're not coated, are particularly vulnerable. On the through-hole mounted ones, the epoxy coating eventually degrades and cracks and the road is downhill from there.

Flamin Joe
July 3rd, 2017, 01:23 AM
Just replace the lot to be safe in my opinion. I had shorted caps on a couple of my TM-100-2A's which ended up blowing an inductor on each of the boards. All the caps looked perfectly normal not a single visual clue to say which one was faulty. So I just ended up replacing the lot to be on the safe side. Did the same with the 5150 motherboard which also had a shorted cap on the 12V rail. No point messing around and potentially revisiting the repair for another blown cap later down the track.

SunDown79
July 3rd, 2017, 08:51 AM
Yeah will replace them all. Fun to see this subject is so much alive amongst all the people here :)
One question; often I have trouble desoldering old stuff, and I am by no means an expert, so does anyone have a tip how to make it "flow" better ? (I currently use a proper solder sucker and desolder at about 300C)

Flamin Joe
July 3rd, 2017, 06:15 PM
Invest in a desoldering gun would be my suggestion. They are expensive but worth it in my opinion. I'm no expert either when it comes to soldering/desoldering but I feel like it after I brought a Hakko 808. :D Has turned what was previously a time consuming frustrating job using desoldering braids/solder suckers into a simple hassle free job.

Your not supposed to, but for me it also doubles as a soldering iron as well. I find the cone shape to be perfect as if you put the right amount of solder on it to cover the hole, you can literally just dip it onto the pin and create an almost perfectly looking solder.

hornbetw
July 4th, 2017, 05:48 PM
RMA Rosin Flux (Kester 186 or similar). Get the liquid, not the flux pen. It helps to get old solder to flow when you desoldering & it's very helpful when soldering SMT components.

Tom

Chuck(G)
July 4th, 2017, 07:04 PM
As we're talking about through-hole components, when desoldering, add some solder to the joint, then suck the joint dry using the big Soldapullt. As all of these old drives use tin-lead (60/40 or 63/37), use lead-bearing solder, not the lead-free stuff.

Bear in mind that one or both legs of these caps are connected to a power plane, it's going to take a fair amount of heat to loosen things up. I use a Weller PTA7 tip on my WTCP iron, unless I need something bigger. Sometimes clipping the cap out before unsoldering can remove a fair bit of thermal mass.