Echowars: Ripple Current

Kevin's Rack

Technics-aholic
Replacing the Power Supply caps in my SA-700 Receiver, the old ones have literally drained through the bottoms leaving residue on the leads and the PC boards. In my quest to find replacements, I have come to a fork in the road: Which would be better for a power supply, The [Panasonic] T-UP series with a ripple current of 7.53A or the T-HA series with a ripple current of 4.80A (at 120Hz). By the way, the originals are 15000uF at 63v. Thanks a lot!!
 
They are both decent caps, and even the 4.8A is more than you will ever need.

I'd buy whichever one fits best...if they are the same, go for the one with the higher ripple current rating.
 
thanks alot. and whoa, you just put your 4500th post, congrats! I figured that either would suffice because it draws just over 4A line current...
 
Are you getting your replacement caps from Digikey? I just opened up a Yamaha Ca-1010 I picked up weeks ago and the PS caps 18000uf @63v are bulging :(
 
gonzothegreat said:
Are you getting your replacement caps from Digikey? I just opened up a Yamaha Ca-1010 I picked up weeks ago and the PS caps 18000uf @63v are bulging :(
Are you sure? The Yamaha's look like a true nightmare to try and replace if it's the style where they 'lay down' on the bottom of the unit... :sigh:
 
re:the old ones have literally drained through the bottoms leaving residue on the leads and the PC boards.

I'm curious - what does residue look like? My Alpha 130 has what looks like wax at the base of its caps - I didn't think anything of it. Should I be concerned?
 
The electrolyte in capacitors is corrosive, and when it leaks it leaves a crusty grunge not unlike the crap that builds up on automotive battery terminals.

If what you see is hard, like dried glue...then that's what it is.
 
This has been the project from hell

well, it looks like I might just write off the project:
My first setback was (about one week ago): I was taking voltages of transistors, and I couldn't get to 2 of them as they were covered by a metal chassis. So I pulled out my drill (to take a little shortcut. In order to get the chassis off, 80,000 other things needed to be taken apart). So I drilled real slow, and got nowhere. So I then throttled it and not only went through the chassis, but the circuit board underneath. Now I had no choice but to remove 80,000 things to get the PC board out. Luckily the drill didn't put a hole but rather cracked off a small piece of the PC board which I managed to epoxy back on and solder the traces together. So once I had the PC board out with the transformer, I had to replace a few parts destroyed by the drill (To put me back at square one). And I noticed a lead to the overseas voltage switch was hanging on by a thread. I must have damaged the innards of it while soldering it back on, as 110 volts didn't give power to the tranny (but 220v did), but it wasnt covered in my schematic :thumbsdn: so i looked at the schematic and according to it, the red and black leads corresponded to the line input, however for me there were 2 sets of red and black leads, so I hooked up the leads I hoped were on the primary, but when I plugged it in, it sounded like a gunshot, then I could just hear the coil inside disintegrate. So Now I just want to like die. Another transformer is $91. So I don't know whether to just buy a whole other unit or just the transformer. :cry: So that's my story of the project from hell.
 
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Owww!!!

That was painful to read.

We all have projects that go that way (in the middle of one now). It might not help too much, but you aren't alone... :)

Sorry to hear...

(might add that it isn't uncommon to have to remove 80,000 things to get to one damn thing...sucks but that's the way it goes sometimes)
 
OOOuuuuccccchhhhh.... I feel your pain.........

You need sharper drill bits, but I realize that this is monday morning quarterbacking.

We've all tried shortcuts... and paid the price.
 
EchoWars said:
Are you sure? The Yamaha's look like a true nightmare to try and replace if it's the style where they 'lay down' on the bottom of the unit... :sigh:

Nope they're standups. The top seal looks like a half-done batch of Jiffy-Pop (c) so while they might be usable, they're due to be swapped out along with a bunch of low voltage units on the PS and driver boards. It'll have to wait until a few other projects hit the finish line though.
 
Hijacking my own thread (LOL)

well, I took the plunge and bought the God-damned transformer. $99 freaking dollars. I figured, who knows if I'll ever be able to get my hands on another transformer and I've worked so hard and done so much. Although it's been 1 step forward and 10 steps back, I have made some repairs which I think contributed to the original problem. The original problem was the protection circuit was sparatic and kicked in and out when it wanted to (or rather when a [large] capacitor finished draining through the collector of the switching transistor :scratch2: . (The offset was only 12mV). I might need a little help troubleshooting the protection circuit if I end up back at square one (If that's ok with you echo...)
 
Ok, I wound up back at square one, it turned out I didn't destroy the transformer, I just arced the bottom of the circuit board. Put it back together: The preamp tuner works great, :banana: Just need some help with the protection circuit, :scratch2: I'll probably put up a scan of the schematic tomorrow. Sorry I havent been able to fill you in, I kinda stepped away from it for a while. :yes:

Thanks a lot. I think the problem is a non-polar capacitor is not really allowing the proper flow, and is sending the switching transistors out of whack, where one's collector is getting a positive rail voltage. (57.6v compared to the correct .7v) Hmmmm...
 
Echowars, can you offer me some words of wisdom please?

Here's how it works:

Q901 & Q902 are DC switches (as per schematic) These have been replaced (2sc828)
Q903 is a switching transistor (as per schematic) This hasn't been replaced (2sc945)
Q904 is a relay driver (as per schematic) This has also been replaced (2sc1509)
Q701&702 are regulators and have been replaced as well (2sd381 and 2sb536 respectively)

Could C903 be the culprit of the various incorrect voltages in the protection circuit??

 
Sorry, it kinda came out shitty. The Schematic I have on CD is protected (.pdf) and I had to print it out and then scan it, and for some reason it printed out very faintly, if you need numbers, let me know...

And thanks a lot!
 
In Idaho with very little access to computers. Going home tonight and I'll try to help once there.
 
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