Have these caps seen better days? – Technics SE-900s

[mrjoe]

Hi all,

I'm in process of bringing back to life this power amp legend.

Power supply is working well but no sound output.

Looking over the board the two main huge capacitors have some purple / red colouring around their bases. See image, are they leaking?

There is no bulging or damage to the caps or baord which makes me think it might be glue that has melted.

Thanks in advance,

joe

 

[sKiZo]

It's a 20 year old amp, and even if the caps are "good", they're probably past their prime. Older caps go muddy and lose impact - Replace them and be prepared to be amazed at how much better the amp will sound.

PS ... I'd think the pink stuff is just glue. Common on larger components that could rock or wiggle.

Oh. Looks like that beastie uses 63v 10000uf caps (don't quote me on this - check what ya got), which can be hard to find. Good news is, you can go up in voltage rating, and the Elna 80v 10000uf caps are fairly easy to find and much better quality than most other options. My only complaint there is the new ones are "snap" mounts, which can make installation in older rigs a bit more complicated. Eminently doable though.

 

[Tim64]

It's glue on the bottom of the capacitors. Just a suggestion I would get it functioning again before doing a recap, will be a very nice unit when you finish it and vu meters don't get much bigger. Good luck on your project and happy listening when done.

 

[nj pheonix]

As said before glue . I don't know about that glue specifically but many adhesives like that become corrosive over time. If you start working on that, try and remove as much of that as possible .

 

[mrjoe]

Thank you both.

I'll keep looking for what the problem could be.

 

[ggregg]

Great advice above, remember in most cases, unless blown apart, it's usually impossible to tell if a cap is good or not by looking at it. Even if leaking it may still test fine and vice versa.

 

[cademan]

No sound?

Check:
- Speaker switch (if it has one).
- Fuses if any.
- Speaker relay engaging (if it has one).
- Output transistors.
- Power supply.
- Diodes/bridge rectifiers.

Not necessarily in that order.

 

[elnaldo]

Or, if you have "PRE-OUT" "MAIN IN" terminals at the back, they need to be connected with a bridge. .. I received a unit to fix and the problem was a missing bridge.

 

[ZOOM]

These amps tend to fail catastrophically and are really difficult to impossible (parts unavailable) to fix, even for an expert. Are you an expert? If not, I recommend an immediate giving up.

 

[Binkman]

the a900s and sm2 use power packs: Svi3205b. I'd get the data sheet and check them first. MCM has originals. They MCM state can't return and can't cancel your order @ $47.74 each. I would pull and assure if testing the pcb for v's not to short any of the solder points. If v's check out? not a promising future. I'll keep my fingers crossed.