Considering recapping...
- Thread starter johnnm
- Start date
Register to hide this ad
Stevesmullen
Well-Known Member
What receiver are you considering for Recaping?
johnnm
Audio Enthusiast
SX-650. I'm spending some quality time with the manual right now, trying to figure out if this is something I'll actually be able to do.
To put new caps in, I'm going to have to remove the board which requires removing the wires connected to it. The wires are wrapped around metal poles, but aren't soldered at all. When reattaching these wires, is it acceptable to wrap it around the pole w/o soldering it?
To put new caps in, I'm going to have to remove the board which requires removing the wires connected to it. The wires are wrapped around metal poles, but aren't soldered at all. When reattaching these wires, is it acceptable to wrap it around the pole w/o soldering it?
Don't unwrap the square posts, and be careful not to break the wires. There's more than meets the eye with those wire wraps.
Yes, the electrolytic caps only. The rest are long term stable.
You need to use both the manual and visual verification to locate the caps and confirm their values. You will quickly learn to recognize the electrolytic caps. In the schematic they usually have a value of 1 uF or greater, with a FEW exceptions in the 0.1uf to 1uf range.
Even EchoWars and myself manage to leave the wraps alone while doing work.
Removing the bottom plate should give a lot of access to the solder connections, and there's usually enough slack to lift the other smaller boards.
I would say be careful about the thermal diodes, BUT the 650 uses modules that are not as fragile.
Yes, the electrolytic caps only. The rest are long term stable.
You need to use both the manual and visual verification to locate the caps and confirm their values. You will quickly learn to recognize the electrolytic caps. In the schematic they usually have a value of 1 uF or greater, with a FEW exceptions in the 0.1uf to 1uf range.
Even EchoWars and myself manage to leave the wraps alone while doing work.
Removing the bottom plate should give a lot of access to the solder connections, and there's usually enough slack to lift the other smaller boards.
I would say be careful about the thermal diodes, BUT the 650 uses modules that are not as fragile.
Wirewrap was a cost saving technique. The tool used to wrap the wire around the post wraps it so tightly it actually bites into the metal post making a good connection. The reason not to unwrap the post is that I think that Pioneer used some aluminum in the post making it very difficult to solder them back on. I recapped my SPEC-2 and had these issues.
Recapping is not needed if things are working fine. I believe these amps didn't use coupling caps in the signal path. The caps you do see are used to filter or decouple interferance out of the signal path.
I think you could save some time and money by picking up a 20MHZ O'scope on Ebay and learning how to use it. If you want to learn more about electronics Google the US Navy NEETS modules. It's a complete electronics course free.
Recapping is not needed if things are working fine. I believe these amps didn't use coupling caps in the signal path. The caps you do see are used to filter or decouple interferance out of the signal path.
I think you could save some time and money by picking up a 20MHZ O'scope on Ebay and learning how to use it. If you want to learn more about electronics Google the US Navy NEETS modules. It's a complete electronics course free.
johnnm
Audio Enthusiast
You've made a very good point not to unwrap those poles. 
That said, a big part of this for me is tinkering and learning. Even if I end up having to scrap the receiver entirely, as long as I learn a lot from it that's okay with me.
I've done a little soldering in the past. I was thinking about getting some cheap stuff at radioshack just to practice with for a while.
If you still that I still shouldn't do this (at least by myself), I'd be fine with paying for it to be done on the condition that I can watch. Think I can find someone to do this in Ann Arbor?
What would I do with an o'scope?
Thanks for the NEETS heads-up. Lot of info there.
That said, a big part of this for me is tinkering and learning. Even if I end up having to scrap the receiver entirely, as long as I learn a lot from it that's okay with me. I've done a little soldering in the past. I was thinking about getting some cheap stuff at radioshack just to practice with for a while.
If you still that I still shouldn't do this (at least by myself), I'd be fine with paying for it to be done on the condition that I can watch. Think I can find someone to do this in Ann Arbor?
What would I do with an o'scope?
Thanks for the NEETS heads-up. Lot of info there.
I won't unwrap the posts, but what's so peculiar about them? They were originally hand-wrapped, no?
Turns out there's several types of capacitors.
Is there a specific type to look for, or just not electrolytic?
There are plenty of electrolytic caps in the 650 that can be replaced (if original) for a positive effect - with LOTS of signal coupling caps. I get REALLY tired of advice that's coming from those that know nothing about the unit, and don't take the TIME to FIND OUT FIRST........ I don't mind correct advice - it saves ME typing - but I have to type MORE when it's necessary to correct things.
The caps could be tested individually with an ESR meter to find the ones that have either gone bad, or gotten marginal. Then repeat every year or two until all are replaced.... or do it all at once for another 20 - 30 years.
Electrolytics are small plastic covered metal cans with rubber seals where one or both of the leads come out. They use a water based chemistry that stops working when they dry out. The hotter the area they are in and the cheaper the seal, the sooner they die.
There's another type called tantalum electrolytics, and for OTHER reasons they too should be replaced (with an electrolytic too). THAT'S why I recommended using the capacitance VALUE as a guide (found in the schematic and manual's parts list) as to what should be replaced.
So yes, re-capping (the electrolytics) extends the life, as long as you don't put them in backwards and blow something up.
The wire wrap's square post cuts into the metal of the wire and forms a "gas-tight" connection, which at that point doesn't corrode. The CUT weakens the wire which can break off short on disassembly, or SURELY on re-wrapping IF you have the CORRECT tool (not easily found anymore!!) applying the correct tension, and that broken off short wire will be a REAL problem.
Please read the schematic before putting fingers in gear. It's (most all Pioneers) FULL of coupling caps. They're far more plentiful than transistors in everything except some final power amp stages.
And the untrained EAR is not the best way to discriminate between working like new, "working fine", bad enough to be audible or stone cold dead in some section. At least use an ESR meter on them. A scope can find an interruption of the signal, but finding distortion of 3 percent or less is difficult.