There are 2 back to back caps in the output bias stage that appear to be in bipolar configuration. They are specced at 220uf 6.3v.
Can I sub in one bipolar cap further away from the heat source, and what value should it be?
Can I sub in one bipolar cap further away from the heat source, and what value should it be?
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With same value capacitors in series the capacitance is divided by the number of capacitors, 110uF in this case, 100uF is close enough. The voltage is added. So 100uF @ 16V or greater will do. This capacitor has nothing to do with the audio you hear, they are part of a low pass filter that provides an input to the protection circuit. The filter passes only DC and very low frequencies to the protection circuit.
Very interesting, and explains its connection to the protection board.
My main concern is that these caps are sandwiched between 2 heatsinks, and they are leaking bad enough to create quite a stink.
Are there any drawbacks to relocating these caps away from the heat using a longer length of insulated wire?
My main concern is that these caps are sandwiched between 2 heatsinks, and they are leaking bad enough to create quite a stink.
Are there any drawbacks to relocating these caps away from the heat using a longer length of insulated wire?
Well, it looks like one of the main capacitors is stinking, and has a slightly raise top cap. another one looks like it is close to being as bad, so this project is going to be suspended for a while.
I will be purchasing an Onkyo ADM2.1 or M-282 to fill in for now.
I will be purchasing an Onkyo ADM2.1 or M-282 to fill in for now.
Ok, some photos aifthe amplifier model being discussed (in its initial state).
Service manual can be downloaded from Elektrotanya.
I don't think that recapping the main boards can be done without disassembling them from the unit - too little space for doing work properly.
Service manual can be downloaded from Elektrotanya.
I don't think that recapping the main boards can be done without disassembling them from the unit - too little space for doing work properly.
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I have the schematic already. I am hoping to gain access to the amp boards by disconnecting only the bottom wires and flipping the boards over the heatsinks.
I can get Nichicon KG's for less, but they have the same snap-in connections. It's going to take a bit of ingenuity to adapt it to the overengineered power bus.
I would unbolt the heatsinks and flip them over the boards - if you do not want to detach them completely so you can work on the board on your work table.
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I ran the amp again tonight for an hour with the cover off, and couldn't detect any smell or leakage from the mains caps. A lower cap on the right amp board were leaking enough to make me originally think that the big guy closest to it was suspect, but not this time.
I am going to go ahead and replace all of the small electrolytics and test it again (fingers crossed).
I am going to go ahead and replace all of the small electrolytics and test it again (fingers crossed).
There are a couple of film caps that appear to be bypasses. One is between the 220uf 35v and the 47uf 50v directly coupled to the latter, which I am replacing with an Elna Silmic.
There are 2 more small ones that appear to be bypassing the 2 10uf 50v input caps, which are also being replaced by Silmics.
I want to possibly remove the film caps if they are not critical. Is it ok?
There are 2 more small ones that appear to be bypassing the 2 10uf 50v input caps, which are also being replaced by Silmics.
I want to possibly remove the film caps if they are not critical. Is it ok?
It would be much easier to follow your intensions if you used component numbers instead of verbal descriptions 😉
In "better" amplifiers the lytics in signal path are often bridged with smaller film capacitors.
What I did in my M-505 was to replace the 10uF lytic with Wima film capacitor and remove the bridging C107/108 capacitors.
How do the Wimas "sound" - I really do not care since I am running the amp in DC input mode.
While you are working on the board you should also clean the selector switch - it has open ends and after so many years its contacts usually look like this:
With one of the M-505 one channel signal was lost after a year of listening.
It boiled down to the loosened contact in the RCA socket so I took these apart too, tightened the "clamps" and when assembling also soldered the sleeves to the lower fixing oval rings:
C204 I would leave in place. Once the designers thought it to be a good idea to have there then it should not do no harm to keep it.
There seems to be some contention over placing Silmics in high stress positions such as the 220uf 35v audio board power input, but we'll have to see how that works out.
I have Nichicon KA's ordered for the power stage of the protection board, and KZ's in the sensing circuit. All values are 25v.
I will leave the film caps where they are.
I have Nichicon KA's ordered for the power stage of the protection board, and KZ's in the sensing circuit. All values are 25v.
I will leave the film caps where they are.
One more thing I remembered about the input board - I think I removed the black wire connecting the RCA socket sleeves.
Idea was to improve channel separation and remove possible ground loop.
Idea was to improve channel separation and remove possible ground loop.
I'm afraid that I may have botched the recapping job using a Radio Shack soldering iron instead of a proper digitally regulated Weller.
It took too long to solder the joints, and I wasn't using a heatsink!
The amp functions and sounds OK, but still smells like bad electrolytics. I suspect that the main caps are contributing to it, but have no way to test them.
It took too long to solder the joints, and I wasn't using a heatsink!
The amp functions and sounds OK, but still smells like bad electrolytics. I suspect that the main caps are contributing to it, but have no way to test them.
You do not need a "weller" to recap an amplifier, you just need to use an iron of enough wattage.
How many seconds per joint did it take?