Why should I replace it? Does it degrade over time also?
& do you have a recommendation for replacement capacitors?
thanks again 🙂
That is a nice job for you as you can measure the dimensions of the old ones and check if they're snap in or normal types. When possible (PCBs often have holes for both types) then always choose snap in types as these are better rated than normal ones. Try to find capacitors with the same dimensions but make it a slightly larger value and possibly voltage too. Or the same value but 63V rated. In the past decades caps have become smaller compared to the old ones. Kemet ALC70 or ALC80 series seem OK from what I've heard. I never tried these. I use Kendeil, Panasonic, Nichicon etc.
*gold contact relays are simply the wrong ones to switch current. The contacts burn in/wear out making them too high in resistance and sometimes making intermittent contact. This wrong choice is typical for Japanese products.... Again, after 30 years of operation replacing them for silver contact types will make the amplifier reliable for years to come. If the old ones haven't failed they sure will 🙂 If you just use 1 set of outputs it is just 1 relay...
Last tip as I have work to do: clean the boards carefully with a fluid that does not leave debri. First clean with a dry brush, remove mold and other stuff and last action is brushing carefully with the fluid. Don't touch potentiometers.
*gold contact relays are simply the wrong ones to switch current. The contacts burn in/wear out making them too high in resistance and sometimes making intermittent contact. This wrong choice is typical for Japanese products.... Again, after 30 years of operation replacing them for silver contact types will make the amplifier reliable for years to come. If the old ones haven't failed they sure will 🙂 If you just use 1 set of outputs it is just 1 relay...
Last tip as I have work to do: clean the boards carefully with a fluid that does not leave debri. First clean with a dry brush, remove mold and other stuff and last action is brushing carefully with the fluid. Don't touch potentiometers.
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Thanks for all the info 🙂
Also found this pretty recent thread about the relays in a PMA 560 (!):
Question about replacing relays | Audiokarma Home Audio Stereo Discussion Forums
edit: this amp has been sitting idle for about 18 of those 30 years (I was living abroad),
so it really has only 12 years of use in it. I've also been good about turning down the
volume before switching it on 😀
Also found this pretty recent thread about the relays in a PMA 560 (!):
Question about replacing relays | Audiokarma Home Audio Stereo Discussion Forums
edit: this amp has been sitting idle for about 18 of those 30 years (I was living abroad),
so it really has only 12 years of use in it. I've also been good about turning down the
volume before switching it on 😀
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It is a choice whether to do a job once or have to do it twice. I replaced countless of these relays and they are known to fail and if they haven't they sure will. Beware of the audio blah blah. The cause is gold contacts. Gold is not OK for current.
Any reluctance to replace 30 year old parts will cost more time. Simple.
Any reluctance to replace 30 year old parts will cost more time. Simple.
How about Kemet ACL70, 15000 uF, 100V ?
(current caps are 12000 uF, 56V)
I see the Nichicon ones are a lot more expensive, but "audio grade": so these would be better / more applicable?
I was going to edit the above post: change the "100V" to "63V", but it says I'm no longer allowed to edit it 🙄
Also the diameter looks to be a factor, most of these appear to be 40mm, but the current ones are 30mm :-|
Are you sure it is 30 mm? That is somewhat unusual for that value and that age. Well, 56V rating is not very common anymore 🙂 If correct look for 30 mm diameter types that are long life, low ESR and have the right pins for your PCB. Diameter is a decisive factor as most are 35 or 40 mm and since they are mounted close to eachother these won't fit.
It limits your choice to 30 mm types in 12,000 µF and any voltage equal to or higher than 56V. Elna LA5 series are available in 12,000 and 15,000 µF 63V in 30 mm (beware they make these in several diameters).
It limits your choice to 30 mm types in 12,000 µF and any voltage equal to or higher than 56V. Elna LA5 series are available in 12,000 and 15,000 µF 63V in 30 mm (beware they make these in several diameters).
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Yes 🙂 :
Looking at the PCB layout though, I'm thinking I should be able to fit larger diameter caps:
There's about a 6x6 cm open area, so space for 4 of these capacitors, or probably 2 larger capacitors.
What would be the benefit of choosing 4 x 8200 over 4 x 6800 ?
edit: looking at these now: Blocked
(that link says "Blocked" on my screen, it's the Nichicon LKS1J822MESB, found on digikey)
choosing one that has "Audio" as the listed application would be better? Or is the only difference the price 😀
("lead spacing" is 10 mm, the holes in the PCB are 15 mm apart, I'm guessing I can manage by bending the leads or drilling an extra hole)
I still have the brochure from that time, which also lists the "big brothers" of the 560, the PMA 860 and the PMA 1060.
Those have the 4 capacitors indeed, here's a picture of the 860:
and of the 1060:
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Industrial version is the best (as usual). "Audio" or "For Audio" has the best specs in gain margin for the sellers.
Somewhat larger value caps make ripple voltage lower but overdimensioning the extreme way will not work out that well. The amplifier type you linked to probably has a higher current rated Graetz bridge.
Somewhat larger value caps make ripple voltage lower but overdimensioning the extreme way will not work out that well. The amplifier type you linked to probably has a higher current rated Graetz bridge.
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The first of those two appears better speced at face value with a significantly higher ripple rating and also 3000 hrs vs 1000 hrs. The hrs rating isn't always as bad as it seems because it is for that cap operating at max temperature and also often at max ripple.
Typical ripple when idling in your amp could be just a few hundred milliamps or less. Temperature a lot less than 85C which all adds to a lifetime of tens of thousands of hours for both caps.
You can easily (by the look of the pictures) drill the PCB to accommodate a different pin spacing if needed. Don't bend legs of big caps and never add wires to them.
Typical ripple when idling in your amp could be just a few hundred milliamps or less. Temperature a lot less than 85C which all adds to a lifetime of tens of thousands of hours for both caps.
You can easily (by the look of the pictures) drill the PCB to accommodate a different pin spacing if needed. Don't bend legs of big caps and never add wires to them.
Thanks again for the info.
It looks like a shipping charge of about 20 euros is typical?
(I was thinking "mouser" is based in the Netherlands, but they seem to charge 20 for "fedex international priority" as the cheapest option, for example).
The only "more local" store I found so far was Conrad, but they only carry "Teapo" capacitors with those specs 😕
It looks like a shipping charge of about 20 euros is typical?
(I was thinking "mouser" is based in the Netherlands, but they seem to charge 20 for "fedex international priority" as the cheapest option, for example).
The only "more local" store I found so far was Conrad, but they only carry "Teapo" capacitors with those specs 😕
Yes the good old days of hobby electronics shops are long gone. DIL was one of the last but eventually stopped in 2015, just like most others had done before. Most online distributors (without an exception all foreign companies) charge high prices and have a minimum order quantity of 50 Euro for free shipping...
There is Mouser, Digikey, Farnell.. all the same... too expensive. Sometimes you can buy together with a fellow DIYer... sorry but that is 2021 🙂 Buying new stuff is cheaper than repairing classic devices but then you have the luck that the new device will fail in just a short time 😀
Don't even bother to try out Teapo.
There is Mouser, Digikey, Farnell.. all the same... too expensive. Sometimes you can buy together with a fellow DIYer... sorry but that is 2021 🙂 Buying new stuff is cheaper than repairing classic devices but then you have the luck that the new device will fail in just a short time 😀
Don't even bother to try out Teapo.
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So I might as well spend some time to figure out what else I need. Don't want to order, then realize I needed one more part 😱
Well that is standard. I ordered for 60 Euro stuff (that is not even a handful of SMD parts) at Digikey only to discover today I forgot to order a few caps and resistors.
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I remember Teapo from when they appeared in stuff in the 90's. And noVer. These were often used in SMPS in TV/VCR type applications. They were not good.
The famous NoVer 🙂 At least the printing on the caps was in gold. Once bitten, twice shy ... Not the case with one of the once worst cap producing companies: Lelon.
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So I decided to get that dinky little "TC1" component tester, and measured the filter caps with it ("meten is weten" as they say in the Netherlands 😀)
It showed:
12.75 mF, Vloss 1.6%, ESR 0.16 Ohm
12.81 mF, Vloss 1.3%, ESR 0.16 Ohm
Is this an indication the caps are still ok?
It showed:
12.75 mF, Vloss 1.6%, ESR 0.16 Ohm
12.81 mF, Vloss 1.3%, ESR 0.16 Ohm
Is this an indication the caps are still ok?