Upgrading some Sony 4650 & 5650 V-fet amplifiers, there are tantalum and 'solid aluminium' caps present.
How about to replace them... or not. Needed?
Polar caps replacing is obvious, but what to do with these? And there are several mylars too!
Any opinion is appreciated.
How about to replace them... or not. Needed?
Polar caps replacing is obvious, but what to do with these? And there are several mylars too!
Any opinion is appreciated.
Solid aluminium capacitors should no need replacement, take a look at the datasheet, they are rated >300.000h at 40°C.
I used those parts in a com system that was designed for the Thailand railway system in the 1980’s wondering if it still is in operation? Semis for the system were all industrial temp grade parts.
I somehow doubt that Sony used those philips parts that you show, to expensive for the application imo. But if you do see them being used I’d probably leave them installed unless they show failure
I myself do not change parts unless they show signs of failure
I somehow doubt that Sony used those philips parts that you show, to expensive for the application imo. But if you do see them being used I’d probably leave them installed unless they show failure
I myself do not change parts unless they show signs of failure
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Sixties seventies tantalum caps were short lived garbage. The larger ones in my 1968 hammond H100 power amp show dates of 1972 and 1974, indicating replacement by the hammond tech. All the small tantalums with the red ends in the attack generator (percussion) were bad by the time I bought the organ in 2016. Times 3, I have owned 3 of the H100's.
By contrast I reworked a 1980 Allen 300 organ with about 300 tantalum caps in the tone generator system. I have not had to change a single one. All the aluminum electrolytics in the power amps and DC supplies were high esr by 2020. The power amps went silent in a service 2019 which is how I managed to acquire it. Hundred watt power amps were putting out 2 watts the next Monday.
By contrast I reworked a 1980 Allen 300 organ with about 300 tantalum caps in the tone generator system. I have not had to change a single one. All the aluminum electrolytics in the power amps and DC supplies were high esr by 2020. The power amps went silent in a service 2019 which is how I managed to acquire it. Hundred watt power amps were putting out 2 watts the next Monday.
It really depends on how they are used in the circuit. The older tants weren't necessarily bad but they were not as robust as modern parts. The real problem was that the manufacturers of the caps told the end users that it was OK to use them at or very close to their rated voltage - 16V parts on 15V rails and such. While tantalums have many redeeming features, surge and over voltage handling is NOT one of them. Modern parts are much better in this regard but it is still a good idea to derate them by at least 50% or so. In short, if they are not used across a power rail then they are probably fine (but look at the rated voltage vs what would be expected in that portion of the circuit.) Otherwise, replace them with modern polymer parts - they easily match or exceed the original tantalums specs and are much cheaper. For that matter, a quality low ESR aluminum electrolytic should do perfectly fine as a replacement and would be the most inexpensive option.
Hal
Hal
Thanks for the reply.
Usually I take at least a polar caps with twice the needed voltage spec, and in amplifiers such as those sensitive V-fet units, all polar caps well above supply rail specs. And, if used around/near the output, bipolars also!
The factor 2 derating is specifically for tantalums, aluminium electrolytics are happy to work at/close to their rated working voltage.
I have a vintage tuner from 1971, I am going to do a restoration
It has a few capacitors but so many CRL tantalum caps, should I replace those tantalum with newer ones ?
It has a few capacitors but so many CRL tantalum caps, should I replace those tantalum with newer ones ?
The 122 SAL-RP and 128 SAL-RPM caps by Philips are about the best caps one can find. Try to find a better replacement 🙂
Still stock these and they are excellent but just don't use them near their maximum voltage. They have some bipolar cap like properties. The only negative thing I can think of is that they are mechanically fragile. Never bend these as the resin will crack near the pins.
Still stock these and they are excellent but just don't use them near their maximum voltage. They have some bipolar cap like properties. The only negative thing I can think of is that they are mechanically fragile. Never bend these as the resin will crack near the pins.
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do not try to bend the ceramics or other parts to make them look neater on the board. it may affect tuning.
Experience, physical properties of the cap like polarity indication with “+”, brand logos, color, comparing with datasheet information, service manual of the device and its BoM, having a few replaced ones of known origin in stock etc.
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