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#1
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
I suspect that this is a common failure, so I am putting my fix out
there in the wild should anyone else want to use what I learned. I purchased this amp in the early 1980s and have always liked it. It was from Sony's high end specialty line at the time. The problem was that the speaker protection circuit first started taking a long time to kick in after power on and then eventually wouldn't kick in at all. You can tell this by the fact that the LED in the volume knob would stay red instead of turning green and the tell tale sound of the speaker relays kicking in never happened. I bought a scan of the schematics off the net. A bit of a rip off, but I couldn't find free ones. From the way the problem developed I figured that it was probably a capacitor which had gotten old. Oddly enough, the circuit is split with some components on the main board and some on the power supply board. So, I replaced capacitors C404 (10 uF,16V), C405 (100 uF, 25V), C406 & C421 (both 10 uf, 50 V NON-POLARIZED). Based on the circuit diagram I suspect that C405 was the main trouble maker. It looks to me like R406 and C405 create the RC time delay which is an input trigger to the HA12002 control IC. All of the caps I changed out are on the power supply board. Be very carefull, those traces lift from the board very easily. Even with care I buggered two of them up and had to do a bit of add on wiring to make things right. For everything except the non-polarized caps I was able to purchase replacement units with higher voltage ratings. Maybe these will last 40 years . Finally, I also switched the rear panel speaker impedance selector to the 4-8 ohm setting. I found out that all this does is to lower the voltage rails to the output stages and thus limit the peak current availability. I never push this amp hard, and given it's age I feel that pulling back on the output drive voltage a little might buy me some extra lifetime. Happy Listening! John |
#2
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
It's nice to win one every once and a while. Congratulations!
James. ) |
#3
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
James Lehman wrote:
It's nice to win one every once and a while. Congratulations! James. ) Thanks. I wonder how many other bad or marginal electrolytics there are in there. The circuits are chock full of the little animals and this is a very hot running amplified. Even under no load it gets quite warm. Perhaps some of the stages are biased more in a Class-A style as opposed to Class B or AB. John |
#4
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
Do you think that the electrolytic juice got cooked out?
I wonder what steps , if any have been taken to prolong the life of a capacitor in the last 25 years. I have several amps from the late 70's, early 80's. I'd like to think that when you get something like that, it should last forever. I know one thing... I never buy speakers with foam surrounds any more. I don't even look at them. I go straight for the butyl rubber or treated cloth or whatever. James. ) "John Horner" wrote in message news:4YSEg.12884$Z1.10502@trnddc03... James Lehman wrote: It's nice to win one every once and a while. Congratulations! James. ) Thanks. I wonder how many other bad or marginal electrolytics there are in there. The circuits are chock full of the little animals and this is a very hot running amplified. Even under no load it gets quite warm. Perhaps some of the stages are biased more in a Class-A style as opposed to Class B or AB. John |
#5
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
James Lehman wrote:
Do you think that the electrolytic juice got cooked out? I wonder what steps , if any have been taken to prolong the life of a capacitor in the last 25 years. I have several amps from the late 70's, early 80's. I'd like to think that when you get something like that, it should last forever. I know one thing... I never buy speakers with foam surrounds any more. I don't even look at them. I go straight for the butyl rubber or treated cloth or whatever. James. ) Nothing lasts forever, especially electrolytic caps. I don't think today's are necessarily any better than good quality ones from the past. I agree with you on foam rubber. Anything made out of foam rubber is on a one-way journey back to goo and dust. The only question is how long it will take. Don't expect the seats in any modern vehicle to still be firm 10 years from now! John |
#6
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
John Horner wrote:
James Lehman wrote: Do you think that the electrolytic juice got cooked out? I wonder what steps , if any have been taken to prolong the life of a capacitor in the last 25 years. I have several amps from the late 70's, early 80's. I'd like to think that when you get something like that, it should last forever. I know one thing... I never buy speakers with foam surrounds any more. I don't even look at them. I go straight for the butyl rubber or treated cloth or whatever. James. ) Nothing lasts forever, especially electrolytic caps. I don't think today's are necessarily any better than good quality ones from the past. I agree with you on foam rubber. Anything made out of foam rubber is on a one-way journey back to goo and dust. The only question is how long it will take. Don't expect the seats in any modern vehicle to still be firm 10 years from now! John Many caps are specifically designed NOT to last as long these days. Look in a DigiKey catalog. Why else would a cap be rated at 1000 hours, but betters ones rated at 2000 hours, etc? I've seen radios at 65 years old which still had (some) good caps in them. Mark Z. |
#7
Posted to rec.audio.tech
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Fixed Sony TA-F555ES Integrated Amplifier Today
Mark D. Zacharias wrote:
Many caps are specifically designed NOT to last as long these days. Look in a DigiKey catalog. Why else would a cap be rated at 1000 hours, but betters ones rated at 2000 hours, etc? I've seen radios at 65 years old which still had (some) good caps in them. Mark Z. Probably not aluminum electrolytics though. |
#8
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Quote:
Thanks for this guide! I have the same amp, and I have a question for you regarding Amp Adjustment of BIAS and BALANCE. I simply cannot complete the procedure of adjustment this amp: I can't set BIAS to 100mV and also cant adjust the V-I board balance. So, the questions are, If you cam, please describe here the procedure of amp adjustment, or, even better if you could scan and send me Your service manual (or parts of it regarding to adjustments). Thank you very much! Regards. |
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