Sansui big capacitor replacement - disappointment
- Thread starter mplsbob
- Start date
- Status
all OT but --
Hitachi calls it 'Series E', perhaps they are suggesting 'Class E' or something. Nothing terribly complex...amp just has two power rails...one at +/-39V, and the other at +/-95V, and switches to the higher rail when needed. No 'short term' thing about it...it is designed to output from the higher rails for as long as you care to drive it that hard.targeteye said:
restorer-john
Addicted Member
Hey Glenn, I have an HMA in the store room- given to me about 17 years ago by a 'tinkerer' who had blown it up. I had the same problem back then, but never bothered to go any further and it is boxed deep on the storeroom. It's a case of vapourised pcb tracks and lots transistors and I couldn't be bothered. It has a dual cap and two separate ones, tiny speaker terminals and one of th biggest transformers in a 200watt amp. Series connected single T03's and I don't know about you, but it is the one amp that I thought was held together by string. How did it actually sound with that commutating supply?
Still OT 
... but/
Haven't gotten that far. The open frame output relay is totally whacked and I'm going to have to replace it with something else (relay was bypassed for the tests) I see nothing on the scope that looks odd or weird as it transitions from one supply to the other, although I tried to make it misbehave.
I don't care for the dual-section can either...if that one had been bad, things would have gotten to be a PITA real quick. As it was, Hitachi used 10,000uf 120V caps for the high-side rails, and the voltage on them is only 95V, so they are getting replaced with 15,000uf 100V caps (I don't really have a choice in the matter, since that's all I can find that will fit).
I'm not exactly sold on gimmicks like this...all that trouble for increased efficiency. Sometimes an engineer just wants to build something to see if he can, and you end up with an amp like the HMA-8300.
... but/Haven't gotten that far. The open frame output relay is totally whacked and I'm going to have to replace it with something else (relay was bypassed for the tests) I see nothing on the scope that looks odd or weird as it transitions from one supply to the other, although I tried to make it misbehave.
I don't care for the dual-section can either...if that one had been bad, things would have gotten to be a PITA real quick. As it was, Hitachi used 10,000uf 120V caps for the high-side rails, and the voltage on them is only 95V, so they are getting replaced with 15,000uf 100V caps (I don't really have a choice in the matter, since that's all I can find that will fit).
I'm not exactly sold on gimmicks like this...all that trouble for increased efficiency. Sometimes an engineer just wants to build something to see if he can, and you end up with an amp like the HMA-8300.
targeteye
Super Member
EchoWars said:
Surely if it were to be driven at 325 WPC continuous Hitachi would have rated as 325 not 200. Afterall for sure back them "bigger was better". Cutting and pasting this off a German Forum so its a "translation".
"Super amplifier HMA-8300
The Dynaharmony amplifier with the extreme power output of 2 x 200 W Sinus/2 X.400 W music. Frequency response 5-80,000 cycles per second. Distortion factor 0.1%. Weighted signal-to-noise ratio 110 railways (AUX).
Dynaharmony, the circuit for more achievement
The principle of this Hitachi development is simple and ingenious: Music point levels arise only in each case for fractions of a second. And for these fractions of a second a second amplifier the primary amplifier switches itself in addition according to the Dynaharmony principle. Thus 2 X.400 W is available then e.g. at short notice in place of the normal 2 x 200 W
Sine steady tone achievement (both channels operated)
with 1 kHz 4 ohms of 2 x200W
with 20-20,000 Hz8 ohms ---
Distortion factor 0.1%
Intermodulation 0.02%"
Steve
restorer-john
Addicted Member
Reliability at 200watts continuous would be good and that's what hitachi hoped to achieve. If they had rated it at 325watts with the consequent FTC power rating requirements, it would have been way more expensive, heavy and uglier than it already is.:yes: With a +/- 95 volt rail, anything is going to belt out way more than 200 watts, even if the rail drops by 40% under load. It is a high voltage beast and I am going to be very interested to see how yours goes Glenn, when finished. Judging by the design, I'd be careful with anything under 8ohms....current limiting was the order of the day with that design. I can't see how the current limiting is anything but assymetric in this design, but my schematic is quite hard to see (an old photocopy) Q708/709. What do you think?
thinking.........
Looks like "maybe" 80% of the electrolytic caps in the average xoxo type receiver "could be replaced with "orange drop" caps..................???
This looks to make it pretty much bullet proof....................yet kinda expensive. But it would pretty much eliminate the electrolytic issues or at least minimize them greatly.
Think that's worth the extra expense to "upgrade" in such a manner??????
That is if yer wanting to hang on to that piece 4ever. :scratch2:
Looks like "maybe" 80% of the electrolytic caps in the average xoxo type receiver "could be replaced with "orange drop" caps..................???
This looks to make it pretty much bullet proof....................yet kinda expensive. But it would pretty much eliminate the electrolytic issues or at least minimize them greatly.
Think that's worth the extra expense to "upgrade" in such a manner??????
That is if yer wanting to hang on to that piece 4ever. :scratch2:
xoaphexox
Supernatural Anesthetist
Unless you shat $100 bills and wanted to keep the amp in your family until we used teleporters to commute to work, it seems like it might be a waste 
On a note related to this thread, to replace a power supply cap (12000uf 63V), the choices between Panasonic T-HA and T-UP - which one to use?
http://www.digikey.com/scripts/dkse...?lang=en&site=US&KeyWords=12000UF+63V&x=0&y=0
On a note related to this thread, to replace a power supply cap (12000uf 63V), the choices between Panasonic T-HA and T-UP - which one to use?
http://www.digikey.com/scripts/dkse...?lang=en&site=US&KeyWords=12000UF+63V&x=0&y=0
When I first decided to recap my old Kenwood KA-5500 years ago, I thought, 'well, why not get rid of the electrolytics and all their problems, and use some nice film caps?' Then you start looking at physical size...a 4.7uf metal polypropylene cap is probably 75x larger than a 4.7uf electrlolytic cap. It's a great idea in concept, and in some places on some PC boards you can get away with replacing a, say, 1uf 50V electrolytic with a 1uf 250V metal polypropylene, but most of the time there's simply no room for the big-ass film cap...and we haven't even gotten into the $ issue yet (but Panasonic makes some really good metal poly caps for a buck or two each).Crazy said:
I don't care much for those snap-in jobs...I use them as a last resort. If you can find a good screw-terminal cap from Newark or Mouser, go with that.xoaphexox said:
xoaphexox
Supernatural Anesthetist
EchoWars said:
So how do you go about attaching the screw terminal cap to the power supply PCB? Would you drill a hole and use an actual screw (after removing laminate to expose more copper for the screw to touch)?
(edit) Wow the screw terminal caps I could find was a Vishay/Sprague and $50 - $70 each! I am suprised.
I have no idea of what you're working on and what your requirements (including mounting) are. If you've found something that looks like it'll work, cool.
Many snap-in caps have extra terminals that must be electrically isolated, so if your cap mounts directly to the PC board, you're going to have some issues.
Pay attention to the lead spacing also.
Many snap-in caps have extra terminals that must be electrically isolated, so if your cap mounts directly to the PC board, you're going to have some issues.
Pay attention to the lead spacing also.
wsjoe said:
Yes, the change you describe is just what we all experience. A total change in sound quality - and the special vintage sound - that beautiful midrange - gets lost. Instead a very dry recessed bass and brittle treble. Nice if you like it. I belive most vintage enthusiasts do not.
Morden2004
Relaxin'
ESR - no standards for measurement
You have to be careful here when considering ESR as a factor in the health of an electrolytic. There is no 'standard' value for ESR in the industry. ESR is a theoretical byproduct of the breakdown in chemical and mechanical composition of an electrolytic capacitor over time and not something that the designers calculated specs for. And only electrolytics exhibit this phenomenon.
As far as I know, ESR was 'discovered' by technicians. It seems -- and I stress seems -- to factor heavily into problematic circuit issues -- circuits that amplify signals, mostly -- which are corrected by installing a new electrolytic for a seemingly OK electrolytic.
So, how does ESR affect a circuit? It is a matter of calculating the difference in circuit behavior at a given frequency for R = 1 ohm (acceptable ESR) and C = x farads vs. R = 50 ohms (bad ESR) and C = x farads. So, not an easy issue to measure. Except when the audio resulting after the component replacement is improved. :thmbsp:
Food for thought.
Paul
targeteye said:
You have to be careful here when considering ESR as a factor in the health of an electrolytic. There is no 'standard' value for ESR in the industry. ESR is a theoretical byproduct of the breakdown in chemical and mechanical composition of an electrolytic capacitor over time and not something that the designers calculated specs for. And only electrolytics exhibit this phenomenon.
As far as I know, ESR was 'discovered' by technicians. It seems -- and I stress seems -- to factor heavily into problematic circuit issues -- circuits that amplify signals, mostly -- which are corrected by installing a new electrolytic for a seemingly OK electrolytic.
So, how does ESR affect a circuit? It is a matter of calculating the difference in circuit behavior at a given frequency for R = 1 ohm (acceptable ESR) and C = x farads vs. R = 50 ohms (bad ESR) and C = x farads. So, not an easy issue to measure. Except when the audio resulting after the component replacement is improved. :thmbsp:
Food for thought.
Paul
Kjell-B said:Yes, the change you describe is just what we all experience. A total change in sound quality - and the special vintage sound - that beautiful midrange - gets lost. Instead a very dry recessed bass and brittle treble. Nice if you like it. I belive most vintage enthusiasts do not.
The change you describe has not been my experience. On the contrary, the basic qualities of my Kenwood gear have not be displaced, rather I would describe the changes as an enhancement.
I would also suggest that some of the so-called "special vintage sound" may not truly represent how the gear sounded when new. Perhaps some of that sonic character is attributable to the audible effect of aging electrolytics.
Knowing exactly how a unit sounded 30+ years ago. when it was new, is no longer possible.
restorer-john
Addicted Member
Knowing how a unit sounded 3 minutes ago. letalone 30 years ago is impossible. I think a lot of the 'sound' we remember is linked to age, times in our lives, the music, our hearing ability at the time and lastly, the equipment used. I would propose the deterioration of capacitors and their effect on overall sound character is less than the natural HF loss that occurs with age. (excluding catastrophic failures of both...). :thmbsp: :thmbsp:
EchoWars said:
OK........I didn't consider the size issue........and I surely have not figured out how to "shat $100 bills".............lol
But I will check out Panasonic poly's.....and try using them where they apply......thanks:yes: I suppose mixing is ok and creates no problems??
I used and like the Sprague screw terminal caps I got from mouser to replace the big power caps in my 881. I wrapped a couple wraps of electric tape around the ends and they fit right into the original clamps snugly, as they are just slightly smaller than the originals.EchoWars said:
For the connections I just soldered round /flat connector terminals from radio shack to the wires and screwed them onto the caps. NO MORE SOLDERING if they need removed again.:thmbsp:
I think these caps were about $8 bucks each and a very cool blue color. They seem not to have effected the "Sansui sound" as far as I can tell. But of course I don't think these caps would anyway.
hpsenicka said:
Well, first of all I just commented on what this gentleman observed (but our conclusions differ):
wsjoe said:
So new capacitors indeed sound different.
And second, yes the aging of electrolytes may contribute to a somewhat more woolly sound than was original present - just therefore I think it can be accepted to install a few new capacitors (with lower ESR) at critical places and still obtain a sound very like the original. But a total recap would in my thinking destroy the musicality.
For myself I can easily remember the sound of early 70's, and when I revisit equipment systems from that period I still hear the same sound quality. Modern hifi sounds terrible in comparison. Very many people I have talked to have the same opinion. People working in the modern hifi business do not agree and have many good theoretical arguments.
If a total recap feels necessary, buy a modern hifi system instead. :thumbsdn:
- Status