I just repaired a NAD C326BEE integrated amplifier.
I am not crazy about NAD, and this one is overly complex and full of SMD components.
Problem: no sound at all, only power LED lights when turned on.
However, power amplifier section just works O.K.
One of the many power supplies was defective.
I had to replace 4 SMD transistors, 1 SMD resistor (nearly invisibly small) and 2 power resistors.
I hate SMD!
I am not crazy about NAD, and this one is overly complex and full of SMD components.
Problem: no sound at all, only power LED lights when turned on.
However, power amplifier section just works O.K.
One of the many power supplies was defective.
I had to replace 4 SMD transistors, 1 SMD resistor (nearly invisibly small) and 2 power resistors.
I hate SMD!
Hi 968driver,
2238 compliment says "I dislike NAD as well" I don't care smd or through hole. I guess if the money is good, but my conscience still tugs at me. Certain brands shouldn't be fixed (or sold to begin with for that matter).
You wouldn't like Cyrus. All smd except for power devices. Great engineering. One model needs about 46 smt's replaced. Some should be matched.
Too bad they discontinued the 2SA968B and 2SC2238B. I stocked lots of those and ran out a decade ago.
-Chris
2238 compliment says "I dislike NAD as well" I don't care smd or through hole. I guess if the money is good, but my conscience still tugs at me. Certain brands shouldn't be fixed (or sold to begin with for that matter).
You wouldn't like Cyrus. All smd except for power devices. Great engineering. One model needs about 46 smt's replaced. Some should be matched.
Too bad they discontinued the 2SA968B and 2SC2238B. I stocked lots of those and ran out a decade ago.
-Chris
Quad hifi set repair
Hi, I recently bought a Quad hifi set from the internet: a 33 pre-amp, a 33 FM-tuner and a 405 power-amp.
I fixed the 33 pre-amp by replacing all the elyts, some resistors to low the input sensitivity to more common values (of today), and intensive cleaning off the switches which had all issues. The last important cleanup was the power-on/volume switch/poti, which was making a lot of noise. I think I will do another step and replace the poti with a new Alps one, while mounting a power switch on the backplane. I will also replace the DIN-sockets with RCA ones.
I also fixed the 405 by replacing all elyts, some transistors and diodes, and the old 742 opamps with two OPA627s.
Now the set sound completely differently than when I bought it; it had never serviced while being between 40 and 50 years old...
While on the internet, I stumbled over a Quad 306 power-amp which I bought as well and refreshed it as well: it sound really good, nearly same as the 606 power-amp I own for 25 years (and which was services twice during that time).
It's really nice to see how good these Quad amps sound even after decades.
Hi, I recently bought a Quad hifi set from the internet: a 33 pre-amp, a 33 FM-tuner and a 405 power-amp.
I fixed the 33 pre-amp by replacing all the elyts, some resistors to low the input sensitivity to more common values (of today), and intensive cleaning off the switches which had all issues. The last important cleanup was the power-on/volume switch/poti, which was making a lot of noise. I think I will do another step and replace the poti with a new Alps one, while mounting a power switch on the backplane. I will also replace the DIN-sockets with RCA ones.
I also fixed the 405 by replacing all elyts, some transistors and diodes, and the old 742 opamps with two OPA627s.
Now the set sound completely differently than when I bought it; it had never serviced while being between 40 and 50 years old...
While on the internet, I stumbled over a Quad 306 power-amp which I bought as well and refreshed it as well: it sound really good, nearly same as the 606 power-amp I own for 25 years (and which was services twice during that time).
It's really nice to see how good these Quad amps sound even after decades.
Peter Walker's incredibly clever current-dumping circuit! Very cool! When I first read about the Quad 405, I remember spending hours trying to work out the mathematics of that balanced-bridge arrangement Walker came up with.
That was the era when solid state audio electronics was still evolving, and completely original new ideas - like current dumping - were still showing up from time to time.
Now audio is a mature engineering field, more than a hundred years old, and there are very few new ideas left to try. This happens to all old mature technologies - eventually, they stagnate.
Audio amplification has been audibly perfect for some sixty or seventy years, so for many decades now, you couldn't make a better sounding amplifier. The only things left to do was to make amplifiers smaller, lighter, and cheaper.
The last dramatic step in that direction happened in a big way when integrated-circuit Class D power amps started to arrive. Class D may be the last significant advance in audio power amplifier technology for a while to come.
-Gnobuddy
Na, there is yet another improvement possible between now and then: the quality of the components they used was by far not what you can get now: transistors were not low noise, opamps even less. These improvements make the 405 sounding better than in its original state. And of course the PSU can be improved either.
When I compare the evolution of the Quad amps I own (405, 306 and 606), it is clear that they have continued to improve Peter Walker's original design.
This I second: my pair of Devialet D-Prime in mono-mono setup (one works as master and the second one only as amp) is a giant step forth.
Where I feel is the most on the move is in the DAC area: they become better and better, and their prices are falling steep (which is good).
Certainly not as low-noise as good contemporary parts. And yet, the Quad 405 had a rated S/N ratio of 96 dB.
A record player rarely did better than 60 dB, and a cassette deck with Dolby B was unlikely to beat 50 dB. So the Quad 405's noise floor was some 35 dB lower than the best audio source you could find at the time...making it audibly perfect on the noise front.
About the quietest background noise level you can find in an urban setting - a dead-quiet library, say - has a background SPL of around 40 dB. Assuming your neighbours (and ears) can stand 90 dB SPL peaks in your music, and your home is as quiet as a very quiet library, that still means the ambient noise floor in your house is only 50 dB below the very loud 90 dB peaks...no matter how quiet your power amplifier might be!
In practice, I found I could still perceive a reduction in background noise going from a cassette deck with metal tape and Dolby C + Dolby HX Pro (60 dB S/N ratio) to my first CD player (with an S/N ratio somewhere around 90 - 100 dB.) My ears were young and pretty sensitive back then. But for all practical purposes, S/N greater than, say, 70 dB in the audio electronics chain produces no audible benefits at sane listening levels.
Nowadays some people obsess about 120 dB and greater S/N ratios, but it's just one more meaningless audio spec, like 0.0005% THD, far beyond the abilities of the human ear itself to detect.
-Gnobuddy
That's exactly right!
Rediculously LOW specs might sound nice and tempting, but certainly aren't required.
People have enjoyed "high fidelity' music for decades now, before the internet and audio magazine media have brainwashed and made people obsessed.
Along with that propoganda, it makes people yearn for "that perfection" that they seemingly never reach - always on the hunt for something else to try.
And that's marketing at its finest - designed to make manufacturers money and keep it flowing. - into their pockets.
So, why is "todays" stuff in some cases lacking such tremendous specifications?
Seems like all those "new" turntables out there have lackluster quality and specs?
I've read plenty of spec sheets - expensively advertised turntables with 0.12%,- 0.2% wow/flutter ratings?
Those ratings were common years ago on midline and budget machines!
My 1986 Kenwood soars in comparison with only 0.025% w/f rating.
And..... a 57db rumble level.
I don't hear anything but music when I play a record - unless the record itself has flaws.
Other people can let marketing nut their brains, I sure as hell don't succumb to that crap.
Hi wiseoldtech,
When I heard a Thorens TD125 MKII compared to my newer Thorens TD115 MKII, I sold my TD115 MKII. Yes, I used the same cartridge model on both tables. The big thing about the better tables is that they are dead quiet compared to your Kenwood and many other brands. That noise you say you don't hear - just wait until you hear a table where you really can't hear it. It is a real eye opener. The difference is not subtle at all. The Linn table is also like that, but way over-priced.
-Chris
When I heard a Thorens TD125 MKII compared to my newer Thorens TD115 MKII, I sold my TD115 MKII. Yes, I used the same cartridge model on both tables. The big thing about the better tables is that they are dead quiet compared to your Kenwood and many other brands. That noise you say you don't hear - just wait until you hear a table where you really can't hear it. It is a real eye opener. The difference is not subtle at all. The Linn table is also like that, but way over-priced.
-Chris
Hi Chris
We've had discussions before on here, and your praise for the Thorens I'm sure is justified, if not slightly biased, and that's OK.
There are a lot of good turntables out there, surely.
But stating that my Kenwood is inferior as far as "noise" is on my end of things not justafiable.
You've never heard my unit, as I have never heard yours, and we both know quality levels from experience working with these things.
I'm not going to "tout" my Kenwood, other than saying that it's absolutely silent during operation.
This surprises me being what it is - because the only background "noise" that results in playing a record is the noise floor level of the recording itself, which varies with manufacturer, vinyl quality, and pressing operation.
These things, I can certainly tell the difference in from record to record, but believe me, the platter revolving under those records does not in any way contribute to the noise that you seem to insist that is there.
My wonderful Pioneer CT-F1250 tape deck.
Gave about 10 euros at a fleamarket some time ago. Had to rinse the pinch rollers and idler wheel. They were all glazed really bad. Never thought cassettes could sound this good! Been at least 25 years since last time
I had a Pioneer CT-F 1000 and had nothing to compare it with at the time but a very good Ferrograph 2 track deck and there was no comparison, the cassette medium was never hifi.
Looking at the Pioneer now, it is just a big heavy lump of mechanics and electronics and cannot compare to a tiny mp3 player I can hide in my fist.
After reading this thread I checked ebay as I thought no one listens to cassettes any more. Well, I was shocked, old CT-F 1000 decks are are being offered for stupid prices. Why is that?
i did not do it my self. my friend got a broken bass speaker at his PHILIPS F-9218 speakers. a ripped rubber band. told him to watch this video (YouTube) and do it by himself..
look what he did! -----> https://abload.de/gallery.php?key=kyhi9TCX
look what he did!
-----> https://abload.de/gallery.php?key=kyhi9TCX
About two to three years ago, I purchased a Hantek DSO6074BC digital USB oscilloscope. Since it requires a Winows XP computer, it is combersome to use. More recent versions of MS Windows can be used, but I do not want to sacrifice a good modern computer for an oscilloscope. So, I bought an old laptop with Windows XP.
To avoid having my worktop disorganised, I will make a wooden or another suitable material base onto which the laptop will be securely fixed. The Hantek DSO6074BC module will be fixed underneath and the USB cabling safely secured to the base.
Before using the laptop with this scope, I will remove its DVD drive and all unnecessary accessories.
To avoid having my worktop disorganised, I will make a wooden or another suitable material base onto which the laptop will be securely fixed. The Hantek DSO6074BC module will be fixed underneath and the USB cabling safely secured to the base.
Before using the laptop with this scope, I will remove its DVD drive and all unnecessary accessories.
Somebody has suggested me to use Openhantek which is for Linux. The problem with this approach is, this particular package depends on driver reverse engineering, and the manufacturer is changing the driver's architecture with releases. Furthermore, openhantek is not suitable for my version of the equipment and its software front end is too limited to swap with what the manufacturer provides users for free. The manafurerer's front end has many useful functions which are not found in openhantek.
Mercury III laser cutter part 2
Well it ended up taking a while. Got a new thermistor when I was out of country. It blew straight off and blew most of the fuses in the building. So after the school ordered the wrong pSu and we finally got the correct one Just before Christmas break. After that was a simple matter of installation and it powered up with no problems. Yet to run a test piece through there but looking forward to nicely engraved face and back plates into the future!!
Well it ended up taking a while. Got a new thermistor when I was out of country. It blew straight off and blew most of the fuses in the building. So after the school ordered the wrong pSu and we finally got the correct one Just before Christmas break. After that was a simple matter of installation and it powered up with no problems. Yet to run a test piece through there but looking forward to nicely engraved face and back plates into the future!!
NOT repaired: crank-up flashlight. 5 years old. Battery not as strong at it used to be. Case is not meant to be opened. Soldered battery would cost $12.55(*) to buy. Whole flashlight $13.33. Not worth fixing. (And not so much toxic metal that I feel over-guilty.)
(*) $6 each with minimum order of $50.
(*) $6 each with minimum order of $50.