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    Not so valuable items. Ordinary people call them junks. But I hesitate to dump them. Could they be back to life again?
(Sorry, English page not available unless otherwise indicated.)




Sansui AU-7700 Stereo Integrated Amplifier

    7+ months have passed since the 3rd lab was established, the ultimate poorman's audio amplifier and dirt cheap speakers provided music good enough to recover from the job strain. But it may be the time to consider upgrade. Seaching a pair of speakers suitable to my need, there was none at a used equipment shop but a nice looking 70's Sansui pre-main amplifier. Even if it is broken, full discrete transistor amp could be fixed with fun, so I took it.



Yamaha MT4X Multi Track Recorder

    Purchased as a part-out material to build an analog multichannel mixer for the newly established NoobowSystems #3 lab, this MTR was found to be in an almost perfect condition except a fatal problem - the tape drive did not play. The attempt to fix this equipment was the very first engineering activity since the new #3 site had become operational.



Aiwa TP-560 Cassette Tape Recorder     [NEW]

    After the Tomioka Silk Mill was listed as a world heritage, the city center became crowded by thousands of visitors. Every time we go there we see new shops, restaurants and traditional souvenirs we have never heard of. A very nice Iranian restaurant opened a couple of years ago is now our favorite, and an antique shop opened also around the same time is where we stop everytime. In the shop this time I found a small tape recorder for voice recording purpose, obviously not working.



Aiwa HS-PS003 Headphone Audio Cassette Player     [NEW]

    Looking for a handy cassette player so that I could listen some music in bed as there are many tapes in my room. In year 2006 the portable audio players are almost all siliconified. At an electonics shop all the cassette equipments were for voice recording or language traing purpose. I should have purchased a high quality audio player before ther were all gone.



Pioneer SE-550D Stereo Headphones

    This Pioneer stereo headphones have been my friend for these 10 years, but their ear pads wore out after heavy use. I bought a new set made by other big name manufacturer, but it disappointed me. It did not sound naturally, loose fit, squeaking headband - even thouth the price tag was the highest at the consumer electronics shop. It was just a crap. So I decided to buy a new Pioneer. Visiting their web site, wrote my recent experience with another make's product and applause to my SE-550D. Unexpected feedback from Pioneer came, that they still carry new ear pads as spare parts which I immediatelty ordered. Price of these parts was such that a low price new set could be purchased, but it was much clever way of spending money. Now I again enjoy SE-550D.



Sony SLV-FX5 VHS Hi-Fi Video Cassette Recorder [English]


    Some Japanese TV programs are tranmitted with bilingual audio. Viewers can choose Japanese or English (or original audio of foreign movies), for example. One day my Toshiba VCR failed so I unpacked and plugged my Victor VCR which was stowed since I left the U.S. It received all the air channels nicely, but it did not have bilingual audio capability.
    The next week I got a broken VCR from my family. Its tape deck had a problem, but tuner worked fine. By combining with those two VCRs, my requirement was fulfilled. But ... broken deck? Okay, try to fix it.



Signal Generators: Heathkit IG-5280 & Leader LSG-100


    Two signal generators are mentioned in this page. Heathkit IG-5280 is a transistorized RF signal generator purchased at a flea market for a radio building project; I thought it was just a case and dial and internal components were removed because it was so light. It was found that everything was in there, and worked. Its frequency stability was inadequate for careful servicing so it was soon stowed. Leader LSG-100 is a vacuum tube type, only 2 tubes are used. Its dial is beautiful, but its performance is not enough for the serious servicing. LSG-100 was marketed in the U.S. under the Lafayette brand.



Lafayette TE-50 Tube Tester


    This simple tube tester can check the emission performance and short circuit of vacuum tubes. Bought it to check junk tubes in my lab, but then more junk tubes are to be purchased in order to use this tester! A tube user can be now called as a tube mania, when the initial purpose is forgotten...

[English Page]



Hewlett-Packard 1200A Oscilloscope


    Having a oscilloscope was indeed a dream of a radio kid. A quarter centuly later my dream finally became a reality, when I found a price tag at a flea market; "Scopes: $8 for two" !!

    One of two units worked nicely, and it helped me a lot. The other unit had a problem; raster did not go rightward. With the aid of working unit, the cause was found to be bad deflection output transistors. Replacing them with surplus transistors regained the nice and stable raster.

    It revived only for a night, however. Intensity became quite low after several hours of operation. Apparently a register in cathode circuit was damaged. Better to fix it before the working one ceases its life.



Trio CO-1301 Cathode Ray Oscilloscope


    This tiny lovely oscilloscope was a low priced kit designed for radio amateurs in Japan back in late 1960s. Its color and style matched to the early Trio (Kenwood) amateur radio transmitters. Obtained from a veteran ham, this unit suffered a raster problem (did not move rightward; somehow similar to my HP-1200A) and unstable operation. Replacing a capacitor cured the raster problem, and replacing the rest of the capacitors brought a stable operation. It works nicely on my bench for monitoring the audio signal.



Sanwa U-70D Multitester


    Perhaps this is the last item my dad bought me at Akihabara, back in 1976. Soon after that he became ill, and more than a dacade later he quietly passed away. He couldn't do much to his family during that time, but the U-70D taught me a lot; basic knowledge of electronics upon which I found my job, prividing me a mean to live.

    Recently my U-70D suffered bad reading on DC 500mA range. Of course I now have enough economical power to buy a new high end analog tester without hesitation, but it is not such story. I must fix it.



Heathkit IT-18 Transistor Tester


    As a non-educated radio kid, I cannot design a radio receiver from a scratch because I don't fully understand how transistors work. Feeling a need of experimenting transistors, I purchased this tester. Simple equipment such as DC hFE can be easily homebuilt, but the price of this kit was much cheaper than purchasing parts.



BayNetworks BayStack Model 50 10BASE-T Ethernet Hub


    In 1998, Ethernet equipment became quite affordable, so I connected PCs in my home. For further convenience I added another 10BASE-T hub in my lab. Price of this hub, made by BayNetworks, was cheaper than unknown brand one. It worked just fine and I was happy with it. The next morning I found no indicator lit on the hub. Quick check pointed out that its AC adapter failed. Brutely opening the case of the AC adapter, it was immediately obvious that the soldering at the power transformer loosened. Perhaps this was the reason of the cheap price at a surplus shop. Okay it's not a big deal. Let's enjoy building a power supply.



Signal Corp. Code Training Oscillator Model Unknown


    Purchased at the Santa Rosa amateur club swapmeet, I did not know what this bulky heavy unit was for. It had three vacuum tubes, the panel carried a "frequency" knob, a "volume" knob, a "key" terminal and a speaker. It must be a CW transceiver or some sort, but there wasn't an antenna terminal. Following the operating instruction attached to the panel, I found this was merely a Morse code training oscillator!



Heathkit HD-16 Code Oscillator     [NEW]

    Santa gave me this small cute code oscillator, supposed that he'd encourage me to continue code practice so that I could operate codes on the air. However, Mr. Santa, I can send codes. What I'm not good at is to receive them. So I modified the phone jack of this code oscillator, converting it into a simple external speaker box. I shall continue practicing the code reception with this cute box connected to a communications receiver.



Leader LCG-381 Color Bar Pattern Generator


    The recycle shop owner did not have any idea what this was and he okayed immediately when I offered a price. This color bar pattern generator was for servicing color TV sets and has 12 vacuum tubes. Salvaging parts was my intention but it might be fun to watch a color pattern generated by 12 tubes...


Nissyo Kogyo NP-101 Regulated DC Power Supply


    While I was in the U.S. mom disposed most of the equipments I used when I was a radio kid. Somehow this small regulated DC power supply survived, and now is one of the oldest equipments still living with me. This time a severe distortion in the output voltage observed, so I opened the case and drew a schematic diagram, and started to investigate to find nothing was wrong....



Samlex RPS1206 Regulated DC Power Supply


    Purchased at a surplus shop with $5 price tag the RPS1206 somehow worked, however it was not in a good health. The output voltage was approx. 11.2V instead of expected 13.8V, and the voltage dropped when more current was drawn. 17 years after purchased as apparently a malfunctioned item, detailed inspection started. Replacing a small transistor used to control the feedback loop brought back the strong operation to this simple and handy power supply.



Too Trivial for a Page     [UPDATED]

    Collection of misc repairs and attempts too trivial. Don't excpect anything here..... Just like the other pages in this website, this is for our memorandum purpose.


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Copyright (C) NoobowSystems Lab. San Jose, California 1999
Copyright (C) NoobowSystems Lab. Tomioka, Japan 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2009, 2010, 2011, 2013, 2015, 2016.

Nov. 20, 1998 Created.
Jan. 30, 1999 Revised.
Sep. 05, 1999 Relocated; Signal Corp Code Generator from Radio Restoration Projects
Oct. 21, 1999 Added Sony SLV-FX5 Video Deck.
Apr. 01, 2001 Added TRIO CO-1301.
Nov. 04, 2001 English version.
Feb. 09, 2002 Revised.
May. 10, 2002 Revised, unified Japanese and English version.
Jul. 28, 2002 Revised links.
Aug. 17, 2002 Reformatted.
Aug. 15, 2003 Added SE-550D.
Aug. 25, 2003 Reformatted.
Dec. 20, 2004 Corrected typo.
Mar. 19, 2005 Added Too Trivial.
Aug. 09, 2005 Added LCG-381.
Nov. 06, 2005 Added IT-81.
May. 04, 2006 Added NP-101.
Jul. 29, 2009 Adapted Japanese text rendering behavior of Google Chrome 2.0.
Mar. 27, 2010 Netscape Navigator compatibility.
Jun. 29, 2011 Added MT4X.
Aug. 25, 2011 Added AU-7700.
Aug. 17, 2013 Added RPS1206.
Jan. 24, 2015 Added HD-16.
Mar. 27, 2016 Added HS-PS003. Reformatted. [Noobow9100D @ L1]