Product Review : Cold and incomplete soldering in CEN-TECH P37772 multimeter cause erratic readings


I picked up a CEN-TECH P37772 11 Function Digital Multimeter with Transistor Testing, Audible Continuity feature, support for type K thermocouple and more functionality for $5 at a recent sale.  These sell new for $20 at Harbor Freight so that seemed like a reasonable price to me.   It is a great meter, but I noticed that it just couldn’t be used on the 0 to 2 VDC or 0 to 20 VDC scale.  The reading jumped erratically to the point where the meter just could not be trusted.
With only $5 at stake, I boldly went past the "This instrument contains no operator serviceable parts" and declared myself eligible for ”Screw removal by qualified persons only" as engraved on the back.
To see what cold and incomplete soldering look like on my Centec P37772 read more….

Sansui 771 Stereo Receiver Troubleshooting Example and Tips

Sansui 771 Power Supply Regulator Speaker Relay Driver

My Sansui 771 Stereo receiver has been with me for more then 35 years .  This article will review a problem that came up 5 years ago and outline the steps I took to fix it. 


While I am unsure of the exact year, my Sansui 771 was manufactured in the mid 1970s with mostly discrete components.  The schematic for the 771 and many classic stereos ise available from which makes troubleshooting much easier. 


The problem I had was two fuses blowing in the power supply and no output from the amplifier at all.   Like most of its peers in this mid-price range, the Sansui 771 delays engaging the speakers when it is powered up by several seconds and that was not happening.  


Read more for the steps I took to resolve this.

Daily Fantasy Sports – Why sites need a salary cap to stay in business agrees with the 40+ US State Attorney Generals who believe that daily fantasy sports sites offer a game of skill which means that players can use real money in the games.  Which, in turn, means the sites can rake the bets to cover their costs and make a profit.
Operators of daily fantasy sports sites know that this is special position of privilege, and so their customers should take some time to appreciate what this means to their daily fantasy sports team selection strategy part1 and part2.
All of the daily fantasy sports sites that offer games to USA residents will use a salary cap.   They will affix a salary to every player in the pool for that game.  You can be certain that the sum of the salaries based on a strategy of selecting all the “best” players will greatly exceed the salary cap.
Why?  Read more…

Arduino Transistor Identification and Transfer Curve Tester - Part 2

Arduino Transistor Identification and Transfer Curve Tester RelayBoard

In part 1 of this series, we reviewed the block diagram and discussed the additional chips that I used for my Arduino based transistor identification and automated test tool.  In this article, we will look at the wiring diagram.  There is no critical wiring or timing path, so any of the common prototype or point-to-point  wiring boards will do.
Read more ...


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