A coworker came in last week with a little mini amplifier (a Fender Mini Tonermaster®) that had stopped working. Being the curious sort, I opened it up, and looked at the main board. I immediately saw that D1 was physically blown (top half had blown off, and was rattling around inside the case). I figured this was probably the only issue, and brought it home to replace that diode (a simple 1N4003). After replacing it, however, the amp still didn’t work… which is why it’s nice I had it at home since I have the gear needed to diagnose the problem there. =)
Archives for July 2014
Recent Repairs/Refurbishes
Thought I would throw this into a general email since neither of these require their own write-up.
I recently purchased another Racal-Dana 1992 off eBay as non-working for $60. Having one of these already, I knew not a whole lot could be wrong, and it was most likely the primary oscillator having come loose from the main board (the CPU in the Racal-Dana uses the Counter reference Oscillator for it’s own crystal). Anyway, on receiving it, I saw that indeed, it didn’t work. Opening it up, the oscillator was firmly seated, and I could see the 10Mhz out at the standard output BNC. Looking around the unit, I saw that the IC for the display (in a socket at the back of the display/button board) was unseated slightly. I pushed it back in, and powered up the unit, and it worked! Easiest fix ever. On to eBay it goes!
The second item was a real find. I routinely visit a local computer “thrift” shop for random bits and bobs, and there laying on the bottom of a shelf was an HP 6624a (http://www.home.agilent.com/en/pd-836785-pn-6624A/system-power-supply-40w-4-outputs). Obviously marked HP, so it’s older, but it was only $10! All it had on it was a sticker saying “turned on, display showed information”. Clearly, whomever priced this must have thought it was a UPS, or old Server, or something, because even cheap ones on eBay go for several hundred dollars. Getting the unit home, I powered it up and spot checked the outputs, and they all work great! It’s not the greatest precision power supply I’ve ever seen, but it is 4 sensing outputs, and according to the manual can sink as much current as it generates, so the uses would be pretty high. That said, I don’t need anything this big, nor could I find a place to put it. So, on eBay it goes. I hope to get enough to just buy a Rigol Bench PSU (DP832) that is mV and mA accurate. =)
Update: Sale of the Racal-Dana took 2 days, and was enough to purchase a programmable load (to help test the HP 6624a), and a GPIB to USB adapter (also be good for testing it, as well as normal lab use). So, hooray!
X-Men: Days of Future Past
Yesterday I saw the new X-Men movie, and I must say off the top, that it may be my favorite X-Men movie to date, and certainly rates as one of the best Marvel movies. Anyway, to the review. And yeah, they’ll be some spoilers). Click the “more” to see the rest.