That's one sweet soldering iron. Is it an American Beauty ?
On Fri, Oct 28, 2016 at 4:31 PM, Peter Reilley <preilley_...@comcast.net> wrote: > I did finally get it open. I used a very large old style soldering > iron and .003 inch steel shim stock. I would melt the solder on the > straight seams and insert small pieces of the shim. Solder does not > stick well to steel so the shim kept the soldered seam open. > I used a soldering iron rather than a torch because I can control the > temperature. > > I could not use the shim at the corners. After all the straight seams > were separated I could pull each corner using a screw in the mounting > hole and melt the solder at the corner. Slowly working my way around, > corner by corner, I got it opened. I did not damage anything so I > should be able to close it up after I fix it. > > Looking around with my scope it seems that the output driver chip is bad > as I expected. It is a TI 14 pin surface mount DIP. It says S30 on it > which if it is a 74S30 it is an 8 input positive NAND gate. The board > layout confirms this as the 10 MHz signal is connected to pin 2 and all > other inputs are tied high. Pin 8 is connected to the output. > > The chip is run off 12 volts so it must be CMOS. But I cannot find any > chip like that that will run off 12 volts. Any suggestions for a > replacement? > > Also, using an 8 input NAND chip for a driver seems an odd choice. > > When I put 12 volts on the unit the S30 chip gets really hot. After I > removed the chip the unit seems to work OK. The current jumps between > about .1 amp to .9 amps. It seems like the temperature regulator is > an on/off type controller. > > The device on eBay, item 261920574725, looks exactly like what I have. > > I have placed a bunch of pictures in my dropbox. > https://www.dropbox.com/sh/52e9d1rva9kpb3w/AABmbIj1aK7Zk2J9SNMmu-JAa?dl=0 > > Pete. > > > > > On 10/18/2016 10:57 AM, J. L. Trantham wrote: > >> Pete, >> >> I'm not familiar with your OCXO but I found one shown on 'theBay' (item >> 261920574725) and it appeared to have an option for 'mounting screws', four >> of them, on the bottom. Interestingly, the 'link' to the datasheet for >> that unit did not show threads for mounting screws. >> >> If your unit has that option, I would suggest placing four long screws, >> mounting the item in a vise, use a small torch (I've used a hand held >> propane torch turned down very low to open a number of units from 5061A's) >> around the bottom of the case while gripping the top with an appropriate >> sized Channel Lock plier and lifting off the top. >> >> If you can repair the OCXO, it should be easy to reassemble the unit with >> solder. >> >> TheBay unit looks like it has a screw cover (which likely has a rubber >> gasket) for mechanical adjustment of the frequency. I'd remove that before >> applying the torch. :^). >> >> If you get it open, I'd love to see some pictures of the insides. >> >> Good luck and hope this helps. >> >> Joe >> >> >> >> -----Original Message----- >> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter >> Reilley >> Sent: Tuesday, October 18, 2016 8:11 AM >> To: time-nuts@febo.com >> Subject: [time-nuts] Opening an Isotemp OCXO >> >> I bought an Isotemp OCXO82-59 with a frequency of 10 MHz for a $3 at the >> MIT flea market. >> As expected it was dead. It heats up as expected but looking at the >> output with a scope there >> is nothing. However looking at the output with a spectrum analyzer I >> can see a faint 10 MHz >> signal. It seems that the oscillator is running but the output >> circuitry is dead. Reasonable >> assumption? >> >> Anyway, has anyone had any luck unsoldering the tin case without >> destroying it? >> >> Pete. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
