the current soundbox/reproducer i have on my gramophone was bought on ebay from india and it arrived in pretty bad shape. for starters, the diaphragm had a hole in it and the rubber connector crumbled into dust when i fitted it on to the tonearm.
i scrounged the world (online) for spare parts and managed to get a new rubber connector a few months ago but i had no luck with finding a replacement diaphragm...UNTIL LAST WEEK!!
i would like to say a big thank you to Mr. Ken Priestley of the U.K for his expertise. i managed to find a new diaphragm from him and those of you looking for spare parts for your gramophone can look for him at his website: http://www.fonograf.talktalk.net/
anyway i ordered a new diaphragm from him last week and it arrived here in singapore within 8 days (as fast as international mail gets around these parts).
he packed it really nicely with cardboard spacer preventing the diaphragm from warping/tearing.
anyway...if you are interested to do a diaphragm replacement on a HMV 5b soundbox, this is how i did it:
unscrew all four screws on the back of the soundbox and the rear (black) plate comes right off. in the picture above, you can see the felt gasket that is fitted around the edges of the diaphragm to make it more airtight. you can see the lousy repair job i did on my old diaphragm...i basically glued aluminum foil around the hole to patch it up!
remove the four screws on the front plate of the soundbox. use a pair of pliers to hold the nut on the needle bar and gently unscrew the pivot screw (both of them). at this point the diaphragm and the needle bar can be gingerly removed from what's left of the soundbox.
you should then be left with just the diaphragm and needle bar as shown in the picture above. the needle bar on mine was soldered on to the spider. you will obviously need a soldering iron to melt the solder, so be extra careful during this step! i put a small precision screwdriver to hold the diaphragm in place as i desoldered the needle bar from the spider like so:
look at the difference in condition between my old tattered diaphragm as compared to the new one, no prizes for guessing which is which!
i soldered the needle bar on to the new diaphragm, making sure to position it in the center of the spider. the soundbox can now be reassembled by working backwards from the steps shown above. if you find the needle bar is out of position after fitting the diaphragm into the soundbox, it can be repositioned by simply touching the soldering iron to the solder and small adjustments can then be made.
i fitted the soundbox back on to the gramophone and played a few records. one of the obvious improvements i noticed straightaway was the increase in volume and overall fullness of the music, no more wasted energy due to air leaks! voices were clearer, strings were cleaner...its a pity i couldn't have gotten a perfect diaphragm sooner, but i'm very happy that i finally do!