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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Thursday, June 2, 2016

Beogram 4002 (5503): Keyboard Repair - Detached Backstops

After restoring the hood of the AC motor Beogram 4002 (5503) another cosmetic item on the list was the reattachment of the broken off backstops of the keypad. This shows the situation that I encountered:
Some of the keys were sticking out. Also the keys were working somewhat unreliably. Often one had to press them repeatedly to activate a function. Removal of the keypad and removal of the PCB revealed this situation:
Several of the plastic backstops had come loose and a previous user tried to re-attach them with double sided tape. Due to the thickness of the tape some of the keys appeard 'elevated' on the top side of the keypad

A bit of wiggling on the backstops that were still attached easily liberated them. The challenge was to glue them back in place in a precisely oriented and with the right pitch. I elected to design 3D printed alignment tools that would hold the backstops in place for glueing them in:
The tools can hold the backstops in the proper orientation and pitch:
Once the backstops are inserted onto the tools, they can be glued back under the keys:
And so the keypad looks good again:
On to replacing the old corroded DIN5 plug with a new one!

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