Some observations based on previous posts:
The Service Manual for HK DPR1005/2005 has a Tech Tips page HKTT2003-01 Rev 5 which addresses the memory loss complaint for numerous models.
The entry for AVR435/635 shows replacement part H03-CEZXA0479MN-0.
The entry for DVR1005/2005 shows replacement part CEZXA0479MN-5.
I strongly suspect these are the same parts, just with differences in the numbering to keep track of how many are ordered for which model. I base this on experience ordering parts from HK in the past which are 'substututed' with sometimes wildly different number but are actually the identical part.
From what's been said here, these physically appear to be a Samsung "Starcap" part SCDA5R5473V. ('SmartCap'
was incorrectly mentioned by a previous poster as being the manufacturer...different company altogether.) The Samsung parts are indeed rectangular and plastic. There's a datasheet PDF for them here: http://www.datasheetarchive.com/SCDA5R5473V-datasheet.html
. I recommend folks look this over. It has a number of graphs and cautionary notes regarding installation.
Basically, the caps should have sufficient charge time...at least an hour. According to the DPR service manual, the part is connected (via diode isolation) to the +5v supply, then to the center tap of a resonator that forms the clock circuit to the receiver's microprocessor. This seems a really strange circuit, so unless the schematic is wrong, there's no real DC 'charging path' for the cap. So charging is happening by a very high impedance pulse source, meaning it will take quite a while to form a charge. My own experience with a new part is that it can take a day or more before it really holds memory up well.
Note that for most models, the Tech Tips point out that without power, 2 weeks (4 weeks for DPR models) is about the normal the memory time expected.
Part number P10790-ND is listed in the Tech Tips for a number of HK AVR models. This is a Digi-Key (electronics component supplier company) number for a Panasonic EEC-S0HD473V
series SD double-layer 'supercap'. These are available in a 'stacked coin' package with vertical or horizontal leads. The posts lead to some pictures of the horizontal version being installed in an AVR, but the vertical ones (with V at the number end) would be closer to the original form factor and lead spacing. The 'electric double layer' is the same technology as the Samsung part, just packaged differently. The're also under $2, so vastly cheaper than the Samsung part from HK.