Power Supply PCB for Nikon Coolscan LS-8000 ED and LS-9000 ED scanners: repair and notes.
Power Supply PCB for Nikon Coolscan LS-8000 ED and LS-9000 ED scanners are switching power supplies with 3 outputs: +5V, -12.2V, and +15.5V (as usual +/- 5% tolerance). LS-8000 ED and LS-9000 ED have similar power requirements and identical power pin-outs, so you can use the power supply from LS-8000 ED to replace the one in LS-9000 ED and visa versa.
Two most common problems with these power supplies are:
1. The ON/OFF switch stops latching n ON position. The scanner can be powered ON and operated but you have to keep the power button pressed by hand. Not a good way to scan. The power switch is ALPS SDL1P-D manufactured in Japan and sometimes you can find it on Ali Express and other second-hand retail sites, just google "ALPS SDL1P-D switch tip foot". It can be replaced fairly straightforwardly.
2. Another frequent problem (in the power supplies manufactured by SANSHIN, I only saw those in LS-9000 ED units) is a bad control IC in the inverter section, the part STRW6756 manufactured by Sanken. The replacement is also straightforward.
I had seen two slightly different looking power supply PCB's in LS-8000 ED and LS-9000 ED:
Older version has a label SD40014-4 (I saw it in both LS-8000 ED and LS-9000 ED but mostly in LS-8000 ED) as shown above, I could not determine the manufacturer.
The newer version (I had only seen it in LS-9000 ED units) is manufactured by SANSHIN, with no distinct model number or label.
One simple but fairly common failure is when the power switch stops latching in ON position. The scanner can be powered ON and operated but you have to keep the power button pressed by hand. Not a good way to scan. The power switch is ALPS SDL1P-D manufactured in Japan and sometimes you can find it on Ali Express and other second-hand retail sites, just google "ALPS SDL1P-D switch tip foot". It can be replaced fairly straightforwardly if you have a proper soldering iron. It is easier to remove the faulty switch if you first cut the metal support stays on its side using dremel cut-off tool - then you only need to de-solder two feet.
I had at some point bought a few of these switches and may still have some extras - write to me and I will sell it to you for what I paid for + shipping. They look dirty and ugly but are unused and work fine - I had used a number of them and never had problems.
Once you have taken the cover out - test the fuse and check for bloating electrolytic capacitors - hopefully you get lucky :).
The most frequent cause of failure of the power supplies manufactured by SANSHIN, (again, I only saw those in LS-9000 ED units) is a bad control IC in the inverter section, the part STRW6756 manufactured by Sanken. The location of this IC is indicated by a red arrow in the photo below.
I had those replaced in a few units and they all came back to life. The IC is not expensive, just google "Sanken STRW6756", it looks like this:
For more serious repairs I had to look for an expert. I had seen people on e-bay offering diagnostics at $50 and then repair at $500. This seems excessive. I had found this company:
Power-Medic
1442 E. Lincoln Ave.
Orange, CA 92865
I had once had a supply I could not repair myself. Dave from Power-Medic had repaired the supply in 2 weeks for under $100 including shipping. I would highly recommend him (I do not have any business arrangement with him :)).