Luxman R-115 and R-117 Remote Select and Front panel select BOONDOGGLE

[phatterplatter]

Hi gang,

I got an R-117 in for service some weeks back . The main issue was one pwr amp blown to smithereens ( all transistors shorted) BUT the other issue that came up
was that the Remote wouldnt command Source selection and neither would front panel buttons ( FM and AM for some reason are diff) No LED indicators lit.
Now, an R-115, that came in as a parts unit for the R-117, has the SAME front panel NO-GO issue
With a scope I can see the front panel select buttons sending a trigger signal to the uPD75104 processor but THAT IC is not responding in kind.
Next step: Check levels and clocks on uPD IC and inspect soldering.
The RELATED issue is that : My client that OWNS the R-117 power amp smoker is having similar control issues with HIS Luxman R-115

I hope to clear up this issue this week and I'll let you all know what I've found

( Bonus this month I now have an HP 100Mhz scope with 16 channel digital analyzer)

 

[phatterplatter]

What I found on my "Donor" R-115 is, a ground connection on the PC board with the microprocessor , that wasnt making it all the way along the circuit board.
The flex jumpers from the main CPU board to the selector IC board make it HARD to work on this unit.
The Switch IC is readily available on Ebay. This week though I'm battling medical issues in both my feet which makes it hard to troubleshoot a light bulb circuit.

This breakdown in communication between the front panel buttons and , allowing the RIGHT component to be selected , is common amongst both the R-115 and R-117

The other item that MIGHT be helpful in this series : Both receivers use ALMOST the SAME power amp assemblies. THere are a few parts different but layout and routing is the same.