The tolerance on 78 and 79-series regulators is something like 5%.
I usually buy the A part when replacing them, as the tolerance is 2%.
So 7805A, with a few other letters after that sometimes, depending on the
mfr.

Bob

--------------------------------------------

On Tue, 4/16/19, t_tangent2003@... [oberheim] < oberheim@yahoogroups.com > wrote:

Subject: [oberheim] Re: Matrix 6R Power Supply Voltage Regulator Replacement
To: oberheim@yahoogroups.com
Date: Tuesday, April 16, 2019, 7:09 PM


#yiv9131763727 #yiv9131763727 --


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All done and working. Actually it was working before,
but seeing as I had to open the Matrix 6R to replace the old
battery that had died, I figured it was worth replacing the
PSU caps and voltage regulators as well.
Readings from the PSU board 15 pin
output connector J03 are as follows.
Pin No.     Schematic (Volts)      
Before Replacement (Volts)       After Replacement
(Volts)      
1 & 2                  
-5                                                      
-5.05                        
                                        -5.04
3 & 4               +5 B            
                                      5.11            
                                  5.10
5 & 6               +5 A            
                        5.06                  
                            5.09
7 & 8                 +12            
                                      12.02            
                                                 
12.31
9 & 10             -12      
                                            -12.30      
                                    -12.14
11 to 15           GROUND
So only minor differences in these
readings, perhaps with the exception of the +12 Volt pins 7
& 8, but I guess this may be due to fluctuations in the
Mains supply and/or tolerances in the voltage regulators and
capacitors, as specified in their datasheets. I would be
interested to hear from others with more experience in
electronics, particularly if anything here looks out of
spec. But so long as the Matrix keeps working for many years
to come, then this was worth doing, I hope. :)
Next job is to replace the tact
switches for the front panel buttons, as several of those
are playing up.
Cheers.