GR-33 Schematic and Service Notes

Started by jimpne, November 12, 2018, 06:07:52 PM

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jimpne

Hi, hopefully I am not breaking board etiquette by starting a new topic partially answered in the "GR-33 FAQ".  But here goes, I believe a site admin made available a scanned copy of the Service Notes and Schematic, unfortunately the Schematics are unclear and I am unable to decipher components and their values. 

You may ask why?  Because I now have 2 problems with my GR-33. 

(1) the on-board battery (CR2032) reads around 1.7 v, even with a new one installed.  I found 2 surface mounted resistors (R271 and R272 on the less populated side of the pcb - values "103" and "105") both open circuit.  I replaced temporarily with 1/4 W resistors, no change in the voltage so I'm assuming 1 or more cap's and/or diodes may have gone, but no idea where to start looking.

(2) even thought the battery reads low, I can still use by loading the system defaults.  Anyway, there is a weird situation which is most prevalent went using patch A22 "Tekno" (ARP is set also), the repeats seem to get louder with what sounds like intermittent crackling.  Without the ARP set it is nowhere near as bad. but still "crackling" somewhat.

Any help and/or guidance would be greatly appreciated.  And, if anyone has a clearer PDF version of the schematic all the better.

Thanks.

So, after some messing about I managed to use another GR-33 and did point-to-point measurements.  Basically R271 (105) and R272 (103)and some surrounding traces had been damaged (looked a bit like corrosion - odd, but there you go).  Anywhoo, added a couple ofjumpers and replaced the resistors with the smallest I could and voila!.  Good readings and no further error messages.

So, for me problem solved, but if anyone manages to dig-up good quality schematics (no offence to the providor of what is available on this forum), please let me know.

HAMERMAN409

I too could use a good quality version of the GR-33 service notes. The one I have is a 1.65MB pdf. You can make out some of the power supply sections but most of the schematics are too blurry to be useful.

admin

#2
Quote from: HAMERMAN409 on May 26, 2020, 08:15:58 PM
I too could use a good quality version of the GR-33 service notes. The one I have is a 1.65MB pdf. You can make out some of the power supply sections but most of the schematics are too blurry to be useful.

Only one available
https://www.vguitarforums.com/smf/index.php?action=dlattach;topic=14682.0;attach=23053

See GR-33 FAQ thread
https://www.vguitarforums.com/smf/index.php?topic=14682.0