PPG Repairs
 
Common problems and soloutions.

Problem ;- When powering up Instead of 'R,T,A,C,D,E' I get '9,9,9,9,9'
Solution ;- they represent a series of routines that the computer goes through on power up.
       these are ;-
         R(1) .... SDRAM Check passed
         T(2) .... Checksum for Program Area 9000-9FFF OK (not sure why it was called 'T')
         A(3) .... Checksum for Program Area A000-AFF7 OK
         C(4) .... Checksum for Program Area C000-CFFF OK
         D(5) .... Checksum for Program Area D000-DFFF OK
         E(6) .... Checksum for Program Area E000-EFFF OK
       If any of these checks fail, '9' is displayed instead of the problematic check result.
       The numbers in brackets represent the same tests in an EVU.

Problem ;- Poor Contrast on the display or no display
Solution ;- Tighten screw under the contrast adjustment, and also the two inside that prevent the lid from flinging open (these are actually earth wires aswell)

Problem ;- When the Wave behaves erratically or unreliably
Solution ;- Clean the possibly corroded PCB connectors.

Problem ;- Waveterm Displays 'BUS-ERR' on PAGE 0
Solution ;- Check that the bus cable is seated correctly at both ends.

Problem ;- No communication at all between Wave and Waveterm.
Solution ;- Try another cable if this doesnt work, replace the 68A21 chip. A 68B21 does equally well and is easier to get.

Problem ;- My PPG Wave just arrived after being shipped and its not doing anything.
Solution ;- The Cards inside the wave are supposed to be held in place be a metal plate and a bit of sponge which keeps the preasure on it. Over the course of years two things can happen, firstly the sponge looses its 'spongy-ness' and secondly it can have lost this plate alltogether. Its probably best to ship it with the cards removed and place in static bags (being carefull about the battery) or to check that this 'SPONGE' is in place.

Problem ;- Waveterm B slow to boot
Solution ;- Clean the floppy disk drives.
Solution ;- Check that the 5V and 12V supply are correct, faulty capacitors in the PSU can cause this to be wrong.

Problem ;- Sticky keys or Multiple gateing when playing keyboard
Solution ;- A superb kit for fixing this problem is availble from here ;- http://members.aon.at/virtual-music/upgrade.html

Problem ;- On PPG Wave 2.0, Two tables good, two tables bad, two tables good, ie, table 0,1,4,5,8,9 good, tables 2,3,6,7,10,11 bad
Solution ;- Broken PCB track as a result of a leaky memory battery,
Solution ;- SN74LS244N faulty on CPU card.

Problem ;- One voice card sounds very different than the rest. Lower level and it sounded more filtered. Checked the CEMs (3320 filters and 3330 dual VCA) and they are fine. The MC1458 op amps are fine, help?
Solution ;- Check the 4 2.2uF/40v electrolytic caps on the voice board. They dry up and loose their capacitance (They'll probably read 0.0uF)