more PPG 2.3 boot failure

[Magnus Danielson]

From: "Paul Maddox" <Paul.Maddox at wavesynth.com>
Subject: Re: more PPG 2.3 boot failure
Date: Wed, 29 Nov 2000 21:48:47 -0000

> Sandro,
> 
> >I'll be very patient (i'm just dealing a Rhodes Chroma with bad Dual
> Channel Boards ...) and I know these things are NOT easy to fix also ...
> 
> Hehe, early poly synths were a nightmare!
> 
> >Anyway , you're assuming I mean that "the cursor scrolls left to right,
> then goes to second row scans left to right and then back to the start "
> >It's not exactly so. In fact , at the boot , the cursor scrolls left to
> right the first row without finishing it - it stops at 3/4 of the first row
> without going to >second one at all.
> 
> OK, its usually the same problem.. make sure all the eproms ae seated in the
> sockets properly...
> You may need to replace these...
> 
> 
> >You also said about PROZ boards,  to have ordered a complete set of chips
> to replace the whole lot as a quicker way to repair it .
> Yeah, its a complex board..
> 
> >Then , may you confirm is PPG 2.3 repairable in these boards just replacing
> chips ? Or it has also "custom" components so that I'd sink in muddy waters
> ???
> >
> 
> There are no custom chips anywhere in the synth, BUT....
> there are some PALs which I have the JDEC files for, these dont usually go
> wrong..
> the fault you are describing is typeical of the CPU board not botting
> correctly.. it could be a loose eprom or a faulty eprom.
> PROZ board problems are anormally related to the picth of the playback or
> the playback sound being wrong..
> 
> >At last , it's an expensive repairing ?
> 
> The one chip that is next to impossible to find is ;- 74F189,
> its a 16by4 dual port SRAM chip.. Philips still make them, BUT you have to
> buy 550 of them at least!
> (anyone know where I can get a lower quantity at a decent price?)

Decent price? Well, I don't know, but they are available from ELFA
(http://www.elfa.se/).

Farnell has a hopeless online catalog, so I was not able to figure it
out. They had search only, which is NOT a good thing.

Cheers,
Magnus - feeling a little blue about not having a blue..zzzzz