Vintage Synth Repair

>
> Hello
> 
> Here is the deal, the 16 programmable switches don't program. The actual function switches still work, and the program change switches appear to change (but not really, mostly just all on or mostly all on) so it doesn't seem that whatever programs were in there are still actually in there.
> 
> Also, the pitch for the lead synth scanning mechanism ("interval write") works as well. However, when switching from "Lock" to "Load" the function switches all freeze.
> 
> So, because the interval write is working, it appears as though the microprocessor system is working, but I can't write to memory. The system is based around a 8048 and the RAM is a 5101. My completely uneducated guess would be the RAM chip as the only function that doesn't seem to work is writing to RAM.
> 
> The RAM is easily obtainable and on its way, and I have an 8048 coming from England, but I don't think it is the main processor, as everything else seems to be working except for the "load" function. 
> 
> I'm somewhat reluctant to go pulling the microprocessor board, just to see if the RAM is socketed, as the Quadra has been extremely tempermental the whole time I've owned it  but I'm also fearful of cascading casualties. I did come across several sites regarding old video games (which also share the 8048/5101 or other type of 8-bit processor) that stated the 5101 was susceptible to battery leakage/failure. Don't know the context, but I've been pretty remiss in changing the 3AA batteries that power the memory. Again my completely uneducated guess would be the RAM chip, as it seems the only function not working is writing to RAM. Although I don't really need the 16 program locations. I am never going to gig with this keyboard, and I am perfectly happy turning on and off whatever section I want when I need it. The only reason I'm concerned is with having something else fail as a result of this failure.
> 
> Any thoughts? I'm thinking maybe the 5101 chip based on discussions I've read on video game/pinball game sites?
>

>
> Sounds like a battery problem to me. Get the old one out and look for signs of leakage and acid-corroded traces. You can replace the old batteries with a 3V Lithium coin cell.
> 
> Cheers,
> Alex
> 
> --- In vintagesynthrepair@yahoogroups.com, "bluejinn" <nchevatarevich@> wrote:
> >
> > Hello
> > 
> > Here is the deal, the 16 programmable switches don't program. The actual function switches still work, and the program change switches appear to change (but not really, mostly just all on or mostly all on) so it doesn't seem that whatever programs were in there are still actually in there.
> > 
> > Also, the pitch for the lead synth scanning mechanism ("interval write") works as well. However, when switching from "Lock" to "Load" the function switches all freeze.
> > 
> > So, because the interval write is working, it appears as though the microprocessor system is working, but I can't write to memory. The system is based around a 8048 and the RAM is a 5101. My completely uneducated guess would be the RAM chip as the only function that doesn't seem to work is writing to RAM.
> > 
> > The RAM is easily obtainable and on its way, and I have an 8048 coming from England, but I don't think it is the main processor, as everything else seems to be working except for the "load" function. 
> > 
> > I'm somewhat reluctant to go pulling the microprocessor board, just to see if the RAM is socketed, as the Quadra has been extremely tempermental the whole time I've owned it  but I'm also fearful of cascading casualties. I did come across several sites regarding old video games (which also share the 8048/5101 or other type of 8-bit processor) that stated the 5101 was susceptible to battery leakage/failure. Don't know the context, but I've been pretty remiss in changing the 3AA batteries that power the memory. Again my completely uneducated guess would be the RAM chip, as it seems the only function not working is writing to RAM. Although I don't really need the 16 program locations. I am never going to gig with this keyboard, and I am perfectly happy turning on and off whatever section I want when I need it. The only reason I'm concerned is with having something else fail as a result of this failure.
> > 
> > Any thoughts? I'm thinking maybe the 5101 chip based on discussions I've read on video game/pinball game sites?
> >
>

On 19 May 2011, at 19:20, "bluejinn" <nchevatarevich@...> wrote:

> Thanks,
> 
> I replaced the batteries a few days ago, and there was some corrosion around the negative terminal, but I checked the voltages on the outside of the connectors and got a good reading. I'll check again, but I didn't see any corrosion on the microcomputer board, (some flakes dropped down onto the phasor board, but I cleaned that up.)
> 
> Will 3v be enough, or should I just get a 4.5v old style CMOS clock battery?
> 
> --- In vintagesynthrepair@yahoogroups.com, "Alexis V. Rogers" <alexis.v.rogers@...> wrote:
> >
> > Sounds like a battery problem to me. Get the old one out and look for signs of leakage and acid-corroded traces. You can replace the old batteries with a 3V Lithium coin cell.
> > 
> > Cheers,
> > Alex
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "bluejinn" <nchevatarevich@> wrote:
> > >
> > > Hello
> > > 
> > > Here is the deal, the 16 programmable switches don't program. The actual function switches still work, and the program change switches appear to change (but not really, mostly just all on or mostly all on) so it doesn't seem that whatever programs were in there are still actually in there.
> > > 
> > > Also, the pitch for the lead synth scanning mechanism ("interval write") works as well. However, when switching from "Lock" to "Load" the function switches all freeze.
> > > 
> > > So, because the interval write is working, it appears as though the microprocessor system is working, but I can't write to memory. The system is based around a 8048 and the RAM is a 5101. My completely uneducated guess would be the RAM chip as the only function that doesn't seem to work is writing to RAM.
> > > 
> > > The RAM is easily obtainable and on its way, and I have an 8048 coming from England, but I don't think it is the main processor, as everything else seems to be working except for the "load" function. 
> > > 
> > > I'm somewhat reluctant to go pulling the microprocessor board, just to see if the RAM is socketed, as the Quadra has been extremely tempermental the whole time I've owned it but I'm also fearful of cascading casualties. I did come across several sites regarding old video games (which also share the 8048/5101 or other type of 8-bit processor) that stated the 5101 was susceptible to battery leakage/failure. Don't know the context, but I've been pretty remiss in changing the 3AA batteries that power the memory. Again my completely uneducated guess would be the RAM chip, as it seems the only function not working is writing to RAM. Although I don't really need the 16 program locations. I am never going to gig with this keyboard, and I am perfectly happy turning on and off whatever section I want when I need it. The only reason I'm concerned is with having something else fail as a result of this failure.
> > > 
> > > Any thoughts? I'm thinking maybe the 5101 chip based on discussions I've read on video game/pinball game sites?
> > >
> >
> 
>

>
> 5101 is a common failure in anything that uses them, so yes I'd look at swapping it out..try to match the speed of the original..some circuits are sensitive to ram speed.
> 
> A new 8048 wont do anything as it has to be programmed from factory, unless you are getting one out of a broken Quadra of course.
> 
> A 3 volt battery should work fine.
> 
> Cheers, Phil.
> 
> Sent from my iPad
> 
> On 19 May 2011, at 19:20, "bluejinn" <nchevatarevich@...> wrote:
> 
> > Thanks,
> > 
> > I replaced the batteries a few days ago, and there was some corrosion around the negative terminal, but I checked the voltages on the outside of the connectors and got a good reading. I'll check again, but I didn't see any corrosion on the microcomputer board, (some flakes dropped down onto the phasor board, but I cleaned that up.)
> > 
> > Will 3v be enough, or should I just get a 4.5v old style CMOS clock battery?
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "Alexis V. Rogers" <alexis.v.rogers@> wrote:
> > >
> > > Sounds like a battery problem to me. Get the old one out and look for signs of leakage and acid-corroded traces. You can replace the old batteries with a 3V Lithium coin cell.
> > > 
> > > Cheers,
> > > Alex
> > > 
> > > --- In vintagesynthrepair@yahoogroups.com, "bluejinn" <nchevatarevich@> wrote:
> > > >
> > > > Hello
> > > > 
> > > > Here is the deal, the 16 programmable switches don't program. The actual function switches still work, and the program change switches appear to change (but not really, mostly just all on or mostly all on) so it doesn't seem that whatever programs were in there are still actually in there.
> > > > 
> > > > Also, the pitch for the lead synth scanning mechanism ("interval write") works as well. However, when switching from "Lock" to "Load" the function switches all freeze.
> > > > 
> > > > So, because the interval write is working, it appears as though the microprocessor system is working, but I can't write to memory. The system is based around a 8048 and the RAM is a 5101. My completely uneducated guess would be the RAM chip as the only function that doesn't seem to work is writing to RAM.
> > > > 
> > > > The RAM is easily obtainable and on its way, and I have an 8048 coming from England, but I don't think it is the main processor, as everything else seems to be working except for the "load" function. 
> > > > 
> > > > I'm somewhat reluctant to go pulling the microprocessor board, just to see if the RAM is socketed, as the Quadra has been extremely tempermental the whole time I've owned it but I'm also fearful of cascading casualties. I did come across several sites regarding old video games (which also share the 8048/5101 or other type of 8-bit processor) that stated the 5101 was susceptible to battery leakage/failure. Don't know the context, but I've been pretty remiss in changing the 3AA batteries that power the memory. Again my completely uneducated guess would be the RAM chip, as it seems the only function not working is writing to RAM. Although I don't really need the 16 program locations. I am never going to gig with this keyboard, and I am perfectly happy turning on and off whatever section I want when I need it. The only reason I'm concerned is with having something else fail as a result of this failure.
> > > > 
> > > > Any thoughts? I'm thinking maybe the 5101 chip based on discussions I've read on video game/pinball game sites?
> > > >
> > >
> > 
> >
>