wierd problem with the analog output board

[blackelk001]

I currently have a problem I've never seen before. Here I go. I have a EIIIxp with 32 mges without the analog inputs. Recently, I was installing a CF drive in place of the Floppy drive in my EIIIxp, and made the mistake of plugging the ribbon cable for the  analog output board in backwards.

 After correcting the cable reversal, and turning the unit on, I notice that the display had developed a problem. It still works, but it's hard to navigate through menus because some characters are replace with different letters and symbols. It makes it feel like it's displaying in a different Language. When it's in this behavior, it still works. I can load samples, and play them back, ect.

The weird part is that if I disconnect the analog board, the display is fine again.

At this point I have not checked all the analog outputs. When the analog board is connected, the headphones output is working. This make me think that the analog board isn't dead.

I know others have asked, but does anyone Have a EIIIxp service manual they can send to me so I can debug this. I'm very experience at debugging hardware.

Thanks
Blackelk

[lubb]

Hi,

I can tell only this:

1. the headphone output is not connected to the analog output board, so you cannot think of it as an indicator of working analog output board. Try the analog outputs with jacks.

2. Once I made a foul mistake when connecting the connector to the analog board in the right direction, but only one row of the pins were connected, the second row rested in the air...! I remember vaguely that very weird things were going on the display after powering up! I switched off immediately and corrected the connection... Then my EIIIX worked normally...

I would suggest to double check if the ribbon cable connector sits properly... (No pins bent, for example...)

 

[blackelk001]

Thanks for the reply. I'll double check the connection. As for the headphone out, I experienced that the headphone connection wouldn't work if the analog board wasn't connected.

Does anyone know where I can buy a service manual?

thanks again

[Data]

I seem to have the same problem. Did you solve this?

[blackelk001]

Yes and No. I was never able to find a service manual. Nor a place to buy a copy. I can tell you (at least in my case) that the problem is with the analog board.

I ended up buying two more units. One of them as a parts machine swapping out the analog board. Now I have two fully working 32 meg machines.

Im still interested in debuging the problem. A service manual would make it much easier.

Did your EIIIx developed this problem over time, or was it a case of a reverse cable like me?.

[Data]

I bought it like this, hoping that i can fix it. I took out the cable more than 10 times already. Change ends, reverse polarity. Bend some pins, bend them back again. Nothing works. Also took a hammer to hit the ends of the cable connectors.

Maybe the cable is broken. 

The characters jump sometimes. IE. letters change.

[ACEOFBASS]

NE5532P Dual OP-Amp,  They are about $2.50 or less each.  When you replace them, make the extra effort and install an 8-pin DIP socket to nest the chip in.
Do all 5!  If you have only one that is bad,  the chances are that the others will go.  It is just age that kills these chips.  Nothing more.

Make sure to also check the MPS5172 transistors, another common failure point on the analog outputs.

If you suck at circuit board repair, remove your analog board and send it my way.  I will fix it and ship it back to you for cheap.  PM me.

Cheers!

-ACE