Re: Req: Help with a sick IIC !!!

[Jan <jankro@vip.fi>]

Hello,
First, thanks for you reply.
All these IIC�s are european versions and so are the power bricks. I have two
bricks with similar  results and correct voltages. Ihave tried three internal
supply�s and they give correct voltages. How is the test screen supposed to look
like? I�ll get different screens on all 3 IIC�s. The one I�m working now, gives
me 24 horizontal bars, 4 pixels each. On the left upper corner, approximately
1/4 of the screen, there are flashing small blocks that keep changing
constantly.No sound is present and the test will not stop (waited a couple of
hours).
Voltages to the memory chips are OK, (4.97V)
I will check the voltages when the drive powers up and let you know.
Thanks for your help.

Jan/Finland

eeastman@NOSPAMappple2.com wrote:

> Jan:
> Two things to check, valid IIc boot disk and power.  Try borrowing a good
> IIc form a user in your area and try using their power supply on your IIc,
> try one of their know good boot disks on your IIcs.
>
> You said you tried the disks on a IIe, are these boot disks ones that would
> work on a IIc?  I know alot of older stuff will not boot on a IIc because of
> the boot rom.  Of course the prodos thing confuses me because ProDOS of any
> variety _should_ work on a IIc.
>
> So are you using the same power supply on all these failing IIcs?  Try a
> different power supply.
>
> What pwoer frequency do you have in VIP.FI? (Your e-mail domain.)  Do you
> have a power supply built for your part of the world?  50Hz AC power
> generates a different voltage when rectified into DC, and may cause problems
> with filtering capactitors.  A different frequecy will totally screw up the
> rectifier and will produce AC laden (unstable DC) and lower current capacity
> and higher voltage.
>
> Since you solder, I assume you have a VOM, check the voltages inside the IIc
> at the memory chips, make sure it is high enough.  Watch for a voltage drop
> when you activate the drive.  If you have access to an osilloscope, check
> the AC component of your DC voltages and see if there is a frequency riding
> your DC that may be causing problems in your ram.
>
> These are the only things I can think to check since all of your IIcs appear
> to be having the same problems.
>
> Thankx,
> Ed
>
> Jan wrote:
>
> > Yes, I tried three different disk drives,and I tested the boot floppies
> > on my 2E.  On PRODOS I get "Unable to load PRODOS" and on DOS33, I�ll get
> > the Hex or assembler message.