Re: Caps a poppin!

[Tristan Mumford <xtristan.xmumford@xgmail.xcom>]

heuser.marcus@freenet.de wrote:

> Tristan Mumford schrieb:
>> heuser.marcus@freenet.de wrote:
>> >
>> > Can you provide a good photo of the mainboard?
>>
>> I took one. Not sure if I'd call it good per se, but it's the best I
>> could do. http://images1.filecloud.com/333356/2clone.jpg
> 
> It is a good picture: It's good enough to confirm that your
> mainboard looks practically identical to the one in my clone!
> (I had this suspicion after I saw your keyboard...)
> Perhaps the clone of a clone? ;-)

What 'brand' is yours?

> 
> I have no schematics but I guess that all chips/parts/traces
> "should" be the same. So if you need any data - ask away.

It seems to be a fairly generic board. I'd love to get my mitts on a
schematic of it.

> 
> 
>> > Which caps did you replace?
>>
>> Going by the silkscreened coordinates they are at roughly D14
>> (At the edge. No silkscreen for 13 or 14) and E9. The obviously
>> pre-replaced ones (may be others that I didn't spot) are at C3
>> and D3.
> 
> After seeing the photo I had bet on these, too - so the picture is
> proven to be good enough ;-)
> 
> Is D3 a tantal cap?

I have absolutely no idea.
> 
>> > Did you try to reseat/exchange the RAM or other chips?
>>
>> I reseated some of the ICs. I'm going to go through and do the
>> whole lot.
> 
> My theory is that more of the chips could be fried - some of the
> caps are next to them and are used as "buffers". The event which
> caused them to explode may have been strong enough to kill
> them, too.

That's possible. But IIRC it worked last time I powered it on. The only
difference was time. At the time it already had the burnt caps.

> 
> In this case reseating obviously won't help much.

Yeah. Pity, that.

> 
> 
>> I don't believe I actually have any compatible RAM chips
>> anymore, which is a pity because I think I killed one.
> 
> You may take RAMs from the language card for tests.
> They should be compatible IIRC but somebody needs
> to confirm this.
You mean that weird 16k expansion?
The chip numbers are different but that doesn't mean much. I'll have to
check them out later.



> 
> My first suggestion would be to take it out anyway as it
> complicates more than it helps, IMHO.
> 
> The fact that you actually get a video signal isn't too bad -
> the question is which circuits are affected. (Video)RAM,
> video scanner, video generator...
> 
> Is the on-screen garbage the only defect of the board or
> are other functions affected?
> 
> Does the machine beep when turned on?
> Did you try to boot from diskette?
> Does it respond to keyboard input?
> Did you try to change the video mode?
> Do the usual BASIC video mode commands (GR, HGR, TEXT)
> show a reaction?

'tis dead.
See the reply to Charlie Springer.
Pulling the character rom and the cpu doesn't even affect it. At least all
the parts except the data on the roms are all readily available. And
perhaps the RAM, but there's always a way around that.

> 
> 
>> > What monitor do you use?
>>
>> My C= 1084S. The type with the D9 and RCAs.
> 
> The 1084 should work but the Videx clone card may be
> defective, too. I don't know if this card works in a IIe but
> this could surely be answered by other people in this group.

Yeah, It's hard to say. If it works at all I feel it's more likely to work
in slot 7.
I gave it another try in the //e. This time paying a little more attention.
I go PR#7, whack return.
I get this
]]
Ie a second close square brace. Nothing else. This is so frustrating. I
finally get some more cards that I can use in my //e and some of them are
dead!


> 
> 
>> I remembered last night in one of those awful half-awake states
>> that I have a couple of RCA connectored mono monitors in the
>> shed. One is some generic  one, which I think has selectable
>> termination resistance. The other is one of the Apple mono
>> monitors where the inside of the case pivots for vertical screen
>> angle adjustment.
> 
> Some monitors have a switch for 80-column-mode next to the video
> input. Other than that I guess the majority of all monitors should work
> with the card without any special settings, like the Apple monitor.
> 
> It may be a good idea to test the video card with one of these.

I'm going to do that. Probably a week from now because of time constraints.
The monitor I want to test with is on the bottom of the shed. Ie with
nearly 2m of stuff on top of it.

Fingers crossed I can get the clone working.

Oh yeah. Have you identified yours on http://www.apple2clones.com/


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