Atari TT - Bus errors, advice needed! - SOLVED

[Steve]

Okay, I have installed the new replacement cracked resistor & I have installed all the SIPs.

Result: No video output on either TT output or VME graphics output :O

* Notes, I can see the hard drive loading, so I think the machine is running, just without display.

Whats my next move, remove all the SIPS?

Here is a photo of my SIP installation:

IMG_20180803_105832.jpg (525.09 KiB) Viewed 3040 times

[Steve]

edit

[exxos]

Have you got pin 1 of the sips right way ? (normally square pads on pcb) and nothing shorting on the pins to pcb or to each other ?

[Steve]

Have you got pin 1 of the sips right way ? (normally square pads on pcb) and nothing shorting on the pins to pcb or to each other ?

Okay fixed it lol. The SIPS were all fine, it was the resistors I soldered in to fix the cracked ones. I dunno why but they were causing the no display.

*update: Now my floppy drive works It is reading, writing and formatting perfect now. Also: ST ram test in Yaart passes no issues, also seems to go through the tests twice as fast!

So I'm getting there.. now I just need to work out what to replace the resistors with.. Here is a photo of the location, note the two missing resistors have a C designation, that is odd..

They are c218 and c220. They were: brown green brown silver silver.
I used these: http://au.element14.com/webapp/wcs/stor ... reId=10184
But obviously I must have gone horribly wrong?

[exxos]

What exactly are you looking at ? "C" is normally capacitor not resistor.. Can you find those parts on the diagram ?

[Steve]

Right above those blue thingy mabobs. I've removed them, the designations are there. Click full screen I added a comment and a box around them.

[exxos]

Right above those blue thingy mabobs. I've removed them, the designations are there.

Can you find them on the TT schematic so we can see what they actually are...

[Steve]

I've had a look but I cannot see them. Maybe Atarian Computing can help with that.

[Steve]

I checked in this persons motherboard photo, on their revision H, they have two of the regular yellow ceramic caps in those places:
https://www.exxosforum.co.uk/forum/viewt ... f=58&t=591

Where mine seemed to have those odd resistors, very strange

[exxos]

I checked in this persons motherboard photo, on their revision H, they have two of the regular yellow ceramic caps in those places:
https://www.exxosforum.co.uk/forum/viewt ... f=58&t=591

Where mine seemed to have those odd resistors, very strange

Well "old skool" capacitors did have colour codes like resistors.. just I haven't seen any for like 30 years

If you look online probably a calculator to convert the colours. Assume it be 100nF or something like that.. depends what its connected to..