Apollo 1240 Blank screen, was working fine. - Page 2

AlfaRomeo · 19 August 2016, 22:17

Thanks for the help Zetr0.

Now, when I tested continuity between via tracks from pins 13 and 14 of the 74F74 (without the IC) my multimeter buzzed saying that somehow they are connected.
Someone know if is it suposed to be like that?

Zetr0 · 20 August 2016, 00:18

@AlfaRomeo

The 74F74 is a Dual Edge Triggered Flip Flop - This controls the memory timing for the RAM from the base clock.

If memory serves pins 13 and 14 will lead off to the small block of jumpers for setting the memory state. - if you haven't already remove the jumpers and test to make sure.

AlfaRomeo · 20 August 2016, 02:28

I will do remove the jumpers and test again.
Many thanks for your help Zetr0

Zetr0 · 20 August 2016, 10:04

@AlfaRomeo

Está mais do que bem-vindo irmão =)

These cards are a dying breed, so any small capacity where I might information to help - its my pleasure, and duty, to offer it =)

I will also buzz out the 74F74 on my 060 and put a schematic up for people.

AlfaRomeo · 28 February 2019, 14:09

@Zetr0

Hi mate,

Quote:

Originally Posted by Zetr0

I will also buzz out the 74F74 on my 060 and put a schematic up for people.

any news about this??

Uplink7 · 03 December 2020, 03:29

Bumping an old thread as I am having the same problem with my Apollo 1240. No boot, black screen and never tries to even look at the floppy and hard disk.

Same condition as above OP, corrosion from the leaking battery on the jumpers and the 74F74 chip.

I removed the battery, cleaned up the corrosion I believe, still no joy. I thought the osc might have gotten damaged when I moved the 1200 as it was falling out of the card and the pins are bent. I bought a programmable osc just in case. Tried that and same results.

I'm thinking about removing the 74F74 and see if any corrosion has gotten underneath. If I remove the Apollo the 1200 boots fine. There is a single SMD Electrolytic I'm gonna replace just for giggles But we are approaching the limits of my diagnostic ability.

Any suggestions?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Apollo 1240 - Black Screen of xxxxx	NovaCoder	support.Hardware	27	27 April 2012 10:39
Apollo 1240 = Black screen	Dougal	support.Hardware	35	20 January 2012 22:31
ACT Apollo 1240? Not working, worth it still?	Mr B	support.Hardware	29	10 December 2011 23:12
Apollo 1240 040 40MHz black screen	vintageit	support.Hardware	38	05 September 2011 02:12
MC68040RC33 not working in Apollo 1240	8bitbubsy	support.Hardware	2	13 March 2010 21:20

19 August 2016, 22:17	#21
AlfaRomeo A1200 040 SAM440EP 667 Join Date: Jan 2008 Location: Lisbon / Portugal Posts: 873	Thanks for the help Zetr0. Now, when I tested continuity between via tracks from pins 13 and 14 of the 74F74 (without the IC) my multimeter buzzed saying that somehow they are connected. Someone know if is it suposed to be like that?

20 August 2016, 00:18	#22
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@AlfaRomeo The 74F74 is a Dual Edge Triggered Flip Flop - This controls the memory timing for the RAM from the base clock. If memory serves pins 13 and 14 will lead off to the small block of jumpers for setting the memory state. - if you haven't already remove the jumpers and test to make sure.

20 August 2016, 02:28	#23
AlfaRomeo A1200 040 SAM440EP 667 Join Date: Jan 2008 Location: Lisbon / Portugal Posts: 873	I will do remove the jumpers and test again. Many thanks for your help Zetr0

20 August 2016, 10:04	#24
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@AlfaRomeo Está mais do que bem-vindo irmão =) These cards are a dying breed, so any small capacity where I might information to help - its my pleasure, and duty, to offer it =) I will also buzz out the 74F74 on my 060 and put a schematic up for people.

03 December 2020, 03:29	#26
Uplink7 Registered User Join Date: Nov 2004 Location: Meredith, NH USA Age: 71 Posts: 28	Bumping an old thread as I am having the same problem with my Apollo 1240. No boot, black screen and never tries to even look at the floppy and hard disk. Same condition as above OP, corrosion from the leaking battery on the jumpers and the 74F74 chip. I removed the battery, cleaned up the corrosion I believe, still no joy. I thought the osc might have gotten damaged when I moved the 1200 as it was falling out of the card and the pins are bent. I bought a programmable osc just in case. Tried that and same results. I'm thinking about removing the 74F74 and see if any corrosion has gotten underneath. If I remove the Apollo the 1200 boots fine. There is a single SMD Electrolytic I'm gonna replace just for giggles But we are approaching the limits of my diagnostic ability. Any suggestions?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)