Forgottenmyname - Progress

[PhilC]

Hi All,

As of today I still get the rolling screen after applying the sync mod on U51.
The Glue is still sending out 15khz on 37 and 60hz on 38.

I do have a lot of activity on /AS /R/W on the CPU, Rom data lines are active on the Eprom but all activity stops after about 10 seconds. BUT this is only from a cold start, never warm start.

/Halt and /Reset are both high (ready to run)

I did have a row of bombs early on today whilst scoping around the eprom but wasn't looking at the TV at the time to know exactly where.

Does anyone know what will cause all activity to pause after 10 seconds after a cold start?

[exxos]

What does BERR do all this time ?

CPU would normally wait for DTACK (should arrive within about 8 clocks of /AS going low).. if it doesn't then something hasn't responded on the bus.. in which case, BERR normally gets set and the CPU gets HALted.

If something is wrong with the address bus, then during startup it could be trying to access a invalid area of RAM, but again BERR should be set then anyway.

[PhilC]

BERR is 5v from startup.

ok, trying to describe what I see, the signals on the databuses, /AS etc all start off with a low value mean but you can clearly see the pulses, then the mean voltage increases and after about 10 seconds its flat lined at 5v.

incomming voltage is steady.

[exxos]

Have you checked the clocks on the MFP ?

Also may help if you can post a capture of V&H sync..

[troed]

As of today I still get the rolling screen after applying the sync mod on U51.
The Glue is still sending out 15khz on 37 and 60hz on 38.

What do you have on the monitor port then? If HSYNC and VSYNC are steady at 15kHz and 60Hz you should not have a rolling screen ... unless your TV cannot handle 60Hz and then it would be predictably vertical rolling only :)

[PhilC]

MFP has 4Mhz on pin 35, 2.45753 on 17 & 18

will check the scart lead before i post a video. wheres the best place to upload vids?

[exxos]

MFP has 4Mhz on pin 35, 2.45753 on 17 & 18

will check the scart lead before i post a video. wheres the best place to upload vids?

I guess YouTube is best place, failing that if you can compress the video to a few MB then can be uploaded here..

[exxos]

BTW does your cable use the separate syncs or the composite sync ?

[PhilC]

It uses this minus the resistors

[exxos]

Probably the thing to do is check composite sync on a working ST and then the STF... it could just be the voltage is a fraction lower than the TV likes or something silly...