text from guy who repair that atari.. "So, like you, I remember, I disconnected everything in terms of switching EPROM (QMEG) Central with original OS ROM, further I removed the switches that turn on the internal Your CART - Top EPROM cartridge with the contents. I unplugged the power cord for the LED and ramdisk from the tow connector to connect SI2SD because of better accessibility to the board atarka. Ok .. Further the board has been interrupted connection MMU c.6 pin PB7 signal for what is memory MAP - use this extension RAM and a toggle team RAMBO / CS ... ok, further signal was interrupted / S5 pin # 12 of the MMU, which led to the flooding of the cart connector and signal / pin S4 C.19 MMU, who was just flooding led to the rear connector ... These views are along the connector adapted from esu 4k7 resistors will be connected to the +5 V and the other side resistors are connected to the signals / S4 a/S5 but on just the connector back and were connected to the switch number 2 discount (if divam atarko the front) that switches signals / S5 / S4 MMU either to flooding connector attached to the rear or the top of EPROM containing CART - signals are connected by the switches and diodes vedenene to pin 20 and pin 22 top EPROM 27256th Isostat switch # 3 is switched from left to address only the top EPROM, thus elected cart contents ..
Well it is not currently on that clean sheet without any adjustments and expansion should go as classic atari 800x ..
Ok, now my testing results:
- PIA, CPU, ANTIC, GTIA, POKEY, FREDDY - are OK, tested on my atari
- MMU what I gave to the other is also OK, tested on my atari
- Equipped with 64kB RAM - DRAM 4164 8pcs left - are OK, tested in my atari, running as they should.
- NE555 - timer to reset - it is also OK
- TC4051 buffers for keyboard - also OK
- 74LS138 and 74LS08 - the floods are OK, tested on my atari.
Summary of tests - all integrated circuits remain intact and working normally as they should. Bracelets 64K survived as the original as well as extensions of 8pcs 41256 DRAM - and they are OK.
Since the board has been interrupted signals MAP-pin c.6 MMU and PB7, c.12MMU pin connector for a cart - signal / S5 C.19 MMU pin connector for a cart - signal / S4, pin # 15 and pin MMU 20 + 22 OS ROM, so I can reuse these on the board after preskraboch restored, and I connected the spot for MMMU CO25952 signals A14 and FA14, FA15 and A15 of CAS signal for 64K RAM ... But frankly, all integration are OK, I measured data links and addresses, they were OK and no short circuits, but at home I do not have an oscilloscope, so I measured the waveforms, shame.
So me of them all already only results that odisiel either some kind of capacitor, choke or resistor, or diode .. I measured diodes, are ok, I measured the resistors, flat look OK ... I have poodpajat caps gradually and thus their measured, since all are between GND and +5 V (that is, mostly) and can not be measured directly on the board (on par piplacka extra hours) .. Hmm, chokes suppose that they should be ok too, she did not look to be anything burned to PCBs or unsoldered .."
"I think not only the fact that Rise why you MLM monitor sometimes .. Heh, I'm a moron, I forgot that in QMEGU nemas SELF TEST, but in its place is exactly why my J MLM home SELF TEST and started up the MLM You sometimes ... interesting, so the cause is the same - caused something shutting BASIC ROM .. hmm .. strange .. Otherwise, frames are OK, but the OS ROM is OK and the BASIC ROM is OK .. only to replace the original OS ROM EPROM their 4os and moves SELF TEST On and after the OK to take place, otherwise the original OS ROM terminates Freeze ... hmm, something in the original OS ROM will probably run you crash the system with self-test still .."
