Jump to content

tf_hh

+AtariAge Subscriber
  • Posts

    1,089
  • Joined

  • Last visited

10 Followers

About tf_hh

  • Birthday 10/11/1970

Profile Information

  • Gender
    Male
  • Location
    Germany
  • Interests
    Microelectronics, Atari 8-Bit Hardware, Atari 16-Bit Hardware, ATMEL Microprocessors

Recent Profile Visitors

19,680 profile views

tf_hh's Achievements

Stargunner

Stargunner (7/9)

1.6k

Reputation

  1. Yes. Currently I haven´t one in stock, but after having no time for several months - real life is sometimes a bitch - for a new batch I´ve started to assembling new ones last weekend. Please load the info PDF in my signature, where you can find all details and how to order. Thanks!
  2. I think this is a very early version of a CPS SALT or SuperSALT cart and won´t work correct with the XEGS. All CPS SALT/SuperSALT versions I know of didn´t really test anything above 48K ($C000). And the "error" message is clear, $04 is the content of the first byte in the XEGS operating system (ROM file offset $4000). I would suggest the PIA is bad. The standard RAM test (48K) is okay, the ROM is okay, ANTIC and GTIA also seems to work. MMU you´ve checked. So PIA should be the one. Just watch PB7 (pin 17) with scope and power on the machine without diagnostic cart. Typically defect PIAs shown a continious low signal or remain always high. All XL/XE operating systems must follow this behaviour: After power-on the PB7 go high, after a few tenth of a second to low, also for a short time, then high again. This is used to mirror the selftest into $5000-$57FF. O.S. uses part of the selftest routines during cold start for a quick RAM test and detected existing RAM size. Without the O.S. will hung up. A diagnostic cartridge (special bytes in it´s header) will started before this test is done, so that´s why it starts.
  3. Yes, they are. Please sent an email, my email address is found in the avatar or the linked PDF file below 🙂
  4. Not sure exactly. One thing is, I´m using the NE5532 OpAmp, which is much better regarding low-noise than the commonly used LM358 and others. The values of resistors and caps are optimized after years of change in the design. Currently I´m raising the low frequencies (bass) a little bit more than other stereo PCBs do, giving the POKEY sound a little bit more oomph 🙂 Secondly, I didn´t know if this is correct for Lotharek´s stereo PCB, this is one of the few items I never purchased from him. But a lot of stereo PCBs made one essential mistake in their design: They´re switching between mono and stereo after the final cap in line. Some "Gumby" schematics have this, too. The problem: The typically used 4016/4066 analog switch chip will be damaged after some time when fed with AC, even when it´s approx 1. Vss. I´ve made this error also in my early designs. So maybe the other stereo PCB is an older design also having this flaw. Just an idea. The effect of a dying 4016/4066 chip is noise, clicks and rasping sound.
  5. Unfortunately I´m sold out with these and until today I never found a new source...
  6. Well... after more than 30 years of repairing and hundreds of 8-Bit systems in my hand I would say: It´s a myth - *when* talking about Atari 8-bit machines. Leaking / dry capacitors are mostly a problem of newer machines, and also then not every model. For example, the Atari ST series is mostly unaffected by capacitor problems, except their power supplies, of course. The newer the machine, the chance of cap issues went higher. Also Commdore Amiga. While Amiga 500 and 1000 machines mostly have caps working until today flawless, the Amiga 600 and 1200 are well-known for leaking SMD electrolytic caps and sometimes heavy damages to the board. Talking about Atari 8-bit IMHO the only two mainboards with cap issues are some XE series and the 800 XLF (with freddy). At those boards the 470 uF capacitor(s) sometimes are bulged and should be replaced. A leaking cap I never saw at any Atari 8-Bit machine except the 1050. The 1050 has four 47uF caps for motor power control, these one often are bulged and sometimes leaking. Just my 2 cents...
  7. Not regarding how useful it is, yes, it works. The Sys-Check diagnostic firmware disables the U1MB BIOS and features (as possible), so you might run the RAM test also having an U1MB installed. The other features (external O.S. switcher and/or external 512 KB RAM expansion) works also, but... the U1MB does it already 🙂
  8. The manual is describing the installation into each Atari XL/XE computer, so please follow these instructions, of course. The operating system used has no influence.
  9. Did you ever make this happen? I´ve tried to expand the memory to 8 MByte. 4 MByte (in four SIPP modules with 1 MByte each) where already installed. When I add the next four SIPPs with each 1 MByte, the system starts with 4 MB in total, not 8 MB. The new SIPP modules work fine, when I place them into the first four rows, the machine works also fine. But info about this system is hard to find. After RAM check the BIOS said "Bank 0 installed 1 MB WAITSTATE 1". Same for Bank 1. Bank 2 and 3 are shown as disabled. But how I can enable these? I´ve tried all jumpers on the mainboard, but no sucess. Any help appreciated!
  10. Hi, I´ve the same machine (mainboard revision) on my desk. I can´t say if this is genuine Atari, but my PC4 contains a Seagate SCSI card and a Seagate ST277N SCSI harddrive. See the pictures below. Do you have a manual for exact this version? I´ve tried to expand the memory to 8 MByte. 4 MByte (in four SIPP modules with 1 MByte each) where already installed. When I add the next four SIPPs with each 1 MByte, the system starts with 4 MB in total, not 8 MB. The new SIPP modules work fine, when I place them into the first four rows, the machine works also fine. But info about this system is hard to find. Jurgen
  11. Surely after 40 years I´m not pretty sure, but it was a german magazine. But this kind of expansions I´ve experienced in a very different ways with different 74s chips used in different computers. The scheme behind was always the same: Using 8 pieces 41256 chips (total 256 KB) and divide them in 64 KB main memory and 192 KB banked memory. This not the correct one. I´m tried to find the article, but failed so far.
  12. Ah, well, overlooked. Sorry. But for that this signal is used... strange.
  13. Nothing will happen, because he was wrong with the chip. It´s the ANTIC, not the PIA.
  14. Beside already given hints, if you check the others out, try to replace the inductor L5 with a simple wire. This inductor reduces the 5 volts voltage a little bit. When you feed the system with 5.0...5.2 volts, normally the +5 volts at the 4050 chip (where you have installed UAV) is around 4.75 - 4.9 volts. Enough for the LDO voltage regulator on the UAV board. But when the main input voltage is already below 5.0 volts under load, it may happen that less than 4.7 volts reach the UAV. And this is too less for proper function. So removing the inductor L5 might fix this problem. Red rectangle shows the L5 inductor. When you already working on the board, it´s also a good idea to change the electrolytic cap in the yellow circle with 100uF instead of only 10uF. Helps to stabilize the video power.
×
×
  • Create New...