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  1. Hi nvdeynde and techknight. I got a defect Mac Plus (240V) that was dead. No power on the analog board so I started to check all components. It was exactly the same fault, R55 had no connection, completly open. It was 33k but I replaced it with a 20k resistor ( according to Larry Pina, Macintosh Repair & Upgrade Secrets) and its working perfect. Maybee should be 33k https://68kmla.org/forums/index.php?/topic/29763-macintosh-plus-analog-board-q12-replacement/&tab=comments#comment-575154 but its working anyway.
  2. Hi bibilit. That’s a little confusing for me. For Mac II-series machines with ROM SIMM slots, check to make sure the W1 jumper is removed (if a ROM SIMM is installed) or installed (if the ROM SIMM slot is empty). http://www.ccadams.org/se/pickle-faq.html According to BMOW , Mac IIsi: Insert a jumper at location W1 on the logic board if a ROM SIMM is installed. https://www.bigmessowires.com/romdrv/rominatorii-instructions.pdf When I got it it was no jumper, no ROM SIMM, no RAM SIMM, (not working). I have tested my MacIIsi board ( 820-0301-A, 630-0265) with and without jumper and w/wo a working ROM SIMM from SE/30. This rom SIMM with number 820-0241-02 has been reported to work in the Iisi before. https://68kmla.org/forums/index.php?/topic/127-iisi-rom-simm-part-number/?hl=820-0241&do=findComment&comment=80676 ROM SIMM W1 jumper Result 0 0 Black screen , no sound, not booting 0 installed White screen, no sound, not booting SE/30 0 White screen, no sound, not booting SE/30 installed White screen, no sound, not booting Is that indication that the ROM is not the problem???
  3. I have used an ultrasonic cleaner that I found on ebay, made in China. Its working fine. During cleaning it was like smoke coming up from the MB under the RAM chips. Cleaned with distilled water mixed with cleaning fluid. The MB looks like new but unfortunately the MB is not working. Same result as before cleaning. I will desolder and clean UB7 and UB8 , maybe that can help. Otherwise I dont know what to do.
  4. Thank You techknight and sigtau for Your comments. I will try to find a ultrasonic cleaner for a reasonable price. If not it will be the dishwasher..
  5. Yes, I cleaned the board with isopropylalcohol after removing the caps. Cleaned with q-tips with aceton were the caps had been. I have recapped SE/30 boards before and I think this one looked rather good. No battery leaking. No obvious destruction on the traces. But I realize that one should look for defects around the caps. All the fuses on the board are tested and are OK. A picture of the board before recapping..
  6. I got this Mac IIsi a year ago. Removed the battery and all caps then. Didn´t test it before that. Now I have started to get it working. All caps are replaced with tantalums, new axial caps. When I turn it on, the fan is working, HD is spinning. The screen is white with no mouse pointer. Only a click from the speaker but no other sound. The PSU is fine, I have also tested with o PSU from a working Mac IIci, same result. No RAM SIMMS, no ROM SIMM. pin W1 is enabled. I guess the IIsi should boot with the RAM on board. I have checked several times for corroded traces but not found any . Also checked the new tantalums for correct capacitans. The speaker is OK. Same result without HD and floppydrive. I have read "Troubleshooting Your Macintosh" by Douglass High page 85: "Hardware initialization A typical Macintosh hardware initialization consists of the following events: 1. Power is applied to the system. 2. The power supply establishes the appropriate voltage levels required by the system. 3. These voltage levels typically are monitored by one of the Sony sound integrated circuits on the logic board. If the levels are acceptable, a reset signal is then generated by this IC. 4. This reset signal forces the central processing unit (CPU), math coprocessor (FPU), primary logic ICs, expansion cards, and other internal devices to come to a known state. 5. The reset signal is withdrawn. 6. The CPU obtains the reset vector (typically four eight-bit words), which begins at memory address 0000 0000 (hexadecimal). A ROM overlay address map then is used by the memory decode and control circuitry to map the standard memory locations to a ROM address. The CPU goes to the reset vector memory address, which is now mapped to ROM. 7. Special program code called the Macintosh reset handler (MRH) is executed. The MRH remaps ROM and RAM to their respective locations. 8. The MRH initiates the P.O.S. T. sequence." Is it the sound chips thats not working? Defect RAM? The soundchips UB7 and UB8 is closest to the caps C9-C11 . I´m greatful for any advice.
  7. I submerged the board in 99% isopropylalcohol for some hours. then cleaned with a toothbrush, high pressure air and dried for some hours. I checked the tracing You described, all Ok. The board looks very clean and nice, but its not working . Same error code. Time to replace the RAMs. I tested with a RAM card of 1 Mb installed. That is from a working portable. No change. I guess that the internal RAM must be OK to use the RAM card. The SRM20256 RAM on the board is 256k, is it possible to mix with 128K ???
  8. Thank You techknight for Your interest in this poor portable. In fact it was a poor picture with some dust on the board. After cleaning its looks like this today Previously I have resoldered that RAM, as the soldering did not looked perfect before. The Connections are OK now and no bridges between the pins. Maybe I will start replacing RAMs on row A-B as they are closest to C4- C5.
  9. The board looks like this for the moment. Any suggestions if I should try and replace RAMs from rows A, B, C etc or from 1, 2, 3 ,4?
  10. Yes. this is an old picture. Its now recapped with Kemet size C tantalums. I replaced all the size B tantalums with Kemet size C.
  11. This portable now show the error code 00000082 00000101. I have inspected RAM pins but not found any obvious damage. Resoldered some pins but no help. I have got some new RAM chips and will try a last effort to save it by replacing the RAM chips. Does the error code give any information were to start replacing RAM chips? Shall I begin near C4 C5 or near the hybrid board? I got 16 new RAM chips so I cant replace all 32. Greatful for any advice.
  12. Aplmak You have solved the problem !! PERFECT. I have measured the capacitance on these new tantalums and one of them is defect. They are marked as 47 uF 16V but one of them (C17) is only 34 uF. Se picture. Exactly as You suspected I have bought these from Hong Kong (Ebay). I have earlier used Kemet tantalums on macintosh boards but these are smaller and easier to solder in place. These small tantalums , size B has the following specification: ------------------------------------ Product Name Chip Tantalum Capacitor Rated Voltage 16V Capacity 47uF Type 3528 B Model Each Size(Approx.) 4 x 3 x 2mm/ 0.16" x 0.12" x 0.08"(L*W*T) External Material Tantalum, Metal Weight 5g Package Content 50 Pcs(±2%) x 3528 Chip Tantalum Capacitor Descriptions: • Great for various digital products and DIY projects. • Small units with high stable performance,lower current leakage and dissipation factor, stable frequency and temperature and long life. suitable for military equipment and computer, telephone and other electronic products. Manufacturer Part Number Does not apply Brand Unbranded/Generic MPN Does not apply UPC 702105334911 ------------------------------------------------- Good to know that these tantalums are crap. Do not buy them. I replaced all capacitors on this board to Kemet size C , the error code 00000014 0000CD36 is gone but instead I’m back to error code 00000082 00000101. That’s obviously is a RAM error. I will check all RAMs but I’m not sure which one is defect. Obviously very important to use high quality components. Thanks again aplmak for Your excellent help.
  13. Thanks techknight for Your answer. I will try to reflux as You suggested. How about the IC LTC1040CN , LT1054CN8 and OP20H? Can that be the problem? They are cheap to buy and can be replaced.
  14. I have now measured the connections between PMGR, VIA and hybrid board on a working portable 5120. This 5120 is working and charging the battery. I have found the same connection on both the working and not working board. Checked two times. Se Pictures. I suppose that means that there is a defect in the PMGR or hybrid board. Anybody know where to continue ? Is there any way to test the hybrid board??
  15. I have checked the traces between VIA and PMGR, the numbers on PMGR refers to pin on VIA. Dont know if I have used the correct pin numbers. se Picture. Also Connection to hybrid board. next step is maybee to measure on a healthy board.