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  1. well, it seems that this will be the last update for this thread. I bought another cny17-3 and this time, instead of soldering it directly I soldered a socket first. It seems I was killing the octocouplers with the heat from the soldering iron. I have been testing the machines for close to 2 weeks now, and everything seems fine. I started to restore the plastic in the macs with 10% hydrogen peroxide and uv light, that is also going great. I have an entire 512K macintosh that came with the lot that I haven't even cracked open yet, so I probably will be returning to the foru
  2. Thanks for the replies! I did not solder a socket, now that you mention it, i should have. there shouldn't be any thermal expansion in the joints, to get it to work I only need to heat it to about 70 degrees (celsius). but maybe the octos are failing in a way that makes them thermally intermittent on the inside, i have no idea why, but they might. As for why I don't use the cny17g-3, I sincerely don't know how i got the Tda ic, it was kind of a miracle, but trust me, I tried every electronics store in the city, and not a single one sold the cny17g-3, one sold a cny17
  3. Well, It seems the problem has not ended yet. I replaced the octocoupler with a 4n37. And the computers worked great for a while, I could switch them on and off all the times that I wanted to and all that. then, the next day I went to turn one of them on and the same symptoms returned, wobbly screen image, low voltages unless I wait or heat up the octocoupler. Now, I know that the octocoupler is the issue here, I replaced it again and got the exact same results (it worked flawlessly for a while, then it didn't anymore) Now, Here comes the question. Is the octocoupler failin
  4. Well, I have found the culprit of my suffering (spoiler alert: its my fault) To make it quick, it is the octocoupler. I thought the one i bought was compatible, but it seems it wasn't. I got started with another one of the other macs to get a break from this one. recapped it, put a new tda in it, new diodes and cp4 and 5. I turned it on, and to my surprise, same exact symptoms, but this time i got a idea, instead of heating from the front of the ic, I heated where the solder joints are, and sure enough, I can spend 30 minutes heating the tda and absolutely nothing wil
  5. Hi!, first of all thanks for your reply! I think we are having different problems here, because your board boots first time but after a couple of minutes the voltages drop off. my board does exactly the opposite thing, the thing starts with the checkerboard pattern but after a couple of minutes it boots and works just fine. But I believe we still can help each other out. First, some questions that I want to ask you. Do you have the computer plugged to 220v? is it connected to ground? What voltage do you measure at ressistor RP1? It is the big 22k 3 watt ressistor
  6. Ok. so I downloaded the bomarc schematics for my board (the late model, without the zener diode dp1) and obviously the first thing that struck me was that at the end of rp1 (22k 3w) there should be 12v ac. I measured and im getting 120v ac both at the start and the end of the resistor AND now at pin 6 I am getting 120v almost double of what I was measuring before!!!. I tested the resistor and it came out perfect. I desoldered cp4 and dp4 since those where the only things connected to pin 6 outside of the 22k resistor, I still got 120v ac. I even desoldered the tda Ic again and measur
  7. Hey Elfen, thanks for your reply! I already have reflowed the usual suspects such as the yoke connector and high voltage parts of the board with flux core solder. I also went arround every solder joint with a magnifying glass for visual inspection of hairline cracks. The logic boards do need recapping, I already have the tantalum caps for that, I just want to finish the nightmare that is the analog board. for testing purposes they do work so I won't worry about them (yet). Today I replaced the tda4605 with a tda4605-3 which I know is compatible. the first start went g
  8. Hmm, the rifa caps apear to be perfect although I haven't tested them yet. As I said in the first post i already replaced the optoisolator, the mosfet, and both 1n4148 diodes. today I will be replacing the TDA ic and see if that solves the problem, I think it will, If not, I will get to testing those rifa caps as you said. Thanks for the reply! will keep updated.
  9. UPDATE: searching this forum a bit more, i saw a post about blasting heat to the A/B to make it start quicker so i grabbed my smd resoldering station and with the mac turned on started blasting ic's with 150ยบ air, sure enough, the mac started almost instantly this time. I narrowed it down to the TDA4605 IC. I will be replacing it tomorrow. will keep updated.
  10. the user im talking about is benanderson89, not 6502 haha. this is his forum post.
  11. hey, this is my first post to the forum. A couple of days ago I bought a lot of old computers in which came 4 Macintosh classics, not a single one turned on. I chose to start working in one of the 220v models as it is the voltage that my country has. After researching a bit on reddit, this forum and such, i came to the conclussion that the Analog board needed to be recapped. after recapping the a/b now the computer turned on, but the screen wobbled a lot and showed a checkerboard pattern, after researching a bit more, I washed the logic board, then tried again, same
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