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shoestring

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About shoestring

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  1. AFAIR there were two different types of original power supplies for the CD32, the heavier brick ( resin filled similar to ones found for a1200/a600 ) and a lighter one. The brick is reliable and will last years, the smaller one not so much.
  2. Baking soda will work. The important thing is to paint them after cleaning or they start rusting pretty much straight away. I used PCB lacquer after wet sanding the metal plate of the a1200 keyboard. But there are better ways. https://retrohax.net/extreme-refurbishing-episode-4-vampiric-amiga-500/
  3. Yes this is a common failure point on A500 keyboards. I knew there wasn't an issue with the motherboard when you measured the signal from the status ( pin 7 ) Starts off as a dry joint due to constant mechanical stress from the A500 enclosure when the two slits for the LED casings are mis-aligned during reassembling. Eventually the traces on the solder side can fail.
  4. Happy days. So if there is a broken leg on one of the custom chips then you can solder another leg from a donor chip if it has enough metal exposed. Some people use a dremel to expose more of it if its snapped at the base of the chip. http://www.ukvac.com/forum/missing-chip-pin-tips_topic350953.html
  5. Sounds like a faulty Agnus ( 10 flashes plus 1 long ). He is right when he said that you cannot put 8371 Agnus in rev 6 board. You need an additional refresh circuit which goes near the trapdoor on the motherboard. The 8371 isn't able to refresh some ram chips ( 44256 ) properly. Some early rev 6 had the 8371 but needed the refresh circuit. Why not just test the 8372a in your original board ?
  6. Well it seems like a memory problem. But clean those 8371 leads and PLCC leads first before you do anything else. Don't bother swapping CIAs until you address the ram issue.
  7. That gouge is the least of your worries. Give those leads a good clean, there's some corrosion and oxidisation taking place on almost all pin leads. They're likely not making a good connection to the PLCC. Use some rubbing alcohol or brasso and a fine toothbrush or cotton ear bud. Don't scrub accross the chip. I'd consider doing this first before looking at the chip ram.
  8. Light green or Green ? https://www.lemonamiga.com/forum/viewtopic.php?t=13978
  9. I'm get a crisp picture from the A1200, not confident I'll benefit much with such a cable but I can only try it out and see. My only complaint is the slight vertical banding I see which is likely associated with the pixel clock of the LCD which I should be able to adjust on the display or OSSC. They are brittle, easy to destroy. But thankfully spare PLCCs in a variety of different sizes are still easy to source nowadays and are of good quality. As for the GARY socket, he/she could have at least trimmed it down neatly with a file so that it ends up flush with the end of the chip, that's what I'd have done after removing those extra pins had I ran short of suitable spares.
  10. Well now I'm curious, I built my own SCART cable to use with the OSSC but didn't use independent grounds ( except for the audio ) or any other components in the schematics from the links above. But now I'm going to build another one to see if the display can get even better. It's possible they had upgraded to an 8372a at some point but put the old one back in.
  11. Also, GARY has had some work done to it with the bigger machined pin socket installed. So you probably find your broken pin somewhere there. You could try applying some pressure to the chip to see if it makes a difference
  12. Well, the AGNUS socket looks a bit fucked up. Looks like the low data select pin ( if i have my orientation correct ) is damaged. Don't know how this even worked when you saw it. Get your money back
  13. If it has a SKART input then it should accept the Amigas video signal. Only 5 wires are needed on the 23 pin connector ( video ground, red,green,blue and csync ). The rca audio cables from the SKART end of the cavle just taps the output from the back of your Amiga into your TV which has internal speakers. Does the new machine have any drive activity despite the white screen? No drive click then. Are you still using the old power supply ?
  14. Needs to be confirmed. Initial power on reset is also triggered by the 555 during power up. GARY will then pulse _RST and _HLT briefly to various custom chips and U37 ( 74LS32 ) which buffers the _RESET to both CIA chips and some of the IO such as the parallel port and the external floppy. I'd check GARY , the 74LS32 @ U37 and 4.7k resistor at RP101
  15. If you're worried about a short at the connector, then you can dial the dmm in continuity mode and look for a dead short between pins 1,2,3 and 4. ( with the machine switched off of course ). Pin 4 is vcc so it should be 5v. Clock and data are held high ( 5v ) before any keyboard transmission begins. The _KBCLOCK signal ( pin 1 ) is driven by the keyboard itself, _kbdata ( pin 2 ) is driven by both keyboard and the Amiga ( bi-directional ). I'd assume that _KBCLOCK should float ( not measure anything ) with the keyboard unplugged since it's uni-directional The keyboard will only pulse _kbreset low when the user presses the ctl-amiga2 combo. So when gary sees low signal, it will assert _reset and _halt to initiate the reset process. _kbreset ( pin 3 ) should be held high by default if the user is not pressing the 3 key combo. I don't know if a white/grey screen is with enough confidence to assume that the ks rom is passing software checks, what version of kickstart do you have ? White or black is screen is common value in color0 register when the Amiga ( denise ) powers up and that seems to depend on the revision too. Lots of other faulty parts of the chipset can cause the machine to boot to white, grey or black screen. Ideally I would start my troubleshooting at the reset circuit, at the 555. It should probably be flashing. Have you checked the keyboard LED and resistor R6 on the keyboard pcb ? Might be blown or loose.
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