Search found 60 matches
- Tue May 21, 2024 9:41 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
FIXED Spectrum +2 grey 5V and 12V power short
So I could not resist and bought a Topdon TC001. Immediately I could see that R8 was hot. 1716149081956_100.JPG So I then checked the 12V and sure enough I had a short there. I admit I could have just checked this with the multimeter, but not as much fun. :D So knowing I already had a bad capacitor,...
- Fri May 17, 2024 9:59 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
- Fri May 17, 2024 9:32 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
- Fri May 17, 2024 8:45 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
Re: Spectrum +2 grey dead short
Followed the voltage gradient drop to C68, removed and voltage level improved but not completely. C68 thinks it is an inductor
- Fri May 17, 2024 6:09 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
Re: Spectrum +2 grey dead short
4 digit, 4000 counts auto range. I think
mV
- Fri May 17, 2024 1:07 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
- Fri May 17, 2024 11:45 am
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey 5V and 12V power short
- Replies: 12
- Views: 427
FIXED Spectrum +2 grey 5V and 12V power short
Hi, I liked my friend's Spectrum +2 so much I decided to get my own but this one is not in a good shape. There is a dead short across the power rails. I have set the bench power supply limit at 600ma for now. Nothing appears to be getting hot. PCB looks OK, bit dirty, and no obvious signs of any pre...
- Sun May 12, 2024 3:12 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey RAM fault but RAM is good
- Replies: 31
- Views: 811
- Sun May 12, 2024 12:49 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey RAM fault but RAM is good
- Replies: 31
- Views: 811
Re: Spectrum +2 grey RAM fault but RAM is good
Bit of progress. :D 20240512_114244_exported_6245.jpg The clue was a stuck key on bit 1 but also bit 4. Both of these bits from part of the joystick interface. So I removed the joystick controller IC and all RAM tests now pass and no stuck keys. Not booting yet but guess that is because I need a joy...
- Sat May 11, 2024 6:22 pm
- Forum: Hardware
- Topic: FIXED Spectrum +2 grey RAM fault but RAM is good
- Replies: 31
- Views: 811
Re: Spectrum +2 grey RAM fault but RAM is good
In summary. ZX Spectrum +2 (grey) displays typical RAM failure pattern on power on. Diagnostics ROM indicates IC31 bit 1 faulty. Removed IC31 and tested off board, and passed. RAM is good. Socketed IC31 and replaced with a new 4164 but faster speed. Problem still persists. Other actions taken but st...