Search found 326 matches
- 14 Jan 2017 18:32
- Forum: HARDWARE
- Topic: MTX512 fault: Blowing fuse.
- Replies: 11
- Views: 17900
Re: MTX512 fault: Blowing fuse.
So, the capacitors have now been changed and there's no difference. I decided to run a longer powered test to see if I could find and chips which were getting warmer than normal: http://www.lingula.org.uk/~steve/images/Memotech-on-test.jpg As it turns out the video chip and all the video memory chip...
- 12 Jan 2017 00:22
- Forum: HARDWARE
- Topic: MTX512 fault: Blowing fuse.
- Replies: 11
- Views: 17900
Re: MTX512 fault: Blowing fuse.
Removing C57 made no difference. Oh well, the tricky C11 will be next. I'll get replacement capacitors from Maplin's at the weekend and replace them both anyway.
- 11 Jan 2017 22:58
- Forum: HARDWARE
- Topic: MTX512 fault: Blowing fuse.
- Replies: 11
- Views: 17900
Re: MTX512 fault: Blowing fuse.
OK, so after replacing the power transistor and the zenor diode (which is what let out the magic smoke) I'm back to where I was. It still blows the fuse. But... with a meter where the fuse should be I'm measuring 0.86 amps and the machine is operating seemingly normally. As you can imagine, the heat...
- 04 Dec 2016 14:36
- Forum: HARDWARE
- Topic: MTX512 fault: Blowing fuse.
- Replies: 11
- Views: 17900
Re: MTX512 fault: Blowing fuse.
Hi Stephen, I guess that you don't need any comments on the "wisdom" of bypassing the fuse :D The burning smell is not a good sign, the problem could be pretty much anywhere on the board. A good, easy anyway, starting point would be to remove all of the socketed chips and try that first. ...
- 04 Dec 2016 14:32
- Forum: HARDWARE
- Topic: MTX512 fault: Blowing fuse.
- Replies: 11
- Views: 17900
Re: MTX512 fault: Blowing fuse.
The 7805 voltage regulator and the TIP transistor work together to regulate the voltage for the +5V line. If the fuse is blowing, too much current is flowing, which indicates that something is breaking down and drawing too much current. But first, if your multimeter has a diode test function, test ...
- 04 Dec 2016 13:06
- Forum: HARDWARE
- Topic: MTX512 fault: Blowing fuse.
- Replies: 11
- Views: 17900
MTX512 fault: Blowing fuse.
I recently bought an MTX512 on eBay which the vendor had previously tested but arrived in a non-working state as the internal fuse had blown. Having replaced C39 and C40 just in case I could get the machine operational by bridging the fuse, though the rectifying diodes got a bit warm. I replaced the...