MZ 80K repair project
Posted: Sun Jun 07, 2020 2:34 pm
Hi all,
First time posting here.
Hoping you are all well.
I recently aquired a MZ80K with the hope of getting it working, so my students can have a go with using it.
Apart from being filthy, the 'first' problem I have found is that the PSU does not work.
I gave it a quick dusting, then fired it up, intending to check the voltages coming out of it; 2 fuses blew. (bottom right, by the transformer, and top right by the black/red/blue wires)
Upon taking the board out and desoldering the transformer to allow easier access, I found the board was coated in some sticky, tarry substance (not sure what that was...) I managed to get most of that off with alcohol and elbow grease.
I have also replaced all of the electrolytic capacitors apart from the 4 larger ones (which I am having trouble sourcing...)
On that note, this is the closest I can find :
https://www.mouser.co.uk/ProductDetail/ ... 4I1w%3D%3D
But it mentions they are 'Low ESR Electrolytic Capacitors'; I'm not sure what that means...so am unsure whether they would be suitable?
After replacing the other capacitors and blown fuses and cleaning the board up, fired it up and the same fuse (far right by the transformer) keeps blowing straight away.
Any thoughts?
I have noticed there is some sort of deposit on these components, but had assumed it was some sort of glue, could be wrong?
Worst case scenerio, as a temporary measure, has anyone had success using a modern power supply on old equipment like this? Perhaps using similar method to the one described here:
https://www.electronics-tutorials.ws/bl ... upply.html
Looking forward to hearing your suggestions!
First time posting here.
Hoping you are all well.
I recently aquired a MZ80K with the hope of getting it working, so my students can have a go with using it.
Apart from being filthy, the 'first' problem I have found is that the PSU does not work.
I gave it a quick dusting, then fired it up, intending to check the voltages coming out of it; 2 fuses blew. (bottom right, by the transformer, and top right by the black/red/blue wires)
Upon taking the board out and desoldering the transformer to allow easier access, I found the board was coated in some sticky, tarry substance (not sure what that was...) I managed to get most of that off with alcohol and elbow grease.
I have also replaced all of the electrolytic capacitors apart from the 4 larger ones (which I am having trouble sourcing...)
On that note, this is the closest I can find :
https://www.mouser.co.uk/ProductDetail/ ... 4I1w%3D%3D
But it mentions they are 'Low ESR Electrolytic Capacitors'; I'm not sure what that means...so am unsure whether they would be suitable?
After replacing the other capacitors and blown fuses and cleaning the board up, fired it up and the same fuse (far right by the transformer) keeps blowing straight away.
Any thoughts?
I have noticed there is some sort of deposit on these components, but had assumed it was some sort of glue, could be wrong?
Worst case scenerio, as a temporary measure, has anyone had success using a modern power supply on old equipment like this? Perhaps using similar method to the one described here:
https://www.electronics-tutorials.ws/bl ... upply.html
Looking forward to hearing your suggestions!