Hi, I'm in the restoration process of M-80. This unit was probably stored in humid conditions for long time or even have been flooded... so there was a lot of rust on body parts. Rust has been removed chemically + mechanically and body parts painted with special Zinc paint and black hammerite paint. Also both transformer has been restored... rust removed on sides and covers, side of body painted with special transformer lacquer and covers sprayed with black hammerite paint.
Good news is that all big caps and all output transistors are good.
I'm planning to do:
- replace all small caps to Nichicon KZ/MUSE/FG (in late stage, once I get it working with standard caps)
- replace all carbon film resistors because corrosion can be seen on many of them... and some others flame proof resistors
- replace some jumper wires - due to corrosion (will replace them with tinned copper wire 0.5mm)
- clean and sand all copper jumpers
- replace few transistors on the meter board - due to corrosion on legs and 2-3 others transistors which has been already diagnosed as faulty
- on few traces remove old solder mask, sand and paint with new solder mask - found that some process of corrosion/oxidation starts... or maybe better will be just cover these traces with layer of solder instead of solder mask?
- clean repays, pots and switches
- replace/upgrade speaker terminals -> https://www.aliexpress.com/item/1005001355022246.html
- replace variable resistors
Are there any known noisy/week components worth to replace/upgrade? Any other suggestions?
Some pictures attached.
Good news is that all big caps and all output transistors are good.
I'm planning to do:
- replace all small caps to Nichicon KZ/MUSE/FG (in late stage, once I get it working with standard caps)
- replace all carbon film resistors because corrosion can be seen on many of them... and some others flame proof resistors
- replace some jumper wires - due to corrosion (will replace them with tinned copper wire 0.5mm)
- clean and sand all copper jumpers
- replace few transistors on the meter board - due to corrosion on legs and 2-3 others transistors which has been already diagnosed as faulty
- on few traces remove old solder mask, sand and paint with new solder mask - found that some process of corrosion/oxidation starts... or maybe better will be just cover these traces with layer of solder instead of solder mask?
- clean repays, pots and switches
- replace/upgrade speaker terminals -> https://www.aliexpress.com/item/1005001355022246.html
- replace variable resistors
Are there any known noisy/week components worth to replace/upgrade? Any other suggestions?
Some pictures attached.
