24-10-2012, 12:39 PM
I thought it made sense to start a new thread on the actual restoration of this.
A quick poke 'round with my continuity tester showed that the caps were shot. I had a go at reforming the reservoir in the PSU and within a couple of minutes it was barely leaking 2mA at 300V.
I then reverted to type and changed the grid coupler and powered it up. This doesn't strike me as too reckless as the fact it's got IEC connectors on its lead shows it's seen some juice relatively recently.
I do tend to take a leaf out of the telly boys' book and try and get some sort of 'first light' as soon as I can so I know what I'm dealing with. There's no point re-wiring, cleaning, changing capacitors &c only to find there's an o/c coil or something equally serious amiss.
I was rewarded with silence. I found the output stage was working but seemed a bit quiet.
Changing the cap across the OPT primary improved things as did changing the cathode bypass. I've just been restuffing the original; sadly the two waxies are of a type that attempts at restuffing would destroy any way. They are brown with the markings over the wax and are a bit chewed-looking anyway. I do plan on restuffing the others though, not least because inside the old ones will be the best place to put the replacements.
The two waxies I've replaced only measured about 80kΩ on an AVO MultiMinor at 1.5V so there no wonder it isn't doing much.
It certainly isn't going to be a half-hour job like a DAC90a - which is no bad thing.
- Joe
A quick poke 'round with my continuity tester showed that the caps were shot. I had a go at reforming the reservoir in the PSU and within a couple of minutes it was barely leaking 2mA at 300V.
I then reverted to type and changed the grid coupler and powered it up. This doesn't strike me as too reckless as the fact it's got IEC connectors on its lead shows it's seen some juice relatively recently.
I do tend to take a leaf out of the telly boys' book and try and get some sort of 'first light' as soon as I can so I know what I'm dealing with. There's no point re-wiring, cleaning, changing capacitors &c only to find there's an o/c coil or something equally serious amiss.
I was rewarded with silence. I found the output stage was working but seemed a bit quiet.
Changing the cap across the OPT primary improved things as did changing the cathode bypass. I've just been restuffing the original; sadly the two waxies are of a type that attempts at restuffing would destroy any way. They are brown with the markings over the wax and are a bit chewed-looking anyway. I do plan on restuffing the others though, not least because inside the old ones will be the best place to put the replacements.
The two waxies I've replaced only measured about 80kΩ on an AVO MultiMinor at 1.5V so there no wonder it isn't doing much.
It certainly isn't going to be a half-hour job like a DAC90a - which is no bad thing.
- Joe
