neevo
Super Member
My Mouser order arrived today and I couldn’t resist having a crack at the power amp board after the kids went to bed.
First up was to attempt my blue wire repair. I kicked it off my separating the posts as they’d been pushed together (I assume to stop them unwinding accidentally). I’d drilled out my wire twisting tool to make sure it went over the post and I have to say I’m very pleased with how it’s panned out:
One on the left is the repair. Posts bent back in place afterwards:
You’d struggle to notice the repair:
Repair complete I set about refurbishing the power amp board. All very simple as I went about replacing 1 cap at a time. It’s amazing how much smaller the new ones are. Then I came to the relay. I was familiar with what to do as I did it on my 7100 refurb too. Trim off the rear legs and solder it in:
Next up I pulled the trimmers, checking the resistance on the meter so I could dial them in as much as possible before I put them in the amp. Easy drop in replacement except for the bias adjusters which require an extension on the middle leg. Easily done with the same wire I used to repair the cut wire:
Transistors next and I wasn’t sure which leg was which, so I used the schematic on Mouser to find out. Luckily the board had each leg screen printed on it:
At this point I’d done all of the consumables except for the main filter caps (I’ll do them later), this involves electrolytic caps, a few of the transistors and diodes:
I like to have all my parts neatly placed on the board, straight, aligned and neat:
Finally I had a crack at doing some of the TO-3’s, the compound is super sticky but I managed to get a thin layer on each Mica. I also cleaned all the connectors to make sure it had a good connection. No idea how you tell if it’s done properly but it certainly looks the part. Before:
First up was to attempt my blue wire repair. I kicked it off my separating the posts as they’d been pushed together (I assume to stop them unwinding accidentally). I’d drilled out my wire twisting tool to make sure it went over the post and I have to say I’m very pleased with how it’s panned out:
One on the left is the repair. Posts bent back in place afterwards:
You’d struggle to notice the repair:
Repair complete I set about refurbishing the power amp board. All very simple as I went about replacing 1 cap at a time. It’s amazing how much smaller the new ones are. Then I came to the relay. I was familiar with what to do as I did it on my 7100 refurb too. Trim off the rear legs and solder it in:
Next up I pulled the trimmers, checking the resistance on the meter so I could dial them in as much as possible before I put them in the amp. Easy drop in replacement except for the bias adjusters which require an extension on the middle leg. Easily done with the same wire I used to repair the cut wire:
Transistors next and I wasn’t sure which leg was which, so I used the schematic on Mouser to find out. Luckily the board had each leg screen printed on it:
At this point I’d done all of the consumables except for the main filter caps (I’ll do them later), this involves electrolytic caps, a few of the transistors and diodes:
I like to have all my parts neatly placed on the board, straight, aligned and neat:
Finally I had a crack at doing some of the TO-3’s, the compound is super sticky but I managed to get a thin layer on each Mica. I also cleaned all the connectors to make sure it had a good connection. No idea how you tell if it’s done properly but it certainly looks the part. Before:
