Roland Huisman
Veteran Member
Last week I've picked up some nice old pieces of history. One of them was the Tektronix 4010.
Because it has collected dirt for 46 years, I first cleaned thoroughly.
And I don't want to sit on my knees when servicing this kind of electronics.
But now I bumped my head several times against the bottom of the terminal.
Slowly powered it up. A bridge rectifier already got quite warm with only 40V mains voltage (set at 220V mains).
And there was one fuse of 8A where a 2A fuse should be. Well, it really does not trip when it is necessary.
The cause of the hot bridge rectifier was in a shorted tantalum capacitor on the -15V supply line on one of the boards.
After some further measurements, the + 20V showed enormous ripple voltage. This was caused by a
dead filter capacitor. And what a worthless construction to get that cap out! So I thought
let me put that spare power in there which I got with it. It might save some time is that one works.
Unfortunately the 5V TTL power supply was faulty on that one. So I had two broken power supplies.
So I repaired the original power supply. Slowly turned up the mains voltage again
and POOF, there went that -20V fuse again! Now on another board a tantalum on
the -15V shorted. It remains old stuff of course
And I put everything back together again...
So meanwhile it is running DIR on PDP8 / F:
Now it would be nice to throw some graphics data to it.
Regards, Roland
Because it has collected dirt for 46 years, I first cleaned thoroughly.
And I don't want to sit on my knees when servicing this kind of electronics.
But now I bumped my head several times against the bottom of the terminal.
Slowly powered it up. A bridge rectifier already got quite warm with only 40V mains voltage (set at 220V mains).
And there was one fuse of 8A where a 2A fuse should be. Well, it really does not trip when it is necessary.
The cause of the hot bridge rectifier was in a shorted tantalum capacitor on the -15V supply line on one of the boards.
After some further measurements, the + 20V showed enormous ripple voltage. This was caused by a
dead filter capacitor. And what a worthless construction to get that cap out! So I thought
let me put that spare power in there which I got with it. It might save some time is that one works.
Unfortunately the 5V TTL power supply was faulty on that one. So I had two broken power supplies.
So I repaired the original power supply. Slowly turned up the mains voltage again
and POOF, there went that -20V fuse again! Now on another board a tantalum on
the -15V shorted. It remains old stuff of course
And I put everything back together again...
So meanwhile it is running DIR on PDP8 / F:
Now it would be nice to throw some graphics data to it.
Regards, Roland