ASR-33 Questions

Tony Duell ard at
Mon Mar 7 17:28:42 CST 2005

> -The one big problem it has is its lack of a reader power supply. The last 

Can't you grab it from your wrecked ASR33 (or did you manage to get that 
one going in the end)?

> owner got it from a government surplus program, but they neglected to 
> supply anything but the unit itself... and so no reader supply. Does 
> somebody have the schematic of one of these so I can build a new one? 

I will ahev to hhunt, but I may have it. Isn't it in the DEC ASR33 
diagrams (which are on bitsavers?)

> -Right now the unit is doing a lot of chattering on both Line and Local 
> when powered on. Initially I thought something might be mechanically wrong 

In Line mode that might be right. The unit will 'space out' (telegraph 
term) if there's no current in the recieve loop. The receiver side will 
run continuously, it'll decode NULs and therefore not print anything.

In Local mode, it shouldn't do that, of course. Start by looking at the 
transmit shaft and distributor brush (rear right of the typing unit). If 
that's spinning all the time, then you do have a mechanical problem. Most 
likely the typing unit came free from the base during shipping, or the 
H-plate is not installed properly, something like that. 

If the transmit side is not truning, then you may well have an electrical 
problem. Most likly the receiving magnet (rear left of the typing unit, 
near the punch) is not energixed. Maybe a fault on the call control unit 

> due to being shaken around in shipping, say one of the clutches on the 
> main shaft locking into an active position, but so far I haven't found a 
> culprit. I'm also wondering if I'm even looking in the right direction 
> for the problem, sooo here's the question: could the lack of a power 
> supply for the reader be causing this behavior? (The reader itself is 

No. That is certainly not the problem.


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