DECtalk Adventures

[Perkunas]

Okay, maybe not as interesting a subject on here as PDP-11s or a VAXen, but I'm hoping some of you may be able to help me get started with this one.

Earlier today my, uh, "dealer" got in a couple DECtalk DTC01s and I snagged one for a whole $5, I was told by one of the interns at the shop that the guy who donated the pair had demonstrated them working to the staff but I guess this particular one was not the one he was using.

As soon as I got it home, I hooked it up to a terminal and some headphones (I didn't notice the speaker built into the unit at first), flipped the switch, and got nothing.

Well, pretty close to nothing, the power and fan seem to be OK, the actual system itself? Not so much. No “DECtalk version XXX is running” as described in the installation guide can be heard, just a brief pop and then static, same with just using the built-in speaker. Of course, the terminal gets no output either. The block of status LEDs on the back was fully lit as well.

I popped it open and visually inspected the mainboard, but nothing seems to really be out of place, the whole unit is practically spotless except for some yellowing, no corrosion or anything else that seems amiss.

I *like* to say I'm decently OK at google-fu but I'm having trouble finding anything meaningful on the web as far as actual troubleshooting goes, the owner's guide only details service plans and the installation guide only gives you very rudimentary troubleshooting procedures. I'm usually pretty lucky with the stuff I get so I don't really get to do a lot of real in-depth repairs on my hardware, so I have no idea where to begin looking to figure out what's wrong.

Has anyone here worked with one of these that may be able to help me figure out what I can do to get this thing running again? I'd be very, very grateful for some pointers.

 

[Lou - N2MIY]

Sir,

Start with the print set (MP-01820) and study how it works. Check the power supply voltages. See if the microprocessor starts and reads code from the roms. All the basic stuff you would check if repairing any video terminal or microprocessor based computer of the time. I think you need to spend some more time researching, studying the available material, and scoping/probing on your bench.

Lou

 

[NF6X]

I don't think this will help much, but I just turned mine on to watch how the LEDs normally behave at power-up. I didn't connect anything but an AC power cable to it. All times are approximate:

• Power on.
• 1 second later, all LEDs turn on.
• 2 seconds later, burst of DTMF tones from internal speaker.
• LEDs change to 11010010 and Stephen Hawking announces "DECTALK VERSION 2.0 IS RUNNING".

I think you got a fine deal even though you'll need to put some effort into debugging. Good luck!

 

[cruff]

This reply won't be helpful, but is a story about using DECtalk at work.

At the National Center for Atmospheric Research (NCAR), we had a Network Systems HYPERchannel based crossbar network running locally developed code for our pre-Ethernet era high speed interconnect for the Crays, IBM mainframes and Unix servers. We had a operations monitor called the MASnet Operations Monitor (MOM), that had a graphical state display on Tektronix terminals both in the computer room and in the hallway outside our offices. The fellow who maintained the MOM code, decided the operation staff in the computer room needed an audio status report if they weren't in the operator's area, so they could investigate problems promptly. He acquired a DECtalk unit and had it hooked to amplified speakers in the room. It would report things like "Node C1 is down", "Node HA is up". I think it lasted about two months before the operation staff turned it off, as normal processing load on some of the slower systems would cause MOM to "cry wolf".

 

[Perkunas]

Thanks for the replies, guys! I'm pretty eager to get this thing talking again. I think I might go down and buy the other one if it's still languishing on the shelf, even though it's also got the same issue.

Start with the print set (MP-01820) and study how it works.

Beautiful, thank you!

See if the microprocessor starts and reads code from the roms.

This is probably a dumb question, and I do apologize if it is, but how would I test this? Monitor the CPU pins with a multimeter?

I think you need to spend some more time researching, studying the available material, and scoping/probing on your bench.

Aye, I'm still relatively new to this. Thanks for pointing me in the right direction.

I don't think this will help much, but I just turned mine on to watch how the LEDs normally behave at power-up.

Actually pretty good to know, if I get this thing fixed again I'll probably compile all the information I can grab on it in one place for anyone else with one of these.

He acquired a DECtalk unit and had it hooked to amplified speakers in the room. It would report things like "Node C1 is down", "Node HA is up". I think it lasted about two months before the operation staff turned it off, as normal processing load on some of the slower systems would cause MOM to "cry wolf".

I can definitely imagine that would get a little old after a while.

 

[m_thompson]

And a similar DECtalk story. The rock radio station WBCN in Boston had a DECtalk system as a on-the-air guest, Karlos. Whoever was running the DECtalk system was really good. Eventually the DECtalk personality got so popular that the DJs protested and they removed it.

 

[Lou - N2MIY]

Perkunas,

I usually like to scope the memory address select lines of the microprocessor to get a feel for if it is running. I usually then like to use the logic analyzer to see something sensible is going on (a loop) or if the processor is heading into deep space (indicative of something not right).

The multimeter however is useful for checking the power supply voltages.

Indeed you should buy the other dectalk unit if it is still there. I have a dectalk III and it was a lot of fun. The scripts written by others to make it "sing" are quite amusing.

Lou