Firehose Replacement Thoughts

[GDMike]

I'm buying

[GDMike]

1 minute ago, acadiel said:

That might actually work.  A replacement PCB for the speech synth, including the speech chips, buffer chips, and the Centronics port.  

... and an external 5v adapter, for appliances and or my cell phone.lol

[+acadiel]

This is what it takes to crimp a 50 pin connector - just in case you haven't seen it

 

 

 

[Omega-TI]

13 minutes ago, GDMike said:

... and an external 5v adapter, for appliances and or my cell phone.lol

 

I still have faith that within 5 years there will be a replacement power supply board that fits INSIDE the TI console with an attachment for a 5V USB charging port.  Further I believe the 5v port will ALWAYS be powered, so people with sidecar TIPI's will never have to use separate external wall warts or have to halt the TIPI before turning off the console.  This could be done with the MeanWell external power supply.

[GDMike]

Yuk. I'm into a round cable, I grew up with round cables. But I guess it can roll up.

[+OLD CS1]

44 minutes ago, acadiel said:

Challenges to this include finding shielded cable and splicing the connectors on the 50 pin cable.  Ask any 1A2 phone guy that still has the tool to put a right angle Centronics onto wire - it’s an art.  There’s also the soldering way.

This got me thinking about whether one could find the parts and maybe find a cable pre-build in certain lengths.  So far, no, and it looks like a couple of other things to consider: the price of these connectors and the type of cable.  For price, I found a place which advertises them for about $7 each, less in quantity.  It also seems modern CAT3 bundles use twisted pair, and I wonder if this will have any adverse effects on signaling.  I used to have some old phone installation cabling which was not twisted pair -- I picked it out of a local bank's refuse when it upgraded back in the 90s -- but tossed what was left when I cleaned out my old storage room a couple of years back.

 

That said, I am thinking about a system I just pulled off the wall at a customer's site.  It was 18 years old and its 25-pair bundles were not twisted pair.  So, I dunno.

 

But even if we consider a package still the size of a Speech Synthesizer, SCSI connectors should suffice.

 

(Mind you, all of this completely ignores the special detail and calculations engineers put into such projects.  Caution to the wind, I say.)

[+acadiel]

5 minutes ago, OLD CS1 said:

This got me thinking about whether one could find the parts and maybe find a cable pre-build in certain lengths.  So far, no, and it looks like a couple of other things to consider: the price of these connectors and the type of cable.  For price, I found a place which advertises them for about $7 each, less in quantity.  It also seems modern CAT3 bundles use twisted pair, and I wonder if this will have any adverse effects on signaling.  I used to have some old phone installation cabling which was not twisted pair -- I picked it out of a local bank's refuse when it upgraded back in the 90s -- but tossed what was left when I cleaned out my old storage room a couple of years back.

 

That said, I am thinking about a system I just pulled off the wall at a customer's site.  It was 18 years old and its 25-pair bundles were not twisted pair.  So, I dunno.

 

But even if we consider a package still the size of a Speech Synthesizer, SCSI connectors should suffice.

 

(Mind you, all of this completely ignores the special detail and calculations engineers put into such projects.  Caution to the wind, I say.)

 

Yep - ahead of you here, I've been looking it up.  A 5' section of cable would run around $15 or so:

https://www.newark.com/3m/3600b-50-300/shielded-multiconductor-cable/dp/52F7603

 

The end connectors are like $8 or so:

https://phoneman.com/25-pair-cables-and-blocks/25-pair-diy-amp-connectors/

 

So yeah, this would be terribly expensive, but would need a minimum commitment of 60 units (to deal with a spool of 300' of cable x 5ft/ea).

 

Edit:  I still haven't figured out how to search for cable that's more 'flexible' vs 'rigid' in the 25 pair realm.  I know the flexible shielded kind exists, I've seen it.

[+OLD CS1]

Interesting notes according to the schematics:

 

PEB sends unregulated 8V down the fire hose to power a 5v regulator for the single TTL buffer (U2, 74LS245 on the data lines) in the side car connector.  That 5v supply also appears to mix with the console's 5v line.

 

The PEB connector card has buffers for all lines except CRUIN, *EXTINT, and READY, but the TI side of things only has the single buffer on the data lines in the side car.  Data lines are handled by a 74LS245 (tri-state di-directional octal bus transceivers) companion to the side car, and all others are handled by three 74LS244 (tri-state octal bus buffer and line driver.)

 

The other lines going out the expansion port are buffered on the console main board by two 74LS367s (tri-state hex buffers) and a 74LS244 except: CRUIN, *LOAD, HOLD/IAQ, RESET, and *EXTINT.  READY is driven by a 74LS03 (NAND gate) in the console.

 

HOLD/IAQ and *LOAD are not passed to the PEB.

[+FarmerPotato]

You can find surplus SCSI DB50 cables like this for example:

 

https://www.ebay.com/itm/292265788428

 

 

[GDMike]

I got one still in the bag. I think it's 15'

I'll look for it. I've also got a spare Peb interface card. Hmmm

Edited October 26, 2020 by GDMike

[wierd_w]

It's not quite enough conductors to fully pull off, but if the wires in the DB50 cables are twisted pairs, just use the alternate conductors for each pair as a ground. Then it will work more like an 80 conductor IDE cable, and have better signal fidelity.

 

Say, prioritize address and data lines for the "twisted with ground" status, and let the ones that dont need that level of isolation be twisted with something else.