CS1 and CS2 Error?

[yell0w_lantern]

There are 2 units on ebay from the same seller. I'm wondering how difficult these might be to fix. Anyone know what these problems might be from or point me to a troubleshooting guide?

 

TI-99/4A BEIGE HOME COMPUTER TESTED FOUND A DEFECT TRYING TO WRITE TO CS2

https://www.ebay.com/itm/TI-99-4A-BEIGE-HOME-COMPUTER-TESTED-FOUND-A-DEFECT-TRYING-TO-WRITE-TO-CS2/264722818076?hash=item3da2b5a41c:g:xBsAAOSwHiBest0g

 

TI-99/4A BEIGE HOME COMPUTER TESTED FOUND A DEFECT TRYING TO READ CS1

https://www.ebay.com/itm/TI-99-4A-BEIGE-HOME-COMPUTER-TESTED-FOUND-A-DEFECT-TRYING-TO-READ-CS1/392790613758?hash=item5b74251efe:g:2rIAAOSwQGpetC-3

[Tursi]

I'm surprised cassette was tested at all, let alone both cassettes. That said... it seems a bit pricey to be sold as defective. They do need a cleaning.

A big part of me wonders if the fault wasn't just the cable though, but not many people exercise their cassette ports anymore.

 

The schematics are widely available and we could probably work through it.

 

[Tursi]

You'll find a drawing of the schematic (and some discussion of possible grounding issues) here: 

Also some information here: http://www.unige.ch/medecine/nouspikel/ti99/cassette.htm

 

 

 

 

[wierd_w]

I dunno, but I can *CONFIRM* that the OEM cable has an open ground.

 

I believe that the rebranded recorder they used combined the ground channels between record and read lines, and that this allowed that defect to go unnoticed. It only manifested for me when trying to attach the cassette cable to a PC for using CS1er, which is why I think this is so. I had to bridge the two ground lines with a jumper wire before CS1er would work.  The generic ONN recorder you can get from Walmart works just fine, it just lacks the program counter. The tape-hold rem port works just fine without modification or anything.

 

 

 

 

[yell0w_lantern]

I'm helping my brother look for a unit but many sellers are asking $60 for untested machines (which is code for broken in my book). I would feel better spending less on one that is confirmed broken but is fixable rather than roll the dice on "untested".
It sounds like there is a chance the CS errors might not be problems with the machines themselves but if the seller knows enough to even test those then they might really be problems with the machines.

All this retro-tech is getting pricey.

[Tursi]

Maybe someone here can hook you up...?