• Please review our updated Terms and Rules here

RX01 renovation.

D

DaveH

Experienced Member
Joined
Sep 1, 2012
Messages
173
Location
Scotland
Iv decided to take a break from my RK05's and look at something were the head is SUPPOSED to touch the media, my RX01. As usual its not been powered since the 80's , iv done the normal, foam, cant find any, PSU, its a linear and seems ok, heads, cleaned them. Now are there any other "gotchas" before I run it up and try a disk in it, bearing in mind that the disks have not been stored to well before I got them, 30 years in a damp garage :(
Last time I used 8 inch disks was in my home build 6809/Flex system in the 80's so should be fun.
Dave
 
Also check the little button of felt that presses against the non-data side of the disk to hold the disk against the head. It's usually filthy or gone completely. In addition, the acme screw head positioner lead screw grease seems to stiffen, so condider exercising that screw by hand a bit.

Lou
 
Thanks Lou, I did wind the heads back and forth a bit and the carriage seems free, I checked the head load button tonight, seems clean and protrudes about 1mm so I guess they are ok. I think the problems going to be with the electronics, judging by the other cards I got with the same "haul", about 150 assorted Omnibus cards :D , I can expect at least 10% of the IC's to be dead :(
 
Dave,

I find it hard to believe that 10% of the TTL will be bad. The RX01 is not too bad to work on. Neither are omnibus cards for that matter. With a little patience, a scope, and a logic analyser, mid 70's hardware is a pleasure to work on!

A haul of 150 omnibus cards sounds like a dream come true! Even a haul of 150 broken omnibus cards would be the find of a lifetime. It would be nice if you catalog those cards, and if you have eight of something and would like to trade for something non-omnibus, let me know. :)

Lou
 
Lou,
Yes, 10% may be a bit on the high side, it was a "guesstimate" based on the fact that I have needed to replace 4 or 5 IC's on several cards, I will have to look at my notes and maybe get a better average figure. Heres one that needed 5, also some other odd pics that may be of interest.

http://www.flickr.com/photos/78027915@N04/10520083735/in/photostream/

The 3 daughter boards , E40,30 and 11 are small PCBs I made up to allow 6380,s and 384,s to be replaced by 74 series, these Signetics seem to be some of the worst to fail. the others replaced on this board are E29 +47.
The "haul" that I got all this gear from had not been well stored, 20 or so years in a not very dry location and I suspect that moisture has a part to play in this.

I should also probably not have used the sad smiley ! as one of the most enjoyably aspect of this hobby for me is the repair and bringing back to life of this technology! I agree completely, its great fun and most of the required IC's can still be found , I even managed to find a replacement core sense amp to fix a 8K Plessey stack in my Lab8, though I did need to mod the circuit a bit .

The omnibus cards and the rest of the haul, assorted 8E's, M's A,s, RX01+2 , RL02, were a MOST AMAZING find, and no its not going to happen again to me! and to be honest Iv now got all the 8 stuff I can handle , apart from a straight 8 that is :D


On the RX01 front, can anyone point me to a copy of the RX8 MainDec Dignostic, thats
08-DIRXA-D or -C

Iv looked in all the normal places, David Gesswein,s site, bitsavers, general Google search, but cant seem to find it, binary or dectape image , cant use on RK05 image right now :(
The Data reliability -8-DIRXB would also be handy.

Dave
 
DaveH said:
Lou,

Iv looked in all the normal places, David Gesswein,s site, bitsavers, general Google search, but cant seem to find it, binary or dectape image , cant use on RK05 image right now :(
The Data reliability -8-DIRXB would also be handy.

Dave
Click to expand...

I assume you have gotten them from the later response. For the future if you click on the more link next to the file name you get an option to convert to a paper tape image so you should be able to use the ones on the RK05 image.
 
djg said:
I assume you have gotten them from the later response. For the future if you click on the more link next to the file name you get an option to convert to a paper tape image so you should be able to use the ones on the RK05 image.
Click to expand...

Thanks for that dig, had missed it, yes I got a copy , not had much success yet as for some reason non of the error codes im getting make much sense !, going to test the M9357 with some basic hand coded code.
Dave
 
Woopee, got the Rx01 working, well mostly .

Heres what I found.
Testing with maindecs in control only i.e. the M8357 showed an intermittent done flag error, changed E 2, 7474 cured this.

Ok on to control and interface diags, again done flag errors. Plugged in maintenance board with a new overlay with the text the correct way up, its downright impossible to use this with it upside down !, single stepping and reading the rom listing showed that he micro was running and seemed to be going through the init ok and in fact ending in the " wait for command " loop, hmm strange, time for some real diagnostic tools.

So out with the LA, an HP16500, an eBay purchase from a year or so ago but never used in anger till now. Now we could follow the code properly, Now there are several delay subroutines , as you would expect , and they use the hardware counter, 8 bits in 2 x 4 ,and we did not seem to be spending the time in here that we should, put the second pod on the op's of these, arr , that does not look like a 8 bit count, more like 2 x 4 bits, the count overflow/carry on the LSB was stuck high, so change E36, 74161 and we now pass that maindec.

Today tried the full test but with just drive 0, rats still get an error, an unexpected error flag, but the listing does say that this could be due to an error in the automatic read sector 0 and as im just testing with an unknown disk could it be the disk ?

Try another disk, I have quite a few but am avoiding any that have labels on in case they have useful content and only want to use clean, scour free so that reduces the number I can try, anyway as I type this there is the steady " click click" of a head step and to far no errors. We may not be all the way there yet but cant be far.

A full both drives test will have to wait as tonight its our annual family TTD "Transport Tycoon Deluxe" night, a classic computer game if there was ever one , even if it wont run on an 8 .
Dave
 
Last edited:
You must log in or register to reply here.
Back
Top