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Tandy 3800 HD Repair/Restoration

Paralel

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Yeah, I binned it. I didn't think about the controller since I don't have any other Conner drives. I generally don't bother with the Conner drives since they're so small, and most of them are on their last legs. The only good thing about this laptop design is that they used a standard 2.5" IDE HD interface. That gives us one component that can be easily updated to a modern, off the shelf part without any trouble.
 
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leeb

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Yeah, I binned it. I didn't think about the controller since I don't have any other Conner drives. I generally don't bother with the Conner drives since they're so small, and most of them are on their last legs. The only good thing about this laptop design is that they used a standard 2.5" IDE HD interface. That gives us one component that can be easily updated to a modern, off the shelf part without any trouble.

HOLD ON THERE, bud!!!

I happen to like this design!
Sure, they could have made it easier to replace parts... but the 'upgrade items' ARE easily accessible.

Admittedly it is from practice, but I can open one of these beasts in < 3 minutes. < 2 if Im in a hurry! :p
I only wish they had made it possible to upgrade the LCD...
 

Paralel

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True, overall, it isn't bad. You can easily slot a coprocessor, put more RAM in, install a modem, the aforementioned standard HD IDE interface, and an easily replaceable battery interface (I suspect they anticipated people would leave the batteries in way too long...).

One significant gripe is no real BIOS/CMOS interface, despite that being a rather common phenomenon at that point in time. My absolute biggest gripe is the non-standard floppy interface which is tied to a soldered ribbon cable on the controller for a very specific floppy model. Floppy interface standards were very well documented/implemented at that point in time. For the 3800 in particular, no external monitor interface. The cut out for the interface is even present on the back of the motherboard! Why they just didn't solder a connecter on there, especially when the video chip can absolutely handle it, since it's the same as the one in the 2810, which has a VGA interface, is beyond me.

When I really look at it, the design, as a gestalt, is fairly good, particularly for that time period. The proprietary floppy connection just really bugs me.
 
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leeb

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Standardization really only existed in PC (desktop) models... and that, because IBM lost control of it.
... and how would you incorporate the 'twist' into such a short cable?
True, the BIOS/CMOS access is pigeon-poop... but NOBODY (AFAIR) had a 'good' BIOS routine in their 286s... I suppose it would have required a major redesign to do it with the 3s so they stayed with the file-based access.

... and other models had the external monitor... it was a matter of 'choice'. (The GRID 1755 is such a beast)

The TRUE sadness is the lack of 'forward thinking' in regard to RAM and HD capabilities... Or, as in DOS, 'Nobody needs more than 640k! :p
... I have 'plans' in mind regarding the floppy drives... at least the ones I have. REPLACABILITY of the ribbon cable(s) is my short-term goal!

:D
 

Conmega

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Alright then... I started looking in my Burroughs out of curiosity... and found that in the floppy drive box... there was a hard drive aswell... so this machine has hard drives and a floppy drive... and when i pulled out the disk controller in the box were the floppy and hard disk was... first off i was smiling with glee having it been my first dick controller board I've ever seen but found a problem... one of the caps EXPLODED and so... thats probably why it was broken and not working... if it wasn't... like i said... no powersupply... no monitor... BUT here is a directory of alllll the board and such out of this computer that someone has taken nice pictures of.
http://bitsavers.trailing-edge.com/pdf/convergent/ngen/pictures/
Everything in it was built by Convergent apparently... Also if you look at the top of this board... which is the dick controller i have... the c45 is the cap blown its the odd cap out on the entire board... Some of the pics are of a different Burroughs computers but some of the pics like disk controller board is the same as mine.
http://bitsavers.trailing-edge.com/...00191-00_Floppy_Hard_Disk_Controller_1984.jpg

So yea... One of the HD is a 43MB seagate... the other one i havn't looked at yet but yea!
I'm having so much fun looking inside of this beast. Sadly I havn't found a way to power it other then the power plug yet... So I'm going to have to find out what the power plug supplied on its pins...
Anyway do you guys have any idea what the cap ratings may be? because it needs to be replaced since mine is a piece exploded black char....
Anyway I'm going back to having fun rooting through this thing... :D
 

leeb

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A cap doesn't USUALLY cause a PS to fail... unless there is HUGE AC ripple in the DC.

C45... 'the odd cap'...

I cant tell which one is the C45... the one in the center of the PS? Do a pic of YOUR PS as is... that will help.
:D

EDIT:
Im somewhat sure the one Im referring to is a 1000mfd... but will have to doctor the pic to know.
Will edit again later.
:)
 

Conmega

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Colora, MD
DUH sorry its cap 43!!!
Gah must have read it quickly... but yea top center of the board... C43...
ALSO I have this 5 1/4 floppy drive out of the burroughs... right? I put it in an old pentium III computer and it says non system disk or disk error... so OBVIOUSLY its seeing the drive... but... I put a floppy in... and it spins the motor for the inside of the floppy right? before i clamp it down inside... but when i do clamp it down inside... it stops spinning the center... then the head moves alittle bit... then it gives up... like... the center of the drive WONT spin unless the floppy is unclamped... but then the top head isnt down on the drive and the center of the floppy isnt clamped down on the center motor.... IVE NEVER used a 5 1/4 floppy drive before.... so... I'm HORRIDLY confused as to whats going on right now.... any ideas? (i tried putting in a microsoft windows install disk one to see if it would start the installer... but like i said the drive is acting funny...

Edit: sorry its a microsoft windows graphical interface install for DOS so... id need DOS to install it.... the computer has windows server 2000 installed but... it gives the BSOD on boot so... I may have an old windows 2000 install disk around somewhere... to reinstall the system... hmm.... I just want to get the data off these floppys... I'll be going to my grandparents sunday and i'm going to take ALLLLL the 5 1/4 floppys in their basement... so when i do get this drive working i can harvest allll the data... there has to be atleast 100+ floppys down there so lots of stuff :D
Oh... also... I'm very worried that the floppys may be bad though.... they all apear to have a dried white coating on some parts on the disk inside the protective plastic cover... its like.. just on some parts... and if i spin the disk from the center a bit the inside self cleaning material seems to somewhat clean it off.... i think this may be on the disks from my grandparents basements have been being damp for some years... theyve been keeping it dry now but... yea... Are all the floppys ruined do you think? geh asking so much but im so confused... 5 1/4 inchers are out of my life time... sorry :confused:
 
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Paralel

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Sounds like your 5.25" drive has issues, probably not dissimilar to the issues we have with the Tandy 3.5" drives. If I'm not mistaken (and I could be, my 5.25" drive anatomy is not nearly as good as my 3.5" drive anatomy), they use a drive belt system as well. So, that could easily be the source of your trouble.

Also, I probably wouldn't worry about the white stuff, unless it's powdery and/or fluffy. If it's powdery/fluffy, you're probably screwed. Powdery/fluffy white stuff is mold, and it eats the substrate of which the disk media is made, thus destroying the disk. Even if you can't see any damage the microscopic structure of the disk is likely ruined since the mold eats at a cellular level. It happens to 3.5" disks at a lower rate, but they're also younger and better sealed. It is also a major problem for old 8mm, 8 track, and cassette tapes, which are all far more susceptible than floppies. Damp, dark basements are the perfect environment for mold to grow, so it is a definite possibility.
 

leeb

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You are working with VERY OLD devices that, on average, are NOT designed/configured to be used with anything else.
MANY old 5.25s had a 'head load'... meaning that the head(s) do NOT contact the floppy all the time... only after the head spins....
The 'head load' signal is likely not coming from the newer PC... cuz it doesn't 'know' about it....
There MIGHT be a jumper/switch to tie head load to MOTOR ON there on the drive...

The head spins a bit upon insertion to ensure centering on the cone... it NORMALLY stops after that.

Having said that,

What kind of cable did you have it attached to? And what kind of cable WAS IT CONNECTED TO?
Are they both 'drive 0 twisted'?
Does the 'twist' include the SAME LEADS as each other?

Have you tried ALL positions on the cable youre attached to?

As for the floppies themselves...
I wouldn't attempt reading them on anything but a newer 1.2mb drive... keeping in mind that they MAY be 360k or less, and should NOT be written to...
... and if the disks are SINGLE DENSITY you will not be able to read them at all... PC don't know how...

It wouldn't surprise me if the 'cushioning material' on the inside of the sleeve isn't disintegrating...
Even so... it wont hurt to treat them to a generous rubbing-alcohol bath... both sides.

Looking forward to seeing what treasures you find on them! :D
 
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Conmega

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Colora, MD
I had a cable that had 5 connectors on it and had the twist in it but I ended up only finding one thats a straight cable 3 connectors one being the now standard floppy connector on the board then two of the over-the-board connectors for the 5 1/4 floppydrive... I will look for the cable with the twist...

Also Paralel i truely hope it isn't mold its strange though... not what you really explained... Its VERY thin and is somewhat clear but has the general color of white... some places (supposedly) being thinner then others causing it to go from clear to a foggy white... It appears as if it could rub off like its just on the disk lightly (NO I will not touch inside of the disk that may have sounded like I did or was going to :rolleyes:)

Also this IS a 1.2MB drive... Its a Mitsubishi M4853 Supposedly from 83-84 for the fact that inside the Burroughs (since its out of that machine) has like 20 date codes all written in sharpy and all the years being 84... Also I know I may need an older machine but I've seen people put these things and successfully use them in probably about pentium 4 machines... I WAS going to try and put it in my main computer (which has an asus motherboard and a core 2 quad processor) but I went to the bios and only had two settings for 3 1/2 drives... SO I went down to my basement and brought up the guts of an old pentium 3 Compaq... Hoping it would work...

The drive does have what appears to be one belt for the head movement but it seems to still move the head fine so I'm leaving it be...

You spoke about jumpers... There are at like 10 on the board... :confused4:
And a rubbing-alcohol bath? Erm... Mind to demonstrate or to develop on that more? Last I heard bringing the diskettes to any liquid isn't quite a good idea...

If all else fails... I'm now looking at another old machine that has the capability to have both a 5 1/4 drive which we know would work and a 3 1/2 to transfer the files onto...
Mentioning such a machine brings back a memory I had as a kid... My dad was going onsite to repair a machine for this small architecture company and I think my dad knew the guy a bit too so he brought me along... When we arrived to the small office my dad got to the computer (probably like a pentium 3-4 something around there) BUT when I turned the corner of a cubical I saw a old yellowed plastic beast sitting on a desk... It had like a 5 1/4 drive and a 3 1/2 drive... and I think it had an old monochrome monitor sitting next to it... My jaw dropped and I ran over to it and the guy my dad was doing the work for noticed that I found the machine and quickly came over to explain it and turned it on to show me him transferring files between the two types of diskettes... He said some of his old architecture designs or something were on 5 1/4 floppys so I guess he still used them! I cant remember what it was but It was an upright case... and made of yellowed plastic... That was probably one of the first times I saw a 5 1/4 floppy drive... Probably where my obsession with these old things came from!
Anyway... I guess I will have to look into a machine like that for transferring my files if I can't get this working...

Oh btw I'm now looking for a Burroughs Terminal... And I found one...
http://www.ebay.com/itm/Burroughs-T...099096?pt=US_Thin_Clients&hash=item564dc75f18
I'd pay the price of it... But... IT HAS SCREEN BURN and the only way I've found to fix that... BUY A NEW TUBE.... tube prices... TWO HUNDRED DOLLARS A PEICE!!!!
So yea...
ALSO when I was looking at the power routing from the power plug... which has like... 10 pins in the plug... I found out... like 5 pins go to ground... the other 5 pins go to a power rail... so... 10 pins... two connections... basically the company made it so you had to buy THEIR power supply I guess... I will either find a way around 'their' power supply or keep searching for the things... I will hopefully post another forum about the Burroughs later...
So yea... Lots to do...
Also update on the Packard if you cared to hear... The front end is all off and the engine is out for rebuild... So things are going along nicely with that... and of course since this is me and my parents working on it... I assigned myself the job of the electrical system... And its a 6 volt system which is interesting and new for me... I haven't worked on cars much but it seems straight forward... I have a wiring diagram... But ALLL the wire needs to be replaced... along with all of its old braided wire... which is sadly cracking and falling apart... I want to find a source for this braided wire though! I want to keep it original and thus I need this braided wire... Anyone know about the stuff? Not the place to ask but you guys have had all the answers so far. :rolleyes:

Edit: That was a LOT more then I thought it was... :eek:
Edit2: Also I said I only saw a belt for the motor for the head assembly, the motor for turning the diskette is right bellow the center piece and is directly attached like new floppy drives are.
Edit3: The description of the Burroughs monitor said the images of the screen are stock images so I contacted the seller asking if both his units are screen burned and also asked for images of the actual units.

Edit4: Leeb... you would not imagine the 5 1/4 floppys I found... i found 13 disks... that says... ACAD 12 EXECUTABLES... :D
like i told you before... my grandfather has been using auto cad for years... so lucky... so lucky they kept these floppys... they moved them from where i saw them years ago as a kid... i thoguht they tossed them... but i found them... :D
actually... i found so many ACAD floppys (27 to be exact)... support disks, renders, and a bunch of other stuff...
 
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leeb

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TOO KEWL!!! :p

All I can suggest RE the Packard is to do some googling for auto electrical restoration... that might provide some leads... (pardon the pun) :rolleyes:

ACAD 12!!! Pity I don't have any 5.25 drives! :( Would be neat to see what all's on those babies!
but... at least I DO have my 10 working now... found that the EXE had been corrupted.
Now I can continue working on my 'Habitrail'... (Dome buildings connected by 'tubes' :p )
:D
 

Conmega

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Colora, MD
Yea I'm hopping to get this 5 1/4 drive working so I can rip the floppys and eventually see if it runs!
But I must get the drive working first... Also I found wire for the Packard we are debating buying the original type wire or not... we may go half and half... so like whats visible is the original type... But yea..
 

Paralel

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SW Quadrant of Michigan
Well, I will end up keeping that second 3800 afterall. Had to take the hard drive interface ribbon out of it after the one went bad in my other 3800. Guess it's good to have a donor corpse for parts considering stuff that is 2 decades old does tend to go bad spontaneously.
 

leeb

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That's why I was telling Con to be VERY CAREFUL... particularly when removing the HDs...
Ive personally lost 2 connectors... once in my original machine....
Lucky me the Panasonic tech place I went to had a salvage machine (FULL-to-the-TEETH with roaches/roachguts) lying around... they sold me the connector for about 1/3 of a new one... to which I was quite pleased. (AFTER fumigation, of course!)

The last time was with the 1500.... when I was diagnosing the HD failure...
Have another one that I need to try recovering... was in the so-hosed-up 1800 that I haven't even TRIED it to see if it would work!

I have always intended to try a 'splicing wire' on the broken one (the bad pin(s) is(are) somewhere around the middle - got pulled too hard...) 2C if it could be 'patched' into working order... but MANY (hundred) things have gotten in the way. :rolleyes:

Sorry to hear about the cable assy... but glad to know the other one is good!
:D
 

Paralel

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SW Quadrant of Michigan
Leeb, can you PM me where you got the belts for the floppy drives? I have been looking around and I can't seem to find a source for that part number anywhere and it's driving me nuts.
 

leeb

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Unfortunately I cant... but
Since you 'forced the issue'... I just put one of them into the Panasonic... not as tight as the previous pieces but believe they will be good.

If it does NOT... I'll let you know.

Look back thru the thread... the guy who posted the info put it there.

:D
 

Conmega

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Colora, MD
Havn't replied in awhile but I've been working on this Burroughs and I think I have it powering on... Main chips start to get warm and the red LED on the front powers on... But otherwise I have no idea... Since I don't want to spend around 100+$ on a terminal for this thing yet... I decided to try and decode the video out port... Which is a DB25 connector... and from what i have researched thats a Burroughs thing... and not common at all...
Since I don't have an oscilloscope this becomes even more fun... I figured out GND and PWR pins leaving 12 signal pins or what I assume are...
I then took DC voltages of each of those pins to get an idea of voltage range and to figure out what I'm working with... Sadly I cant trace the connector back to a chip easily there's wayyy to much going on... But I do know the video boards main chip is a mc6845p which is apparently a common video chip that was used in IBM video cards for DB9 CGA video I think? But anyway most of the other chips I couldn't even find datasheets for so tracing it was a dead end... But here I'll post what pins I do have traced and average voltages coming from them in DC compared to the pin and GND.
Untitled.png
1-0.3
2-0.05
3-0.05
4-5
7-0.2
8-0.2
14-0.2
17-0.2
18-0.2
21-5
22-0.2
23-3.5

Hopefully someone can shed some light on this... I'd love to see this thing running on display instead of just staring at a red LED...
Oh I'll probably make a separate thread for the Burroughs under the Other section in a bit just to let you know.
Oh also by the way the plug on the board for the video is a female DB25 so that image is as if your looking right down onto it pinout wise... Atleast I think thats correct...
 

leeb

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This is the FUN part (NOT!) of the job... getting things to 'talk'!

I wish I could help... but you obviously have more clue than I!

:thumbsup:
 

Conmega

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Colora, MD
Now ok I do have an oscilloscope... Feeding the output into the mic jack of my computer and using software... its so strange though... its showing different voltages now... and some of the GND pins that seem to obviously be connected when doing a test with a multimeter... yet hooking them to different GND to read the data lines gives different results... its very strange... but i am seeing signals that are consistent and repeat every 17ms on it... and they only get to about a max of 0.2 volts... Gah need a video expert... I'm tring to take screen shots of alll the signals when the system is on... off (still draws power when off and it does something over the lines) and with the power completely off from the powersupply... strange thing... it still puts out signals with the power off... which... confuses me... I seriously need some help here...
 
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