Enterprise Forever

:UK => Hardware => Maintenance => Topic started by: Witchy on 2016.June.16. 23:54:29

Title: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.16. 23:54:29
Hi folks,

I've dug out all my EP stuff again after FAR too many years and I'm sadly not surprised to see some things have failed given the age of the components. Thanks to this forum (hi Zozo :ds_icon_cheesygrin:  ) I've already fixed a video problem with my main ep64 and the ep128 came back to life by itself so I'm expecting that one to fail again soon, probably dried out capacitors.

Main issue I have at the minute is none of my expansion boards work any more and I'm trying to find the common problem between them all. I have at least 2 EXDOS modules, the original Spectrum Emulator and 3 bridge boards but none of them seem to work any more and I can't remember the mechanism that detects the expansion board.

Voltages are OK and the bridgeboard's 7805 is generating +5V for the expansion boxes. I haven't dared to open the EXDOS modules as they're still 'as new' but if they have died over time I'm going to have to. I'm using the same Spectrum+2 PSU I did last time all this kit was at an exhibition in 2005.

Thinking about it I also have a couple of old prototype HDD cards, I'll dig those out too.

Any clues?

Cheers!
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.17. 00:29:09
Hi! Welcome on the forum!

You are from http://www.binarydinosaurs.co.uk/ ? Then we mailed lot of many years ago :-)

Firstly I suggest clean all contacts (even if not look dirty).

And my tactics for plug in: firstly plug the Brige to the card, and see from bottom the pins going on the right way.
Then try to plug to the machine.

The original English Bridges (grey) are better than the Hungarian ones (black).

In the machine possible the motherboard little moved (especcialy when disassembled it for the repair) in the case then the connection will misaligned.
It is can be best viewed if the machine top removed.

And you are tried on various machines? I have some motherboards which have a problem with expansions :-(

If EXDOS connected then try this:
10 for i=0 to 7
20 print speek(32,i)
30 next

This print the first bytes of the EPROM, if only 255 printed the something very bad.

The cards are worked previously?

"I also have a couple of old prototype HDD cards, I'll dig those out too."
We talked some businiess about one of these and some other EP stuff, for a TVC configuration :oops:


Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.17. 01:53:19
Hi Zozo,

Nice to be back!

I remember the TVC, I recently found the pictures you sent all those years ago when I was clearing up the hard drive of my webserver and realised that machine would be long gone by now. September 2008 that was.... From the hardware summary it was closer to a Camputers Lynx than an EP? Still a nice looking machine though :)

The last exhibition I did was in Croydon UK 2005, the EPs I had on show were put in their box and not opened again until last month, nice to see the flashing ENTERPRISE screen again! You're onto something with the contacts, with the case of a UK bridge removed and the top of the EP shifted slightly I got the nice pause while it looked for a floppy then :help showed EXDOS :mrgreen:

So I put everything back together again and....nothing. Tomorrow I'll shift the motherboard slightly and try the Hungarian bridge again, according to my pictures that's how I ran it back then so fingers crossed. I'm wary of messing with this particular EP128 since it's one of the original factory upgraded 64s.

Cheers!
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.17. 09:50:28
I remember the TVC, I recently found the pictures you sent all those years ago when I was clearing up the hard drive of my webserver and realised that machine would be long gone by now. September 2008 that was....
It is still waiting for you!

Quote
From the hardware summary it was closer to a Camputers Lynx than an EP?
Yes, if you think about the 6845.
From software side very similar to the EP, because Bruce Tanner wrote both BASIC, and the OS and DOS also created from the Enterprise versions (downgraded :-) ).


Quote
nice to see the flashing ENTERPRISE screen again!
Yes! :ds_icon_cheesygrin:

Quote
You're onto something with the contacts, with the case of a UK bridge removed and the top of the EP shifted slightly I got the nice pause while it looked for a floppy then :help showed EXDOS :mrgreen:
Great! Then I think no any serious problem. Just need to find the right position. Contacts cleared?
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.17. 18:38:56
Quote
It is still waiting for you!

Really? Wow!

Quote
Great! Then I think no any serious problem. Just need to find the right position. Contacts cleared?

Not yet, that's the plan for tonight, I'm also hoping the board will shift by 1mm or so and that will be enough. I still haven't perfected a method of re-inserting the keyboard ribbon cables without fear of damage.

W
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.17. 18:45:53
I still haven't perfected a method of re-inserting the keyboard ribbon cables without fear of damage.
After the first 20-30 time you can do with closed eyes :ds_icon_cheesygrin:
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.17. 23:24:11
OK, I can't get consistency out of the 128 unless I have the top cover off which makes plugging the keyboard in awkward. I've also discovered whilst trying to load things off floppy that the bottom left row of keys doesn't work which means a fault on the right-hand keyboard connector which LOOKS fine. New membrane time?

Time to get out the unused 128 and see if it works as it should; be interesting to see if the bridge will work without its case off!
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.18. 01:03:14
Quote
Time to get out the unused 128 and see if it works as it should; be interesting to see if the bridge will work without its case off!

answer: yes. And I can read most of my floppies. But the screen has started waving which I assume is the C9 capacitor drying out? It'll feel weird fixing a machine that never got used :roll:
Title: Re: EP64/128 expansion port no longer working
Post by: Bagpuss22 on 2016.June.18. 02:35:00
Hello matey,

Nice to see you on here!  Time to get them EPs working!

If they are original membranes then time for a shiny new one! :)

R
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.18. 11:36:02
Morning Mr P,

I'm on it, always loathed to break open the serial number sticker on a brand old machine but needs must today I think. I'm also wondering why my trusty stalwart 128 won't work with disks unless it's in bits but that's the one that needs the new membrane. I'd steal the membrane from the loose 64 but I've already snipped that one once.

Heh, if one of my non-modded Speccies breaks a membrane I just grab another one off the pile :ds_icon_cheesygrin:

Feels good to be back!
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.18. 17:02:16
I'd steal the membrane from the loose 64 but I've already snipped that one once.
You can buy new membranes here. (http://www.sellmyretro.com/offer/details/new-enterprise-64-~~-128-keyboard-membrane-2153)
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.18. 18:03:33
I know; that's open on another tab in Safari ;)

If swapping C9 doesn't cure the wavy screen on the unopened 'new' 128 I'll get one of Rich's membranes for the old exhibition-weary 128...
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.22. 21:26:21
Is any news?
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.23. 02:18:09
No, I found my box of Oric Atmos bits including the Cumana floppy interface and a bunch of disks so I've been finding out how many failures I can get with 5 Orics. I can load games OK now via a tap2wav converter running on an old win98 machine I've just built today so back to the EP tomorrow! I've discovered the TOSEC haul of all things Enterprise also in TAP format so if nothing else I can do the same trick with either the 64 or 128.

A
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.25. 20:28:34
OK, finally time to look at this board and straight away noticed that TR4 will wobble the screen when touched or tapped. Standard 3904 or so it seems. The soldering looked well dodgy:

[attach=1]

so I reflowed it. Still the same. Rummage in my bits box and find another 3904 but I get full-on wobble with that one in place. Odd. Put original back in and it's fine until it's tapped (or, I guess, heats up in use). Find a spare EP64 board that's previously been robbed of bits and use TR4 from that, still the same screen breakdown. Put original back in and all is good so over to the transistor tester.

Original as seen in the pic: hFE 213, Vf 718mV
Replacement from spare board: hFE 433, Vf 674mV

Both 3904s so why the big difference?

W
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.25. 20:31:56
hm, edit function isn't working. The second transistor I mention is a new one, not the one from the other board...
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.26. 11:01:17
Both 3904s so why the big difference?
It is not a surprise at transistors. Need to be sorted if want a enough same pairs.

First idea: check both +5V circuit are working. If one 7805 not working (or bad soldering or cracked pin) then D2/D3 make a cross supply, but voltage droped on diode. Then only about ~4V on the non working +5 side.
Once I found this situation, then the machine running, but the screen don't stable.

Another idea. try adjust L2.
Title: Re: EP64/128 expansion port no longer working
Post by: BruceTanner on 2016.June.26. 11:44:23
Possibly a very fine crack in a PCB track near the transistor, you might not even be able to see it.
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.26. 14:08:26
Quote
Another idea. try adjust L2.

Good call! That worked with the new transistor so I'm back in business. Just need to find the jumper settings required for a fairly modern 1.2MB floppy drive since I have a brand new one that I hope can 'dumb down' to EP levels, currently it's just saying 'drive not ready'. My others appear to be 40 track only and I'm assuming I need 80 tracks?
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.26. 14:49:59
Good call! That worked with the new transistor so I'm back in business.
Great!
Quote
Just need to find the jumper settings required for a fairly modern 1.2MB floppy drive since I have a brand new one that I hope can 'dumb down' to EP levels, currently it's just saying 'drive not ready'.
Yes because the 1.2MB drives spin at 360RPM, for the EP need a 300RPM mode.
TEAC FD55-GFR are easy can be used: photo 1. (http://ep128.hu/Ep_Hardware/Pic/Teac_FDD.jpg)  photo 2. (http://ep128.hu/Ep_Hardware/Pic/Teac_FDD2.jpg)

TEAC FD55-Fxx are originaly 720K (300RPM,80 tracks, DD) drives.

I also know some NEC 1.2M drives which can be jumpered as 720K. Others need to view the jumper manual.

But these are only important if you already have a 5.25" EP disks (you got with the EP stuffs?).

For 3.5" any 1.44MB drives can be used with EXDOS. At default the PC drives work as B: , if possible set the Drive Select to DS0, then will be as A: , this also can be done with cable modification.
Need to use DD disks, or cover the HD hole on 1.44 disks, and reformat to 720k on Enterprise.
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.26. 15:03:30
Quote
But these are only important if you already have a 5.25" EP disks (you got with the EP stuffs?).

Yep, a few original games, some converted Spectrum games, utilities, CP/M stuff etc all on 5.25. However I've also got the TOSEC software bundle downloaded so I might try the 3.5" floppy route too. I've got a pair of external 3.5" DD units from the QL as well as a Cumana dual set that may have come with a Memotech MTX but I can't remember. I've moved house so many times in the last 10 years I've lost track of where some things came from originally!

A
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.26. 15:33:42
Yep, a few original games, some converted Spectrum games, utilities, CP/M stuff etc all on 5.25.
Can you upload these? Compare with the know softwares.
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.26. 16:06:42
That's the plan once I've got this exhibition out of the way next weekend \o/

Forcing my 'new' floppy drive to 300rpm and 720k still produced 'drive not ready' so it's possible the drive itself is toast, shame as it's never been used! In a cupboard I found a switchable Cumana single drive and that's currently working nicely.

Just found a copy of IS-DOS V1.0 that includes the EP128 demo which is currently making a disturbing noise in my kitchen :mrgreen:

[attach=1]
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.26. 20:48:57
found some 'new' DD 3.5" disks and my Cumana dual stack reads and writes as can the floppy drive I've just added to my kitchen PC (10yo Dell). How do I write disk images? RAWRITE or dd or something? On the Oric side of thinks there's a WriteDsk utility but the Oric disk images are a .dsk file extension...

Cheers :D

A
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.June.26. 21:39:53
RAWRITE or dd or something?
Yes.
On EP side, you can found DISKCOPY on the IS-DOS disk, for copy the 5.25" disks to 3.5".
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.June.26. 22:57:02
I'll have to nail something together after next weekend. Tonight's task is to attempt to get a 3" floppy working on my win98 box. Either that or take my garage apart trying to find a slim folder containing a 128K Spectrum 6 pack of games. Surprisingly out of all the Speccy peripherals I've got a disk interface isn't one of them :/

W (getting buried in retro gear)
Title: Re: EP64/128 expansion port no longer working
Post by: Zozosoft on 2016.July.05. 14:40:26
That's the plan once I've got this exhibition out of the way next weekend \o/
How successful was the exhibition? Some photos? :-)
Title: Re: EP64/128 expansion port no longer working
Post by: Witchy on 2016.July.06. 00:40:01
No pictures yet, I've been checking whether I need clearance to post them because of kids being involved but it was an open event so I'm sure it'll be fine.

Crazy busy day, LOTS of questions about the EP128 because none of the assembled geeks had seen one before. Typically my floppy drive started failing on me but it didn't seem to matter because people were surprised at the disk interface and DOS-like commands. I also had it sat next to the SAM Coupe and one of my modded Speccies so lots of questions about those too. Good stuff!

Thumbs up from the organiser too so yay for that :mrgreen:
Title: Re: EP64/128 expansion port no longer working
Post by: sinclair200 on 2016.August.19. 23:55:25
Hi! Welcome on the forum!

You are from http://www.binarydinosaurs.co.uk/ ? Then we mailed lot of many years ago :-)

Firstly I suggest clean all contacts (even if not look dirty).

And my tactics for plug in: firstly plug the Brige to the card, and see from bottom the pins going on the right way.
Then try to plug to the machine.

The original English Bridges (grey) are better than the Hungarian ones (black).

In the machine possible the motherboard little moved (especcialy when disassembled it for the repair) in the case then the connection will misaligned.
It is can be best viewed if the machine top removed.

And you are tried on various machines? I have some motherboards which have a problem with expansions :-(

If EXDOS connected then try this:
10 for i=0 to 7
20 print speek(32,i)
30 next

This print the first bytes of the EPROM, if only 255 printed the something very bad.

The cards are worked previously?

"I also have a couple of old prototype HDD cards, I'll dig those out too."
We talked some businiess about one of these and some other EP stuff, for a TVC configuration :oops:

Zozo to me it's the same when you insert the clone ExDOS card, seeing the comment mate, I see that to me it's the same, it is as if unaligned the bus enter the edge card connector ... ...
Title: Re: EP64/128 expansion port no longer working
Post by: gflorez on 2016.August.20. 09:10:42
My friend from the Retrowiki Spanish forum  is using Google translator to communicate, and this time it has returned a complete mess. As I already know his Enterprise issue, I think he is trying to express this:

"Hello Zozo. I have the same error than the mate at this commentary, when I insert my clone ExDOS card. For me is like if the bus and the edge card connector where misaligned..."
Title: Re: EP64/128 expansion port no longer working
Post by: sinclair200 on 2016.August.20. 19:38:02
My friend from the Retrowiki Spanish forum  is using Google translator to communicate, and this time it has returned a complete mess. As I already know his Enterprise issue, I think he is trying to express this:

"Hello Zozo. I have the same error than the mate at this commentary, when I insert my clone ExDOS card. For me is like if the bus and the edge card connector where misaligned..."
Gracias gflorez......
Title: Re: EP64/128 expansion port no longer working
Post by: sinclair200 on 2016.September.12. 02:37:12
Today gflorez partner has installed me in my Enterprise a memory of 576K ......
I am indebted to the .....
(https://dl.dropboxusercontent.com/u/13583266/512K%20ram%20enterprise.jpg)
Title: Re: EP64/128 expansion port no longer working
Post by: gflorez on 2016.September.14. 12:36:58
Some other people(JLtursan) aided him with the two Exos card clones. The expansion connector works but one of the cards has been damaged, probably by bad alignment of the connector. The original Exdos card works perfect, as it is connected by a bridge.

A 32k Rom hack has been planed for it soon. May be one of 64k will be better, but it is not my card....