Ben's Hobbies http://www.benophetinternet.nl/hobby/hobby/index.php Copyright 2012, Ben Versteeg Ben Versteeg en-US SPHPBLOG 0.4.8
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Repairing a Disciple disk interface: using GAL's instead of PAL's http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120517-102616
It caused a ZX Spectrum not to boot, with garbage on screen etc.

I immediately suspected a PAL chip to be the problem.

I know from the past these died quickly in a Disciple interface, and being very expensive: MGT enabled security on the PAL chips so it was not possible to read the contents and clone them back then.
Fortunately someone once received a repaired Disciple interface with PAL chips that did not have that security, and he was able to read the contents and publish it on the net.

There is no legal limit anymore because MGT does not exist anymore, so I can happily download the PAL files.

I do not have PAL chips in stock; they're obsolete and should be replaced with GAL chips.
But the files I downloaded were not compatible with the GAL chips.
I needed to translate them.

For this, Lattice, the creators and manufacturer of PAL and GAL chips, publiced a GAL to PAL translator.
This command line utility will convert a PAL jedec file to a GAL jedec file.

I downloaded the utility, converted the PAL20L8 files, and tried to program a GAL20V8 chip with the new files.
Then I replaced the PAL chips on the Disciple, and it works!!!

So the Disciple boots again, and everything seemed fine, except for the 7805 voltage regulator on the Disciple, which is overheating.

I replaced the 7805, but it still get's to hot, possibly causing instability.
I am currently adding new cooling paste, and replacing the cpacitor at the 7805.
Hope that will solve all problems.

-Update-

I suspected the inhibit and nmi buttons to have problems due to aging, so I measured the resistance: I found values of about 30 ohms.
I desoldered the switches, and measured again: no problems with high impedances.
So the conclusion is: the soldering contacts are bad.

I resoldered all important contacts on the Disciple board: all chips and more.
Now all problems seem to have gone.
So 20 - 25 years of aging of these Disciple interfaces seem to give result in bad soldering contacts! Just to let you know! ]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120517-102616 Ben Versteeg Thu, 17 May 2012 08:26:16 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=12&m=05&entry=entry120517-102616
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Check out my sales section! http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120416-164441 the Sales page.

From there you can easily check out my currently offered eBay items, and lot's of other rare stuff I am not (or not yet) offering in eBay, but which is available by direct order only.

So check it out (click)!]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120416-164441 Ben Versteeg Mon, 16 Apr 2012 14:44:41 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=12&m=04&entry=entry120416-164441
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ZX Spectrum 128K composite video fixes in 1 document http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120126-204743
Click here for the topic on WoS.]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120126-204743 Ben Versteeg Thu, 26 Jan 2012 19:47:43 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=12&m=01&entry=entry120126-204743
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Selling nice stuff on eBay http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120122-072414 http://www.ebay.co.uk/sch/quantit/m.html

I am offering lot's of rare sets the coming weeks.
On right now: a very complete boxed ZX81 set!

These are some of the items you can expect the coming weeks:
- Boxed 128K heatsink ZX Spectrums (yes, more than one)
- Opus Discovery disk systems (again, more than one)
- Disciple disk interfaces (unbelievable, even more than one of these)
- Lot's of 48K ZX Spectrums
- Interface 1 + Microdrive sets
- Original ROM game-cartridges
- ZX81 sets
- And much more....

So, put my eBay channel in your browsers favorites to not miss one of these incredible offers!]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry120122-072414 Ben Versteeg Sun, 22 Jan 2012 06:24:14 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=12&m=01&entry=entry120122-072414
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Hires Opus Discovery board pictures http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry111201-123839
Here's a video in which I'm dissassembling a floppydrive from an Opus because I forgot to set the driveselect correctly:
http://www.youtube.com/watch?v=JjvzLBlzDgY

Here they are pics (click for hires):









Some problems I had to repair with these Opus Discovery interfaces were:
- defective rectifier
- defective ROM
- one didn't have a 6116 ram chip, don't know if it is needed, but I ordered one anyway
- one had a defective WD1770 floppy controller; replaced it with a WD1772 from an Atari ST: another model but pincompatible, and that worked great!
- one floppydrive failed, but luckally that Opus had two! Only needed to make a bracket to cover the space
- the soldered wires on the 'flying' LM317's come off easily with some movement: very frustrating when you are repairing an interface...

I encountered these interesting things:
- two had a rom v2.2 (one even had a paper with rom changes, but I didn't scan it, sorry!); the lowest rom version I found was 2.1, probably the default factory-rom
- I had one large filled floppybox with about 40 floppies filled with data; very rare to have owned as all others had only one or two or no floppies at all
- there are some different ways of how the voltage regulators are mounted
- there are some different board versions, haven't checked for numbers

This seems a lot of trouble, but believe me: ZX Spectrums fail a lot more and at a lot of more parts.

All together the Opus Discovery is a very solid system, which still works after so many years!]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry111201-123839 Ben Versteeg Thu, 01 Dec 2011 11:38:39 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=11&m=12&entry=entry111201-123839
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Playing the ZX Spectrum laserharp at a retrocomputer fair http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry111105-104317
I brought my laserharp, here's a video (click on pic):


]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry111105-104317 Ben Versteeg Sat, 05 Nov 2011 09:43:17 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=11&m=11&entry=entry111105-104317
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Stereo sound enhancement for any 128K ZX Spectrum model available http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110922-201637 new topic on World of Spectrum (click here) with info about ordering the new stereo sound enhancement.

It's a complete kit including stereo audio output socket and switch to choose between ABC and ACB sound.
All is explained in this manual (click here).

]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110922-201637 Ben Versteeg Thu, 22 Sep 2011 18:16:37 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=11&m=09&entry=entry110922-201637
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Yamaha DB60XG wavetable card on my ZX Spectrum http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110821-130307 Spectrum.
So that is also the function: to create sound for my
laserharp (look at my Youtube videos).

It took some hours to get this working as the DB60XG somehow needs a reset after it's powered on.
Then the second thing it needs is a GM initialisation.

I'm trying out different sounds in this video. The setup was for prototyping only. I will build the electronics into a case together with the DB60XG.

Here's a video of the setup working:
http://www.youtube.com/watch?v=9zGFNfNAVXw

Some pics:







]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110821-130307 Ben Versteeg Sun, 21 Aug 2011 11:03:07 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=11&m=08&entry=entry110821-130307
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More Dutch retro computer fairs in 2011 http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110508-171711
2 October 2011, Apeldoorn, The Netherlands:


18 September 2011, Steenwijk, The Netherlands:


Visit the Bonami site for more info!

Or click here for the English translation.
]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110508-171711 Ben Versteeg Sun, 08 May 2011 15:17:11 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=11&m=05&entry=entry110508-171711
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News http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110205-110310

Next batch of DivIDE


I'm still waiting for some parts for the next batch of 50 DivIDE interfaces, and sold the remaining 5 from the last batch this week.
Wow, there is still so much interest in the DivIDE!

Shipment costs


Our national post-company Tnt has raised rates for international packages with about 85%! It's absurd.
To still be able to send for fair prices I looked for a solution.
I now am able to ship in a new box that fits through your mailbox, so I can use letter-rates for the shipment, but I always used signed and insured shipment.
This way the package is only about 3 euro more expensive than before, instead of about 10 euro.

I repaired a floppydrive! Lol!


My Sam Coupe needed a repair or other floppydrive.
Read the story on WorldofSpectrum (click)!
]]> http://www.benophetinternet.nl/hobby/hobby/index.php?entry=entry110205-110310 Ben Versteeg Sat, 05 Feb 2011 10:03:10 GMT http://www.benophetinternet.nl/hobby/hobby/comments.php?y=11&m=02&entry=entry110205-110310