Laser 2001 & Salora Manager - official thread

Discuss computers from the Laser series, Time & Fun handhelds, etc.
Gabriele72
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Re: Laser 2001 & Salora Manager - official thread

Post by Gabriele72 » Thu Jun 03, 2021 12:14 pm

Inside:
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Scouter3d
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Re: Laser 2001 & Salora Manager - official thread

Post by Scouter3d » Fri Jun 04, 2021 7:41 am

Hi Gabriele72, wow this is a really nice boxed machine!

Sadly there is no schematic available, but most of Creativision schematic also fits the Laser 2001 (only the PSU, keyboard, Joystick and Tapeport are a bit different) and yes, the Laser 2001 is a nightmare to repair ;0)

what i have are highres images of the PCBs and annotated pictures of all the interfaces and connectors, that might help...
We also created a bios dump... please provide me with your email and i can send them too you.

But first things first:
1) what is the fault?
2) What equipment and "solder knowledge" do you have? (Multimeter or Oszi?)
3) Does the Laser come with its original PSU?

As first steps i would recommend measuring the voltages that go from the PSU-board to the mainboard... see attached picture, the Laser needs +5,+12 and -5V present (for the RAMs)

Do not worry! We WILL get it to work again! :0)
connector_to_psu_pcb.jpg
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Gabriele72
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Re: Laser 2001 & Salora Manager - official thread

Post by Gabriele72 » Fri Jun 04, 2021 8:10 am

Hi Scouter3d, thank you for your reply.

I'll provide more detailed information and pics in the next days, however the fault is that I get a dark green screen with the usual annoying sound at startup. This leads me to think that the cpu doesn't even attempt to program the VDP or reset the PSG. Inserting a cart doesn't change anything.
I have the original power supply, internal voltages seem ok, only the -5V looks a bit high in absolute value ( -5.35 V ). I can see the +5V and +12V regulators but I didn't understand (yet) how to fine tune the -5V generation.
The reset signal seems to correctly reach the CPU when I press the button.
From a first analysis, there's a LS245 as data buffer and several LS244 on address buffer, a cascade of logics is probably responsible for generating chip selects (though I couldn't figure out how yet).
There's 4 masked ROMs for sure, plus a fifth soldered upside down that could be a ROM or a (possibly) a 2K static RAM (6116).

My setup includes a multimeter, a 4 channel 100MHz scope, soldering iron, the usual chinese desoldering station, a cheap digital probe for quick checks, an ESR meter for capacitors and EPROM programmers of every possible kind (also a Fluke 9010 indeed but, alas! ... no pods :| )

My greatest fear is breaking a trace when attempting desoldering... without a schematic to fix it :(
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MADrigal
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Re: Laser 2001 & Salora Manager - official thread

Post by MADrigal » Fri Jun 04, 2021 8:44 am

That is a beautiful box variant - I had never seen that 'mit 5 spiele' sticker before - love it!
I look forward to getting large resolution photos of that sticker, and also good photos of your 16K expansion.
Gabriele72
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Re: Laser 2001 & Salora Manager - official thread

Post by Gabriele72 » Fri Jun 04, 2021 12:13 pm

Some more pics...
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Scouter3d
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Re: Laser 2001 & Salora Manager - official thread

Post by Scouter3d » Fri Jun 04, 2021 8:30 pm

Hi, PM sent...

My Laser had 4 ROM ICs, may Salora had 2, the content is nearly identical, apart from a few characters and a few minor changes.

The Upside-down Chip on your board is strange, but it may be a 6116 RAM (to free an extra 4K, that would be used to supply the 1k a Creativision has from $0000 if this is so ) But that would not make much sense!

My guess is: it is a masked ROM and was patched on later to replace ROM2... there is a cut trace on the board from the 74LS139 to ROM2 one half of the trace is connected to +5V, the other is connected to the 5. Chip that would be /OE i guess, so it would replace Chip 2

Maybe your Laser is an early model...

Sofar i had faulty PSU, CPU, faulty VDC and faulty RAMs in the Creativision the Laser had a broken internal PSU, the Salora had a broken solderjoint
the faulty VDC produced a blackscreen like yours

I would start with the basic measurements using your oszi:

1) CPU RESET (not the RESET BUTTON, this is only on NMI, but the Poweron-RESET)
2) CPU Clock
3) then i would watch the data and adresslines on the CPU
4) look at the DATA IN/OUT on the 4116 RAMs

If the ROM is faulty, you could try inserting a CSL Cart (i guess, but have not tried it and i am not sure if it works with a LASER, the same way as with a Creativision) that replaces the internal BIOS with the external version

Ciao, TOM:0)
Gabriele72
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Re: Laser 2001 & Salora Manager - official thread

Post by Gabriele72 » Sun Jun 06, 2021 10:48 am

Tom, thanks for all the material you sent.
Currently I can't make sensible tests until I reconnect the two boards, but I'd like to make it in a clever way. Two options I can think of: install a 2x17 female header so that I can plug-unplug without desoldering, or install two 2x17 90° male headers and connect them with an uncrossed floppy cable (that would make both boards accessible for probing when running but I'm not sure if such a cable can handle the required power).

Meanwhile: I think your guess is right, I see a cut trace that goes under ROM2 and could be a chip select, the source has been rewired toward pin 20 of the unknown chip.
I desoldered the CPU and tested it in another computer (1MHz though) and it works fine, it is now socketed in the Laser 2001.
The clock is 1.77-1.78 MHz, phi1 and phi2 are correctly phase shifted though they are a bit out of sync with phi0 (there's a 40ns delay and rising edge is quite smoothed - capacitive effect?)
The reset button in my unit must be connected to the /RES pin, for it drives pin 40 low when pressed, while NMI is left unaffected.
Next I will probe the data and address lines but it's quite hard to understand what's going on without a logic analyzer...

Two questions: do you have a dump of the 4 ROMS? Also, do you have the pinout for those TMM2432 chips? 4K ROMs/EPROMs exist in slightly different variants (2532, 2732, 2332, 2432...) often regarding chip selects and their position (some have 1, some have 2, some are active low, some high...)

Unfortunately, I don't have a CSL cart. A couple of years ago I had developed a prototype "MenuCart", a menu driven version of the multicart. It also featured jumpers to turn it in a "BIOSCart" which allowed to replace the internal BIOS with your own, stored in the cart EPROM: my goal was to put in the EPROM a diagnostic program that could run even if the BIOS was dead. It works in the Creativision but nothing happens if I plug it into the Laser, not sure if it's a matter of architecture or a fault of the computer.
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Scouter3d
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Re: Laser 2001 & Salora Manager - official thread

Post by Scouter3d » Mon Jun 07, 2021 7:02 am

Hi, PM with the BIOS is on the way... :0) (sorry i have forgotten it last time...)

during my Salora Manager repair i connected the 2 PCBs with small ribbon cables temporarily

Regarding RESET: then the Laser must be connected differently to the Creativision (It was only my guess it is connected the same way)

Regarding DATA and ADDRESSlines: I would not so much look for the correct Bitcombinations, but in the first step for activity and correct signal-levels, that way a faulty bus-buffer or a line, that is pulled high or low can be found...

If you have a spare 6502 CPU you can easily build a NOP generator (by conneting a few CPU DATA pins to high and the other DATA pins to GND) the CPU then scans thru all its Adresslines- that way you get nice alternating signals on all the Adresslines, that you can follow from the CPU thru all the buffers and Select-circuitry to the RAMS and ROMS and all the other chips (to check for damaged signals, faulty buffers or multiplexers)

Your MenuCart sounds very nice!

Ciao, TOM:0)
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Scouter3d
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Re: Laser 2001 & Salora Manager - official thread

Post by Scouter3d » Mon Jun 07, 2021 8:32 am

Hi,

i looked it up, the Laser has a slightly different pinout for the cartridgeport, so a CSL Cart and your BIOS Replacement Cart may not work as on the CV...

Ciao, TOM:0)
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Scouter3d
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Re: Laser 2001 & Salora Manager - official thread

Post by Scouter3d » Mon Jun 07, 2021 8:45 am

creativision_cart_pinout_v3.jpg
connector_cartridge.jpg
here for reference the Laser2001 Cartridgeslot and the standard CV Cartridge pinout
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