S3200XL backlight replacement joy

Akai S3200XL original backlight for replacement

This is Lee’s old Akai S3200XL, the man who ran off to Canada to escape drum and bass. (Maybe not strictly true, but it’ll do.)

We used it in our daft hiphop band at the end of the 90s (along with the standard issue Atari ST), but it was always a bit of a mystery to me, never having much of a chance to play with it. I half-wonder now if we could got away with using my A1200 and Octamed, which I was using for my own dodgy big beat and drum and bass. Loading times would have been a drag off floppy discs, admittedly.

Unsurprisingly Lee didn’t take it with him, so it’s bounced around a bit before it ended up with me, still wrapped in the plastic it came in and looking generally pretty clean, but just with a dark screen. The photo above was taken in a super-bright room, which doesn’t help, but it was practically invisible in low-light as well.

Let’s have a look inside:

S3200XL overview of the inside

Nowhere near as stacked up inside as the packed-out S950. Nice how it’s separated by internal walls, presumably to shield each part (power supply and floppy/motherboard/digital to analogue audio out).

Here’s the power supply – says here it’s a Cosel PMC50E-1:

S3200XL power supply

…and it looks alright? It’s not been the most heavily used box, not like my S1000, so I’m hoping that there’s plenty of life left in those caps. I’m sure I could slot in a modern 50W PSU with +5V and +/-12V outputs in if I needed to.

Here’s a closer look at the analogue out section:

S3200XL audio out

Loads of PCM61 DACs, and a couple of unused spots on the board – one for another SM5840EP digital filter, and another for an 18CV8 (?): on searching around it seems like this would be a programmable electrically erasable logic chip, which has the pleasing acronym of PEEL.

Here’s the inverter for the screen! This might actually be the culprit as to why the screen is so dull.

S3200XL inverter

Alright, enough blurry photos of the innards, we’re here to replace the backlight. I’d seen this article on replacing the backlight on a S1100 with one from iPhone 6 Plus and wondered if I could do the same for this S3200XL.

This is what we’re faced with.

S3200 taps orffffff

Love that space next to the floppy, originally meant for a magneto-optical drive. Lee just used an external Zip drive, which actually still works, although he did always take care of his stuff. Maybe we could shove a bluescsi or SCSI2SD in there.

Once the power connections on the right have been desoldered, the backlight slides out from behind the display

S3200XL power connection

Here’s the backlight, which measures 13.6cm x 4.2cm.

S3200XL backlight

The power supply connects to this distribution board – I think this connector with the red and black wires was going to the floppy drive:

S3200XL power supply connectors

Somewhere in the blur there is the connector P410 – the lower two pins have ground and +5V on them, which is perfect for powering our replacement power supply for the backlight.

I didn’t have quite the right kind of connector but this one fits anyway:

S3200XL backlight power supply connector

And here’s the XL6009 DC-DC step-up board – 5V to about 17V. In retrospect this probably should have gone on the other side of the (grounded) wall, but anyway.

S3200XL XL6009 step-up voltage converter

When it came to wiring up the connector, I killed a fair few of the backlights.

Dead iPhone 6+ connector

The connector itself is really small, and it’s extremely easy to tear it off from the rest of backlight, and equally easy to tear the wires off and pull a part of the connector with it. The wires I was adding were heavy enough by themselves to twist the connector around. It’s worth testing the backlight as working, and putting some glue on the connector; also on this one I put some of the extra protective plastic from the backlight as a backing for the connector to make it a bit stronger. I didn’t take any photos of the resulting mess.

I decided to run the +17V through a resistor and a pot to set the brightness – and here it is in the same (very) bright room as earlier – way more readable, if not amazingly bright.

S3200XL new backlight installed

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bluescsi and an Akai S1000

I’ve got four or five old rack samplers which I’ve been poking at again recently, including this S1000 which I’ve had apart to replace the backlight.

akai s1000, having tea and biscuits in the front room

More on that calamity another time.

I thought I was alright with floppy discs, but I’ve been getting read errors. Possibly they’re just reaching the end of their lifetime, which makes me fret about all those Amiga disks I’ve not backed up yet.

Most of my samplers have built-in SCSI interfaces (apart from the S950, aieeee…) so I bought a SCSI2SD v5.0a off a vendor on ebay, and although it works fine with my S760 and my ESI2000, the thought of spending £109 for each of them for my various samplers wasn’t filling me with joy. (£109! I feel like I was done now – to be fair, the usual UK vendor of SCSI2SD boards seems to have been out-of-stock for a while)

Enter the bluescsi, which is intended to offer an open-source solid-state storage solution for vintage computers, mostly old Macs at this point in time. It’s based on the cheap “blue pill” STM32 board, hence the blue bit in the name.

There was some suggestion on their Discord server that it would work with Akai samplers, so I bought one from https://bluescsi.flamelily.co.uk for £32.

This is it plugged into an Amigakit DB25 to 50 pin IDC adaptor, and then into a DB25 to Centronics 50 pin cable so I can plug into the back of my poor, abused S1000.

Anyway, so I plugged it all in, turned the Akai on, and watch it boot up OK, although it didn’t seem to pick up the hard drive. I poked the hard drive settings for a bit. And then smelt a suspicious smell. And then watched in horror as smoke started to pour out of the back of the SCSI expansion board at the back of the S1000. I hurriedly yanked out the power cable.

The Amigakit adaptor just uses a right-angle header as the IDC connector, and it’s possible to offset the connector in the bluescsi socket by one pin, hence the smoke, which was caused by a burning track on the S1000 SCSI expansion. The track leads to a diode which presumably was blocking the voltage, so hopefully it didn’t cause any catastrophic damage.

If you buy one of the Amigakit adaptors, make sure you seat the connector correctly. I’m sure you’ll be more careful than me anyway.

The bluescsi is intended to work with hard disk images as files on a microSD card, with the card itself formatted as exFAT. I tried creating a blank disk image, but couldn’t get this to be detected by the Akai.

In the end I downloaded an Akai format ISO file from vintagemusicsamples, renamed the ISO to HD00_512.hda, where the first zero after the “HD” bit is the intended SCSI ID, and copied that onto the SD card.

Once I’d twiddled the settings in the Akai to use 0 as the hard disk ID (and moved the Atari disk ID out of the way to 7), it picked up the SD card as a disk, and I was able to load samples from the ISO. I wasn’t really that interested in the sample disc, although it’s nice to know it works, so then I used Arrange in the disk settings to initialise the directories. This had practical effect of binning all the existing samples, or at least marking the space as overwritable, so I was left with hard disks from A to I, with two partitions on the first drive.

The S1000 wouldn’t let me format the disk, which is a bit weird. Possibly there’s some bit set in the file for Akai format CDs which stops it from being able to format. I tested saving some files from an Akai S950 floppy, and that worked, and they loaded from the SD card after a reboot.

For a while I was mystified as to why I couldn’t rename the volumes, but it turned out that you actually need to have a file stored on the volume to rename it – this is common to actual S1000 hard drives as well.

The bluescsi supports multiple drives as files – I’ve had the other sample discs I downloaded as files HD10_512.hda, HD20_512.hda, and HD30_512.hda, accessible via the SCSI IDs 1, 2, and 3 respectively.

The bluescsi itself seems fairly quick, massively so compared to floppies, and infinitely quieter than the noisy hard drive I’ve got in there currently, which is also on its last legs. I wouldn’t be surprised if the limiting factor in terms of speed would be the S1000 given it originally came out in 1988.

The bluescsi has an advantage over the SCSI2SD v5.0a in that it supports more disks, but the v6 supports up to seven, and also allows files to copied to it over USB. But then the SCSI2SD v6 is usually three times the price.

Here’s me booting the S1000 (off floppy! I’ve still not plugged in the v4.4 ROMS yet), and loading a bunch of homemade drum loops I’d previously recorded on my S950 and saved to the bluescsi drive.

From the timings on the video, and given that this S1000 is fitted with 26MB of memory, and the loops take up 20% of the memory, it seems like it took about 17 seconds to load about 5.2MB of samples.

The (newly backlighted!) screen looks a bit rubbish in the video at this angle, but it’s much better from slightly above, and more legible in real life. I think it’s had a hard life – possibly I should’ve just stumped up for the LED screen.

It’s worth keeping an eye on the RaSCSI project as well, which is based on the Raspberry Pi – I just couldn’t find a UK source for the board at the time I looked, although it might be easy enough to buy some boards off DirtyPCBs or something. Check the Open Retro SCSI Discord for further discussion.

My “format an ISO” tactic to get the bluescsi up and running doesn’t seem particularly ideal, but it seems to work – let me know if you find a better way. Now I’ve got to put my S1000 back together, and to work out if I want to install the bluescsi in place of the floppy, or do something else.

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s950 screen replacement

Saturday afternoon, got a couple of hours, let’s change the screen in my S950.

Here’s the problem – backlight really dim in the late afternoon light. Even with the curtains drawn it’s hard to get a photo with the reflections. If anything this makes it look more readable than it was.

Dim looking screen on Akai S950

Let’s take it to bits.

Front panel removed from S950 to reveal buttons and original screen

I’m using the (slightly confusing) instructions from the Gearslutz Pimp my S950 thread. I bought a 40×2 display from buydisplay via Ebay – this is the one:

Stock photo of replacement display

The original screen has a 14-pin data/power connection on the left-hand side, and the backlight power connection on the right-hand side here:

Close-up of power connection on original screen

I was just interested to see what kind of voltage was appearing here, but it was hard to measure – didn’t seem to be getting anything much, maybe half-a-volt? Partly I suspected that screen is probably fine, but the inverter is stuffed – here it is, lurking in-place behind the front panel:

Power inverter for original screen - probably knackered

The connection on the left is the 5V and 0V connection from the panel – this is what we’ll use to provide the power for the backlight on the new display. The data and power connection for the display uses the bottom 14 pins on the connection, with the 15th and 16th pin taking 5V and ground respectively for the backlight.

As Don suggested in the thread, I connected a 1K pot (albeit linear, it’s all I had going spare) in series with the 5V connection to control the backlight – I nudged it down a bit from the maximum, and it’s probably a bit too bright still but it’s readable.

It took a bit of finagling to get the screen in place – it has to go behind the screw holes because the screen is thicker than the old one. The screws had to go in from the back, which was a bit of a faff.

New screen in place

Here it is with the front panel on:

S950 with front panel back on, screen glowing brightly

Looking loads better. Shame about the scratch through the screen, though not much I can do about that. It was only 75 quid when I bought it (including a massive box of discs) so I can’t complain really.

While I had it open I took some photos of the insides. Easy to see the eight voices on the top board.

View of inside S950 from the top

Getting a bit closer – loads of regulators attached to that chunky heatsink:

Top of power supply

Towards the back on the left we’ve got the power inlet, transformer and the MIDI board – PC900V opto represent.

Transformer and MIDI connection

And there’s this bit, caused me some trouble last time.

Jack board output and PCB

It’s all back together now and happily propping up a bunch of other relics.

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