Alesis HD24 repair/upgrade

[Tubetec]

So I found a HD24 going cheap ,
Guy offered to drop the thing to my place .
Anyway he arrives , we plug in the HD24 .......... nothing ,no spark or flash or bang , dead ,but he insisted it had been working .

Anyway I struck a deal on the unit at an even more reduced price ,
Turns out theres an issue that arises in the Smpsu , theres an AC to DC convertor right around the input ,
takes in mains power ,puts out 5.7vdc .
This component has a habbit of blowing up , TOP227YN is the modern equivalent
Looks like its an easy job to replace .

The unit contains the usual dual IDE caddy HD , only one drive was included ,
I'm interested if anyone has any of the Sata drive caddies for the HD24 left lying around ,
Seems like a few of our members here used these machines in the past , so just let me know if you happen to have any spares left over .

 

[Tubetec]

So I got to dig down into the main HD24 forum , theres some solid advice there ,
The hard drive caddies ,as there supplied dont mate well ,
There were quite a few issues reported from people who used the HD24 live and experienced problems with reliability because of vibrations ,
I took the advice from someone on the forum ,added a couple of 0.5mm thick washers between the header and the caddy ,now it mates up with much more satisfying engage and lock down of the carry handle, at best it was marginal before ,no wonder people had failures.

I got to check out the problematic psu a bit closer ,
good quality , all through hole ,high quality caps everywhere , plenty of space to cool and good screening between adjacent sections ,then old style linear regulators with fat bypass caps 2x 2200 per rail ,with a high current inductor forming a CLC at the ouput .
Alesis dont provide any service info on the psu , simply reccommend replacement from some supplier who no longer exists , so repair is the only option .

I found the the main AC/DC ic , TOP227 is still available , that needs replacement , it blew its top The opto isolator is also a readily available 6 pin DIL , I'm measuring and I dont see any sign of a diode on the in or out circuit , same ohms even when I reverse the +/- on the meter, Im going to assume its broken and replace it , theres a few other transitors nearby , they all measure good cold ,no sign of burned or scorched components anywhere .

I also found the transformer core in the Smps had broken loose from the bobbin, a few strategically placed globules of cyano gel locked it back down where it belongs ,

Ive had a check around on availabillity of the Alesis SATA caddys , pretty much extinct ,
I think for now I'll just make the best of the IDE ,
A later laptop style IDE drive should be able to do the job quieter and without needing the 12v rail so easing the load on the psu and reducing heat inside the case .

A closer inspection of the inside of HD24 reveals adapter cards at the back of the drive caddy enclosures , looks like it goes to 50 pin SCSI and back to the HD24 main board
So even if your using the correct Alesis SATA caddies , your going from an SATA drive to an SATA to IDE adapter ,then an IDE to SCSI adapter to the motherboard , its bound to become problematic .

 

[Whoops]

Still easy to find the Caddy online:

https://www.recordcase.de/en/alesis-adat-hd-24-caddy
https://www.ebay.com/itm/222486348457
https://reverb.com/item/73061462-alesis-hd24-caddy-w-82g-drive

 

[Tubetec]

Thanks for that Whoops ,
All those caddies are IDE , I have two of them that came with the machine ,
Its really the SATA enclosures I want to try .

Did you have any experience using SATA drives with the HD24 in the time you used them ?

 

[Tubetec]

I replaced the damaged part (TOP227CN) in the HD24 smps ,
its working now again ,

I was able to update the firmware from 1.20 to 1.21 using MidiOX to send the sys-ex file ,
took a little fiddling with the buffer settings and a few failed attempts , but all good in the end .

I tried the BRC , it seems to work ok but pressing rewind to zero caused a minor issue because obviously the tape based adat can go back before 0,00 but the HD24 doesnt ,
The HD24 wont go into record at the 0.00 position , just allowing a few seconds before the song start locate point and thats no longer an issue .

I took a bit of a risk buying the unit faulty , cost me 200 euros , the BRC cost 70 ,
the new IC cost 5 euros ,its still a good deal for a decent 24 track standalone recorder by anyones measure ,so Im happy as a pig in his proverbial muck

Many thanks also to user 'Spiritworks' .

 

[Whoops]

Ive used that unit many times,
It was the recording setup when we needed to record on location for outside the studio. We recorded many Orchestras with it.
My personal experience was good, it was solid, never had a bug or any problem at all with it while recording. I think we had 2 units for 48 inputs.

I remember there was an unofficial computer software for it much better than the oficial Alesis one, I don’t remember specifics, but I remember it was much easier to transfer the files with that software than using the Alesis software, this was in 2009…

 

[Tubetec]

HD24 tools ,
I had a chance to try it earlier with the drive removed from the caddy ,connected with an off the shelf USB to IDE/Sata adapter ,it works.....

The internal fan in the HD24 is noisey and probably has way more airflow than required for the job .

 

[Gavin Pursinger]

I still have/use my HD24. it was setup by my friend to run with SATA drives. Only difference between that and IDE was that we could use Terra byte SATA drives for live recordings of festival stages. As a studio multitrack recorder I have NOT noticed any difference from IDE. BRC is cool to have for time code, but LRC is the preferred remote for session work...punch ins and quick shuttles. I love this unit as it replaced my 2" Scully 16 tk when tape was not available or
prohibitly expensive (since most of the great artists were starving musicians.) Mixed to 1/2" 2 tk still had MOJO.
These are great machines even NOW...ENJOY

 

[Tubetec]

Hi Gavin ,
thanks for that , functionally probably no difference with the SATA ,
but in a studio situation probably a little quieter than the clunky IDE drives .
I had read the BRC isnt as fast for dropping in but I got the LRC along with it anyway .

Last time I checked a spool of two inch tape would set you back nearly 300 euros ,
and typically you might use 4 or 5 spools to do an album at 15 ips , I do miss the sound of tape but not the pricetag .

I have a Studer C37 1/4 inch mono machine in full working order ,so I could in theory use it to process one overdub track at a time ,then compensate for the delay after .

 

[Gavin Pursinger]

Isn't the c37 a deck Beatles used early on ? I ran my 288-16 at 30 when possible...loved the effervescent sound and enjoyed pushing or not the tape. HD 24 is neutral there but front end choices naked that more fun. In my otherwise analog world. I could not hope to fix an ailing alesis..good on you for doing that

 

[Tubetec]

Actually it was the J37 variant the Beatles used ,
thats a four track one inch machine based on the same transport as the C37 .

The fix for the HD24 was quite simple , aside from the dc-dc convertor chip being blown the transformer core was loose on the bobbin, a couple of dots of superglue gel fixed that issue , its probably worth keeping in mind just in case your machine developes a similar problem .

 

[Tubetec]

Ive got the BRC and the HD24 hooked up , theres a power up sequence that needs to be observed
BRC master first then HD24 , It seems to be important to factory reset the BRC the first time you connect to the HD to allow the settings initialise properly , once you get those things right it all functions as it should
If the HD24 is triggered from the front panel or connected LRC it doesnt transmit the commands back to the BRC and timecode stops
Theres an obvious delay (200ms)when you press play on the BRC compared to the HD24 , having said that the drop into record from the BRC is very fast ,and thats what matters in a recording situation .

I'm invisaging the HD24 as the tracking machine , then seamlessly you swap over to the pc for the overdubs ,where virtual tracks ,comping and editing is easy ,
external AD/DA over optical and proper clocking will need further looking into ,

I was also able to use HD24 tools to transfer a SMPTE time code track to ch24 of the machine ,then in turn sync the BRC to incoming time code from the HD24 ,

Cooling fan and hard drive chatter means this thing needs to be housed in a machine room as is,
I soak tested it with the fan dissconnected and found no major heat build ups on the pcb , the hard drive however ,while writing 24 channels dissptates signifigant heat . Without harddrives mounted the internal fan shuts down and everything on the PCB still runs nice and cool .

Preferably I want the BRC and HD24 on a small mobile rack at arms reach from the monitoring position , A silent fan makes a big difference but noise from the internal hard drive then becomes the dominant source .
The original SATA caddys are hard to find , the Magic Sound caddy also doesnt come up for sale that often ,

A deep dive into the HD24 forum reveals third party SATA to IDE adapters havent given good results with the HD24 ,for most people anyway , one contributor on the forum suggested implementation and apparently random component variations means these things dont work as they should ,also that imprecise clocking causes lock ups and freezes .

I might give one of the boards below a try , the typical ebay offering tends to only have a crystal clock source , but this seems to have used a more modern TCXO and maybe better quality control . A reliable way to convert the standard IDE caddy to SATA would give a new lease of life to these machines .
https://www.reichelt.nl/nl/nl/sata-22-pins-ide-44-pins-converter-delock-62686-p163995.html