Refurbishing SVI-767 datacorder

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protek

protek

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I recently bought an SVI-767 datacorder for using it with my MSX, CPC and Spectrums. It was untested and it turned out it wasn't working. The reels didn't spin even though I could hear the motor running.
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The battery lid was also missing and the PSU had been directly soldered into battery contacts even though there was a PSU connector.
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So off with the top and let's have a look inside. The battery/record led wire had come loose and the wire going to the head had peeled somewhat but it seemed to be ok. The belt going from the motor capstan to the reel was still there but it was slipping so I have to get a replacement. Might as well renew both belts.
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I wired a new connector to the PSU but I may have to look for a replacement as my multimeter says that it gives out 9 V even though it's nominated 6 V. Any reason to that?
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I resoldered the led wire but it seems I may have to replace that too as it didn't lit, when I powered it. I also covered the peeled wire with electric tape. It would probably be wiser to use shrink tubing but I'd have to desolder the wire from the head.
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I called a local electronics repair shop for belts and they told they should have some. Hopefully I can find a suitable replacement. I also have to dig out my old wall wart, which has adjustable voltage. Not sure, if the PSU that came with the SVI could be fixed so that it would output a correct voltage.
 
The 9 volts may be because you are measuring it with no load. Try running a motor or something with it and measure it then, probably the voltage will come down.
 
I actually measured it, when it was still directly soldered to the recorder and it was giving 9 volts already then. On the other hand the other PSU that I have gives out exactly what it's supposed to.
 
Was the recorder running at the time? If it gives 9V under a load, it's probably mislabeled or failed somehow.
 
No, not running, just connected. This is not the original PSU for the recorder. I suppose it's safe to test the voltages under load since it has been directly soldered into it. Still I think the PSU may have failed.
 
out 9 V even though it's nominated 6 V
Click to expand...
sounds just like an unregulated power suply, see answers above

prob not a good idea run it in from the batry terminals, shouldt do any great harm but batries are pure DC so that wont have the filterin on that bit unlike or likely the psu conector has a bit of filtering on
 
cosmicfrog said:
out 9 V even though it's nominated 6 V
Click to expand...

prob not a good idea run it in from the batry terminals, shouldt do any great harm but batries are pure DC so that wont have the filterin on that bit unlike or likely the psu conector has a bit of filtering on
Click to expand...

Yeah, wonder why it has been soldered directly in the first place. Would've been just as easy if not easier to solder a new plug. Well, that's sorted now.
 
I measured the voltages from the PSU under load and it was 6.8 Volts.

I'm going to go and get the new belt tomorrow on lunch break.

The case top would make an excellent project for Retr0brighting.
 
New belt fitted and did some testing. Couldn't yet load anything and experienced very intermittent operation with the motor where it was working at one moment and the next it wasn't. I even ended up dismantling it again as the motor contacts read only 0.9 V and wouldn't spin. I also noticed that one of the caps had spilled its guts and the led ground wire was broken.

Then, when I put it back together the motor started working again and showed correct voltages. I plugged it in and again it wouldn't spin but when I fiddled the cable I again noticed that it would spin intermittently. Turned out that the remote cable was broken and is going to need a new plug. If the remote isn't connected it will spin.

I tried loading some games but it doesn't seem to load them even though I can hear it loading data in the monitor mode. Haven't cleaned the head or adjusted the azimuth yet.
 
Too low output? If "lock tight"(red stuff on the screws) wasn't broken, azimuth probably is not an issue.Is there any trimmers on PCB?

added

Ah, you have output regulator. Maybe you should "refresh" it.
 
I own a SVI-328, but sadly no datacorder or floppy drive.

When I have the time I will try to build this cassette interface, then it should be possible to use an old mp3-player or mobile phone to read and write data. Or just any old tape recorder.

http://www.spectravideo.org/projects/CUC-UniversalCassetteInterfaceForSvi328.pdf

And if you just want to read data (i.e games) then the write part and the motor control part can be omitted for an even simpler circuit.
 
@Storhemulen:

The SVI-728 is MSX compliant, so it already uses ear, mic and remote plugs in the peripheral end. Therefore there's no need for an interface. :)
 
I soldered a new remote plug yesterday morning. Also got an insight how the remote line works. It practically switches on the motor, when you type "cload" and press play. A bit odd that if not enabled by the MSX, you won't be able to fast forward or rewind the tape. Of course, you can always unplug the remote line to do that. The C1530 is much more logical in that sense.

Still wasn't able to load games. The datassette does have a monitor switch, which outputs whatever's running from a small speaker. Not sure if it also outputs something from the ear at the same time or are they exclusive.
 
yep plug your headphones in the jack and make sure its making a sound, or plug something similar

yep remote is just an on/off pause for the motor
 
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