Voltage tests

MIDIbox SID
1

Hello!

This is my first post, rilly excited!

I’m approaching finishedness of my sweet Sammich and I’m having some questions popping up.

First, not such a big deal, is the LCD display.

There are some details about how to put the jumpers depending om what kind of lighting the display has ( edge lit vs LED array).

However, I can’t for the life of me make out any indication as to what kind mine is!

The only hint as to what it might be is on the front, where there’s a small “5V” in between the display and the encoder.

Oh well, I set the jumper config to the 25mA settings to play safe and I seem to get the screen to start up after doing voltage tests and plugging it in.

Now to my main problem..

Seeing as the manual strictly states to Never use 6581’s (R4, which mine are) with the JP set to 6581 (which I have) with an unregulated PSU..

Well, I thought I got a regulated one from the store.

It’s an adjustable one, and measuring it up produces some strange results.

It’s supposed to be 1000mA regulated PSU.

Measuring the current gives me results sligthly below 3(!) Amps.

Also, the output voltage (unloaded) set to 12V gives me around 14.5 V.

Plugged into the unit (without the SID-s installed) gives me slightly lower results.

The 9V setting produces about 11.9V unloaded.

I’m unsure of the brand, but I got it from here:

http://www.electrokit.com/batterieliminator-1-512v-1000ma-stab.49112

Thanks for a great community and a beautiful product!

Regards

/M

2

A few short comments about the power:

  • you can’t trust any PSU without a load (but linear PSUs seem to be less affected by this). For testing purposes you could use a small lamp to create a load.

  • More amps is not a problem. Your PSU apparantly can deliver more than you will ask from it.

  • High and/or unstable outout voltage is a no go. I would never power my precious chips from anything unreliable. I would suggest to at leas extensively test your PSU before plugging it into your SID.

3

Hello!
I have now reached the level of finishedness that I should get to installing the SID-s.

The flashing of the EEPROM was successful after some turns and troubleshooting that turned out to be caused by me not soldering one of the MIDI out legs.

Silly mistake.

 

The previous strange values was the multimeter being low on battery.. 

Now I get a steady 11.29 V between pin 28 & 14 on both SID-sockets.

All values seem slightly lower than they are supposed to be.

I’ve tested two PSUs of the same kind and two different multimeters (now with sufficient battery power) so I’m still hesitant to installing the SIDs.

 

The value seems very low indeed but is it a safe low?

The uploading of the application went fine as I said and now I get the beautiful startup sequence when I power on the device. ^^

 

Regards

/M