Got a bit of problem/problems, Sammich SID *FIXED*

MIDIbox SID
1

Hi all,

I’ve just finished soldering the sammichSID kit, done the voltage tests and inserted all IC’s except SID’s and bank IC’s.

The problems are:

When I did the voltage tests, all 9v and 12v was not up to spec.

The adapter I got is set to 12v but only 10.5v when I measure the output (ends up being 7.7v on 9v checks and 9.9v on 12v check points).

It’s not a switchmode adapter.

So question 1: Should the next steps work despite the voltage discrepencies ?

E.g. the MIDI in/out checks, loading firmware etc. ?

Question2: I don’t get any MIDI I/O at all, have doublechecked the computer side with another synth (VirusB), so the computer side works.

Tried the shortening test of pin 25/26 of the PIC socket (if I remember the number correctly, I pulled the PIC before :)).

No loopback feedback.

So I started to check the In tests, checking resistors, which at least with my multimeter is close but not perfect.

Not sure if it’s the tolerances of the components or the meter (the meter is brand new).

E.g. 1.2kOhm is 1.18.

Anyway, then there check in regard to the optocoupler and that the notch should be in the orientation in the J11 direction.

I’ve soldered the IC socket correctly and the notch is in the same direction as the notch in the socket.

So I guess that is right but since I can’t spot J11 it would be great with a confirmation.

That is as far as I’ve done so far.

If you have any great hints/tips that would be great.

Yes, there are shunts in JMI and JMO (using the outlined pins).

2

Update, hooked everything up again and when I watch the LCD it will end up with “Ready”, I do a query from MIOS Studio, it displays “Rebooting MIOS”.

So it might be a Midi out problem from the SID.

3

Hello,

you could try to put caps into JBP to override the bridge rectifier. Which voltages do you have then?

And which voltages do you have between GND and 5V ?

I have a non-switchmode adapter 12V but it only outputs 11.51. I currently run the Sammich sucessfully with the method described abobe.

With bridge rectifier I have 8.5 at 9V , maybe exactly the half missing V.

A general tip that helped ME, is to get the pcb charts and make sure everything works. Doing only the voltage tests described in the buildnig manula did not help in a few occasions.

http://www.midibox.org/dokuwiki/lib/exe/fetch.php?hash=a55f1b&media=http%3A%2F%2Fwww.mb6582.org%2FsammichSID%2FsammichSID_Base_PCB.pdf

http://www.midibox.org/dokuwiki/lib/exe/fetch.php?hash=b46a35&media=http%3A%2F%2Fwww.mb6582.org%2FsammichSID%2FsammichSID_CS_PCB.pdf

I hope I could help a bit but the more experienced guys will surely do so :=)

4

Update 2 :slight_smile:

Got it working, as I mentioned I tried the Virus to verify the connection and it did work.

But to double check I hooked up a small midisport 2x2 interface that I haven’t used for ages, and lo and behold it was working.

Have verified that buttons etc. work, LCD works etc.

Did a recheck on the meter against the adapter and whenever I measure it now it’s betwenn 11.3 and 11.5v.

Will see if it works with the 6582 SID’s or not.

5

Hello,

you could try to put caps into JBP to override the bridge rectifier. Which voltages do you have then?

And which voltages do you have between GND and 5V ?

I have a non-switchmode adapter 12V but it only outputs 11.51. I currently run the Sammich sucessfully with the method described abobe.

With bridge rectifier I have 8.5 at 9V , maybe exactly the half missing V.

If I check GND and 5V it’s 4.99v->5.01v (most check at exactly 5.0v).

Yep I saw your thread in regard to the same question, will follow that and see what happens (I’ll do it before installing anything else).

6

Something is definitely off if you’re not reading correct voltages out of the voltage regulators. Those should be very close to the rated voltage of their outputs, so try checking the outputs of those and work your way forward. If you don’t get the proper voltage there, start working backwards and check for shorts. Typically, the regulators either output proper voltage, or close to none at all so if you’re reading incorrect voltages there, something is amiss.

Keep in mind, too, that you need about 2V above the rated voltage of normal 78xx regulators. So for a 7809, you need 11V. 10.5V may be too little. Also, knowing if you’re using AC or DC may be helpful as 12VAC would give you about 14VDC unregulated after the rectifier, depending on what your actual input voltage from the wall is.

You mentioned that your power supply is “set at” 12VDC. That sounds to me like a switch-mode. I don’t know of any wall-warts that allow configuring out the output that are not switch-mode. That, however, is probably not a factor for getting proper voltages as long as the wall-wart is rated correctly (I think up to 500mA is recommended for the Sammich, but I would check the docs on that one).

7

Did a recheck, The 7805 voltage regulator show 5v between GND and 5V, the 7809 show 8.2v on the 9v and 9.8v on 12V.

The adapter as I said in an earlier update now measures 11.3-11.5v, not sure if I failed to measure it correctly the first time.

As far as I can tell from the webpage of the shop that I bought the adapter from it’s not a switchmode adapater, they have different categories for switching and non-switching.

8

9.8V on the 12V is likely just due to the voltage drop over the bridge rectifier. You can verify that by looking at the voltage from the DC in jack and then after the rectifier. I run a 12VDC supply on my Sammich so it’s probably ok, though 11.5V is a little low. It’s better to be slightly over than under (though the more over you are, the more heat those regulators will generate).

8.2V seems low after 7809. I’m not sure how low you can go, but I wouldn’t like to go under 8.5V myself (some other folks may want to chime in here about that). I wonder if there is something going on with GND. I would double-check for any shorts for anything that’s close to a ground pin, particularly around the regulator section.

I would pull your chips for now as well. I wouldn’t stuff them again until you fix the voltage issue. In fact, I would re-check your voltages with no chips if you haven’t done so yet.

9

Have now put the shunts in JBP, now the 7809 show 9.08v between GND and 9v, and 11.24v between GND and 12v.

10

Hmm something sounds amiss there then, perhaps somewhere in the SID section. Using a 12V supply and 8580/6582 SIDs, you should now need to bridge JBP (in fact looking at the build doc it says NOT to do that - the jumpers for JP should be in the horizontal position). That said, those voltages look good otherwise. I think there’s still some sort of grounding issue afoot.

11

Maybe I’m wrong but to me it sounds like the adapter is delivering what I’ve measured, which is 11.3->11.5 (11.24 on the PCB after I’ve put the shunts on JPB).

I tried the JPB “workaround” as Param1 says above.

http://discourse.midibox.org/t/topic/15215

So as far as I can tell it’s the adapter that is not up to spec.

12

I think it’s worthwhile to test it that way; I just dunno if I would leave it. Could be your power supply but it’s odd you’re getting low numbers from the regulators. If you had another supply, I would definitely try it. Before you go and buy another PSU though, I’d try to get another opinion (as in, other than mine :slight_smile: )

13

No problem m00dawg, since Param1 have done it under similar circumstances I took the plunge and tried it.

And everything is working and I even got sound :slight_smile:

Wooopie!

14

Sweet!