(sammich)Filter doesn't works

Testing/Troubleshooting
1

Hey folks,

next problem with my sammich babe.

The filter doesn’t works :

I use the 6581 SIDs with 470 pF capacitors (Slot 2/3 4/5). When I set the filters active for channels 1,2&3 I hear nothing.

(And when I activate it on every single channel, this channel produces no sound)

I recognize, that all presets with fitler action doesn’t sound right.

The soldering connection between the caps and the board is right. A voltage test at the caps during power on seems to be successful.

Ok let’s start to locate the error.

Thanks ! :shifty:

Tom

2

If *everything* except for the filters is working, then your SIDs most likely have broken filters. Do you have a way of testing them in a C64 or some other known-to-work circuit?

3

On my MB6582 I had to turn up the max res in the Configuration menu to FFF to get my 6581 filter right

4

@nILS

No way to test out the SIDs. I will ask a friend of me, he own a C64.

@JRock

Not working. I tested it yesterday too.

I wrote the person, which sold me the sids. He tested the SIDs in his own sammich but I don’t know, if he tested the filters.

5

I test the caps. without power with a analog Ohm/Resistor test device.

Result

C1L ~8k

C2L ~8k (but a little bit more than C1l !)

C1R ~7k

C2R ~11k

Logical C1L must be the same like C2L and C1R=C2R, hu ?

6

An ohmeter test on capacitors doesn’t give you usable result. E.g, the resistor value changes if the cap is charged or not…

Did you already check that the 6581 are supplied with 12V?

Because at 9V the filters won’t work properly.

Best Regards, Thorsten.

7

You measured the resistance of the caps… Interesting :wink: Since you don’t really know what’s hooked up to the caps in the SID (unless you can read the die-shots) the only thing you can learn from that is that, well, they’re different. That doesn’t really tell you anything though. The filters in the SID are analog and hence have some tolerance, hard to tell to which degree those tolerances are “normal”.

8

With the words of Wilba “a shot in the dark” :wink:

@12V

I do the voltage tests which written down in the Sammich Manual.

All the market test-points shows the provided voltage values.

9

Could you please test the 12V voltage again under load, I mean when the SIDs and the PIC are plugged into the sockets?

Just an idea that your PSU is too weak

Best Regards, Thorsten.

10

I test it with two PSUs (with SIDs and PIC, everyhting) … all fine.

The guy who sells me the SIDs means, the filters working in his sammich.

11

Did you switch on the filtermode (to L, B, H or a combination)?

I know this should be obvious, but it’s easy to miss.

Another idea: Can you check if the capacitors have proper contact to the SIDs?

I don’t know how this looks on a sammich, but maybe you can measure resistance between the capacitor-legs and the pins of the SID.

Here you can see which pins to check: SID schematic

12

I switched the filtermods and only on H I hear the original sound. In this case, when I change the CutOff/Res values, nothing happen.

The legs of the caps have contact with the SIDs/Sockets (and with the soldering points too)

13

Sounds like broken filters IMHO.

Are you sure your seller is reliable?

Maybe someone else could check your SIDs?

14

If *everything* except for the filters is working, then your SIDs most likely have broken filters.

…and that’s fairly common with SIDs, especially with 6581s.

15

Today I go to a friends party. Maybe we find some free minutes to check the SIDs … maybe.

We will see :twitch:

16

No way to test it out, yesterday.

But in 30h we will try again.

17

It seems to be the final result : one SID is broken, one SID have a no functionally filter.

But how it’s possible ? The seller reassure that the SIDs working fine. Maybe a damage on the post way ?

Now I will ask to him and try find a way for both sides :clover:

… and I looking forward to buy twi 8580s on eBay *sigh*

18

The seller reassure that the SIDs working fine. Maybe a damage on the post way ?

Without saying that any of the below is correct, there’s more than tzwo options :slight_smile:

a) SIDs were broken to begin with

b) Damage during transport, kinda unlikely though

c) broken while fiddling with and trying to build them into a midibox SID

d) aliens obducted them and brokeded them in the process (aliens do not like chiptunes)

19

D ! :frantics:

20

OMG! Aliens are abducting & harming SID chips?! :alien: You bastards!