Audio Gone only Hum left

[Tron77]

Hello fellow Sidders.

I've got and old version Sid completed somewhat a Year ago. Could troubleshoot everything easly myself thanks to the Applications and this Forum. Great! Only just before I wanted to upgrade to V2 my audio signal dissapeared and left a Hum (the type when something isn't properly grounded)to irritate my ears:(

I did run the 1 Khz App again, but ofcourse no result. Checked the sid Interconection, wich has probabely nothing to do with it, but wanted to try the new version anyway --> possitive results, nice work Thorsten!. But now I'm really stuck.

One thing to notice is that played around with an other DIY-Synth (A Benjolin) and plugged it differents out (Saw/Puls/Filter etc) out in Sid's IN and OUT (I know this doesn't make sense, but I didn't mark IN and OUT on the back of the sid...)

One of the sids's gets a bit hot, although the voltage of my psu ok (5.2V)

Does someone have an idea if I could have damaged something this way, or if not some other hint?..or maybe just a link to the topic I didn't see with the same problem?

Greetings, Youri

Edited January 14, 2010 by Tron77

[lylehaze]

The Problem:

"Audio Gone only Hum Left"

The Solution:

"Try turning the balance control to the Right".

Sorry, that's all I've got. :)

Good Luck with it,

LyleHaze

[Wilba]

You need to check the other supply to the SID... i.e. at pin 28, and where it's connected to the 9V or 12V (depending on SID type).

You can try a different test to narrow down what the problem might be:

- take out the SIDs from both modules

- bridge pins 8 and 27 with a 1K resistor

- run the testtone app

This will generate a 1kHz square wave tone (same as the testtone app makes with the SID) by toggling pin 8 at 1kHz, which is thus connected to the audio buffer circuit at pin 27 (the SID's audio out pin). Pin 8 is connected to SID:J2:SO so this is another test if this connection to the PIC is working.

Refer to the SID module schematic so you know what I mean by pin 8 and pin 27 of the SID IC socket: http://www.ucapps.de/mbhp/mbhp_sid_v3.pdf

[Tron77]

Ok did run the testtone app without the 8580 an 1k res. between Pins 8-27. got a nice 1 khz tone! Also tested the Voltage between 28 and 14 --> 9 Volts exact.

One thing I found out was that I had switched the + and - on the Audio jack sockets from the beginning (so Tip was - and Sleeve was +) Funny that I could play with it for about a year without problems, although Hum decrease now when hearing the testone.

I'm afraid that plugging the other DIY synth has seriously damage something because of the switched + and -. I have some 6581's so I will change them and try. I'll keep an update.

Thanks for the help so far!

Greetings Youri