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https://www.decware.com/cgi-bin/yabb22/YaBB.pl SUPPORT FORUMS FOR ZKITS >> ZKIT 1 Support forum >> Everything seems fine except....no sound https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1270027433 Message started by Evo on 03/31/10 at 10:23:52 |
Title: Everything seems fine except....no sound Post by Evo on 03/31/10 at 10:23:52 I have just finished off my zkit1. As per the instructions I have checked all resistance values and solder joints prior to powering up. First I powered it up without anything attached and check the voltages at the four locations specified in the instructions. Tube lit up and voltages were good. I then attached the speakers. You could hear a quiet speaker noise, but no hum. Good. Then attached a cd player - nothing. Turned the volume up and down and the background noise increased and decreased accordingly, but no music. Checked the source elsewhere - no problems with the source. What might the problem be? What things should I check? How do I check that? Any help welcome, Matt |
Title: Re: Everything seems fine except....no sound Post by dank on 03/31/10 at 13:07:22 Matt I'll assume you have a VOM and no oscilloscope, right? There are a couple of revisions of Zkit1 printed circuit boards out there. Mine, which is probably older than yours, had the input to the power tubes wired to pin 8 (an unused pin) and left the control grid input pin 2 open. The fix was to install a short jumper wire on each output tube from pin 2 to pin 8. Check that the 1k resistors go to pin 2 of the power tubes - check with your Zkit1 unplugged and your VOM on ohms...one side of the 1k to pin 2 should read around zero ohms, the other side of the 1k to pin 2 should be around 1000 ohms (1k). If you read infinite - try measuring to pin 8. If you get good readings to pin 8 you will need to install the jumpers. This problem would account for no sound. Try this and let me know what happens. Dan |
Title: Re: Everything seems fine except....no sound Post by Evo on 04/01/10 at 23:06:22 Thanks Dan. I checked the board layout and the new board has the 1k resistors connected to pin 2 of the tubes. I found out the problem - I hadn't wired the RCA connectors on the board correctly to my remote RCA sockets. Music is now playing, the problem now is that one channel is quieter than the other. I have swapped the speaker connectors around and the RCA connectors from the CD player to just exclude speaker/source issues first. I have also swapped the tubes over. It is definitely the amp. My next plan was to work back from the speaker outputs using my multimeter. Sound like a good idea? Any ideas what the most likely cause would be? |
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