Repair ZP120

Lyricist III

I just wanted to check in saying that the CONNECT:AMP arrived over the weekend and it is in good shape. As far as I can tell it has not been opened. I plugged it in and sure enough no lights. With the holidays coming, I am going to have limited time to work on this, but I am planning on building the dim bulb tester today or tomorrow and hope to have a first look at the amp this coming weekend. I will report back what I find.

Lyricist III

OK I have an update. I successfully built and tested the dim bulb tester today and decided to plug the connect:amp into the tester to see what happens. I was expecting the bulb on the tester to glow bright indicating a short, however the bulb went momentarily bright and then quickly dimmed out. I am using a 60 watt bulb in the tester btw. I don't have time to open the unit right now, but I was hoping the m0untainman or someone else on this thread might be able to tell me what my results indicate.

Thanks in advance,
Andy

Trending Lyricist I

This indicates that you dont have a short nor a blown fuse. Did you say that you get any blinking light?

Lyricist III

Thanks gruv. That what I thought too. When I plug it in, no lights, no burning component smells. I do see the table lamp beside the plug flicker momentarily like the amp is drawing power. That seems normal.

Trending Lyricist I

Yes, you are charging the big input storage caps. That is what is making your dim bulb tester glow.
Please please please respect the high voltages that you are working with. Keep one hand in your back pocket while probing or doing anything with a live circuit. Your dim bulb is at high voltage too!

Lyricist III

Will do gruv and thanks for the warning. I have worked with electricity at different voltages from 125V house to low 5V circuits but never really worked with power supplies. I suppose I am going to have to open this thing and start a visual inspection to see if there is anything indicating what the problem could be. DO you have any theories?

Trending Lyricist I

I would start with the bias converter.
It sounds like it is not doing anything.

Scroll to the first page of this thread (I believe) and see the test aid that I made. Probe and check for those voltages.

Lyricist III

gruv: I opened the amp and checked some of the voltages you referenced on your page 1 post and all check out except the 15.4V P-FET voltage. I only had .3vdc on that. One question on the winding voltages. Did you use the RTN points or GND when checking?

Lyricist III

After reading m0untainman's post on page 2, I saw he used the RTN so I checked the voltages on the secondary and it is not registering any voltage at all (0V). I am thinking the issue is the PWM.