I have a new ( 2 weeks old) Hartke 5210C combo bass amp. I plugged it in and turned it on, and after about three seconds, I heard a louder click than usual. I plugged my bass in and hit about three notes, when I heard the same click, and the amp went dead. Lights still on, but no sound. Checked the fuse and it's not blown. When I turn it off and then back on, I get the usual subtle click that it does, but no sound. Any ideas?

Contact Hartke directly to inquire.

The schematic is here. http://music-electronics-forum.com/attachments/6771d1256866984-a70_sch.pdf

Sounds like you burned out the sub channel usually due to having a sub the draws more watts than the system can push, effectively blowing a capacitor or node within the internal motherboard of the AMP.

Sounds like the loudspeaker relay switch is disconnecting the spkr.
i) Check heat sensor on heatsink has good connection to PA board. Dust on h'sink/fan usually needs vacuuming off!
ii) Check voltage on the amplifier output resistor R334 is at 0v (referenced to chassis) - if this voltage is raised,the amp stage is faulty.
Otherwise the fault lies in the speaker protection stage (IC301).

Are the internal speakers properly connected via the rear-mounted 1/4 inch "Speaker Output" jack? If so and still no sound, try connecting a separate external speaker (floor monitor, pa cabinet) for a "low volume" test.

The OM says the internal speakers are 4 ohm so it's unlikely that a wiring problem with speaker connections would cause all four to stop working. With AC power disconnected from outlet check for an internal speaker protection fuse BUT be careful. Charged capacitors can hold a charge for weeks!!!

The amplifier takes a bit of time to come to DC balance and same thing happens as power goes down. Some fancier units will have a relay to disable speaker until balance occurs, but this one does not. As long as the cone centers within a couple seconds it will not cause a long term problem.

Transformers don't often fail. I have heard that some of these have a thermal fuse in them and they sometimes open. If you can get to the fuse in the windings, you can replace it and save the transformer. The fuses look like a silver tube about 5/8 inch long and 3/16 inch diameter with a lead out each end, They are marked with the temp they open and are a one-shot thing that have to be replaced.

Easiest way to check is to measure the resistance between the ground pin of your cord and the chasis of the unit. It should be very low. That is the only critical one... Look at a receptacle. See one bllade is wide? That is the neutral. The other one is the HOT side. The HOT SIDE should go to either the fuse or the switch first in your unit. If you have those right the third wire will be right.
When powering up an amp there often is a noise until the amplifiers balance out. Very high quality and high power amps have a relay that disconnects the speaker until balance is reached... but the smaller amps do noot have this feature.

A simple test is to connect internal speakers across an AA battery (for about half a second) & listen for a click as battery is connected & another as battery is disconnected.

If this does not happen, check the internal jack plug connection & its connection to the speakers.

If OK, then you can test each speaker individually using the same battery across each in turn.

If this advice is helpful, I would appreciate a rating.

Connecting the CD player should NOT have caused any damage if they were power from the same receptacle and both had grounded plugs OR a walkman type was used which had no external power to it. Power transformers RARELY fail. Check if it has a fuse that has blown BUT do not replace the fuse until the cause of it blowing is found. Switches on a lot of these are POOR and they do fail.