hartke 3500 power-on problem

[wireguitar]

I have an ancient Hartke 3500 that is now experiencing a power-on problem. I have to hit the Power switch 20 or 30 times before it will turn on and stay on. Once it "takes", it works just fine. It's getting it to stay in the On position that takes an effort. Any thoughts? I can follow a schematic, but I'm not a great diagnostician.

[oc disorder]

Hi Wireguitar and welcome to the forum.

Before getting complex is it just a faulty power switch ie do any lights come on to prove the power is getting to the amp or can you hear a faint physical
humming/buzzing coming from the transformer when the switch is on ?

The amp does have a protection relay that wont connect the speakers if there is a fault that could damage the amp and or the speakers.

Use the search function on the forum as there are many posts regarding
Hartke 3500's .

First we need to ascertain thats its not just the power switch.

[Jazz P Bass]

Hartke 3500

Resolder the main power supply board.
4 screws in the front (metric allen cap) 4 screws on the bottom of the front panel. 3 screws on the main board.
Pull it front & flip it over.

[wireguitar]

Hi Wireguitar and welcome to the forum.

Before getting complex is it just a faulty power switch ie do any lights come on to prove the power is getting to the amp or can you hear a faint physical
humming/buzzing coming from the transformer when the switch is on ?

The amp does have a protection relay that wont connect the speakers if there is a fault that could damage the amp and or the speakers.

Use the search function on the forum as there are many posts regarding
Hartke 3500's .

First we need to ascertain thats its not just the power switch.

The switch works - eventually! When the amp finally powers up, it works perfectly. The appropriate lights come on, the fan works, and my bass sounds terrific. The problem is like trying to start a car with an ignition problem: It takes many tries for it to "turn over". Once it does, it works the way it has for the past 17 or 18 years.

[wireguitar]

Resolder the main power supply board.
4 screws in the front (metric allen cap) 4 screws on the bottom of the front panel. 3 screws on the main board.
Pull it front & flip it over.

Thanks! I 'll give that a try.

[oc disorder]

The switch works - eventually ?
I gleaned that from your first post,

What I meant was the switch could be faulty ie worn out or
a bit of grit or whatever preventing it from switching the power through to the transformer.

In this case no power anywhere no light or no faint hum coming from the transformer and obviously no sound.

But if the switch is ok and the amp has power to the transformer then the amp may still not work as there is some other problem preventing the amp
turning on.

In that case then the suspect would be as Jazz P Bass suggested a faulty solder join on the main power board or similar which is making the protection relay go into fault mode thus not allowing any output.

In this state the mains power is actually on - a faint buzzing from the transformer but no sound as the fault is not the switch.

But if the switch is faulty it doesn't matter what you do downstream (soldering etc) the fault will remain.

Eg A faulty ignition switch will work some times - you need to check if the power is getting to the starter motor before you start pulling that apart and changing the brushes and contacts.

[wireguitar]

The switch works - eventually ?
I gleaned that from your first post,

What I meant was the switch could be faulty ie worn out or
a bit of grit or whatever preventing it from switching the power through to the transformer.

In this case no power anywhere no light or no faint hum coming from the transformer and obviously no sound.

But if the switch is ok and the amp has power to the transformer then the amp may still not work as there is some other problem preventing the amp
turning on.

In that case then the suspect would be as Jazz P Bass suggested a faulty solder join on the main power board or similar which is making the protection relay go into fault mode thus not allowing any output.

In this state the mains power is actually on - a faint buzzing from the transformer but no sound as the fault is not the switch.

But if the switch is faulty it doesn't matter what you do downstream (soldering etc) the fault will remain.

Eg A faulty ignition switch will work some times - you need to check if the power is getting to the starter motor before you start pulling that apart and changing the brushes and contacts.

I agree completely. I have long thought that it was a relay elsewhere that was preventing the amp from turning on. After 20 or 30 tries, I get lucky and the relay doesn't go into a fault mode. As soon as possible, I intend to reflow the solder joints, cross my fingers, and hope that it works as it has always done.

[wireguitar]

The switch works - eventually ?
I gleaned that from your first post,

What I meant was the switch could be faulty ie worn out or
a bit of grit or whatever preventing it from switching the power through to the transformer.

In this case no power anywhere no light or no faint hum coming from the transformer and obviously no sound.

But if the switch is ok and the amp has power to the transformer then the amp may still not work as there is some other problem preventing the amp
turning on.

In that case then the suspect would be as Jazz P Bass suggested a faulty solder join on the main power board or similar which is making the protection relay go into fault mode thus not allowing any output.

In this state the mains power is actually on - a faint buzzing from the transformer but no sound as the fault is not the switch.

But if the switch is faulty it doesn't matter what you do downstream (soldering etc) the fault will remain.

Eg A faulty ignition switch will work some times - you need to check if the power is getting to the starter motor before you start pulling that apart and changing the brushes and contacts.

I agree completely. I have long thought that it was a relay elsewhere that was preventing the amp from turning on. After 20 or 30 tries, I get lucky and the relay doesn't go into a fault mode. As soon as possible, I intend to reflow the solder joints, cross my fingers, and hope that it works as it has always done.

[Enzo]

If the switch ITSELF is working, then you should hear the sound of power in the transformer. if there were some sort of relay system, they would need the transformer working. If there is ZERO sound from the amp - the amp, not the speaker - then I suspect you have a plain old bad power switch. Just because it clicks back and forth doesn't mean the contacts inside are working.

Unplug the amp from the wall. measure the switch contacts with your ohm meter. They close and open or they don't.

Alternatively, use a clip wire to bypass the switch. Now the amp should be on whenever it is plugged into the wall.



This amp has very simple power wiring. The power switch is in series at the mains input. There are no relays in the power circuits. ONly relay in this is the speaker relay. it has nothing to do with lights, fans, preamps, etc.

Check the switch ITSELF. Electrically check it.