Hartke 3500 relay problems?

[apdale]

So I recently became the owner of an older Transient Attack version Hartke 3500. First day it worked great, second day its started cutting out. I suspect it has to do with the Protection Relay Circuit. Same exact sound that it has on power up. It cuts out when I play louder, not dependent on preamp volume level or power amp volume level as far as I can tell. It'll kick back soon between 2-10 seconds later. I can play quietly for quite awhile without any trouble but the more aggressive I get the more it cuts out. I've tried zeroing out everything individually with no luck. I plugged into the Effects Return jack and could not get it to cut out but the level was lower than if it ran through the preamp as well so thats not a positive answer. Next thought was to try the send loop into another amp and see if the problem was still there. I can swap out the 12ax7 but I don't think thats the problem, visually its not got a white top or anything obvious wrong with it. I also tried cleaning the effects return jack as I've seen that cause problems on several Crate amps that I've owned but that didn't seem to help any. Any advice would be greatly appreciated. I'm new to the forum but pretty familiar with the inside of amps and would very much like to fix this one. I can provide sound clips or pictures of anything needed if that helps anyone. Thanks!

[Jazz P Bass]

Hartke 3500

I would seriously think about checking the soldering job the factory did on your amp.
10 to 1 it sucks.
As it is it works. Kinda.
Something is half ass if it is going into protect intermittantly.

[apdale]

I read in a couple other places that the soldering jobs weren't quite up to par on some of the Hartke's, this amp has had a long life already and it could be that one of them got stressed out a little much. Thats something cheap to look into that I'll have to check out. Hopefully the board isn't to difficult to remove and I can just reflow all the pads. I thought I read the older (transient attack) model had a little better quality than the newer model, not to say that there weren't problems with the older model as well. Any other ideas? I should have a chance to open it up tomorrow and poke around.

[Jazz P Bass]

Hartke HA3500

Make sure you make a drawing of where connectors go
You do not want to cause problems.
I would remove the power supply board first.
Resolder it.
I have (3) different schematics for HA3500
Here is the oldest. January, 2002
The other ones are Rev A & Rev 1.35
Let me know if this is the correct one.

[chipprogr]

if the relay is truely clicking in and out, id check the small electrolytic capacitors . I would do a capacitor test with a VOM meter to C316,317,318. Ive had experince with the same issue. If you hear no click but the amp is cutting out, reflow all solder joints on front pots and be sure to set it up where the top is off, your playing a mp3 player or cd music source thru it and start tapping and wiggling wires gently, small movements., look for a small sinal wire connecting to AN101, wiggle it gently, if you hear the amp cut out, clean pins on connector.. Also suspect the efx loop balance control.

[Enzo]

I agree, but I'd include C315 as well. In fact, I would just replace them, C315 through 318. They get leaky or their ESR goes high and they don;t do their thing any longer. The 7317 then drops out the relay thinking the peaks are higher than they really are.

The Hartke amps use this IC and support circuit, and so do a lot of the Samson power amps.

[Mike T]

Apdale,
I used a 2000 for years and it only gave me a problem once - symptoms similer to yours. I took it to a tech - he told me he had to re solder the earth joints as they had damaged with vibration. I had put it into an SKB rack and then packed it inside the rack case for added protection -turns out it had the opposite effect. Problem was my doing!
The other thing you might look at is the tube socket. I had real probs with a valve amp one time, violently changing volume. This was a problem with gunge, like a kind of fungus, on the tube sockets - you just have to spray them with some cleaner so that the contacts are good again.

[apdale]

if the relay is truely clicking in and out, id check the small electrolytic capacitors . I would do a capacitor test with a VOM meter to C316,317,318. Ive had experince with the same issue. If you hear no click but the amp is cutting out, reflow all solder joints on front pots and be sure to set it up where the top is off, your playing a mp3 player or cd music source thru it and start tapping and wiggling wires gently, small movements., look for a small sinal wire connecting to AN101, wiggle it gently, if you hear the amp cut out, clean pins on connector.. Also suspect the efx loop balance control.

It does sound like the relay is clicking in and out, I wasn't super clear on that on the original post but thats what I hear it doing.

Is there an 'easy' way to bypass the protection circuit to verify that that is the problem? The protection circuit seems to be after the power amp so it should be doable to just jumper over it. Looks like I can just skip the relay and see how that sounds, I don't want to put a lot of DC voltage on the speakers but I've got some cheap ones that I'm not to worried about.

[apdale]

Apdale,
I used a 2000 for years and it only gave me a problem once - symptoms similer to yours. I took it to a tech - he told me he had to re solder the earth joints as they had damaged with vibration. I had put it into an SKB rack and then packed it inside the rack case for added protection -turns out it had the opposite effect. Problem was my doing!
The other thing you might look at is the tube socket. I had real probs with a valve amp one time, violently changing volume. This was a problem with gunge, like a kind of fungus, on the tube sockets - you just have to spray them with some cleaner so that the contacts are good again.

Mike T, was the relay clicking in and out or was the signal only cutting in and out? I've had problems in the past with a capacitor losing a ground reference and then the amp would cut out when the cap charged up then came back after it discharged. That sounds similar to the earth ground problem but that sounds like something easy to check and verify. I'll definitely look into it.

[chipprogr]

check the solder joints on the main power supply capacitors, seen bad solder joints there in the past and that would cause the same issue.

[chipprogr]

on the main amp module you will see a coil of copper wire, right next to it is a 10 ohm 3 watt resistor. its a larger resistor than most on the board. you can attach to either side of that resistor. This is the speaker output just before the protection relay. Just understand you ARE defeating the protection circuit this way- your at your own risk.

[apdale]

Looking around inside I found the Power on LED was knocked out of place and resting on R405 and R406, R406 now has part of it melted off but it ohmed out to be in range still. Hopefully this is the cause of the problem and leads to the culprit. I can upload a picture if needed.

[lowell]

JPB or Enzo would you mind posting the other schems for this amp? I have one but the component numbers are different. All the power amp board components are in the 600 range.

[Jazz P Bass]

Hartke 3500

That's a way new one for me.
Time to call Hartke, heh?

[Enzo]

I don't know about part numbers, but this drawing works most times for me.