Hartke 3500

[shortcircuit]

I have a friends early model 3500,worked fine one day,not the next . Get a low signal ,and a sound like the wind is blowing . It was in a certified shop , diagnosed power amp module , there is no replacement available any longer, so it was given to me to try what ever. Reading past threads on this and several other forums ,this is what I've tried so far. re flow , replaced all electrolytic caps even though they tested ok , tested resistors (still in circuit ) diodes (in circuit) , all main transistor readings match with each other, I pulled a few out just to double check, they tested good. Replaced the relay and the IC7317, all with no results. have 90v b+ -90 B- 63.4 ac , no burn marks on anything and I haven't smoked any components with changes I've made. I'm green but cautious
This has the 2s1429 and 2sd2155 transistors , I have +90 -90 there . Hartke says the fullcompass replacement won't work with this model Ha3500.pdf

[The Dude]

Welcome to the place!

Schematic here:

http://music-electronics-forum.com/a...00_1.35-1-.pdf

[shortcircuit]

Thanks for the reply,I've added the 3500 schematic to my post ,yours is for the newer HA models, but greatly appreciated.

[The Dude]

In no particular order:

1) I'd completely ignore what the "certified shop" said. If they were any good, they'd have been able to fix it. The amp isn't that complicated and there's no reason to replace an entire amp module, unless it caught fire.
2) Use the effects send to drive another amp. Does that work normally? Plug directly into the effects return. How does that work? That will narrow it down to a preamp or power amp problem.
3) Don't just throw parts at the amp, as in "replaced all electrolytic caps even though they tested ok". You could install more problems. Troubleshoot the amp and figure out what's wrong with it. No reason to replace the relay unless it wasn't working and since you hear noise out of the speaker, it probably was.
4) Your schematic link isn't working- at least for me.
5) You say you have 63.4VAC. Where did you measure that?

[g1]

Schematic:

[Enzo]

I too am suspicious of the certified shop, when they say there were no power amp modules available. Well, we don;t replace modules, we repair them.

Where in Michigan are you? I am in Lansing.

[J M Fahey]

Maybe that shop is Authorized for Hartke, and someyimes replacing a full board is best, specially if:
a) it´s available (duh!!!)
b) being AWSC and amp still under warranty, Factory *will* send a new board for free and pay Tech to replace it, so why waste time repiring it?

But if out of warrnty, with board unavailable or very expensive, any tech worth his salt can repair it, period.
Unless incompetent/lazy that is.

[shortcircuit]

plugging into return yields nothing , have 63.4 vac at pin 6 of con501. After going back to Nosaj post 3500 no output (which by the way is the correct schematic) sorry my link didn't work, I'm suspect of Q309 I have my b+ at the collector , not at the emitter , have b+ at collector not the base on q313 thru 319. I should have it here correct. Your wisdom is greatly appreciated

[Enzo]

You have voltages, but does the relay click on?

If not we need to find out why, first step being check the output bus inside the amp. Pick an output transistor, is there Rail voltage on the emitter leg? it SHOULD settle to zero, does it?


That 64vAC? It makes a DC supply with D309 and C314. That is used to reference pin 1 of the relay IC. Is that supply present?

In my experience, when the relay circuit doesn't work, but the amp itself seems OK, it often boils down to the small electrolytics, especially C317, C318. Those small caps seem prone to drying out.


And check at the power amp input connector, is signal present?

[shortcircuit]

Yes the relay clicks on , what reading should I have at an101 ?
plugging into fx return yields nothing , After going back to Nosaj post 3500 no output (which by the way is the correct schematic) sorry my link didn't work, I'm suspect of Q309 I have my b+ at the collector , not at the emitter , have b+ at collector not the base on q313 thru 319. I should have it here correct? Your wisdom is greatly appreciated
I do have a signal at the outputs , controlled by the volume pot ,it's just very low

[shortcircuit]

I too am suspicious of the certified shop, when they say there were no power amp modules available. Well, we don;t replace modules, we repair them.

Where in Michigan are you? I am in Lansing.

I am in Coldwater

[shortcircuit]

Hello
J M Fahey do you still have test point chart you used for Nosaj from the 3500 no output thread ? the HA3500pwr01.png is the correct schematic , I've never found the test point png

[The Dude]

Check and make sure your +&-15V supplies are there.

[Randall]

Have you tried a cable between the send and return jacks on the back panel?

[shortcircuit]

Check and make sure your +&-15V supplies are there.

I have my +&- 15v at all ic's I can find on the schematic at pins 4 & 8 , I don't find 2pin an404 which is on the send /return on the schematic , I have a 3pin con coming from an401 off the pre board I get -14v on both pin 1 & 3 0v at pin 2 on the pre board not at the send/return all the traces on the harness check good