Harthke 7000 mosfet amp schematic need

[marcas58]

Hi, i have a hartke 7000 mosfet amp to repair
i need the schematic...please help...

thanks..

[Jazz P Bass]

Try this link: HARTKE HA5000 7000 Service Manual free download, schematics, eeprom, repair info for electronics
Wait until it says "This file is downloadable free of charge: Get Manual"

[marcas58]

hartke 700

Try this link: HARTKE HA5000 7000 Service Manual free download, schematics, eeprom, repair info for electronics
Wait until it says "This file is downloadable free of charge: Get Manual"

I alredy have this one, is not the one i need this has transistors in the output
the one i am looking for has mosfets, the one in this page is the HA series.
thanks

[J M Fahey]

FWIW the one with Mosfets turned out bad and unreliable, so it was replaced back with the bipolar version.
Don't know where you live, but if you are a regular Service Tech (not "a Musician with a soldering gun"), Samson/Hartke will sell you a new power amp pcb , with all parts except power transistors, which you get on your own.
Write them.
Just in case, also ask for the MOSFet schematic.
Just curious: which MosFets does yours use?

[Enzo]

The only difference between the 7000 and the 7000MOSFET is the power amp modules themselves. The bipolar ones and the MOSFET ones have the same connections and can be interchanged.

Samson should send the MOSFET drawing if you ask.

Juan is right, they quit the MOSFETs, the amps were not reliable. And last I heard, the cost of a replacement bipolar module complete was not out of reach. If you go that route, ask them if it comes with output transistors. I have this notion that the board comes complete but no output transistors. because you mount the board and the transistors, THEN solder them to the board. Otherwise you have to guess how much lead to allow.

[oc disorder]

It's a bit rough but here's the 3500 with Mosfets ('bout 1.3 meg)

[Jazz P Bass]

Hartke 3500 MosFet Schematic

Here is a pdf copy of the Hartke 3500 MosFet file.

Thanks OC.

[marcas58]

FWIW the one with Mosfets turned out bad and unreliable, so it was replaced back with the bipolar version.
Don't know where you live, but if you are a regular Service Tech (not "a Musician with a soldering gun"), Samson/Hartke will sell you a new power amp pcb , with all parts except power transistors, which you get on your own.
Write them.
Just in case, also ask for the MOSFet schematic.
Just curious: which MosFets does yours use?

i use the irf240 and irfp9240 this you can find a replace from NTE semiconductors
and i dont where they fiand here in the store where i get my parts..they have te originals
240 an 9240 that came with almost all the mosfets amps..
i live in Juarez Mexico..

thank yuo for all your help i'm going to call samson support to see if they can help me or if can buy the boards
both of the boards have burned resistor and some has been gone from the board.

[J M Fahey]

Dear Marcas, I see 2 *BIG* problems here.

1) I very much doubt they used IRFP240/9240 there which are "switching" type.
You *can* use them in linear amps, many do, but you need to provide a very good thermally tracking bias source or they will either crossover distort horribly or will thermally runaway and die.
The schematic you show is the typical one used for *audio* MosFets (2SK/2SJ types).
And *if* Hartke used IRFP types there ... that would explain the reliability problems.

2) even if it had the proper MosFets, the protection circuit design is WRONG.
Will do nothing on normal operation, but MURDER the driver transistors when shorted, how's that?

No wonder they changed the design.

[Jazz P Bass]

Here is a pdf copy of the Hartke 3500 MosFet file.

Reload of file.
PDF.

[Enzo]

What WERE the stock output MOSFETs in those, I sure don't remember?

[Jazz P Bass]

In this link http://music-electronics-forum.com/t14868/ the OP says the installed mosfets (one side) where "IRFP240 2U4T 9222"
& Samson sent "IRFP240A 747" as a replacement.

[marcas58]

hartke 7000

Dear Marcas, I see 2 *BIG* problems here.

1) I very much doubt they used IRFP240/9240 there which are "switching" type.
You *can* use them in linear amps, many do, but you need to provide a very good thermally tracking bias source or they will either crossover distort horribly or will thermally runaway and die.
The schematic you show is the typical one used for *audio* MosFets (2SK/2SJ types).
And *if* Hartke used IRFP types there ... that would explain the reliability problems.

2) even if it had the proper MosFets, the protection circuit design is WRONG.
Will do nothing on normal operation, but MURDER the driver transistors when shorted, how's that?

No wonder they changed the design.

mmm...you make think about this mosfet and find out that ampeg use the same mosfet...

[J M Fahey]

Yes, I also use them , but we use it right and Hartke uses it wrong.
As I said , it is not thermally compensated (what were they thinking?) and as their own Service Tech says:

Those MOSFET power amps were problem-ridden and USUALLY went up in flames (literally).

So even if you repair it as-is .... you can't trust it

[Steve Conner]

The IRFP240/9240 can be used without flames, but it is not trivial, Rod Elliott explains how.
Using HEXFETs in High Fidelity Audio

Now you know why International Rectifier and other vertical MOSFET manufacturers don't recommend HEXFETs or their equivalent for linear applications - they are simply not designed for the purpose. Yes, they most certainly will work, but just be aware of the limitations.