Hughes & kettner Grandmeister 36 needed ! anyone can help?

[cervik]

I got a problem with my GM 36 and service is far away ( living on small island)... someone maybe can help me.

[Jazz P Bass]

O/k. I'll bight.

What exactly is wrong with the amp?????

[cervik]

There is a problem with EQ. The middle potentiometer doesn't work. Sound is very low and thin. I am able to fix it but without schematic is not possible. The circuit sooo complicated.

[drewl]

Is the pot physically broken?

Can you measure it's resistance to see of it changes when you turn it up or down?

[cervik]

The poti is OK. But it working just a control of dig. circuit. There is some problems with circuit around digital programable potentiometer. No chance to find it without schematic...

[Drewline]

Grandmeister_36_Head_Servicedokument_1A.pdf

Here's a copy of the schematic:

Hope it helps.

[cervik]

Hey guy, you saved me ! Thank you sooo much! !!

[tedmich]

[ATTACH]37994[/ATTACH]

Here's a copy of the schematic:

Hope it helps.

Yeow thats pretty complex, thank god its well laid out.

[Gregg]

What a nice PC is that amp...

[J M Fahey]

Ok, you have a PC disguised as an amplifier
or
you have a PC with a tube powered sound board

pick one.

You do NOT have a tone control there but some linear pots sending 0>5V to some DSP port which reads that voltage and acts accordingly.

So all it needs and you can get is that sweeping pot from 0 to 10 you get 0 to + 5V at the junction of C11-R58 .

If yours does not, check those 3 parts involved, the tracks, that solder is fine, etc.

If it does, yet no response as expected, that main board is landfill material and if you can't get ba new one, thye whole amp is thye same. Sorry.

Given your limited access to the outer World next time I'd buy a conventional amp
Even an old used 80's Peavey would be much better in your situation.
Just sayin'

[Gregg]

AD5282BRU are +/-5 or 15V digital pots in a TSSOP package which is smaller that the "regular" SMD package and soldering/desoldering those without special equipment and skills is a living nightmare which also involves the possibility of lifting the tracks and creating a big mess.
I didn't check the schematic thoroughly but I assume the signal is attenuated somewhere before it hits the tone stack otherwise those ADs can't stand the voltage amplitudes coming out of the CF.
By the way years ago AOpen released a mother board with an audiophile tube sound section:

https://www.google.bg/search?q=aopen...HcG0DYUQsAQIGQ

[Zouto]

Ok, you have a PC disguised as an amplifier
or
you have a PC with a tube powered sound board

pick one.

You do NOT have a tone control there but some linear pots sending 0>5V to some DSP port which reads that voltage and acts accordingly.

So all it needs and you can get is that sweeping pot from 0 to 10 you get 0 to + 5V at the junction of C11-R58 .

If yours does not, check those 3 parts involved, the tracks, that solder is fine, etc.

If it does, yet no response as expected, that main board is landfill material and if you can't get ba new one, thye whole amp is thye same. Sorry.

Given your limited access to the outer World next time I'd buy a conventional amp
Even an old used 80's Peavey would be much better in your situation.
Just sayin'

GREAT, yeah IT IS indeed a PC with a tube powered sound board in a weird package, soundwise as well.......

[AmpFix]

I never really liked the Hughes and Kettner stuff: After sales service in terms of parts and support is limited and replacement parts are priced in such a way that repairing the amp is simply not worth the time and money. Of course, there are exceptions.

[nafo]

Thanks!!! Drewline!