Madison Divinity Head (3 channel)

[tbonuss]

With yet another lapse of judgement I'm fixing one of these for some really nice guys.

I'm hoping someone has the TSL approximation, not the fugazi Ashton fugazi DSL.

Super convenient that they call all of their "variants" the same thing...

(BTW, I got the power amp section working, and it is mystifyingly good).

Thanks in advance, for any help at all.

[J M Fahey]

What I saw in Madisons is a as generic as they come Chinese copy of some Marshall amp with a space on the front panel "write your own brand here", sold to anybody who wants them for a low price and be resold as own making.

Even the schematics were written in Chinese.

The ones I saw looked very close to real DSL so yours "should" be very close to a TSL, use a TSL schematic for servicing it.

I mean, same way as you could use a Tweed Bassman schematic, voltages, etc. to service a Marshall JTM45, back in the day.

Small details and parts *designations* might not exactly match, but the whole circuit blocks should , I donīt see them redesigning anything.

In any case, what is the actual problem with yours you need to solve?

[tbonuss]

Juan my old friend, I hope this post finds you hale and hearty!

Thank you for the helpful response. I see what you mean for sure. Everything has actually tracked per se so far with the Ashton schematic (DSL) so far.

Lots of things wrong here, but I'm not really stuck yet. I don't want to get yelled at for posting in the wrong place, so I'd gladly post about the two "bonus" caps to ground in the DC power supply, if someone wants to school me on that...I thought that would just be a mistake on the Ashton copy, but Marshall does it too....so its got to be right, right?...I swear that would only serve to make it less "firm"...maybe some weird inrush i idea...i dunno...

Right now, the boost switch seems to shunt signal to ground (just very clean mutes it).
The caps in the DC power supply are "plump" and it drops to <5.5VDC if I stick the 4*el34's in it...
Bunch of flying resistor mods to up the gain. I suspect that was because of the literally cold ax7's. Maybe. I dunno.

Oops. I got carried away. I love this stuff. Mea culpa. Sorta'.

[J M Fahey]

Thanks, hope you are ding fine too

Of course this is a friendly mutual help Tech Forum, so feel free to post doubts as you go along.

That said, you mentioned the dreadful "mods" word, lots of worm cans there.

Personally I would return it back to normal, make it work, and then IF any, tweak something here and there.

[tbonuss]

Well thanks Juan. I will try to restore it back to original functionality if I can tell what that is...

An amp built to the Ashton schematic per se simply wouldn't make desirable amplifier sounds.

Right now, I've ordered some caps, and delivery is super slow where I live now. Seems like good order would suggest that I systematically fix the things that I "know" are faults.
As I very patiently return it to stock.

The other side of me just wants to attack the flying resistors gnats with a pair of nippers.

I'm gonna eat some turkey and see what happens.

Thanks again Juan, I appreciate your help.

[tbonuss]

[g1]

two "bonus" caps to ground in the DC power supply, if someone wants to school me on that...I thought that would just be a mistake on the Ashton copy, but Marshall does it too....so its got to be right, right?...I swear that would only serve to make it less "firm"...maybe some weird inrush i idea...i dunno...

Which caps, which DC supply? I'll take a guess you mean the two 1n caps across a couple of the diodes in the HV supply? But only one of those goes to ground. They are to suppress diode switching noise.
As for filter caps, extra capacitance will make things more firm, not less.

[tbonuss]

G1!

Thank you. Let me apologize for not clarifying that I meant the DC *FILAMENT* supply.

C11 and C13 just don't look right to me.

I wouldn't think that they are necessary, but I'm super okay with being wrong and learning.

Take good care,

Steve

[g1]

I meant the DC *FILAMENT* supply.

C11 and C13 just don't look right to me.

I wouldn't think that they are necessary, but I'm super okay with being wrong and learning.

Here's the TSL version, which is clearer. C1 & C3 the caps in question.
I would say they are providing extra filtering as well as a ground reference for the DC heaters. If there is more to it, I hope others will advise.

[tbonuss]

Thanks guys. It's just too hard. Schematic wrong, factory "mods" including flying resistors with duct tape insulation, components that were never soldered in place, two of the pots on the front weren't ever connected...but this was the straw...I can't interpret what they mean here. ...ripping everything out but the xfmrs, pots and switching board. It'll make a fine SLO Clone.

[g1]

That is very poor labeling. Sounds like aside from that, the amp is quite a disaster. Good luck with the rebuild.

[tbonuss]

It seems like this thing wants to be SLO Crunch and Dirty with Alembic F2B clean (with reverb).

I can create a thread on the build if there is any interest at all. As always, thank you.