Winston GA-200 revisited

Burns, Selmer, WEM, and more

Winston GA-200 revisited

Postby Racing on Fri Sep 11, 2015 1:21 am

You oldtimers know that i´ve been into a Winston amp or two.
The story i guess you know by now,and..if not just search for the old posts on GA-200 and PA-200.

Anyways.
I just recently bought yet another GA-200 down in Germany,this one though lacking its stock wooden cab.

Image

Image

Someone had gone through the trouble of fabbing a sheet metal one for it instead. Judging by the pics i was like..to hell with it,but TBH all said and done and amp in hand.. Someone did their homework on this one. Fits great and really covers all the bases. All in all IOW..it´s just plain different.

Image

According to the seller the amp had an issue,and that was that it hummed more then it should. Amp was to be ok otherwise. Having taken delivery of the unit and unwrapping it showed that it was basically dirty. That was it,and many a time..old amps that are dirty is a good thing. Normally means that within reason the amp´s been left alone.

Image

Struck me as bit of peculiar. All that work as far as the cab...and the rest of the amp looked like it hadn´t been tampered with. At all.
It was all there.

Image

Yep. Even the powertubes survived the trip from Germany up here (Sweden).

Image

Uhu. The good ol´ stuff. Telefunken brown base.

Image

Like stated. Someone had really done their homework. Stock that piece right there is lacking. Instead the chassis bolts to the floor of the wooden cab.

Image

German style. The thing here is that the supersized "JMP wannabe" chassis coupled with German engineering means that the components basically needs a cellphone to speak to each other.

Image

Someone HAD been at it. Them there solderjoints sure ain´t stock,i´ll tell you that much! Took to checking every e-lyte in sight for capacitance and ESR. They all checked out.
Solderblobs like that tho are a friggin abomination why i took to stripping some fresh meat out of the wiring and redo the entire thing. As it SHOULD be done.

Image

Only thing PCB of the amp that sees any real power is the PSU card. They all seem to share the same PSU fwiw,so..nothing new there really. However..notice the fuseholder the closest to us. That there didn´t look all that promising..

Image

In a way these are hybrid amps,then again in a way not. The DO carry transistor entry stages but...basically they´re there to boost signal ever so slightly before letting the signal hit the ECC-808´s onboard.
The left tubesocket is the second gainstage for each channel respectively. The tube to the right in turn is an ECC-82 that is used for the tremolo.

Image

A feature,or whatever you want to call it,of the Klemt/Echolette amps is that most of the later ones all sports longtailed pair phaseinverters. Just as any Fender or Marshall out there. Just that this one ends in a presence setup that is actually usable. The tail of the PI is headed for a multiposition switch that sets the center freq for the presence followed by an intensity pot for the same. Rather neat setup really.
It all ends vs the powertubes with a quartett of 100nF caps.

Image

Quartett? Yeah. See,bias is individually adjustable pro tube. All them Winston amps sports that setup. So...bias was reset. Wasn´t off by all that much. Then again..Telefunkens that been run a little while and...well. I rest my case.

Image

The stock old DIN standard mains jack was scrapped and an IEC jack installed in its place. The leftover hole to the right is for a "mains out" socket and as we sure as hell ain´t gonna have any of that...that was deleted.

Image

The stock DIN mains jack has safety ground running through the jacks chassis into the amp chassis. With the IEC jack that needed to change,so a separate solderlug was installed to the chassis.
Speaking of which...take a look at the refreshened solderjoints for the e-caps..and compare to above.

Image

Ah! The suspect fuseholder. Indeed it had seen some severe abuse so i took the solderwick to it and cleaned the entire thing out before reinstalling it all. While at it i hit every one of them joints with the pen.
Amp had surely seen one SERIOUS crossover at some point.

Image

"Amp hums". Ok.
Now...the heater circuit for the powertubes had seen some serious action (the amp sports two,one for the powertubes and one for the preamp). Well,seing that... the one for the powertubes sees ground reference by simply tying one of the taps to ground. Now that ground solderlug is held in place by one of the rivets that hold a powertube socket in place. In such a scenario it sure as hell helps if that rivet isn´t completely loose.
In turn the balance pot for the preamp heaters had been omitted and was replaced to work in the same manner the powertubes SHOULD have done...by hardwiring one of the taps to ground.
So. I took to tossing all of that out of there and replaced it with trimpots vs ground to be able to adjust balance for both windings. Bingo. Amp went WAY WAY WAY down in idle illness.
Now..the last straw as far as that is a Winston specific one. See...the PSU card hits chassis ground via one of its four bolts. The ones i´ve been into..ALL of them have had the nut that handles the torq for this basically no more than finger tight. No good,so..tightened down on that M4 nut..and we had ourselves an amp dead silent in idle.
At wide open all you hear is a slight hiss. German engineering....nuff said.

Image

As much as most of what´s under the hood was untouched that there can was busted and see..it´s the can that holds the photoresistor and bulb for the tremolo. Then it helps if it doesn´t let light in hip-hap. So..some superglue to mend what was cracked and some electricians tape to make it all dark within again and indeed..we had ourselves a WAY "deeper" trem.

Image

A good clean. Electronics and clean is always a good idea. Big difference vs what i unpacked at least.

Image

Right. Had a couple of them stock solder supports surplus from my PA-200 which came in handy. So..tossed a few new resistors at the PI and a few caps...presto...PPIMV time.
On that note.
These amps are INSANELY loud (just like the Peavey Roadmaster i just did) and hence some means of controlling output volume is needed. In my case i more often then not settle on PPIMV for this,with IMO real good results.

Which brings this one to a point where we have ourselves a clean and well working GA-200 again. Most likely built in 1969. Now for what to do with it....
Stock is out. That much is at least clear. These are clean amps and clean amps ONLY stock.
The PPIMV let´s it run balls to the wall and..indeed it WILL distort but hey... :lol: . We´re way off even JMP levels here.
Racing
Squire
 
Posts: 749
Joined: Wed Dec 21, 2011 11:07 am

Re: Winston GA-200 revisited

Postby Racing on Sun Sep 13, 2015 1:18 pm

Gave the whole concept some thinking and i arrived on that a "combination amp" was the ticket.

Ie;one that handles guitar really well and in turn handles bass at a rate where bassist at least don´t shy away from it.

At that time i also considered how to handle this from a tech point of view. Gave Tubetowns turretboards a moment...but..nah. Got a few of them stock ceramic soldersupports laying around since previous Winstons so...let´s keep this one all Winston shall we.

Image

Image

So. By rethinking how the stock setup was done i freed that soldersupport installed by me up...and thus we have the materials needed to make this thing go full circle.

Image

The amp was at this stage well behaved to say the least. No matter..new is new and hence i replaced the resistors of the PI with modern day n era metalfilm ones.
The idea of mine is to put an amp together for pro USE...

Image

Yep. Tremolo is out. Cleaned the entire preamp out and rewired the heaters. Now with way more stringent twist to the heater wiring.
Idea here is simple.
Going to make this thing turn all tube...


...one Winstons GA-200 for modern day n era rocknroll coming up boys!
Racing
Squire
 
Posts: 749
Joined: Wed Dec 21, 2011 11:07 am

Re: Winston GA-200 revisited

Postby Racing on Sun Sep 13, 2015 1:23 pm

The only way is forwards gentlemen so...

Image

Going hardwire has a tendancy to look like a snakepit in heat. Keeping it this "short" though...nah. We´re good. At least in my book. Anyone that opens this amp up eventually and knows a thing or two will know what´s he´s looking at,which is good enough for me.

Image

You live and learn. The transistor preamps has been deleted and kept intact. Been replaced by a couple of pieces of cut to fit aluminium sheet metal.

Image

Amp had been worked on before. That brought that the insulating washer for the last of the two electrolytes in series was missing. Someone had obviously missed out on what it does. So..one was installed...aaaaaaaaaaand....

Image

Headed right here. As stated these amps do NOT comply to "the golden rule" stock,and as we´re to push amplification factor up...like into orbit,it friggin needs to.
Might be that the boys at Klemt thought-"to hell with it"-seing the rather limited amplification factor. I have a hard time seing that they didn´t know what they were doing,and indeed the stock amp is silent as they come in idle.
However..that is with a real limited amount of amplification...and as i´m to turn this into a roaring rocknroll amp..that reasoning simply won´t do. Hence...time to make "the golden rule" apply.

The whole thing works as such that the bridge negative runs for the standby switch. A solution that carries tech merit but..lacks out from a practical point of view as no tech these days gives the mere thought of a negative standby cut a second thought.
What?
Well. What such a setup brings is that IF you cut power via the standby...and then pick the amp apart it is possible that the circuit within still retains hundreds of volts...and you´ll get zapped as you won´t give this a second thought.
Anyways.
From the bridge negative to the standby switch and that switched is "looped" by a 10k ceramic resistor. From there the whole thing runs for the PSU card "stud" that heads the whole thing into the chassis. To act as chassis ground.
Well.
Before it hits that stud there´s a fuse... So what i did was head the grounding of the first in series pair of electrolytes for that point. The "off" side of the fuse.
Mission accomplished.

Image

These two in turn serves the rest of the preamp. The tangs of their grounding washers are tied together,so separated those and ran groundwiring from each stage to the e-lyte that serves it. THEN tied the two e-lytes together,to head for main chassis ground.

Well.
Next up is drilling a hole for yet another noval socket. The socket that´ll form the preamp for the "bass" side of the amp. Rail voltage has already been headed where it needs to be so...a solder support and i´d say we´re in business.

What´s more i plan to implement dual PPIMV´s. These will be controlled by an LDR...as most guitarist ask for a "solo boos"..well,this is it.

In short?
Well gentlemen...to be continued.. :say_what:
Racing
Squire
 
Posts: 749
Joined: Wed Dec 21, 2011 11:07 am


Return to Miscellaneous British Amplifiers

Who is online

Users browsing this forum: No registered users and 6 guests