Hello,
I have this amp opened up and am looking for a PA Schematic.
Chassis was QC'd in 1994
It is not either of the PA boards covered in the GP7 150-300W manual.
Although it is very similar to the Mosfet Power Board...Designators are different, values vary, and...
I do have a request in at Trace Elliot via E-mail...but no response as of yet.
Post a couple closeups and a transistor list, so we at least know whether it'ss Bipolar or Mosfet.
I don't think there were a dozen versions, just basically these two, an maybe some minor variations.
Upon closer inspection...
I have found that the Mosfet board is very similar... I did take some board shots and will trace it out as I get time...
2sk1506 and 2sj162...so that's not too fun.
Quote2sk1506 and 2sj162
Well, that already solves the mystery, it's the MosFet version.
Part labels mean nothing, you can name one PCB version starting left to right, another
exactly the same right to left and no designation will match, yet schematic is the same.
What mattgers is whhat's connected to what else.
I suggest you print a nice large copy of the schematic, if necessary in 2 sheets and tape them, and go over the PCB identifying parts and relabelling them (say, in red or blue or enclosing it in brackets) on the paper copy.
They might have not fitted some part, added a small capacitor for stability, changed some part value, etc. , no big deal.
Then you take a nice sharp well illuminated picture of the edited schematic and post it here.
By the way, what's the actual problem you are trying to solve?
So, say,
Yeah, I was on that track...have the PA board out, MosFets out, FilterCaps out...Tracing and Marking...Plenty of room for error. haha!
Anyway, T.E. dropped this to my inbox...below.
TR7 and TR9 are done for.
R13 is charred.
R3 is brown.
Was not blowing fuses, Was not passing signal, Was not brightly illuminating the lamp.
Transformer and DC rails be good.
STOP THE PRESSES
THAT SCHEMATIC HAS GROSS ERRORS
Shows that:
a) TR6/TR8 source pins go nowhere, they must be in parallel with TR7/TR9 source respectively, to drive the speaker out.
b) protective Zeners Z3/Z4 do not work because they are in series with D1+D2 out of phase and D3/D4, same error, which is an open circuit.
Maybe there's even others, but those are already enough.
Inform T.E. about the error so they correct it, can't believe it's an official schematic.
Will search for some I may have somewhere.
Good Eye!
I have alerted T.E. to the issue.
in the meantime...I have marked up the existing schematic with these corrections.
I breezed over the board node by node with the meter and did not notice anything else out of place.
I guess what I really need to do is figure out what/where I'm going to score the finals...
There are British made finals, for reasonable prices.
Search for Exicon, Semelab, Profusion PLC, etc.
One of them actually makes the dies in bulk, sells them encapsulated or to others for finishing and resale, under different brands, all are very good.
Most (all?) sell direct, even in small quantities.
Personally I'd replace all 4 , sell the 2 good original ones in EBay or in Corksniffers.com and buy a Ferrari with the $$$ remainder.
CorkSniffers.com
This domain name is FOR SALE
Hurry!
Once it's sold this domain will be gone!
Own it today for only $1395
Even for that domain they rip off all your limbs at that cost.
I'll be d*mned !!!!!
I thought it was a joke .... but it DOES exist !!!!
http://www.hugedomains.com/domain_profile.cfm?d=corksniffers&e=com
Even worse: they are looking over the shoulder, at the bottom of the page source there's a line of text stating that it was "seen at SSGuitar" and gives this thread address .
Big Brother is Watching You !!!!!
haha!
Looks like I can score Semelab BUZ901P/BUZ906P from Newark/Element 14....@ $70usd +shipping...
or the Gamble on a "respected" ebay dealer with pairs of the Hitachi version @ $15shipped = $30 total...buy 3 times the quantity needed for the same price...for 3X the headache? haha!
I would not buy them in EBay, period.
Strange that no bricks and mortar shops offer them, only EBay :(
That said, the Australians have them at $15 (Au) each, Newark's $70 each is nonsense.
http://www.altronics.com.au/p/z1450-2sk134-ecf10n16-n-channel-to-3-power-mosfet-exicon/
That said, if I had that amp on my bench, in Argentina, I'd straight modify it for IRFP240/9240 and call it a day.
$2.50 each, always available, so far no fakes.
Power and sound will be the same.
Please post a picture of the heatsinks showing the transistors, maybe it's not difficult for you to do.
Yeah, the $70 was all Four MosFets in the TO-247 package...I think with Shipping and what not, they work out to Approx. the same...Too Much!
Modifying the circuit may be the way to go. I will post some board shots when I get to the Lab computer.
Quote from: J M FaheySTOP THE PRESSES
THAT SCHEMATIC HAS GROSS ERRORS
...
Maybe there's even others, but those are already enough.
"You never find just
one roach in a kitchen".
Quote from: DrGonz78... for only $1395
A steal at twice the price. :lmao:
I had someone try and sell me "ozvalveamps" domains for China etc., they were giving me "a last chance to buy" as "somebody else was interested".
I pointed out that a website called "Australian" anything based anywhere else was pretty stupid, and besides, if anybody else tried that I would be after them like a shot for trademark "passing off" and cyber-squatting. They rapidly lost interest.
Altronics is an old and respected company, but I would certainly consider the modification
JM suggests.
Here is a sampling of shots...
Cool.
So you already got it with the TO247 plastics, I thought you'd have the TO3 metallics which of course are unobtainable.
That said, I LOVE the simplicity of Lateral Transistor power amps.
Pity they all but stopped making them.
If you decide to mod it for IRFP240/9240 remember gate legs match but Drain and Source are inverted.
No big deal, as long as you remember it.
I believe that I will go with the BUZ901/906p. The amount of re-fabricating to mount the IRF's Would eat up any savings that may be had.
Cool :dbtu:
The best solution is not universal, depends on each one's circunstance.
In my case, I'd have to order them from USA or Europe, and Customs makes my life miserable, so I always try to work with whatever's available locally, even if it involves mechanical work.
Post results :)
ok, should be able to finish up tonight... I need to verify my work and Reassemble... I dont know what the Idle Current draw for the Amp would be...
Will 800mA be enough to fire this up.
Should I use a larger Wattage bulb than 100W?
No! Start small and work up is the general rule, maybe as low as 20W to start, depending...
Try, observe, evaluate, repeat.
Good luck. :dbtu:
Of course I reassembled the amplifier bolted everything down and closed the lid....
well, I missed something....
bulb is bright
No Voltage on the rails
I just powered down the bench and locked the door.
Roly!
Thanks for the Guidance I'm Glad I didn't go ahead with the larger Wattage Bulb.
The reason I asked about the light bulb wattage is that I have a Sunn Concert Slave that Oscillates with a 100W bulb in series but operates normal on straight line voltage...and previous to this Trace Elliot, the Sunn was the largest SS amplifier I have ever worked on. I attributed the Oscillation to the 100W bulb not passing enough current to run the PowerAmp.
Ok, I hope to get back to this amp soon. Open it back up and figure out what I did wrong, or what I missed.