Servicing a PG 3.0X with new caps/op amps/output transistors

[trickyricky]

If this is the wrong place to put this post then mods please move it to the correct spot. I just figured this was the right spot since it states "Rebirth of the Phoenix" and thats exactly whats going on with this old school beauty, lol.

I am in the process of replacing a boat load of components in my PG 3.0x. Why you ask, because I had excessive DC on my speaker terminals also left channel was about 3.5v different than the right channel (was worse before I started replace a few blown resistors and output transistors).

So far I removed all wet caps and op amps (BA4560), four transistors (211,212,111,112) to be replace with MJE15030G/MJE15031G, dont know if I should go ahead and replace the Toshiba output transistors (they seem to be okay, not shorted) but if so I'll replace them with Motorola's that are compatible (Motorola MLJ4302A and MJL4281A). As for the op amps I will probably upgrade to OPA2134PA or just keep it stock BA4560 (haven't made my mind on that one since the 3.0x has 6 op amps thats a lot of money for op amps, lol).

I'll post more pics later today or with progress and where am currently at. Oh by the way I re-flow the solder on the power, speaker and RCA pins because some of them where breaking off (too much force when hooking up the RCA's, power & speaker cables) <<-- thats why am very careful and take it nice and easy when hooking up an amplifier, can't never be too careful, lol.


If anyone has any tips or revisions/mods for this amplifier please notify me (pm or post here). Am also thinking about going slightly bigger on both the 12v side and rail caps. Nothing crazy aslong as it fits and have a long life at 105celcius. Thanks.


SPECIAL THANKS TO my friend thats helping me on this one... you know who you are and I'll see if you dont mind me posting your name, lol.

1000uf 16v caps leaked, hard to see when they were in place. Easy to spot once removed.

1000uf 16v caps location cleaned off. I use alcohol and a fiberglass brush to remove the residue.

1000uf 50v caps, once I removed them I notice right away leakage. Again almost impossible to see when on board.

1000uf 50v caps location cleaned.

Bottom of pcb with all parts removed. Before I do any soldering I like to give the via pads a good brushing with my fiberglass pen, then add a tiny bit of flux and boom goes the dynamite.

[IsakAlexander]

Is it the one with white cover and logo on?
Post some more updated pics
Which type of caps did you use to replace the seven 1000uF/16v?

[trickyricky]

No i went higher in both voltage (25v) and capacitance. I'll post pics in a minute, it it's white.

[IsakAlexander]

I´ve bought new caps for both of mine. New Panasonic FC for both 1000uf/50v and 1000uf/16v. The original caps had a silver/blue isolation? Can´t remember the type or model

[trickyricky]

I think they are "ec", I'll have to double check but mouser carry them (if am not mistaking). I have to upload recent pics.

[IsakAlexander]

The crossover on this, does it work both on amp and xover out connectors? The manual are for the first edition without the xover out and also the cutoff are different fom 30-600 on the first and 15-300hz on the white later model. Lowpass at 15hz seems a bit low

[trickyricky]

Yes, if you use the low xover then your xover out rcas will be high pass. I don't recall checking the low pass when set on 15hz, but i believe it's more like 25hz....already that's what it sounds like i would have to see the output signal with my scope to see where it actually starts to roll off.

[IsakAlexander]

So one has to choose either low or high pass? Maybe that is why many people arent impressed with these. Should be some way to bypass the xover since my hu does all processing/crossover and I dont need a extra 12db filter in the signal path.

[trickyricky]

So one has to choose either low or high pass? Maybe that is why many people arent impressed with these. Should be some way to bypass the xover since my hu does all processing/crossover and I dont need a extra 12db filter in the signal path.

Yeah that is possible. Just skip the crossover OP amp and directly into the pre amp section.

[IsakAlexander]

Any chance you could mark where to put the jumpers and cut the circuit trace on your picture? I wouldnt know where to bypass it without a diagram.

[trickyricky]

U101 is the pre amp, all other OP amps are part of the crossover section. Ask one of the pg techs here if it's possible, i believe it is just as you mentioned a few cut traces and jumpers.

The schematics i have are blurry and hard to tell if there's a trace already that send the input signal straight to the pre amp (it's labeled w101/w201 but not sure if it's an open trace or what it's purpose.....maybe for this mod, now that would be sweet)

[IsakAlexander]

"There is a jumper denoted in my documents W101 and W201 if this jumper is connected it will bypass the crossover section effectively jumpering the signal from the input RCAs before compensation to the input of the gain circuitry at switch 101 which is your high pass low pass switch in front of the gain control stage.
Or you can hard wire the pin of left RCA to R101 on the side that is connected to the crossover switch. And your right RCA pin jumps to R201 again connected to the switch side of that resistor. This mimics the jumpers denoted on my information W101 and W201...hope this helps some...

You can also lift the end of the resistors connected to the switch listed above if you want the crossover completely out of circuit"

Quoted from
1moreamp
over at diyaudio

How cool is this? Finally we can explore the sound quality in these without a crossover to worry about.

[trickyricky]

I'll take his word any day. I knew it was easy to do but i haven't experimented and i didn't want to give the wrong advice/instructions.

I might just do the same but i just dropped new OP amps in it, lol.