Ampeg PF500

[bsco]

Good evening....I did bring this up in another thread for differential probes.but decided to start a new one here.....I had received the parts the other day and installed them...two fets, 4 driver transistors,the HI-Lo driver chip and the two diodes...(the two 10 ohm resistors were fine)....it was a learning experience in using the hot air soldering/de-soldering technique...had to practice for abit.....got all the parts installed and viola....it is working great...will run it for awhile tomorrow before sending it back to it's owner....thanks for everybody's help...
Cheers

[J M Fahey]

cool
Show a gut picture or two so we know what you had to face,

[bsco]

Will do....I will get you one tomorrow.....I still have to practice the soldering aspect of it...the de-soldering wasn't that bad once I got the hang of it...have to get a bit more comfortable with the soldering...I have a few things to look at now that will require the use of hot air....kind of nervous working with something so small...

[The Dude]

FWIW, and maybe you already know this: Use plenty of flux when re-soldering SMD. It will help keep the solder where it's supposed to go and away from where it's not supposed to go.

[bsco]

cool
Show a gut picture or two so we know what you had to face,

Here you go J.M. as I do more of this type of soldering I would hope that I will get better as time goes on.....

[J M Fahey]

Thanks

Lots of little tingies there , but still looks "repairable" , sort of.
I have seen others (TC Electronics, etc.) wich were even smaller and more cluttered, we´ll have to get used to them.
And ICE Power and such even worse.

I imagine old repair guys when they saw the first Kustom and Ampeg SS amps in the late 60´s.

Oh well.

[glebert]

Thanks

Lots of little tingies there , but still looks "repairable" , sort of.
I have seen others (TC Electronics, etc.) wich were even smaller and more cluttered, we´ll have to get used to them.
And ICE Power and such even worse.

I imagine old repair guys when they saw the first Kustom and Ampeg SS amps in the late 60´s.

Oh well.

I think the PF500 layout is reasonable. I have one that I am working on and compared to an SVT7PRO it is quite roomy. I think the PF output section is very similar to 1/2 of the SVT (which is a bridged design).

[J M Fahey]

Yes.
Didn´t check the PF500 schematic yet but what I like about PF350 which should be similar is that it uses basically a "known" or "close to datasheet example" circuit and they show it in full, also using "found at Mouser" class components so it can be repaired at component level.
An amp which will also be repairable in the future.

Don´t start me on those lazy designers (Fender/GK/Kustom/TC Electronics/1000 more) who only design a preamp and stick an ICE Power or similar store bought power amp, with NO data at all .

Full board replacements are currently available .... for a price and not sure for how long.

Oh well, disposable mentality

[bsco]

The owner called me tonight and told me the amp is working great....he jammed with it for a couple of hours and all is good.....so now that will give me a bit more confidence in working on Class D SMD stuff.....

[bsco]

The owner emailed me over the weekend and said the amp went back into protect mode again....once I open it up and see what is wrong I will post here......
Cheers

[Axtman]

I recently repaired an Ampeg PF500. Instead of component replacement I just bought a new board ($180) and swapped it out.

https://www.fullcompass.com/prod/275...pcb-for-pf-500

[bsco]

I recently repaired an Ampeg PF500. Instead of component replacement I just bought a new board ($180) and swapped it out.

https://www.fullcompass.com/prod/275...pcb-for-pf-500

Thanks for the tip...I will check that out....
Cheers

[Axtman]

The internet is littered with people having problems with the Ampeg PF500. It seems the earlier version of the amp, especially Revision C had quality control problems. That said my faulty amp had revision J which I think is the latest version. The Ampeg PF350 and PF800 do not seem to have as many problems as the PF500.

I actually know the retired engineer, Rene' Jaeger at Ampeg that helped design the amp. I reached out to him for repair advise. He basically told me to check the FETs. He said when they go they take out other components. I was nervous about doing repair to this amp because of all the surface mounted components and that it is a Class D amp. I have had terrible problems with other Class D amps. Rene' recommended swapping out main boards like I did. It was expensive but and easy repair and so far my amp is functioning well.

[bsco]

the amp came back with one of the fets shorted again...bummer....I will have to go through it again to see if I can get it working again.....
Cheers

[Mars Amp Repair]

Hello folks,
I know the posts are 4yrs old, but I've found that trying to repair these Dclass amps is mostly an exercise in futility as you need to find matched FETS which I doubt are even available from Ampeg as they used to be for the SVT-Pros.
As AXTMAN suggested, it makes more sense to just replace the board for $180.00 with minimal time involved. Anymore my experience is that folks are just expecting the $500.00 1000watt amps that used to cost upwards of $2000+, are just disposable.
As BSCO indicated, the little bastards just keep coming back for reasons that are difficult to discover or understand AND when they crap out, it's a complete rebuild all over again as you never know what other parts the shorted FETS take out. Way too much lost labor for someone trying to make a living doing this not to mention the damage to the techs ego!
for the ones that are blown up, I've decided these amps aren't the hill I'm going to die on.
Just my take. More power to those who have more success with these amps that I believe were not built to be repaired in the first place.
g