# Restoring my amp



## circa40

I am in the process of restoring my PG MS1000ta and want to document the changes/upgrades to this amp. So far, I already replaced most of the capacitors in this amp, so there isnt many stock photos.

These boards are basically the same as the original MS2250/2125/1000 and MPS2500, so there are many parts on this board that was left off.

I've owned this amp for a while now, but never got to use it or work on it. This amp was pretty bad when I got it...blown fets, fuse resistors, resistors, and several flash marks on the PCB. One of the first things when I received this amp was to was clean it up and look for damages. This amp is mounted on my wall so fixing it and making sure it performs correctly wasnt really my first priority. This amp will still remain on my wall though. 

There are several areas on this amp that needs to be addressed which I will document if possible. I would love to replace those cheap gain/bass boost pots but still havent found suitable replacements or made sure if there are any other circuits that need to be added to modified for them to work properly. 

For the most part, this amp will retain stock value capacitors...except for the rail and filter caps, in which all will be replaced with higher capacitance. 

Replacement parts...
All caps are/will be from Nichicon, Panasonic, Cornell Dubilier (thanks Ace956) and possibly WIMA.
Bur-Brown OPA2134PA opamps with 8pin IP sockets 
Rail cap fuses (bypassed from PG)
New RCAs
new chrome and stainless steel hardware. 










































































Note diode D319, which appears to have fried in the past and took out some of the gold trace next to it. 










I will add pics when parts arrive.

Any tips on cleaning these boards? Cleaning it reminds me of cleaning windows, if done incorrectly, streaks will be visible and looks like poop.


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## envisionelec

circa40 said:


> I am in the process of restoring my PG MS1000ta and want to document the changes/upgrades to this amp. So far, I already replaced most of the capacitors in this amp, so there isnt many stock photos.
> 
> These boards are basically the same as the original MS2250/2125/1000 and MPS2500, so there are many parts on this board that was left off.
> 
> I've owned this amp for a while now, but never got to use it or work on it. This amp was pretty bad when I got it...blown fets, fuse resistors, resistors, and several flash marks on the PCB. One of the first things when I received this amp was to was clean it up and look for damages. This amp is mounted on my wall so fixing it and making sure it performs correctly wasnt really my first priority. This amp will still remain on my wall though.
> 
> There are several areas on this amp that needs to be addressed which I will document if possible. I would love to replace those cheap gain/bass boost pots but still havent found suitable replacements or made sure if there are any other circuits that need to be added to modified for them to work properly.
> 
> For the most part, this amp will retain stock value capacitors...except for the rail and filter caps, in which all will be replaced with higher capacitance.
> 
> Replacement parts...
> All caps are/will be from Nichicon, Panasonic, Cornell Dubilier (thanks Ace956) and possibly WIMA.
> Bur-Brown OPA2134PA opamps with 8pin IP sockets
> Rail cap fuses (bypassed from PG)
> New RCAs
> new chrome and stainless steel hardware.
> 
> Note diode D319, which appears to have fried in the past and took out some of the gold trace next to it.
> 
> 
> I will add pics when parts arrive.
> 
> Any tips on cleaning these boards? Cleaning it reminds me of cleaning windows, if done incorrectly, streaks will be visible and looks like poop.


Cleaning boards by hand is tedious and almost always looks like poop. I use a PCB washer specifically for this - it's like a dishwasher with chemicals and 20 wash/rinse/dry cycles. 

So, no idea...sorry.

What I want to know is - why does that capacitor near the RCA inputs have a TO-5 heatsink attached to it?


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## circa40

envisionelec said:


> What I want to know is - why does that capacitor near the RCA inputs have a TO-5 heatsink attached to it?


It was there when I bought the amp. I dont think its OEM PG. It was attached to the factory cap, when I replaced it I slipped it on the new cap. 

I cant imagine it ever needing a sink. Its kinda funny looking though :laugh::laugh::laugh:


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## circa40

Update...

Some of the parts that came in  Some are for other amps


















With some advice from my friend Cecil, I decided to mount these transistors underneath the board for better cooling efficiency (more sink). Similar to the way Soundstream/DLS/Zuki and others mount their transistors. 









PG uses clip on heatsinks. 









Taken off









I bent the leads at a 90* angle









Soldered underneath the board. I also used a little speaker gasket (adhesive lined foam) to isolate it from the board. 

















You can see that in the past, the transistors got so hot, the thermal paste basically melted and flowed all over the pcb


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## circa40

The closer I look the worse it is  

D319

















C227


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## envisionelec

C227 is a polyester that can't leak - there is no electrolyte. It seems someone was probing around it and accidentally shorted the trace to ground. Acetone is an effective carbon residue removal chemical.


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## circa40

envisionelec said:


> C227 is a polyester that can't leak - there is no electrolyte. It seems someone was probing around it and accidentally shorted the trace to ground. Acetone is an effective carbon residue removal chemical.


OK, thanks for the advice....one less thing to worry about  Yeah I've been using acetone for all of these flash marks on the board.

It looks like I'll have to clean up all of the flux residue with the acetone and then clean the whole board with alcohol as well. More elbow grease :laugh:


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## JAX

sigh...how I love old PG......


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## sqshoestring

That thing is a monster. I use acetone mostly, but I don't worry about them being perfect. Use a smaller paint brush to get behind things and spread it around. Lamp oil makes them shine, but collects dirt/dust, and I don't know if that is really good for them lol. I be one could spray vinyl protectant on it, the type that dries up some.


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## circa40

sqshoestring said:


> That thing is a monster. I use acetone mostly, but I don't worry about them being perfect. Use a smaller paint brush to get behind things and spread it around. Lamp oil makes them shine, but collects dirt/dust, and I don't know if that is really good for them lol. I be one could spray vinyl protectant on it, the type that dries up some.


Yeah it looks like acetone then alcohol does the trick at cleaning these boards...a major PTA and tons of elbow grease though.


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## circa40

Not much of an update today since Mouser messed up on my order and sent me the wrong rail caps. I'll probably have to wait until next week for the correct parts. 

I was able to install the rail fuses, since for some odd reason PG left them on in their anniversary amps. They used a buss bar to bypass them..perhaps they never blew? Anyhow, they are added now. 

These are the rail fuses in my original MS2125









These are the new ones in my MS1000ta









I went ahead and replaced the factory current draining LEDs from blue to white.










Some people ask me why do I replace the capacitors in these 15-20yo amps.
This is why









I didnt get too much done today on the amp i am supposed to work on since I dont have the correct caps. I did however get a chance to do a total recap on my PG MS2125, Outlaw, Bandit, M44 and Audio Art 70.2. 
Graveyard of old ass caps.









Im doing my soundstream reference 300 + 200, PG MPS2500/2240 this weekend. Further carnage to be continued :laugh::laugh::laugh:


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## MarkZ

One thing to keep in mind is that not all transistors generate the same amount of heat. So if you couple some to the main heatsink, it could actually heat them up more than they otherwise would.


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## circa40

MarkZ said:


> One thing to keep in mind is that not all transistors generate the same amount of heat. So if you couple some to the main heatsink, it could actually heat them up more than they otherwise would.


Good point. I'll have to look into that


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## envisionelec

circa40 said:


> Good point. I'll have to look into that


If the main heatsink got as hot (or hotter) than those transistors, the amp would thermally protect itself. There is no harm in doing what you did. Those transistors do get hot, but that's part of the reason the amp sounds so good. (Not the heat...but their function).


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## envisionelec

circa40 said:


> Not much of an update today since Mouser messed up on my order and sent me the wrong rail caps. I'll probably have to wait until next week for the correct parts.
> 
> I was able to install the rail fuses, since for some odd reason PG left them on in their anniversary amps. They used a buss bar to bypass them..perhaps they never blew? Anyhow, they are added now.
> 
> These are the rail fuses in my original MS2125


Uh...the LEDs aren't for current "draining", they set the constant current source operating point in the amp's front end. Please do NOT change them unless you know exactly what you're doing. 

It reminds me of the guy that changed all his RED LEDs to Green because they'd match the rest of his gear. Little did he know that he just increased his kilobuck PG amplifier's distortion by several magnitudes.


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## MarkZ

envisionelec said:


> If the main heatsink got as hot (or hotter) than those transistors, the amp would thermally protect itself. There is no harm in doing what you did. Those transistors do get hot, but that's part of the reason the amp sounds so good. (Not the heat...but their function).


It won't do much harm, but it won't be of any benefit either.


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## envisionelec

MarkZ said:


> It won't do much harm, but it won't be of any benefit either.


True. I don't remember one failing from getting too hot. Too hot to touch is OK for most semiconductors. What you _can_ screw up is heat sinking parts that are supposed to be hot or aware of their ambient conditions. PG obviously knew what they were doing - that amp was built this way for the better part of a decade with little change.


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## circa40

envisionelec said:


> Uh...the LEDs aren't for current "draining", they set the constant current source operating point in the amp's front end. Please do NOT change them unless you know exactly what you're doing.


OK, im glad I didnt trash those OEM LEDs, I try to dig them out and reinstall them, thanks!



envisionelec said:


> True. I don't remember one failing from getting too hot. Too hot to touch is OK for most semiconductors. What you _can_ screw up is heat sinking parts that are supposed to be hot or aware of their ambient conditions. PG obviously knew what they were doing - that amp was built this way for the better part of a decade with little change.


Well, I guess the best part of this is that it can be reversible....although disassembling and putting back together is a pain.


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## mhyde71

*subscribed*


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## itchnertamatoa

very nice work Vin
is this the MS1K that was on your wall ???


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## marko

looking very good, can't wait to see the finished article


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## circa40

itchnertamatoa said:


> very nice work Vin
> is this the MS1K that was on your wall ???


Yes sir, thats the one


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## mhyde71

oh snap- thats you huh vin???

say i still have your plates here for plating... hope you havent forgotten...
I am assuming that these plates i have here for plating are for this project here?

Shoot me PM if you would like to discuss the end game of these getting plated.
I have not gone to bring the stuff yet for plating... but i have done 80% of the prep of the parts need to go and i will be finishing up on those this week/end... and looks like i will be dropping off on monday. 

need to chat with you about them... and all that stuff... wrote to you like 4-5 months ago on the other forum.. but havent heard back yet... glad i stumbled upon you here though... 

matt


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## circa40

mhyde71 said:


> oh snap- thats you huh vin???
> 
> say i still have your plates here for plating... hope you havent forgotten...
> I am assuming that these plates i have here for plating are for this project here?
> 
> Shoot me PM if you would like to discuss the end game of these getting plated.
> I have not gone to bring the stuff yet for plating... but i have done 80% of the prep of the parts need to go and i will be finishing up on those this week/end... and looks like i will be dropping off on monday.
> 
> need to chat with you about them... and all that stuff... wrote to you like 4-5 months ago on the other forum.. but havent heard back yet... glad i stumbled upon you here though...
> 
> matt



Nice hearing from you Matt, I sent you a PM. 

I havent visited or logged in that forum in a long, long time....heck I might not even remember my login :laugh:


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## circa40

Metal film resistors, rail caps, and Wima caps 










I'll work on it when I have the chance this weekend


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## circa40

I didnt get too much done today as its too damn hot in the garage. I did manage to replace some of the resistors and install the rail caps. 

I bought about a 10:1 ratio of resistors (10 pc for every 1 that I needed) so I can double check and select the resistors that was closest to the factory spec. These resistors are pretty damn close to spec though.









I like to pre-tin these caps as well as the solder pads where the caps sit. 

















PG likes to use a little silicone were the cap touches the board. Seems like a good idea to me so I did the same.









My friend Cecil recommended that I place a small bead in between the pins so if it ever leaks its harder for the cap to short out....great ideal IMO.










Soldered









Clip the excess leads then clean up.


















More updates when it cools down a bit and when I have free time to work on the boards.


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## AVIDEDTR

lovely work..I always admired the O/S Pg amps.


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## circa40

I want to replace those disk capacitors with poly caps and I was wondering if anyone knows where I can find poly film caps thats 83pF 500v? All of the ones that I've found on Digikey or Mouser have been discontinued  



AVIDEDTR said:


> lovely work..I always admired the O/S Pg amps.


Thanks! I hope I can get this amp up and working in a week or so.


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## circa40

I finally got some time to work on the amp today....

I found the OEM LEDs and reinstalled them....luckily didn't trash them

To properly do the transistor mod I had to sand down the powder coating beneath the boards. The easiest way that I can think of to remove the coating was to simply use a orbital sander. I started with 60 then 220 grits then finished up with 400 grit. 










Factory isolator pad with rectangles cut out for the transistors.



















Im waiting for some screws thats supposed to arrive today. If I have time I'll assemble the boards today...thats if it doesn't get too hot out.


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## circa40

I had a chance to work on the 1/2 the amp yesterday.

Thermal paste on the under board transistors. 









Believe it or not these gold screws took forever (and a PTA) to get...and wayyy overpriced for what they are 



















I didnt want to spend much more cash so I used chrome bolts for the transistor clamps. 





































I'll have to check to see if any parts of the board is accidentally grounding out tomorrow


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## circa40

Final update for this thread. 

I got both boards up and running today. All four channels run flawlessly so far. 
The amps ran upside down for about an hour and the only section that get hot is the middle of board where I reverse mounted the transistors. Otherwise the sink stayed slightly warm.




















Quickie connections









Just in case if anyone doesnt know what the backside looks like 









The crappiest sounding tweeters in the world! Absolutely no bottom end...I guess it doesnt hurt much since they cost about $4.99ea 










The only concern that I have so far is that the amp appears to consume only about 1.5A at idle (only power hooked up). The bias adjustments may be way off?  I may be wrong though. 











For comparison purposes I hooked up my original 2125 and it drew about ~3.8A at idle. hummmmm


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## marko

i've just done my 3 original ms2250's and they pull about 4 amps on idle with no load.. 1.5 does seam very low but then again yours are ms2250 "TA" editions so might be a little lower..

what size thread are the clamp bolts? i'd love to swap mine all out for gold ones some time..

Mark.


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## circa40

marko said:


> i've just done my 3 original ms2250's and they pull about 4 amps on idle with no load.. 1.5 does seam very low but then again yours are ms2250 "TA" editions so might be a little lower..
> 
> what size thread are the clamp bolts? i'd love to swap mine all out for gold ones some time..
> 
> Mark.


I wish my 2250 wasn't storage, I would check it as well. 

The clamp bolts are 6-32 .625" long.


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## Mr.Lovr

circa40 is so kahrayzay brah!! 
:thinking2:


I think I luv him :bowdown:


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## circa40

Mr.Lovr said:


> circa40 is so kahrayzay brah!!
> :thinking2:
> 
> 
> I think I luv him :bowdown:



humm, I took a few days and tried to analyze what this means....Im still not sure what you're getting at lol. Thanks though...I think :laugh:


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## manina

I can not see the Wima that you mentioned earlier - did you installed them or I just need a new pair of glasses?

Nice work, BTW


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## circa40

manina said:


> I can not see the Wima that you mentioned earlier - did you installed them or I just need a new pair of glasses?
> 
> Nice work, BTW


I didnt order enough and didnt want to reorder. I decided not to use them after all since the factory caps were already film caps, just not "wima" labeled


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## envisionelec

circa40 said:


> I didnt order enough and didnt want to reorder. I decided not to use them after all since the factory caps were already film caps, just not "wima" labeled



Good job!

It's best to leave ceramic disc capacitors alone - they're not used because they're cheap - but because they're fairly lossy. This is exactly what the designer wanted.


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## circa40

envisionelec said:


> Good job!
> 
> It's best to leave ceramic disc capacitors alone - they're not used because they're cheap - but because they're fairly lossy. This is exactly what the designer wanted.


Thanks! 

I'm bringing it to my amp tech this weekend for a power test and to pick up some of my other amps that he repaired in the past.


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## jacampb2

I thought that amp and it's story sounded familiar. I thought you had decided to leave it blown and just make it wall art forever. I'm glad you decided to take on the repair-- now, where is the plexi I made for you??? Is it still part of the display? And, do you still want that M22xx one we talked about way back?

Good to hear you are still alive brother!

Later,
Jason


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## lust4sound

Mr.Lovr said:


> circa40 is so kahrayzay brah!!
> :thinking2:
> 
> 
> I think I luv him :bowdown:


Yup, I was thinking the same thing, crazy. If he lived next door, he'd be my best bud..

Looks incredible BTW..


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## JAX

Good job Vin. I love that amp.


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## 9mmmac

circa40 said:


> It was there when I bought the amp. I dont think its OEM PG. It was attached to the factory cap, when I replaced it I slipped it on the new cap.
> 
> I cant imagine it ever needing a sink. Its kinda funny looking though :laugh::laugh::laugh:


The only thing I can think of (and I ain't no electrical engineer; not even sure if I can spellz it...)- maybe it's because the cap itself made some kind of whiny harmonic? Haven't some people posted about power supplies making physical noise? Maybe it's some kind of restraint collar and makes the cap shut up


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## h1-vltg

Reading through this old post is making me itch to dig out my old PG amps (MS2250, 2 X MS275 and MPS2500)...and start by recapping them.


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