Wicks Posted June 10, 2014 Report Share Posted June 10, 2014 Time to refurb another old school classic. This is a Precision Power (PPI) Art Series A404 and in really good condition considering it's close to 20 years old. PPI Specs: 4-Channel Model: A404.2Continuous Power Output per Channel, x 4 Stereo, x2 Bridged4 Ohms, 11-15 VDC, Stereo: 50 Watts2 Ohms, 11-15 VDC, Stereo: 100 Watts4 Ohms, 11-15 VDC, Bridged: 200 WattsPower Fuse: 50 AmpDimensions (inches): 2x9.25x13"Shipping Weight: 8.5 lbs. Gave it a test run to see how it would perform before the refurb. Voltage swing (unloaded) on the front right output: About 15.7 Vrms Voltage swing (unloaded) on the Rear channels Bridged: About 30.4 Vrms Signals look pretty clean and close to what they should be. Lets start the tear down. Popping off the bottom cover I bought this used off of eBay and I can tell from the Kapton (yellow) tape (not original) and rubbed off FET markings that this amp was previously reworked. Even more reason for me to refurb it and verify that the correct parts go in it and that they are matched. FETs from different date or lot codes could have slightly different characteristics which could affect the performance of the amplifier. You can also notice the leftover flux residue and re-soldered (shiny) pins. Here is the power supply. Look down the board Signal input side of the board Board pulled from the chassis The bare chassis Top of the board Bottom of the board More evidence of prior rework. Flux residue and a "FULLPACK" TO-220 MOSFET (fully plastic encapsulated). They tend to have more thermal resistance and aren't used in such amplifier designs. They would tend to be sticking up in the middle of a circuit board where thermal issues aren't as importnat and where they need to be insulated from shorting out against something. Some of the old crusty thermal paste which needs to be refreshed for better thermal conductivity. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Soccerballzs Posted June 10, 2014 Report Share Posted June 10, 2014 Going to sound great with new mosfets. Clean for age. http://www.stevemeadedesigns.com/board/garage/vehicle/2438-jeep-commander/I Pioneer P99RSAmpere 38002-Ampere 125/44-6.5 inch Hertz HSK XL Mids4-8 inch JL Audio ZR Midwoofer 2-5.25 Satori Mids2-Morel Tweeters, 2 Hertz Milles 3 inch on A pillars2-Hertz Silk tweeters DC Audio Level 5/12 Skyhigh Wire Mechman 320 XS Power D3100MO Funniest Thread of the Year 2013: http://www.stevemead...dy-being-a-pos/ Link to comment Share on other sites More sharing options...
Mtnbikecrazy55 Posted June 10, 2014 Report Share Posted June 10, 2014 Awesomeness. I hate long signatures.... ...what the fuck is wrong wiht you you fucking fuckity fuck fuck head... Mtnbikecrazy55 Feedback Link to comment Share on other sites More sharing options...
Wicks Posted June 10, 2014 Author Report Share Posted June 10, 2014 Here are the "plugs" that PPI used to allow for easier install and removal. Notice how dirty the connection posts are. That will need some cleaning. Pulling the electrolytic capacitors Tested the capacitors on an LCR meter to look at their condition. Still in spec and not too bad. These are the 12V input caps which smooth the B+ voltage coming into the amp. Notice PPI used 50V caps. Over rating the caps is a good idea but overrating them by 35V is excessive. I can replace them with 25V caps which will allow me to increase the amount of capacitance at the input Here are the power rail caps. Interestingly PPI used the same value of cap for this part of the circuit. I would guess that both are compatible in each circuit and by using the same cap, PPI would be purchasing more of the same part which would lower their costs. Here is my replacement for the 12V caps. I chose Panasonic 2700uF 25V caps. Still plenty of voltage rating (2x) with an increase in capacitance of 2.7x and a reduction of ESR (Equivalent Series Resistance) by 1/3. My selection for the power rail caps. Panasonic 1000uF 50V caps. Same value as before but you can see that the new caps do have more capacitance (987uF vs 826uF), a better Dissipation Factor and a much better ESR. A lower ESR will cause less internal heating to the cap and better release of current. Also a longer life due to less heating. Ready for FET removal. Best way to remove the output transistors...just clip them off. All outside FETs/transistors removed This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Wicks Posted June 10, 2014 Author Report Share Posted June 10, 2014 Oxidation on the connectors Cleaned up with a "Flux Off" cleaner. Dare you to say "Flux Off" quickly ten times......... Solder on the fuse holders was a little weak looking Added some flux and re-soldered This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Wicks Posted June 10, 2014 Author Report Share Posted June 10, 2014 Since I was upgrading parts, I looked around the board and saw the opamps LM833's are pretty basic. I did some research and found a LOT of great reviews for LM4562's. http://www.ti.com/product/lm4562 The LM4562 is part of the ultra-low distortion, low-noise, high-slew-rate operational amplifier series optimized and fully specified for high-performance, high-fidelity applications. The LM4562 audio operational amplifiers deliver superior audio signal amplification for outstanding audio performance. The LM4562 combines extremely low voltage noise density (2.7nV/√Hz) with vanishingly low THD+N (0.00003%) to easily satisfy the most demanding audio applications. To ensure that the most challenging loads are driven without compromise, the LM4562 has a high slew rate of ±20V/µs and an output current capability of ±26mA. Further, dynamic range is maximized by an output stage that drives 2kΩ loads to within 1V of either power supply voltage and to within 1.4V when driving 600Ω loads. They're also relatively cheap. DigiKey had them for ~$3ea Installed the new opamps Time for the new FETs and transistors The power supply used IRFZ44's which are rated at 60V and 57A with 230A of pulsed current and 12mOhms of On-resistance. I selected ST STP75NF75 FETs to replace them which are rated at 75V and 80A with 320A of pulsed current and 11mOhms of On-resistance. These are the same parts I used in my Rockford Fosgate Punch200DSM refurb and its worked great over the past year. Power supply rectifiers were a combination of ST BYW29F and Vishay FESF8DT. Rated at 8A. I didn't like using a combination of two different parts so I replaced them all with ON Semi MUR1520 which are rated at 15A. 12V Input caps ready to be installed. Inserted Here's a trick if you need to flip the board over to solder the parts and don't want them to fall out, just flare the leads out. Rail caps ready PPI uses transistors in the output section rather then MOSFETs so I had to make sure to replace them with appropriate parts. The board had BDT81 and complimentary BDT82 transistors which are rated for 60V and 15A. I couldn't even find those parts anymore so I needed to look for a similar replacement. I found ON Semi 2N6488 and 2N6491 transistors rated at 80V and 15A. These are widely used and well regarded You need complimentary NPN and PNP parts as one conducts the positive voltage rail and the other conducts the negative power rail. Parts loaded This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Wicks Posted June 10, 2014 Author Report Share Posted June 10, 2014 Looking at the bare chassis, it has a bunch of old crusty thermal paste on it Thermal paste is MESSY so I decided to just rip off the old tape and add some new. New tape ready to go The Kapton tape (or mica sheets) are needed to insulate the FETs/transistors as the metal tab is exposed to the rail voltage which would short out on the chassis otherwise. Ready for new thermal paste Test fit before I add the messy new paste. All parts fit evenly against the chassis. Paste added and board installed This is the bottom cover, notice all the "fingers". PPI uses those fingers to hold down all the FETs/transistors. Therefore you should NEVER run an old PPI amp without the bottom cover. Some of the parts could easily overheat. I'm not a big fan of this design, but it is what it is. As a precaution, I used a needle nose pliers and bent all the fingers out a little to make sure they all made good contact. Bottom installed BOOM Refurb complete! Time for testing! This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Wicks Posted June 10, 2014 Author Report Share Posted June 10, 2014 I connected the amp to a bench power supply and fed it a test tone with my iPhone. Here's the unloaded voltage swing on the Front Right channel, same one I checked before the test. 15.9 Vrms. Here is the rear bridged channels. 31.4 Vrms Minor improvements but I didn't expect it to be anything drastic. The unit works and the signals are CLEAN. I'd love to send this to BIGDWiz and see just how clean it is, especially with the new opamps... I connected a 4ohm power resistor load to the amp to pull some current through it. Here is a front channel Here is a rear channel Looks like a solid, consistent and unclipped 56W per channel which is right on the specs. Can't wait to get this in the M3 and really give it a test run. This post sent with 100% recycled electrons. 2004 BMW M3Mechman 280A 2 - XS Power XP30001 - XS Power D375 500F of Maxwell SuperCaps (soon to be 1000F) iPadMini2Dash mounted O-scopeAudison bitOne (Remote DRC MP) Highs Amp - PPI Art A404 Hertz HSK130 (HSK165 waiting...) DC Audio DC9.0K 2- DC Audio XL12m2LEGAL - 147.3dB @ 41Hz OUTLAW - 150.2dB @ 45Hz OUTLAW - 145.7dB @ 30Hz JUNE 2014 SOTM WINNER 2014 COLORADO PEOPLE'S CHOICE WINNER SOTM BUILD:http://www.stevemeadedesigns.com/board/topic/141656-wicks-e46-m3-build-bass-turbo-button-and-a-big-new-addition/page-68#entry2802026 Link to comment Share on other sites More sharing options...
Azagtoth502 Posted June 10, 2014 Report Share Posted June 10, 2014 Very nice sir. pa-pa-platypus sorry not everybody has a companies nuts so far down their throat they catch every drop ball sweat when it falls Link to comment Share on other sites More sharing options...
Kevin M Posted June 11, 2014 Report Share Posted June 11, 2014 Awesome thread. 2005 Ford Focus zx4 AMT's and Planars 18" Infinite baffle Link to comment Share on other sites More sharing options...
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