Power switch mod?

Oldskoolfan

Oldskoolfan

Journeyman
Joined
Aug 27, 2022
Messages
192
Location
Ste. Genevieve, MO
Greetings all, long time lurker here. Been schooling myself on the wonderful mods and upgrades these amps get, but I haven't come across a mod to install a proper power switch. Is it even an option? How do y'all power up/down?
 
You can also parallel both sets of contacts in the original switch.
 
Oldskoolfan said:
I have a pl400 series 1, 8 fin. No switch.
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If you have installed the DC Protection Relay/Delay Board, you can power up from a upstream preamp without hearing the dreaded "Thump". The DC Protection Board gives you 1-2 seconds before the relay shifts your speakers from Ground to the Amplifier Output circuit.
The fewer power switches you have in the line, the better. Especially with older equipment; the years of arcing can take a toll on the switch contacts and turn them into low wattage resistors that like to summon the fire department.
 
mlucitt said:
If you have installed the DC Protection Relay/Delay Board, you can power up from a upstream preamp without hearing the dreaded "Thump". The DC Protection Board gives you 1-2 seconds before the relay shifts your speakers from Ground to the Amplifier Output circuit.
The fewer power switches you have in the line, the better. Especially with older equipment; the years of arcing can take a toll on the switch contacts and turn them into low wattage resistors that like to summon the fire department.
Click to expand...
I haven't done anything to this amp yet. Honestly, I haven't even plugged it in yet. I have the capacitor upgrade, new output and driver transistors, and the DCP mod on the shelf. I am taking it to a highly qualified friend to go through it first and make sure it's in good condition. Ya never know what you get from ebay.

Are you suggesting I should consider leaving everything on and power up from a main source? Thats somewhat counter intuitive to me. The current surge on power up could overwhelm a standard house circuit. I have a component system so that tends to add up, especially since I'd have 2 power amps on the line. Sequential power up on a power strip is a good idea. Of course the pl400 would be first with all other components poweered up after...I like that.
 
I would not plug it in...
and I would not have anything hooked up to it. ( RCA Inputs, and defiantly not the Speakers)
I would open it up and look at the inside and do visual inspection and look at the Board and the caps to see how old they are? and the outside to.
Did it work or was it sold as is? also I would check all the fuse to see if they are blow.
 
MusicSteve said:
I would not plug it in...
and I would not have anything hooked up to it. ( RCA Inputs, and defiantly not the Speakers)
I would open it up and look at the inside and do visual inspection and look at the Board and the caps to see how old they are? and the outside to.
Did it work or was it sold as is? also I would check all the fuse to see if they are blow.
Click to expand...

Yup, did every bit of what you suggest the day I got it. Seller had pics of it plugged in (VU meters lit). Inside was clean, all fuses good. All original inside. Original output transistors (Outputs XPL910, date code 7547 Drivers SJ2741, date code 7439). I'm thinking it was built early 1976. Would that make it an early Pioneer build? Sold as is, but with all the options to rebuild, I don't think I got a bad deal. It'll be gone through and I'll see what the tech recommends. I have on hand a power cap upgrade kit (thanks Mr. G), a DCP kit (Watts Abundant), and all the output and driver transistors. Just waiting on getting an opinion on condition then I can make a decision on how to proceed.
 
might as well plug it up with dcp installed...
dbt will be bright primarily then slowly dim...use 100w bulb...if major problem...relay wont engage ...
if it engages you will see relay close and hear it...about 3 second delay....my dcp has a blue led that is lit when engaged...if all is well...check offset and bias...
gotta do it sooner or later...
 
Oldskoolfan said:
The current surge on power up could overwhelm a standard house circuit.
Click to expand...
Probably not. Standard house outlets are wired to a 15 Amp breaker. Yes, there is a current surge but not a short circuit, so the circuit breakers in the power panel will not trip. The current surge lasts a few cycles until the magnetic field surrounding the transformer stabilizes, maybe 1/2 second.
Don (wattsabundant) has done tests along these lines. In the first microsecond of power up, the surge could be as high as 200 Amps, but it drops so fast, the electronics do not have time to react. The PL400 is rated at 750 Watts (Max Power In). Ohms law tells us that this is equivalent to 6.25 Amps (at rated power out). Two PL400 amplifiers would be 12.5 Amps, add another 1 Amp for a preamplifier and 1/2 Amp for a CD player and you still only have 14 Amps. Although I would be using a 20 Amp breaker in my power panel, just to prevent nuisance overloading of the circuit breaker.
 
mlucitt said:
Probably not. Standard house outlets are wired to a 15 Amp breaker. Yes, there is a current surge but not a short circuit, so the circuit breakers in the power panel will not trip. The current surge lasts a few cycles until the magnetic field surrounding the transformer stabilizes, maybe 1/2 second.
Don (wattsabundant) has done tests along these lines. In the first microsecond of power up, the surge could be as high as 200 Amps, but it drops so fast, the electronics do not have time to react. The PL400 is rated at 750 Watts (Max Power In). Ohms law tells us that this is equivalent to 6.25 Amps (at rated power out). Two PL400 amplifiers would be 12.5 Amps, add another 1 Amp for a preamplifier and 1/2 Amp for a CD player and you still only have 14 Amps. Although I would be using a 20 Amp breaker in my power panel, just to prevent nuisance overloading of the circuit breaker.
Click to expand...
I just put together 2- Soft starts. Wow what a different ( no more nuances trips)
 
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