HELP! Rescuing Dad's old PL400 S2 (pics)

[gadget73]

Gadget, I had a 400 I loaned out to a guy in Phoenix, Az. . It pulled 2 ohm duty for months. It had a custom set of copper heat sinks and had forced air cooling and was White Oaked. It did just fine..

right, but thats not quite a stock PL 400 I expect that has to do more with the current handling capacity of newer output devices than anything else though. The heat is definitely a factor too, and it will get much hotter the more current you draw. Of course the lower the impedance of the load, the more current its going to demand and the more heat it will chug out.



The resistor required per the service bulletin is 5 watts 500 ohm, not 500 watt 5 ohm. BIG difference.


And yes, its possible that if the RS-III's are what the PL 400 used to drive that you have found the reason it died.

 

[laatsch55]

Right, and if you read a couple more posts down I didn't recommend a stock amp to drive em. Agreed it's the improved output devices. But he has MJ 15024's, so it's a LOT better than the XPL-909's...

 

[lightfall]

Interesting, I just got the preamp fuses and deoxit. I cleaned everything, swapped the fuse, and resoldered a loose rca jack but the DBT didn't glow under any circumstance but the unit turned on. The fuse did not blow. I tried 40 60 and 100w bulbs.

 

[laatsch55]

Well then something is right...if you want some guidance on De-oxing the 2000, there are a number of threads documenting that...

 

[Northwinds]

Duh... I thought his amp was already WOPL'd (re: Infinities). I hate reading threads backwards LMAO

 

[lightfall]

I found the deoxit / 2000 threads and followed the procedures: good recc on the deoxit! The stuck button on the 2000 freed up after a spray and some actuations, I was very pleased. I bought the hosa branded deoxit, which I found out is the same company as CAIG and ordered it through amazon prime which was really nice.

For some reason I though the bulb was supposed to turn on then off and then fade back to a glow, at least that is what the video I was watching told me. In any case I suspect the unit is OK, and now very clean.

I also ordered my refoam kits and started tearing down the infinity set. There are some good guides on that but I can't finish the process yet because I need the amp working so I can generate the 30hz tone while reseating the cones on the VC. Also the foam sound insulation on the upper part quite literally dissolved and left behind a tenacious adhesive. Googone won't touch it and alcohol only makes the paint mad. I am going to be forced to aggressively scrub it off which will ruin the stock finish underneath so I need to find a good thin tight foam to put over it or refinish the entire face with a coating of some sort.

 

[Northwinds]

I can't finish the process yet because I need the amp working so I can generate the 30hz tone while reseating the cones on the VC

Use a battery

 

[laatsch55]

We have a pretty good refoamer in member--chris----he'll log on when he gets off work but that's about 2:00 AM. He'll be along when he can...

 

[lightfall]

Use a battery

OK you got me, I can't figure out what this means and I tried looking up a few phrases "battery power speaker" etc, what is the battery for and how??

 

[gadget73]

If you have any sort of amplifier, that will do for this. You don't need much power. A set of computer speakers pulled apart to access the speaker connections is probably sufficient, or anything that can make sound.

 

[lightfall]

Finally got to open my mail from last night, lo and behold a nice package courtesy of Lee, WHOA! I have to find a way to repay your kindness, patience, and generosity!!!

Now I think I will sit down today and start replacing bits! I have been taking apart the infinity speakers in the meantime. Removing the old foam from the face of the unit was an enormous pain, and I am in the middle of removing the old foam from the woofers. Everything else is pretty much OK. I made an attempt at replacing the face foam, but the adhesive on the back of the replacement face foam is kind of weak and I think it is already starting to separate so I will need to buy more foam and a different adhesive, maybe auto headliner glue, and attempt to reaffix the mostly cosmetic foam. If that doesn't work I will try speaker cabinet carpet.

30 year old glue is a major headache to remove, and certainly not a delicate process. Restoring this gear is great, I don't think I could spend less than $5k today and get a similar sound to what I think I am in for when this is all set. I am already considering rehabbing a 700...

 

[laatsch55]

Everything besides the outputs are for later. For now get the outputs in and dim bulb it and see what ya get...

 

[Northwinds]

OK you got me, I can't figure out what this means and I tried looking up a few phrases "battery power speaker" etc, what is the battery for and how??

You use a 1.5V AA battery, hook it direct to the speaker terminals, woofer will extrude out and you can check the VC centering. Move it around a bit and you will feel when it hits the sides. You can leave the battery on as the glue sets just to make sure your centered well. Some people use a 9V square battery but that's overkill for what you need

 

[lightfall]

You use a 1.5V AA battery, hook it direct to the speaker terminals, woofer will extrude out and you can check the VC centering. Move it around a bit and you will feel when it hits the sides. You can leave the battery on as the glue sets just to make sure your centered well. Some people use a 9V square battery but that's overkill for what you need

Wow what a cool tip! With all of the videos and guides I have read on this process NO ONE has mentioned anything like this and it is extremely convenient. I will use this method for sure, thanks for the tip!

I am going to swap all of the outputs now and dim bulb this baby ASAP!

 

[laatsch55]

BEFORE you power it up!!!!!!, Check for continuity between ground and the cases on the outputs.....AND when you hit the switch, if the bulb does not start dimming after a couple seconds power OFF.

 

[lightfall]

OK. What do we consider ground. Since the power plug does not have a dedicated ground do I just touch the case, heatsink with one lead and the OT with the other?

Shall I swap in all new output transistors and drivers at once so they are matched and test them first or just swap in piecemeal the ones that were bad before and the GE ones? Just want to be sure. I am just double checking the unit now and doing additional cleaning

 

[laatsch55]

Put in the bottom row of drivers(RCA-410's, or 66456's) then check for shorts by positive on case of output, negative on chassis. Then power on through DBT. If all goes well, put in a row of the MJ 15024's, accross horizontal, NOT vertical. Read in the manual how to set the bias before going any further. You want to set the bias on the first row of 15024's to get it close and not give false readings through the bulb. A high bias setting will make the bulb stay bright.

 

[lightfall]

Also should I put in the AGX 5 in place of the stock AGX 8 for added protection and these AGX 10 32v in place of of the AGC 10 stock fuse?

 

[laatsch55]

AGX 8's were only recommended for sine wave testing. AC mains in are 10 amp, rail fuses are 5 amp. Some folks use a 2 or 3 amp fuse in the rails when powering on after a rebuild but the DBT takes care of over current situations...

 

[lightfall]

OK just wanted to make sure the AGX 10 32v was OK to swap for the AGC 10.