My New Early Model PL400 w/ 4 Fin Heat Sink

[Gibsonian]

Looking good. Soon tunes shall pass thru

 

[punchback]

When I bought this I was hoping to get it upgraded to the bare minimums until I got the WOA board. I'm afraid to try and adjust the offset. I'm sure those 45 year old open frame pots are not very trust worthy. I've read about possible catastrophic meltdowns trying to adjust offset using ancient pots.

The speaker protect boards will be here in a week or so. Maybe I'll have to move up the WOA control board purchase.

Alan

 

[punchback]

I was able to get p/n's from the pots. Each channel has (2) X201R254B or 250K Ohm 1/5 W 20% 1 Turn and (1) X201R502B 5K Ohm 1/4W 20% 1 Turn. Neither of these are on the schematic for the PL400C in the service manual which, as I understand it, is the board I have. I think this circuit board possibly predates the service manual that I have.

 

[WOPL Sniffer]

Yeah, the speaker protection (DCP's) won't do you any good if the amp goes up in flames....

 

[VSAT88]

It will save speakers though ( ask me how I know) . The more you talk about this amp the more I would like to see you restore back to factory ! Seems like you have such an early model that it would most definitely be considered a collectors item, at least by some of us. My 700 is very early production. I want to get back on it as soon as I can and it will be a stocker . Nothing against WOPL. Those pots you seek should be in stock at Digikey . I did get and end of life notice from them not too long ago so be aware of that.

 

[punchback]

I'll be installing the WOA control board. I really want this to be a solid daily driver. Based what @oldphaser said, the sn is from the 4th month of production. So maybe it was one of the first 500 made. I have no idea how many per month they were making so maybe just the first 1000. Not sure how valuable that would make it. I want to deal with the high offset but I'm not sure which pot does what. I don't want to blow up any of the stock output xsistors so I'm just going to ditch the PL400C.

When I install the WOA board, I'll be happy to donate my PL400C to the Phase Linear 400 museum of natural history .

 

[laatsch55]

I don't believe there is more value in a PL 400 with a PL400C board than one with say a PL 14 or PL 020. Gotta remember there were a LOT of these made. Rarity is not a store of value here...

 

[62vauxhall]

I'll be installing the WOA control board. I really want this to be a solid daily driver. Based what @oldphaser said, the sn is from the 4th month of production. So maybe it was one of the first 500 made. I have no idea how many per month they were making so maybe just the first 1000. Not sure how valuable that would make it. I want to deal with the high offset but I'm not sure which pot does what. I don't want to blow up any of the stock output xsistors so I'm just going to ditch the PL400C.

When I install the WOA board, I'll be happy to donate my PL400C to the Phase Linear 400 museum of natural history .

Was there a hand written sticker on one of your filter caps? There was on my 4 fin....it said "Sue"

 

[Billboard]

My PL700B cap had “Ruth” on a sticker

 

[punchback]

No sticker just a J in sharpie on one of the big caps.

 

[punchback]

I was looking at the release notes for the WOA PL14 REV E. They seem to say that one must switch to MJ21196 to maintain a SOA. I found that SOA means "safe operating area"?? Will it be OK to keep the PL909 if you're not playing it at concert levels? I understand they are 45 year old transistors.

 

[laatsch55]

The 96's are a dedicated audio part. Less noise, better distortion specs. .

And remember, a shorted output RARELY results in just a shorted output...

 

[VSAT88]

Running all matched number 909's in mine until it smokes. Then I will do something different..."The torture never stops" Quote , Blackie Lawless, WASP.

 

[Gepetto]

Yes you can run the old PL909s. They are just not very robust compared to what is available today, even when they were new.

 

[punchback]

I'll probably press my luck with the PL909 and hope for no whammies.

 

[laatsch55]

36.00 is gonna be cheap if one output goes...

 

[VSAT88]

Can you use the MJ21196 for the drivers as well ? And where can the be bought for 36.00 Lee ? I dont mean to be carrying on here too much but for that matter I wonder where you can even buy them at all .

 

[punchback]

You probably meant $63 (12 x $5.25) for a 96 and a silpad from WOA. I might just bit the bullet and make sure there's no whammies. Throw another log on the fire!

 

[VSAT88]

Crap, I forgot all about seeing if Joe may have them ! I did look on Digikey site. (Mouser says call for a quote, none in stock) Digikey has the MJ21196GOS-ND by ON semi in stock it seems. I guess this the same or close enough ?

 

[punchback]

You'd probably look for a MJ21196G. I believe the G means RoHS compliant.