Wow. I just wanted to get an old PL400 working again. I just did not know how deep the water was. Have PL400 series II S/N 4A 30901. I cant relate that S/N to the list. Anyway. If I just want to get the ole gal just goin again, what is the minimum I should do? I bought this for my brother many years ago. He gave it back with one channel dead. In reading on your site, looks like i need cap upgrade, maybe control board at minimum? I plugged it in and immediately blew one of the AGX fuses. Bad ouput trans?? I am willing to spend couple hundred but not like 500 or more. Is it a lost cause? what are my next steps? I piddle with electronics. have bachelors inEE (that dont mean nothin). but do know my way around basics of old school schematics of transistors and use of DMM an.d such. So know a little, not a lot. I did some looking in the forum, but like I said, the water is deep. Took me over an hour just to hopefully figure out that WOPL means White Oak Phase Linear???
Lost ball in the tall grass
- Thread starter dave5701
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if you are blowing fuses....most certainly a shorted output transistor.....not too difficult to find which one...once you determine which channel is shorted....
do you have dim bulb tester....if not...build one...it will save you many times over...
that fix is cheap....but, could be the tip of the iceberg....
or the beginning of a chain of events to come...
if you change the control board with a wopl....depending on what you want from your system...
you will still need to fix the output....
start there....then let your budget be your guide...
many smarts here...l.ots of knowledgable members...
welcome aboard...
great hobby!!!
gene french
do you have dim bulb tester....if not...build one...it will save you many times over...
that fix is cheap....but, could be the tip of the iceberg....
or the beginning of a chain of events to come...
if you change the control board with a wopl....depending on what you want from your system...
you will still need to fix the output....
start there....then let your budget be your guide...
many smarts here...l.ots of knowledgable members...
welcome aboard...
great hobby!!!
gene french
Welcome Aboard Dave,
All depends on your goal for your amp.
If you want to simply get your 400 up and running, then addressing the outputs would be a good place to start. Speaker protection is an absolute must as well !!!
The components from White Oak are first class, so a cap upgrade, and speaker protect board from Don (wattsabundant) are definitely in order.
The outputs, and existing control board, backplanes, etc. are 40 years old. Just repairing the outputs, and new power caps, will undoubtedly keep you chasing your tail. I recommend doing it once, and doing it right.....then enjoying your amp for many years to come.
The control board in conjunction with new power caps, and new outputs (all of them) from White Oak, and Don's speaker protect board will give you a functioning amplifier that will not destroy your speakers.
Be careful, this work is very addictive, and you now found that rabbit hole in the tall grass !
Enjoy, there are many great people on board here.
All depends on your goal for your amp.
If you want to simply get your 400 up and running, then addressing the outputs would be a good place to start. Speaker protection is an absolute must as well !!!
The components from White Oak are first class, so a cap upgrade, and speaker protect board from Don (wattsabundant) are definitely in order.
The outputs, and existing control board, backplanes, etc. are 40 years old. Just repairing the outputs, and new power caps, will undoubtedly keep you chasing your tail. I recommend doing it once, and doing it right.....then enjoying your amp for many years to come.
The control board in conjunction with new power caps, and new outputs (all of them) from White Oak, and Don's speaker protect board will give you a functioning amplifier that will not destroy your speakers.
Be careful, this work is very addictive, and you now found that rabbit hole in the tall grass !
Enjoy, there are many great people on board here.
Dave, here's a link to Don's "Watts Abundant" website. You'll find the service manual there. Go to the site, click on Audio Karma Digital Docs, find and download the service manual.
Don is a member here and sells his output protection relay on that site.
http://www.wattsabundant.com/id13.html
Don is a member here and sells his output protection relay on that site.
http://www.wattsabundant.com/id13.html
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looks like mr. george forgot the link....
www.wattsabundant.com
i will save you the trouble of searching for the service manual...
be very careful....these rabbit holes are full of money sucking rabbits...
also very addicting...
www.wattsabundant.com
i will save you the trouble of searching for the service manual...
be very careful....these rabbit holes are full of money sucking rabbits...
also very addicting...
Thanks to everyone of you. I am going to give it a try. I have been a "garage saler" for years. I have vintage Pioneer, Sansui, Denon stuff back when it was made proper. This amp is just my first attempt but would like to proceed. I worked in a high end audio shop in my college days and I know all about the audio rabbit hole. Buying fridges to keep records in. Changing out all caps in a brand new unit to tantalum. We even had a record cleaner that used a vodka wick to mop the vinyl then a vacuum line to suck up the mess. Question, what is this dim bulb tester? My dad was a service tech at local electrical supply. He used a 220v bulb as a test bulb with just bare wire leads coming off bulb base. Is this the same thing? If so what am I supposed to see if all is working, just a "dim bulb"? Or if those training docs tell all, then tell me to go read. THANKs again.
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here is a very simple one...use 100 watt incandescent only bulb....
this limits the current to less than one amp....even with shorted outputs...
it will not blow the fuses...and gives you time to diagnose without blowing crap up...
a short will only make the bulb burn bright...but limits the current to 100 watts because that is all the bulb will draw...
absolute necessity unless you like buying parts...
go dave go!!!!!
mr. george has a series II also...
this limits the current to less than one amp....even with shorted outputs...
it will not blow the fuses...and gives you time to diagnose without blowing crap up...
a short will only make the bulb burn bright...but limits the current to 100 watts because that is all the bulb will draw...
absolute necessity unless you like buying parts...
go dave go!!!!!
mr. george has a series II also...
Ok guys. Im at the starting line but not sure if I can get a green light. I have all the TO3's to replace one side of the 400. Have the cap kit. All this from white oak. I have tried several times to contact wattsabun with no success. I have ordered and have in hand all the parts from mouser for the speaker protect kit. Know how to get in touch with WA other than normal email?? Since one side of amp is shot, I figure to change TO3's to get working, then cap kit, use dim bulb to check stuff. When I think I have it, hook up speakers to see if works. Once all is working, then tackle the speak protect. What yall think? Yep im from texas since I said yall.
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watts work long and hard often traveling...
he will contact you...not to worry...
i would change caps first...eliminate that possibility before you tackle others...
dont connect to good speakers without dcprotect...
i keep a pair of junkers just for testing...until i put the covers on...
connect one row of outputs at a time...then check with dbt...if it burns brite then dims....you are ready to do the next row...until populated...be careful not to overtighten output screws...just snug...dont wrinkle sil pads...
once populated and no outputs shorted...check offset as close to .0000 as possible...
then set bias at .350 volts....
post pics and post often...lots of smart guys here...
he will contact you...not to worry...
i would change caps first...eliminate that possibility before you tackle others...
dont connect to good speakers without dcprotect...
i keep a pair of junkers just for testing...until i put the covers on...
connect one row of outputs at a time...then check with dbt...if it burns brite then dims....you are ready to do the next row...until populated...be careful not to overtighten output screws...just snug...dont wrinkle sil pads...
once populated and no outputs shorted...check offset as close to .0000 as possible...
then set bias at .350 volts....
post pics and post often...lots of smart guys here...
