file Vintage amps specs.

15 years 10 months ago #21 by jbl_man
Vintage amps specs. was created by jbl_man

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15 years 10 months ago #140 by guest
Replied by guest on topic Vintage amps specs.
link to studiomaster page doesn't seem to be working.

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15 years 10 months ago #201 by jbl_man
Replied by jbl_man on topic Vintage amps specs.
sorted!

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15 years 10 months ago #284 by guest
Replied by guest on topic Vintage amps specs.
Cheers Ian!

I'm servicing/cleaning up a pair of mosfet 1000's from the back of the lock up and I'm still trying to find info on these. various repairs have been made over the years so It'd be good to find out origional component values. I do have partial schematics, but these show an input polarity switch which I can't find... bit of a back burner project as there are more sensible things on the go too but I can't leave these to the spiders.

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15 years 9 months ago #1023 by jbl_man
Replied by jbl_man on topic Vintage amps specs.
Interesting you should say that Imageoven....i have just picked up a couple of those...along with some more of the Studiomaster 800c`s as well....on servicing the mosfet 1000`s, (dated 1983 and 1984) there were a couple of burnt 10ohm 5 watt resistors on the output boards (next to the chokes)...i have now replaced these with more substantial RS versions...and have left the "lead in" wires deliberiately long,so they now stick-up into the fan airflow to cool them......the mosfet 1000`s are quite well built....with a total of 6 pcbs...and 20 hitachi mosfets....they appear to be type J50 and K136.




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15 years 9 months ago #1033 by calsystems
Replied by calsystems on topic Vintage amps specs.
i had my eye on those too Ian. What did you get them for? and what time where you there?
They didnt answer my questions on if they where working or not so decided not to chance it.

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15 years 9 months ago #1070 by guest
Replied by guest on topic Vintage amps specs.
That ones a bit smarter than mine! Do they have a polarity switch on the input?

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15 years 9 months ago #1074 by jbl_man
Replied by jbl_man on topic Vintage amps specs.
Imageoven...nope,here is a photo of rear panel...no polarity switch.








Dave,all 4 were dead,the 2x mosfets need new power switches...and had burnt resistors on the output boards...changed the resistors,but having trouble finding right size switches.... i have rebuilt the pair of 800c`s this weekend...i have lots of new RCA bipolar output devices for those here...both of the 800`s are now serviced andup and running .



These are a different class entirely...twin 5 inch fans,16x RCA output devices,built likea tank....much nicer than the later mosfets.


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15 years 9 months ago #1083 by calsystems
Replied by calsystems on topic Vintage amps specs.
they certainly look tidy enough. Im glad i didnt go down to get them, as i simply dont have time to fix stuff most of the time. Im glad you bought them Ian as im sure they will make a nice addition to your collection. Your missus must be very understanding!

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15 years 9 months ago #1150 by jbl_man
Replied by jbl_man on topic Vintage amps specs.
Yep,quite a lot of work involved there Dave,i now have all 4 up and running....the mosfets sound nice,but not terribly impressed with the circuit design....each amp has 4 power resistors which get very warm,and are mounted to close to the actual PCB`s,so consequently the boards tend to get scorched...it would have been much more sensible to mount them on longer leads,so they stand prowd of the boards,and get better cooling from the fans.

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