Fisher CA-800 Rebuild Thread!
- Thread starter Bassblaster
- Start date
Bassblaster
Super Member
While i wait for the new boards to arrive i pulled the working STK pack and cleaned the old flux off the board.
Keeping this guy
Keeping this guy
Bassblaster
Super Member
Boards arrived, and i got the PCB's assembled. need to take the adapter plates to the garage in the morning and try to shine them up a little. there a little grummy. but it was nice to find out that im missing 2 of the insulating shoulder washers for the TO-220's. so thats nice.
Bassblaster
Super Member
Got the modules assembled, i took some fine wet sandpaper and got the plates shiney-er
Got it temporarily mounted, and it works! i haven't seen those power needles move in a long time.
Got it temporarily mounted, and it works! i haven't seen those power needles move in a long time.
Bassblaster
Super Member
Been a while since i posted, just today i got the back panel cut to fit the new packs. all thats left is to drill the heatsink to mount them
warriorfan
Well-Known Member
This thread is the only reason my ca800 with a bad stk pack hasn't left a shelf in the basement. Good stuff brother!
Lookn good. Out of interest I simulated the design with the stk module, looks fine as far as I can determine. lets hope it powers up without a hitch.
I am looking over this design, it use a fuse as the only means to protect your speakers. It lacks a DC offset detector, which normally opens the speaker relay if the amp fails. It is easy to make one if you want too.
I am looking over this design, it use a fuse as the only means to protect your speakers. It lacks a DC offset detector, which normally opens the speaker relay if the amp fails. It is easy to make one if you want too.
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Bassblaster
Super Member
this has to be one of the most pain in the ass projects i have ever done. i just drilled the heatsink with all new holes, and broke a drill bit. was in the process of threading the holes, and the threader tip broke and is now stuck inside of the hole.
Fredrik 1977
Super Member
the gods of hifi dont want this to be finished
so you have to simply ignore them and do it anyway...!
but seriously...the threader tip, is there any part of it still sticking out you can grab with a wire cutter or sometning and try to screw it out.
usualy they break if the hole is to small
so you have to simply ignore them and do it anyway...!
but seriously...the threader tip, is there any part of it still sticking out you can grab with a wire cutter or sometning and try to screw it out.
usualy they break if the hole is to small
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Bassblaster
Super Member
i cant grab the threader tip since it broke halfway inside the hole. i was trying to thread for a 4-40 thread since thats what came with the eBay kit.
Fredrik 1977
Super Member
well then we have a problem. a picture might help.
what drill did you use?
what drill did you use?
gpounce32768
Active Member
If the material is thin sometimes you can punch out the broken portion. it does tend to mangle the threads a bit but sometimes can save a job,
Trodder
Member
With it being aluminum, think he can pound it out in reverse and then re-thread since aluminium is so soft? I would think it would be very challenging to finish punching it through the direction your started. Not sure if I am stating the obvious or not.. just thought I would throw it out there. I just want to see this monstrosity finished! So cool!
Bassblaster
Super Member
Threader tip. i was able to get the drill bit out with pliers. this one, not so much
Fredrik 1977
Super Member
thats the back of some big heatsink?
is it possible to mount those amps say a cm in some direction. drill and thread new holes?
if so just grind that tip down.
is it possible to mount those amps say a cm in some direction. drill and thread new holes?
if so just grind that tip down.
Fredrik 1977
Super Member
when trying to get a grip on this "4-40" tap i started googling. and to me your system in the us for this stuff seem to be very impractical..
here is a drill size chart.
http://www.americanfastener.com/tap-and-drill-size-chart/
i googled the "#43 drill bit" and it looks like its a 2,26mm can that be correct? that is 0,089inch
here is a drill size chart.
http://www.americanfastener.com/tap-and-drill-size-chart/
i googled the "#43 drill bit" and it looks like its a 2,26mm can that be correct? that is 0,089inch
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gpounce32768
Active Member
I assume this is fairly thin aluminum, in which case the broken tap can be driven out. Such an op will tend to tear up whatever threads are there, then a fresh tap can be run in to clean them up as well as may be. I would punch out in the reverse direction. 4-40 can be troublesome, particularly if tapping by hand- any flex can lead to breakage.
Bassblaster
Super Member
thats the heatsink to this fisher. the bit they mount to is 1/4" thick. the screws are 1/2" long, which is perfect since the adapter plates on the new modules are also 1/4" thick or very close too
EDIT: Its also not possible to move the new packs elsewhere. only thing i could do if i can get that tip out would be to flip the heatsink 180 degrees
EDIT: Its also not possible to move the new packs elsewhere. only thing i could do if i can get that tip out would be to flip the heatsink 180 degrees
gpounce32768
Active Member
1/4" thick isn't much- have you tried giving the tip's good end a good hard tap with a drift and hammer, to try and push the fragment out in reverse? If you're lucky the tip will pop out of the partial threads with very little damage to the threads already cut. Then go in again more carefully with a new tap.
Fredrik 1977
Super Member
most definitely worth a try. the alu will always loose in this case
