Discussion in 'Fisher Forum Stickies' started by larryderouin, Oct 15, 2010.
There's nothing in New York?!?!
Not anywhere near me. Not anymore. Luckily, sort of, there's still a radio shack. Last time I was there the salesman asked me what I needed, I said I'm looking for a rectifier. He said a what? Never mind, I'll just dig in the bins.
Alan; FISHER used at least 3-4 different Fuse or Festoon type lamps in their separates and console tuners. They generally were festoon and there were short (as used in the Solid State receivers) Fuse, and short or long festoon as used in the tube receivers and Console tuners. The longest are the almost 3" long festoons used in my 1965 Futura and Custom Electra. I have to take 1/4" tubing and solder it to the ends of the new fuse or festoons to get a fit.
BTW; FYI www.joe.com has fuse types in 6-8-12v and 1 or 2 festoons. Hell of a lot cheaper than P.E. Festoons like arts allluded to are a vanishing breed, and electrical surplus houses are probably the best place to find them
I got lucky, mine work. For now. Haven't checked my FM90 yet. I'll keep all that in mind. It'll get to the bench after I get the x-101-c in the rack and after I straighten out my Bogen.
Alan: I forgot to mention most electrical lighting supply places can order parts for you if they don't have them in stock. But you need spec's. Voltage, amps, or watts, length, diameter at minimum. Prbably best to take one with you to get best results.
Yes sir, I'll have to remember that in case one of mine breaks. Thanks
The Mouser part # in your original post for the 8A 400v bridge rectifier is incorrect. # 512-GBPC3504W is for a 35A bridge.
Good eye King Fisher. I checked my stock and made the change after checking the # on Mouser. RECTRON 583-BR84
After searching around on various threads discussing the construction of these individual tube bias boards ive noticed that none of the 500/800 builds place the grid leak resistors directly on the board. The 220k resistors usually are somehow cobbled precariously in their original location with one lead flying unsupported to a lead going back to the board. Is there a reason for this, would any issues come from locating the grid resistor on the IBAM and wiring leads to the original terminals?
Old Habits Mainly. No reason why you couldn't move the grid return resistors to the IBAM Board as long as your board will accomodate the extra parts. As i recall the 800c terminal strips are long enough to accomodate both ends of the grid return resistors.(going from memory here so don't take it as GOSPEL.) Just remove the common bias buss wire and then add the individual bias wires to the end needed. (Again, going on memory here). On the 400, I use a terminal strip or two mounted to the chassis, to tie down the flying end of the resistor and to connect the bias leads from the IBAM BOARD.
The long wires may be an inductance issue. I'd leave them where they are but that's just me.
On the 400's you can replace the 2 terminal strip shown circled with 3 terminal strips, and connect the resistors individually so no flying leads. You can do the same thing on the 500/800's. Might be a tight squeeze, but do-able!
This is a 400. You can do the same thing on a 500/800.
There is no current to the node where the coupling capacitor, 1k and 220k resistors meet. So I wouldnt think parasitics in 8 inches of wire would matter at all....thats why i was wondering why people insisted on leaving the grid leak resistors as close to the original location as possible.
Yup, this is a good lean way of doing it. The original design has three terminals...two for each node to the 1k resistors, then a common point for the bias voltage wire. Adding a new terminal strip would do it cleanest. I just dont like the flying leads at all.
Sometimes a Brick Flies, sometimes it doesn't.
You lost me here Larry. I have no idea what a bucking transformer does or why it may be necessary. Could you explain that?
It lowers today's higher wall voltag that may be higher than what a piece of gear is designed for. Usually used for amps, but tuners, receivers, consoles also benefit. Say your wall voltage is 125vac. ad for example, Your gear says on the back it's designed for 115VAC. The wall voltage is almost 10% higher than spec. In tube gear that means higher voltages in the tubes, and the heaters or filaments are overloaded and will burn out faster, and may cause a H-K short (heater to Cathode) which is very bad.
Click on this link to google which has all audiokarma threads pertaining to Buck/boost transformers. These will answer your questions better than I can.
Ahh I see. Thanks for the info. I'll consider this for my 500c I'll eventually be restoring
Do you have any part numbers for buck transformer builds? My wall is 121-123V
Is this suitable for bucking transformer build?
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