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Istari

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    H. H. Scott 99 series troubleshooting questions

    in Technical/Restorations

    Posted

    I'd like to ask a couple of questions to the resident tube gurus.

    For starters I'm using a Fluke 23 digital multimeter (autosensing) and a generic variac to adjust line voltages , I also have a digital meter hooked up to the variac to acurately measure its output voltage.

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    I have a H.H. Scott 99A that Id like to rebuild. I have a bit of an electronics background but its somewhat rusty. I do have the schematics for the units (Sams Photofacts). One of my questions is this: On the 99A I have checked the voltage of V6 - 5Y3GT (output side of a new or original 5Y3GT, I tried both thinking that the old tube may have been defective) at pins 2 & 8 and it measures 396 V after a 10 minute warm up. The voltage measurement on the schematic reads 355 V. I have the 99A plugged into a variac that is set at 117 VAC, which the Photofact states in the nominal voltage. (The Photofact states: Nominal tolerances on component values makes possible a variance of + or 15% in voltage and resistance values.) The higher reading of 396 V throws off all of the other readings Im taking on tube V2 12AX7 (pin 1 actual 210.2 V, schematic 175 V; pin 6 actual 241.3 V, schematic 195 V and on tube V4 6V6GT (pin 3 actual 359 V, schematic 325 V; pin 4 actual 364, schematic 320 V.

    If I adjust the variac to 106 volts, I then get the correct reading from V6 pins 2 & 8 of 355 V and the other readings are very close to the schematic values.

    My question is, should I worry about the higher voltage readings since the schematic says that there could be a + or 15% in the readings of voltage and resistance? Should I insert a high wattage pot and reduce the output voltage on V6 pin 2 or 8? I have changed out the coupling caps but not any of the multisection cans.

    I have a 99C that is exhibiting similar increases on the 54UGA output and 12AX7 and 6L6GB tubes. I have replaced the 4X20 MF multisection electrolytic capacitor and I have replaced the coupling caps with orange drop equivalents. Would replacing the multisections have an effect on the voltage readings of the rectifier tubes?

    Both units power up and play well, I just want to be sure that the 99A can last another 53 years!

    I intend on using either the 99A or the C as center channel amps, the C model looks better with the Scott 222A I have, but the 99A is a real looker with its brass faceplate all polished up. The Scott 222A was rebuilt by Craig Otsby (NOS Valves) about two years ago and works well. Id just like to see if I can bring these back up to equal the 222A.

    I'll attempt to attach the 99A schematic to this post.

    Thanks for the help!

    protecting speakers

    in Technical/Restorations

    Posted

    Since they are going to be in a colllege set up, I would fuse them. Buy enough of the inline fuse holders and put one each in the + (Red) lead going to the speaker. These are easy enough to put in the speaker wire. I'd start with a 1 amp fast blow fuse. You can get both items at a Radio Shack or at Parts Express. You'll be glad you did the first time a fuse blows and saves your speaker!!!! Be sure and buy extra fuses for replacements.[:)]

    Do bose headphones suck?

    in Home Theater

    Posted

    "except in the noise canceling effect",

    Ah that's why you buy them..... They are noise cancelling..

    I have a pair of the bose noise cancelling headsets and they work pretty well for their intended use. They do reduce the noise but not eliminate it. They are pricey and there are other units at 1/3 of the cost. If you are in a larger airport look for the Brookstone stores. They have a model that pretty nice.

    DEFINITIVE 1812 OVERTURE

    in 2-Channel Home Audio

    Posted

    Dr. Bill,

    I remember that one back in '72 great disc.

    I guess what sets it off is the Mo Tab singing the Russian Hymn, I haven't heard that on any other disc. I really think it tops the Telarc version.

    BTW, thanks again for the center channel box, it works great!, I'm currently driving a Belle as a center between Klipschorns.

    OT: What you want for Father's Day?

    in General Klipsch Info

    Posted

    I'm with you R Cherry.

    You know, I think it would be different if W had a son out pounding the ground. But no, he would do what his daddy did, pull strings and get his son a safe job here in the states. There is justice in the system, but its spelled "Just Us" and it takes money and political power to use it, the first Bush proved that.

    I'll be thinking of the boys and girls who won't have a father this father's day due to this private war in Iraq.

    Now before people jump in my _hit, I'm an Army Vet, served 6 years, 5 months and 12 days, I have earned the right to complain, and I have also earned you your right to complain. But you cant _itch if you haven't been in a troops boots.

    Good night all!

    Forte Fever

    in 2-Channel Home Audio

    Posted

    er, Input Protection.... Output from the amp, input to the speaker.

    I wouldn't go over a 1 amp Fast Blow, I'd probably start at a 1/2 or 3/4 amp, it depends on what you listen to and how loud you listen to it.

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