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  1. fred soop

    Fisher XP-18 opinions?

    Yes, the "K" is Kloss. L and H were Malcom Low and J Anton Hofmann. The Advents were allegedly the best selling speakers of all time but for Kloss, they were only to provide income to finance his research into video projection. He later founded Cambridge Soundworks.
  2. fred soop

    Uh-oh. My HK Citation 22 has got a hum!

    The transformer can produce a hum mechanically from vibration of the core. I have this on a Citation 24 (same as 22 except lower power and only one transformer). The fix is to remount the transformers on longer screws with flat washers and the transformer flanges trapped between a pair of rubber...
  3. fred soop

    Fisher 500-tx warm-up quirk

    Could be an intermittent open circuit that is sensitive to being heated. Maybe try to wiggle various parts and see if that will cause it to start, or quit.
  4. fred soop

    Fisher 600t question

    Much of my work on 43453K was replacement of then 48 year old electrolytic capacitors. There were a number of minor changes, some electronic, some physical layout. But there were few changes in actual circuitry other than the bias network in the power amplifiers. The IF is powered from the front...
  5. fred soop

    Fisher 600T restoration cost ?

    There were 2 600-T projects. The first was s/n 434535K which was mostly a refurbish done around 2014. The second was s/n 38215G around 3-4 years ago and was a total rebuild other than FM IF and Multiplex with completely updated circuits. Power supply is close to original. The power amplifier is...
  6. fred soop

    Fisher 600t question

    Right behind you Larry.
  7. fred soop

    Fisher 600t question

    The jumpers with corrosion are to bypass the reverb loop. I did a rather complete restoration of a 600T. Serial number is 43453K. You should be able to search for the posts (around 2014) by the serial number. ALL electrolytic capacitors should be replaced as they are almost 60 years old...
  8. fred soop

    Oscilloscope use, how to use, need to learn

    Google Tektronix, go to Support. Scroll down to Learning Center and Resources. More information than you will ever be able to use.
  9. fred soop

    FM-200 reception issue

    The main tuning capacitor is closer to fully meshed at the lower end of the dial. Look carefully at the capacitor plates to see if any may be shorting. Maybe surrounding heat is distorting one or more plates to the point of shorting.
  10. fred soop

    Fisher 1800 problem

    Is the noise still present if the stylus is not in contact with a record? If so, then the problem is probably not acoustic feedback.
  11. fred soop

    info on used parts

    There is an eBay seller "JoeOldAudio" that has a lot of stuff, probably more than he can reasonably list. Might do a "contact seller" and ask. Another possibility, but a long shot, would be Mark Oppat.
  12. fred soop

    Gettin’ my Fisher SS groove on

    The diodes have to be disconnected before checking continuity or you won't really know what you are looking at. I assume you disconnected the speakers, but that large coupling capacitor will show continuity from the very low meter current for a long time before the capacitor charges enough to...
  13. fred soop

    TX-200

    Connections are relatively unchanged. Big changes are R25, R27, R29, R31 (numbers from my schematic) and their counterparts in the other 3 locations. Values of R21 and R23 (and their counterparts) are slightly different but not critical. My 600-T has 35144 transistors in all 8 positions, again...
  14. fred soop

    TX-200

    Attempting to respond to a PM but the damn 450 character limit ..... I am not familiar with the TX-200 but from what I can readily determine, it does use the 4 output transistors per channel similar to the TX-300 and 600-T receiver. It also has a similar power rating and was sold about the same...
  15. fred soop

    Damn 400 word limit. Go to the Fisher forum for a response.

    Damn 400 word limit. Go to the Fisher forum for a response.
  16. fred soop

    Gettin’ my Fisher SS groove on

    The 700T and a few other SS units do not have the usual split power supply. The single transformer secondary feeds the rectifier bridge. 2 of those rectifiers connect to chassis ground. The other 2 connect to the positive output.
  17. fred soop

    Standee resistor identification tx-200.

    Those packages are 2 separate resistors. One is switched to be in series when using a 4 ohm load. The other is in series with the remote speaker terminals to raise the total impedance if both main and remote speakers are being used.
  18. fred soop

    Heathkit ID?

    AR-29 as noted above. I believe this was second in the lineup just below the AR-1500. Approximately 1970.
  19. fred soop

    What was the Fisher grounding scheme?

    More than you would ever want to know about ground layout. This mainly applies to solid state stand alone power amplifiers, but the principles are the same. https://hifisonix.com/wp-content/uploads/2019/02/Ground-Loops.pdf
  20. fred soop

    Heathkit AR-1500 volume pot. Compatibility with other Heathkit units?

    Total resistance of a volume pot is not critical. The tap is for the loudness circuit. The AR-15 also uses a 25K pot but mechanical design might be the biggest issue.
  21. fred soop

    Which of these amps would you pair with AR3As?

    AR-3a minimum recommended power is 25 watts continuous. Can handle any amplifier up to 100 watts or peak clipping level of the amp. They recommend a 1 3/4 amp fuse that should be in an open fuse holder (not the insert in a cartridge type). AR-3a will handle 67 watts for 10 seconds, 22 watts for...
  22. fred soop

    Anyone ever use the Tape Head input?

    Interesting. I have seen information that setting a tone control can compensate for the difference in 7 1/2 ips and 3 3/4 ips tape. There are so many tape equilazations that it is actually hard to follow.
  23. fred soop

    Anyone ever use the Tape Head input?

    Fisher was big on Tape Head inputs but they also made consoles, some of which had tape playback transports. I modified the tape head input for CD. This also eliminated wiring of 2 round trips between the low level preamp and the selector switch, making the phono input a bit quieter.
  24. fred soop

    Heathkit AR-29 Help: Low Volume on Right Speaker Channels

    Does that unit have a tone defeat switch? If so, that will bypass the tone controls.
  25. fred soop

    I have a problem with my TA-600

    The tuners were manufactured as separate units and tested as such before going over to be installed in the receivers.
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