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  1. tusntuk2

    Could use some help on a +B Power Supply problem in a Kenwood KR-5600

    I'm restoring a Kenwood KR-5600 that was in working condition, at least I know the FM and the Tape inputs were working, and I started with the power supply. The KR-5600 has a history of heat problems with its design, so I boosted the clumped resistors to 3 watts and the caps to UPW 100/50v...
  2. tusntuk2

    Could use some help on a +B puzzle in a Kenwood KR-5600

    I'm restoring a Kenwood KR-5600 that was in working condition, at least I know the FM and the Tape inputs were working, and I started with the power supply. The KR-5600 has a history of heat problems with its design, so I boosted the clumped resistors to 3 watts and the caps to UPW 100/50v...
  3. tusntuk2

    Pioneer SX-727 Blown Internal Fuse - what can I do?

    Hello AK, thanks for looking in. I'm having trouble identifying the cause for blowing an internal 3A fuse (# 2) in a Pioneer SX-727. I have reviewed other threads here and made some changes to my unit, but the fuse blew again while on the DBT, so I'm stuck, now. Can't measure voltages if it...
  4. tusntuk2

    Can you replace 2sc1318 with Ksc2383 here? Sherwood S-7100A

    Wish I understood this better... how transistor application changes with the type of circuit and how it is used in this power supply and main amp. Problem: Replacing the C1318 in different circuits, (with what I have on hand). Can you can use a KSC2383 in the power supply of the Sherwood...
  5. tusntuk2

    SX-727 blown fuse - please help identify parts

    Merry Christmas AK'ers! I could use a little help solving a blown fuse problem on a SX-727. This unit was my first recap project, done 4 years ago. Following AK threads I bravely dug into a SX-727 to recap it, but little did I know how hard/easy it was! I figured even if it blew up it could...
  6. tusntuk2

    SX-727 Schematic changes for AWM-027 D Protection Board

    Holiday Greetings, AK'ers! My beloved Pioneer SX-727 blew an internal .5 fuse, so I checked it out. AK threads suggested the power supply or the protection circuit were common culprits. You might remember that the Protection Boards in the SX-727, and several other SX and SA series amps, are a...
  7. tusntuk2

    SX-626 Problem - Has this happened to you? (I hope to focus repair)

    Greetings, AK'ers. Thank you for tuning in here. I was listening to a digital conversion from my TV in AUX, signal had lots of heavy bass rumbling in the scene, and the 626 went "pop" and there was distortion on the left output. This unit has been recapped, it has been working well for two...
  8. tusntuk2

    HELP! Can't set BIAS on Kenwood KA-3500

    Greetings fellow Ak'ers! This puzzle has me stumped - any good puzzle solvers out there wanna try it? I have rebuilt a Kenwood KA-3500 amp with a full recap, many transistors, resistors and diodes, and new Bournes trimmers, too. This is my 12th recap of this model, but I'm stumped. The Left...
  9. tusntuk2

    Source needed for MJE15033

    Ran into another stock supply problem, then Mouser said the MJE15033 was obsolete. What? Anybody got any ideas where to get a couple of pairs of these? (033 and 032) Any suggestions for replacements? Using them for regulators in the power supply of a Kenwood KA-7100. THANKS!
  10. tusntuk2

    Odd Relay behavior in recapped KA-7100 - Please Help!

    Here's a puzzle - I just finished recapping a KA-7100, and the relay acts kind of backwards than expected. DBT test was quickly dimmed, offset and bias set easily, LED may be suspect, although replacing LED also created a weird response. I know LED is involved in normal operation of relay and...
  11. tusntuk2

    Can you help me use a 'Scope to find oscillation?

    Looking for a patient teacher to walk me through using a 'scope to find an apparent oscillation in a Kenwood KR-5600. I'd love the help if anyone has the time to try! There is a sudden hum/buzz current draw at the full open position of the Treble control. I'm thinking it could be oscillation...
  12. tusntuk2

    "Treble Max" Problem - Can you help with this puzzle?

    Hi y'all, hope you are staying healthy at home! My main home activity has been to recap/rebuild a Kenwood KR-5600, and things are going pretty well for a difficult layout - except the inevitable mystery problem has cropped up. Maybe someone else has heard of this? It goes weird when the...
  13. tusntuk2

    Kenwood KR-5600 Strange Tone Problem - Know what this is?

    I'm rebuilding a Kenny 5600. Original description was "one side out", and all the lamps are out. This improved some with deoxing the controls, but there were two anomalies. The FM had terrible distortion on one side, and while checking a signal thru the AUX, the Treble control, when turned...
  14. tusntuk2

    Sx-626 FM Stereo problem - Does this sound familiar? Need some help.

    Just finished recapping a lovely little SX-626, and the FM board doesn't want to go stereo. The Muting switch sometimes works, sometimes cancels all strong signals and goes silent. The Stereo light flickers while tuning, sometimes indicates stereo on weaker stations, but often does not glow on...
  15. tusntuk2

    How do I set Bias and Balance on Sherwood S-7100a?

    Currently recapping a delightful little Sherwood S-7100A, and trying to set bias and AC balance for the outputs. My last project was a Sansui AU-505, also cap coupled (and an inspiration!) so I thought things might be similar. In the S-7100A there is a small bias trimmer, but no second...
  16. tusntuk2

    Need help figuring out probable oscillation in SWR Studio 220 Bass Amp.

    I'm restoring an SWR Studio 220 bass amp. The amp had a bad hum, so I replaced all diodes, zener diodes and all electrolytics. I boosted the main caps from 4700 to 6800. Grounding is a possible hum issue due to the design, but more on that later. When I powered it up (DBT) it seemed to whine...
  17. tusntuk2

    Which OpAmp for Kenwood KT-7500 tuner mod?

    There have been a couple of great threads about modding the KT-7500 to improve the sound. I'm not looking for the FM tuner mods to the filters and such, just looking to improve the sound. I've done several Kenwood restorations now, and the last success (KA-7100 - wow!) has prompted me to try...
  18. tusntuk2

    Need a substitute for a 2SC3834 for a SWR Studio 220 Bass Amp

    Help! I'm over my head trying to compare specs between transistors. I can read in the chart when a transistor can handle more voltage, but I do not know how to read a schematic to determine the purpose and working environment (or expectations) required. Chart wise a FJP13009H2TU seems like a...
  19. tusntuk2

    KSA1220ays supply or equivalent

    Seems like the KSA1220ays trans is out of stock at DigiKey and Mouser. Latest info from Mouser (Jan 22) indicates a June delivery, which was pushed back from Feb. Not a good sign. Anybody know a suitable equivalent replacement or another qualified source? Application - driver for main power...
  20. tusntuk2

    Need help replacing KR-5600 bridge rectifier M4B-3

    Need help replacing KR-5600 bridge rectifier S5VB20. I used dlucy's suggestion of a 400v/35a bridge on a previous KA-3500 restore, but I found it larger than the original. Space is tighter in the 5600. Could I use something like a KBPC804PBF? It's 400v/8a (Vishay). I plan to use 10,000uf...
  21. tusntuk2

    Bias problem on a KA-7100, new trimmer does nothing

    Can't set Bias on a KA-7100 Having a problem with an ineffective bias trimmer on a Kenwood KA-7100. Got a KA-7100 to restore and after initial DBT test and a little de-oxit I tried setting the trimmers for center voltage and bias before the restoration. The Left channel trimmers would not...
  22. tusntuk2

    How do you tell what is most important when substituting transistors?

    A constant topic - transistor substitution. I needed a sub for a 2sc1222, and as the dates on the threads change, so do the answers. Some is due to obsolescence, of course, but it is changes due to the understanding of how the transistor is applied in the circuit that seem the most important -...
  23. tusntuk2

    Have you seen a KA-3500 with no power supply regulator?

    Looking at my second KA-3500 with no apparent regulation of the power supply. Missing parts - diodes, resistors and Qe25, and only two jumpers in place of the diodes. Is this legit? Wouldn't it affect many more parts that were designed for a regulated supply? Would it create more noise...
  24. tusntuk2

    Is KSA916Y a good choice for replacing 2sa915 on KA-7100 Bias circuit?

    Is KSA916Y a good choice for replacing 2sa915 on KA-7100 Bias circuit (Qe7-10)? Other suggestions? Trying my best here, but I want to double check with anyone who has replaced these before. Funny it's so hard to find with so many recaps of this great amp. One thread said KSA992's were too...
  25. tusntuk2

    Please help to find treble pot for Kenwood KA-3500

    Hello again - need some help to find a 50K (dual) treble pot for a Kenwood KA-3500. It's a PCB mounted "spider" design, also seen in a few Peavey amps. Anybody know where I should look/ask for one? Thanks!!
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