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    KR-5340 Protection and Noisy Channel Questions

    Have a KR-5340 in pretty good cosmetic shape. Picked it up for $40 a few years ago and am now just starting to work on it. First issue was the protection relay closing. I removed both amp boards and the relay would close. I haven't done this before on any receivers - does this isolate one of...
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    Identifying GE Amplifier from C367g console

    I picked up this GE console from an estate sale. One channel works. I thought maybe there were bad transistors (germanuim) but when looking to pull the amp & tuner it appears that the wiring was messed with and one speaker isn't connected at all. Someone may have been trying to bridge the left...
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    Reference 180R No Sound

    Looks like the search on AK is down now as it errors out for me - might be due to some maintenance on the servers. I have a 180R on which I get absolutely zero sound on all channels. I get lights and no short on the DBT. Fuses all check out - main and power supply board. I know there are no...
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    Fisher CA-800 Meters Not Working

    I bought this at an auction untested. It had one channel working and was able to get both channels going after replacing one blown STK pak. However neither meter is moving. They do move and come back if I carefully move them manually. Reading at the shared post #2 on the tone control board is...
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    Why is the easiest solution the last you look for?

    Thought I would share a funny story. Working on recapping a Pioneer SX-450. Initial testing prior to working showed just dirty pots. Completed the recap, replaced the 2SA725s and blew out the dust a little more and went to give it a final test before starting on cosmetics (lights, etc.). But...
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    Fisher CA-800 With Blown STKs - Emitter Resistor Value?

    Came across this amp at an estate sale tucked away in a closet - now I know why it was there. Both STKs are likely dead. - both fuses on the main PCB were toasted - 50+V DC on both left and right channel speaker outputs (good thing I didn't hook anything up) - both of the emitter resistors are...
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    Pioneer SX-550 Short - Where to look?

    Have an SX-550 that originally had blown speaker fuses FU1 and FU2. Left outputs were visibly blown. Replaced with TIP41C/TIP42C. Unit still shows a short. I am looking for advice on where to look for the source of the short. With new FU1/FU2 fuses installed it shows a strong short on the DBT...
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    Filter Caps on GE Receiver - Four Negatives?

    Getting this unit up to speed for a friend's uncle. It's an old GE receiver - likely early 70s and not much to look at but he has had it since his military days. I am replacing the filter caps but need a little advice on how to replace with a modern cap. The caps are 2000uf/50v which is easy...
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    KR-4400 No Relay Click and SM confusion

    Working on this unit for a friend. It powers on but there is no relay click. Checking the SM it says to check QE23 (2SC1416) and QE24 (2SC1213C). However when looking at the actual amp board in the unit it has the four outputs marked as QE21-QE24. The 2SC1416 is actually marked as QE25 and...
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    Motorola 7252 Transistor Replacement?

    Working on a Sylvania CR-2742 (also briefly rebadged as a Realistic STA-250) with blown outputs. I know this is common on this unit and it isn't a great unit but I am using it as a learning experience. Someone had already replaced with two of the outputs with 2SC421 but the others (I assume the...
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    How to test SX-650 volume pot ACV-179?

    This unit has volume on one channel even when pot is turned to zero on both phones and speakers. I cleaned it several times, reflowed the solder points, and checked the resistors and ground points per this post. I want to rule out a bad volume pot before I go looking for a replacement or an...
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    Replacing wire wound resistors

    Working on an HK 330B with a bad right channel. Found that the emitter resistors are bad. Would the following be acceptable? The originals are 0.47ohm / 2W. The one I have are 0.5ohm / 2W. Wondering if the small difference in value would be of concern - its only a 6% difference. Also...
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    SX-650 - Left Channel has volume at zero setting

    Okay, this is a new one for me. I have experienced dead channels, weak channels, distorted channels but never one that is too strong. At zero volume (7 o'clock) the left channel sounds like it is at 9 o'clock. Right channel sounds about right with zero volume at 7 'clock and good sound at 9...
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    Suggestions Needed on Sleuthing SX-550 - Distortion/No Bias Reading

    This unit came with a blown output transistor. Replaced output transistors with TIP41/42. Now it powers on with no short but I only get garbled sound on the right and only bursts of sound on the left as I adjust volume. I also cannot get any reading adjusting the bias. I pulled the double...
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    Converting Kenwood KR-4140 from 220V to 110V

    Picked this up for next to nothing due to the European plug installed so I need to wire in a new power cord. There is a switch on the back for 220V or 110V operation which is already in the 110V position. I compared it to another unit I have that is for 110V already (no switch on the back)...
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    Pioneer SX-650 Pop/Relay Issue

    I was recapping another SX-650. I was replacing the caps on the GWR-101 board and did a test on the DBT to check my work. Bulb (60w) did not stay bright but instead kept a slight glow. After about 5 seconds there was the familiar pop and smoke. Never had that happen while on a DBT before. I...
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    Large Knight Speakers With Jensen Components

    Got these through an auction for little $$. They test out okay, just needed some contact cleaner in the pots. Wondering if adding in some insulation would improve the sound? They are really large cabs at 21 x 14 x 27. Haven't dabbled in speakers much beyond doing some refoaming and caps.
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    Using LEDs on Onkyo TX-2500 MKII stereo/tuned/locked

    I am replacing the 12v lamps as they are all burned out. I am interested in using LEDs but for these the LEDs stay dimly lit when they are typically "off" and then light up bright when they are "on". Obviously they are still getting a little voltage even when they are considered "off". So how...
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    Knight Bundle - What Have I Done?

    On impulse I bid on a collection of Knight gear. I am not familiar at all with the brand apart from what I found on here. Includes: - KG-895 amplifier - 265B tuner - two large speakers (model unknown) - two small speakers that look like some sort of horn I pick them up tomorrow so we'll see if...
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    CR-840 Dial Lights

    Have a nice 840 that is working well but all of the dial lights are out (meter and pointer bulbs are working). I believe these are 14v per other discussions here. Unique little socket design. Questions I only get 3.3V AC at the leads to the circuit board. Shouldn't that be ~14V? I would...
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    Yet Another SX-780 Darlington STK-0050 Thread

    I think I know the direction I am going after reading the many threads on the subject and advice from markthefixer (thanks mark!). But wanted to check my logic. The unit has no relay click. No short when running off DBT. Here is my progress to date: Took measurements: Pin 25 -41V -...
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    Testing SP-40W for SX-650 out of circuit

    Working on a 650 where the relay wont click. Thinking the SP-40W is blown - see my thread on that confirmation. https://audiokarma.org/forums/index.php?threads/confirming-blown-sp40-powerpack-sx-650.939201/#post-14322885 I bought a replacement SP-40W that supposedly came from a parts unit. I...
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    Voice of Music Microtouch 2G Auto Return Issue

    I have cleaned and relubricated this unit and its running well but it won't auto-return. This one of the mid-60s models. Looking at the mechanism it appears that the lever from the tonearm (near 1) is supposed to nudge the aluminum slide to the left which eventually pushes the plastic piece...
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    Identifying burnt resistors in A-760

    Picked this up on the cheap for $40 as it was non functional. DBT shows a short. Open it up and find a few burned resistors. Problem is the service manuals freely available are of such bad quality I can't read the board layouts. I think I have some deducing but wanted to see what y'all have to...
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    Confirming Blown SP40 PowerPack SX-650

    I have been going through my collection of SX-650s which I had accumulated and not one had a blown PowerPak. Most had a dirty relay or needed new differential transistors (1647s I believe). Well I am on my last one where the relay won't engage and I think I finally found a bad PowerPak based on...
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