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My Fisher RS-2010 has very weak AM tuner. It barely picks up one station. The FM is fine, but has an occasional pop, just one pop at a time . I’ve looked at the schematic and took some voltage readings. IC05 - All pins have the correct voltage except pin 15 is 3.2 mvDC, should be 133 mvDC. And...

Hello! I have a Lafayette LR-221. I'm in need of a service manual for it. One of the right channel fuses was missing. Also noticed one of the bias adjustment pots (RV501) is broken. Never had this model before, but I hear they sound quite nice. Any help is greatly appreciated. Thanks

Hello. I have an Akai GX-635D reel to reel machine, with a broken pitch control pot. The shaft is broken clean off. This is a 1 kOhm b pot with a center tap. Three terminals on bottom like a standard pot, but with a center tap on top of pot. I’ve looked online and can’t find one like this one...

Hello. I have a NAD 2100 amp that is in Protection mode. The center voltage is at -1.2 VDC for both channels. Shouldn't be no higher than 100 mvDC.... I can adjust the bias in each channel to the specified 15 mvDC. So, seems like the problem is in the protection circuit, but I've yet to find a...

Hello all! I have my buddies Luxman R-117 on my bench. When using CD Direct, it sounds great, but if I turn off CD direct, the audio is awful sounding, it’s garbled, and seems to only output the loud peaks of music. Also, I hear CD and FM together. Seems like it’s a problem in the Analog SW...

Hello. I just repaired a Marantz 16 amp. It's up and running fine. But I want to check the bias. The only info in the service manual is 1.25 volts on a 0.22uf capacitor, of the driver board. I want to use my multimeter on the emitter resistors, but I’m not sure if it’s an emitter resistor on...

I’m wanting to check the bias on a Sansui BA-5000 amp. The Service Manual says to remove the transformer wires. And then insert meter set to amps, between the wire and its connection. I understand that. But, I’m not clear on which wires to remove. Is it the white wire? Or the yellow wire? Looks...

Hi Everyone. Picked up a MCS 3223 receiver. I can't find a service manual for this model. Can anyone tell me the correct idle bias setting? I measure across one 0.33 ohm emitter resistor and set idle bias to 5 mvDC, for each channel. The heatsink is not hot, just barely warm, after 30 minutes...

Hello! I picked up an old all tube Pioneer SX-82 and after replacing all film capacitors and most electrolytics, I got it singing nicely. All but the Right channel in FM and AM. The Left channel tuner sounds good, the right channel tuner is very weak. If I put my ear near the speaker of bad...

Hi. I’m starting a repair on a Toshiba SA-775. Two of the output transistors are blown. This unit has had an attempted previous repair and I want to make sure the four output transistors Q601-604, are in the correct location. The service manual is not clear to me on regarding this. Looking at my...

Hi. My buddy brought me his 2100 to diagnose. The mains fuse looked ok, but failed my meter continuity test. I pulled both driver boards and tested every component, found no problems in either board. I then pulled every output transistor off the heatsinks one at a time, and tested them on my...

I have a Marantz 2330B with no bias voltage in Right channel. DC offset adjust's perfect. Left channel Bias and DC offset adjusted fine. It came to me with several blown transistors in the main amp board P700. And one blown output transistor. I've replaced all electrolytic caps in the main amp...

Hi All! I recently picked up a Pioneer SX-838. In working condition. I used Deoxit D5 on all control pots and switches. Set the DC voltage , and idle bias voltage to service manual specs. All good. When playing music (CD through AUX), and treble and bass flat, the front panel lights, dim to the...

So, I’ve been tinkering with this G-6000 off and on for a while now. Came to me non working. It’s been giving me a fit. Today I noticed TR05 looked like it was installed backwards. But the pin out corresponded with the screen print on the F-2856 board. So, I looked at the service manual, and...

Hello! I have a Bose Spatial Receiver model 108787. Someone has messed up the speaker relays. The relay covers are missing too. They’re 22 pin. Probably 12 volt. Anyone know of a replacement for these? The service manual only gives a Bose part number 112174. See pics. Thanks in advance!

Hello! I recently acquired a pair of Acoustat 2MH speakers, with Mk-131 powered subwoofer interface. The 10" woofer foam was dry rotted in both MK-131's. I re-foamed them. The work fine, But the panels can't handle much bass frequencies. I've re-foamed hundreds of speakers over the years. No...

I took on this AU-888 as a complete capacitor restoration. When I first brought it in. I plugged it up to full AC, and gave it a listen about 15 minutes. And it sounded fine. So I started replacing the capacitor’s. Started out with the tone and filter boards. Checked on DBT tester, all good...

Hello Everyone! I have a neat little Scott 2500 combo stereo that is in working condition. I'm looking for a service manual, or info on bias setting/adjustment. May recap it too. It sounds surprisingly good. Thanks in advance!

Hello. My elderly neighbor brought me his SA-7500 to repair. When I got it, it sounded fine. The problem was, when turning up the volume to around 3, the protection circuit kicked in. I couldn’t find any off voltages. So, I started pulling components for testing. I installed a component, if I...

Hello! I have a Setton RS-660 that I want to check and adjust the idle bias. The Service Manual is confusing to me. I found another AK post explaining the procedure, but I want to make sure I fully understand before attempting the job. Here's the AK post I'm referring to. Thanks...

Hello guys! I'm working on a Sansui 9090 receiver. I pulled all eight NPN output transistors which are ST5949 transistors. 4 of the 8 are shorted. All of the bottom row! Someone has replaced these before me. Stock transistors should be 2SC116A. I plan on replacing these with MJ21194G's. But...

I have a Sansui 6060 that keeps blowing R611 (2.2 ohms fuse resistor). It’s fine on my dim bulb tester. I was able to adjust proper bias. but when I give it full AC, it blows R611, every time. I’ve been replacing it with 4.7 ohms 1/2 watt resistor. I’ve replaced all output transistors with...

Hi everyone. I’m in need of assistance on my buddies Harman Kardon Citation 17 preamp. I’m looking for transistor substitutes/replacements. Q1 is marked 29832 Q6 is marked 25972 Q3 and Q5 are marked 27722 IC2, IC4 are UA79M24 AUC IC1, IC3 are US78M24 These were all made by Motorola I believe...

Anyone know where I can get a replacement tweeter for a Yamaha NS-50T? One of mine is blown. I took it apart, and tried repairing it, but I couldn’t find the break in the coil. Yamaha part number is: JA0534 See pics. Thanks

This G-6700 belongs to a good friend. He asked me to check it out. Once I got it home, I started testing components with my DMM. I found both output transistors in one channel shorted (2sc2581 & 2sa1106N). I replaced them with NJW3281G & NJW1302G. And their respected 5 watt emitter resistors. I...