power supply

Thank you all! I am restoring a Pioneer SX-828. While it's not my first time restoring a receiver, it is my first Pioneer. At this point, all the boards have been re-capped, new semi-conductors on the Main, AF, Head, Protect and Power Supply. The unit operates normally, protect relay...

Hello Everybody! Exxtreeemely long time lurker here Very quickly, let me introduce introduce myself. I've been lurking on here for years, and I've gleaned so much valuable information from you guys and gals! I just want to say thank you for the absolute treasure trove of valuable information...

Hello all, joined some time ago and have not been doing much... Until recently. Helping a friend set up a new restaurant/bar in town, and trying to make a clean install at the centralized "command center". One big issue, he's running five TV's, each using a Comcast box, all said boxes are...

Need some help as the amp won't come out of protection mode and my troubleshooting knowledge has a long way to go. Got this amp knowing that the left channel was out. Turned out to be the same issue others have had with the wire connection to the volume pot (see post #5 here...

Hi, I am currently working on a Bogen RP60. I just noticed that 2 resistors in the power supply do not have the value indicated in the schematics. R84 and R87 are supposed to be 33K but have apparently been replaced with 10K like R85 and R88. Can anyone confirm that the value of the factory...

OK>>>> pretend I said TRIAC.... ugh... sorry I've done a fair amount of work on this, and did the complete MKII upgrade and attempted to set the bias and voltage, but the supply voltage came on at about 60v and then started to decline... I pushed the main voltage reostadt just a little and the...

Problem: Marantz 4240, Back panel fuse blows when powered on. Troubleshooting: Test 1: Transformer: Disconnect input power leads on bridge rectifier 5B2. Power up unit. Measure voltage at transformer output: 42.0 Volts AC, Front panel lit. Conclusion: Transformer is good. Test 2: Power...

A friend asked me to service his Kenwood KR4010. It played but was real noisy so I knew it needed the usual De-Oxit treatment. I recapped the Power Supply section and had it sounding pretty good with one small problem. Sometimes the left channel sounded like a broken speaker. A little freeze...

A friend asked me to service his Kenwood KR4010. It played but was real noisy so I knew it needed the usual De-Oxit treatment. I recapped the Power Supply section and had it sounding pretty good with one small problem. Sometimes the left channel sounded like a broken speaker. A little freeze...

Will this plan work for a KLH-3 Analog Bass Computer (ABC) wall wart? From everything I've read the ABC requires 13 - 14 VAC, 220ma, it draws 9 watts, and is an ac to ac adapter. I think the adapter below is correct, and I can just replace the connector with the one listed, or similar. Am I...

I've got a condenser mic and I've been using it without a power supply for a while but it's a bit annoying to use. The audio I get from it is very noisy and with noise canceling on I have to be right up on the mic to get decent volume out of it. I started to look around for a power supply hoping...

I know, that's a loaded question. :rolleyes: I've restored a few SX-950's over the years. A friend recently picked one up and just wants the bare minimum to get it into a reliable state, not trying for a full restoration. Was planning to rebuild the power board (usually very toasty in my...

Just a quick summary of a couple of easy fixes i did to resurect a clean but dead Denon AVR-1609 in case anyone else wants to work on one of these: - Checked the power supply expecting the typcial 7815/7915 regulator failures and found no voltage feeding them. Traced the problem down to a...

Hi, I have a considerable hum (or buzz?) coming from the SA5300. Somewhere in the 100 Hz range. In both speakers, also in the headphone. The hum is present when no inputs are connected and when volume is down. Doesn't turn up when turning up volume. So all these aspects points at the filter in...

I have just took the capacitors out of this power supply, and I'm a bit worried about those brown-ish spots that formed around the connections, do these look like I burned the board? and if so, anyway to "fix" it? I have read that burning things is unlikely if you're careful because not many...

Hello. My first post. I recently came across an old Magnavox Tube radio. Model OFM-026 that has a smoked amplifier Power Transformer. I sent it in to have it recapped and reconditioned. Model 8601-20 amplifier and my technician tells me the Power transformer is cooked. My question is; does...

Hi to everyone... A few days ago I took on the task of rescue my old Nakamichi 700 II (1973-79) and the first thing I come across is a lack of 12 Volt output from the power supply PCB, the voltage It is not stable and varies randomly to such a degree that in the multiple measurements I made I...

I just now have also found a smoked R801 resistor on my 2275 PS board. The resistance measures over limit (OL) and it is burned. What related issue may have caused this resistor to burn? Is this R801 resistor intended to fail in order to protect other components? I was planning to replace it...

Trying something new to create some fun around here(maybe). I am giving away a FREE Soundcraftsmen tee-shirt to the first person that can tell me what two components determine the A5002 amp's 3 second(approx) turn-on delay and protection reset. And give a description of how it works. This is one...

Hi guys, I wanted to share some measurements I've made with a choke input supply. The test conditions were as follow: - Same amplifier (Allen Organ) with a 500 VCT -> dual 5AR4 rectifiers -> choke -> 250 uF -> B+. - Same tubes and test methodology. - Line kept at 120 VAC in all cases. -...

Has anyone seen older power supply like this. It was running a receiver, reel to reel, and turntable till i could not get any power to the TT after cleaning it. Tested the TT motor inside and it ran okay, but not in the cabinet. So i pulled the SLT-7Q1S power out to clean and check, but i don’t...

Dear AK friends, A friend of mine brought a couple of NAD amplifiers (C320 and C370) with issues. Although I am more a Sansui-Guy, I just thought I would give it a try in finding out the problem. Tee C320 does not turn on at all, so I thought that would be the easiest one...... but I am lost...

Pioneer hot power supplies that have been toasted. A while back I got one for my 1980, and there were a couple different manufacturers. I asked a couple of the well known rebuild guys and the new supplies seemed to be deemed a viable alternative. Updated parts, and in the case of my 1980 moving...

I haven't been able to find a good schematic that has voltages on it for this unit. I am assuming that the transformer is suspect. I have 121VAC between the brown and gray wires which Ii assume are the inputs to the transformer. On the output side I have 2 red, 2 orange, a black, and a blue...

I am rebuilding a KM-Q7 and just realized that the first ,the big one, resistor may be burnt. The code reads tiel,brown,grey or blue,yellow. It measures 633 ohms which has nothing to do with the color code.It bridges a dual section 100mfd cap.,coupled to the second cap., which is a dual 50mfd...