Now I have a problem....

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Now I have a problem....

Post by Wildcat445 on Sun Jun 19, 2016 9:14 pm

My old dependable Pioneer SX-1050 just shot craps. I've had it since both of us were lots younger. It is part of my music processing system which is the worst part.

When I turn it on, there is a loud pop from the speakers and something clicks inside the cabinet that kicks out the speakers. Any time I move a control, I get a loud pop in the speakers, regardless of volume setting. This is not good, sounds serious. And the thing is solid state. There is nothing in there that looks familiar to me. What do I need to look for first, other than bulging caps and that.

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Re: Now I have a problem....

Post by Conelrad on Sun Jun 19, 2016 9:26 pm

Caps, both coupling and filter. Couplers can drive bias points off the chart, putting devices into runaway.

It can be a daunting task, as gear of that age used a lot of discrete devices in Darlington circuits, and one of them never goes without it's mate.

The hassle is silicon scatters where tubes just get a bit testy in the same time frame.

Dennis

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Re: Now I have a problem....

Post by Wildcat445 on Sun Jun 19, 2016 9:51 pm

This is really strange.  I can hear the FM in my computer speakers (pre-amp circuit of the SX) but not in the speakers.  The phono inputs do not work at all.  The left side appears to be dead, except when I throw a switch on the front panel, then there is a pop in the speaker. Methinks that the audio section is kaput.  I guess I'll put my Marantz 2245 in its place temporarily and take the top off the SX and see what I can see.  I have heard about idle currents and bias this and that.  Thanks, Dennis.  This might make a good project for this winter in AZ..... Very Happy

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Re: Now I have a problem....

Post by Wildcat445 on Sun Jun 19, 2016 11:56 pm

I'm jinxed.

I have another dependable piece of equipment that just quit tonight while I was using it. My old Sony TC-WE305 cassette deck. It just squeals when I start the tape. The tape does not run. I suppose there is a belt that drives the mechanism. The odd thing is that this is a dual deck and both sides are afflicted. Unbelievable! Shocked I

I found a Marantz 1090 integrated amplifier in my storage shed I forgot I had. 45 wpc, but that is enough. The funny thing about this is that the tape output is affected by the volume control. It will work until I find something better.

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Re: Now I have a problem....

Post by Wildcat445 on Mon Jun 20, 2016 1:00 am

My frau refreshed my failing memory. First off, I had been having problems with a dirty switch on the SX for some time. Today was its day to die. I have worked on things tougher than that and I might learn something. The one side of my cassette deck went out last year. Tonight, the second side died. Fast forward and rewind works, so the capstan drive belts are bad. I have three other cassette decks with the same problem. I need to learn to replace belts on cassette decks, apparently. I can get an assortment of 35 belts for $6 on ebay from an outfit out of Hong Kong. Free shipping, so how could I go wrong? There is surely a domestic source for belts, if I'd do some looking. My equipment is all old. I was running on borrowed time. But all in the same evening? This Marantz amp is not going to work for my music processing. I'll dig out the 2245 and try that.

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Re: Now I have a problem....

Post by Wildcat445 on Wed Jun 22, 2016 4:05 pm

My music processing has been rescued. I found a neighbor who was going to toss a Technics cassette deck that still works. And, my Marantz 2245 can provide enough pre-amplification to satisfy my music software. On with the show.....

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Re: Now I have a problem....

Post by Bill Cahill on Thu Jun 23, 2016 9:13 am

Output transistors are often known to kick the b ucket, and, often take coupling transistors with it.


Last edited by Bill Cahill on Thu Jun 23, 2016 4:38 pm; edited 1 time in total

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Re: Now I have a problem....

Post by Wildcat445 on Thu Jun 23, 2016 10:06 am

If I decide to fix it, I'll have to solicit someone more proficient in transistor servicing than I am, certainly. I know zipkus about solid state stuff.

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Re: Now I have a problem....

Post by 75X11 on Sun Jul 03, 2016 9:43 pm

A good source for replacement belts is MCM electronics.  They also carry a lot of replacement parts and assemblies.
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Re: Now I have a problem....

Post by CaptainClock on Mon Jul 31, 2017 11:19 pm

MR. Wildcat, A lot of those older Pioneer SX-xxxx series stereo receivers are known to have failing or failed Amplifier Coupling Capacitors which were usually sourced from the infamous Elna company back in the late '60s and early '70s my Pioneer SX-1000 TD from 1969 (the very first Solid State Stereo Receiver made by Pioneer) had an issue with failed Amplifier Coupling Capacitors which were 10,000 MFD 50V electrolytic capacitors, one for each channel, and once I got those replaced the stereo receiver has been fine since, I am actually currently working on a Pioneer QX-9900 Quad Receiver from 1972 for someone that has the same issue and it has 4 (yes 4) 4700 MFD 50V Electrolytic capacitors in it for amplifier coupling purposes, 1 for each channel (which in this case would be 4 because of it being a quadraphonic receiver). The clicking noise you are hearing in your receiver is the sound of the Protection Relay kicking in and puting your receiver in to protection mode so that your amplifier's output transistors don't get fried due to runaway voltages. That protection relay actually always makes a clicking noise even when operating normally because it does a "self check" at initial power up of the receiver to make sure everything is running normal, and if it is, the relay kicks off and the receiver will play normally, but if it detects abnormal voltages or something then the relay click again and the stereo goes into protect mode and then basically all the receiver will do is run the pilot lights and that's it you won't hear any audio or anything, so that way your super critical parts like your output transistors and what not don't get fried.
Hope this helps.

Levi

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