Lights out (really out) in QRX7001, advice?

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deandallen

New member
Joined
Jul 2, 2007
Messages
6
Location
Signal Hill, CA, USA on a hill above the City of L
It's hard for a man to admit he's done something stupid, so if I'm posting in the wrong place, shoot me later. Actually, just direct me in that case -- I'm cool.

I've been enjoying my Sansui QRX7001, although not having an adequate space set up for it, it's been in my bedroom, on a dresser, where I listen to it using only the radio (while I hunted down a quad turntable), but not really much else, except for my lugging it over and onto my bed and carefully cleaning the guts of it, slowly and gently with a soft brush and a PC keyboard vac, getting to know it as I go along - bonding, as I refer to it, and the only problem it had was 2 meter lights out and some dim or flashing dial lites. Beside the sound, what I love about Sansui is the look. So, I order the bulbs, changed them and for a couple of wonderful days had a face for my new friend (I may need to get out more.) Stupid part coming up:

On either side, the bulbs tended to flash out and back on, even after changing the bulbs, and I felt really frustrated by that. It was no picnic getting into the case (I stripped out the screws - they'd been put in at an angle, I think with a power tool) and to get in I had to break in. Ok, I can fix that, sort of, then find a new case. Anyway, I go back in, growling -- I hate to do something like this twice in a decade. I bought a soldering iron set and hand solder vaccuum, but was afraid to use it. Never done it, it looked easy enough, but I'd been researching the process, and the general attitude was "not idiot proof." As an idiot with a shop tool, that tended to put me
off.

Well, I wiggled this bulb, and then that one. I'd read that you should solder the bulb posts (?) as the joints get loose, but as I said, the soldering iron was "on display" on my dresser, mocking me. I had a screw driver in my hand, and I had left the machine on to look at the lights to see if anything changed as I wiggled wires. Then, uh-oh, the screw driver touched something behind the light panel it shouldn't and ZAP! All the lights went out. I thought I'd fried the whole thing.

After a stiff drink and a good kick at the cat (I always miss and he knows I will) I tiptoed back into the bedroom where the hulk (not smoking - good sign) sat, dejected and accusing. My new friend had lost his face again, all of it. How Mel Gibson...

However, everything else *seems* to work. Sound's ok, miraculously, and an inspection from the top , and from bottom, showed nothing. No burnt little electric ic's, or diodes (or whatever they are called), no blown fuses, except the fuses beneath the two meters, which were, in fact, extra krispy. I had hoped that they took the bullet and the rest of the unit (including the darned light panel) was saved, but no. Of course not.

So, this morning, after staring at at the Sansui on the dresser (it did not stare back) at 4 AM, I taught myself to solder. I can do it! Wow! I was patting myself on the back as I completed the light socket change-out on my Sansui G-3500 (lights are important to me -- can you tell?) which included soldering, and I figured I'd go ahead and solder those "bulb posts (?)" on the QRX, and if I couldn't find them, why, I'd solder everything that seemed loose. More is better? And I did, and it's a messy job. If I don't get better at it someday, I may retire early from self-applied , no-training and no aptitude, electronic component repair. But, for all that, stiff wire joints and all, none of the lights work. The meters work, but dark. You can see them with the room light on, dancing away, as if to tease.

I had planned on this going to Quad Bob later this year for the restoration service he performs. I hadn't planned to hand over a wreck of my own creation. At this point, by the time he gets it, it may be a total ressurection. He already knows about the stripped screws, but not the vandalized case. Now, I've got this electrical situation, and I'm game, if anyone on here recognizes what's happened and can point me in the best jumping off place to start, to look for the most likely site of the problem and, if I can solder the trouble away, fix it. If a whole board needs switched out, that's not neccessarily insurmountable.

I bought a multimeter to read the various voltages, current, etc. and there's power until right after the display panel where the wires that traversed the LEDs/fuse lamps exit and enter a vertical board, at right, and to the rear, mid-way, where the connections all seem sound, and again, no burnt areas, no obvious damage. Readings from this small board are at almost, but not quite, zero. Seems pretty elementary, but, nothing about this machine has been elementary so far, and I'm betting that the problem goes deeper, to the areas you can't see without tearing the whole thing apart. And besides, the little board looks fine. What could I do, if the problem was there? Start hunting for that board, I guess, and maybe come Christmas time, I'd finally find one.

I would like to have some idea of what to look for, assuming the problem does go deeper.

My stupidity about the screwdriver, for one thing, and my fear of soldering the other, is costing me full enjoyment of my machine just as my vacation has begun,:( and I had hoped to fully set it up and play several quad records and reel-to-reel tapes for the first time. I had been saving this experience for my vacation, since any money I might have spent on vacation has gone into all this equipment - thanks, Ebay.

It still works - I think - but without the indicators, I'm not sure, and, it's not the same. Any helpful advice from anyone experienced with this make of machine (or similar, I guess) would be greatly appreciated. I've never yet heard my QRX7001 decode CD4 and I bought several albums in that,(QS and SD, too). My apologies for the length of this appeal. Thank you, in advance. Dean
 
Hi Dean,

Sorry about your display lights. I can't speak about the QRX-7001, but my Akai AS-980 has a small circuit board that contains a rectifier circuit that powers the display lights. A rectifier circuit contains four diodes that convert AC current to DC current. If the Sansui has this type of configuration, check the four diodes to see if any are cooked. A diode will normally "open" when they fail. You may need to remove each one to check them.

Spence

P.S. A schematic of the circuitry will help greatly.
 
ask bob to sell you a machine he already has - its cheaper than shipping yours to him - he gets a lot of trade-ins - get him to pack it really really well for the trip back. - the lights are problematic for that early series - willy
 
ask bob to sell you a machine he already has - its cheaper than shipping yours to him - he gets a lot of trade-ins - get him to pack it really really well for the trip back. - the lights are problematic for that early series - willy

Hello, Don't seem like anyone has given solid advice, but to ship the Unit out, or a similar schematic.

If all lights are out, more than likely the first place to look will be the fuse for all of the Lamps on the Power Supply Board.

The Fuse may look good, and may even look good with an ohmmeter, but still may indeed be blown. Tough to isolate with VOM in some cases, but it can be done.

Many times these dastardly little buggers may be soldered onto the Board, looking like any other regular fuse, but with a wire sticking out of each end, and hard soldered to the Board. This can be a real headache for the layman, with removing the board, getting proper access to both remove, and re-solder in a new Fuse. Also finding these particular fuses will be almost impossible, I've tried myself once. Bypass that dilemma, and I'll explain below:

Here's an easy way out, and will save you mucho grief.

It won't look pretty, but your main goal-concern is getting those lights back up, right?

Firstly if the fuse is indeed blown, find out the value of this Fuse.

Hypothetically, lets say it's a 1 amp 250V Fuse.
OK, you may have problems finding a 1 amp 250V fuse, no problemo. If you're in the US on 120VAC, buy a 1 amp 120VAC Fuse, it will work fine.

At Rat Shack, buy a package of Fuse Clips. Take two fuse clips, and solder them back to back. Make a pair of them (4 fuse clips total)

Clip each of these Fuse Clips on to each side of the blown Fuse, then place your good fuse on top, in essence "piggybacking" the new fuse on top of the dead old fuse. This as I say won't look so "pretty", but in effect, you will have replaced the fuse without ripping out the old fuse, and possibly damaging the Power Supply Board in the process as well.

I hope this helps you, and gets that baby of yours glowing in the dark again. I've made this same error myself on my QRX-7500 many moons ago. All is still well with the piggybacked fuse. Mark
 
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