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Beogram 6500 fuse constantly blowing

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Steve
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Steve posted on Tue, Jul 26 2016 7:15 PM

Hi 

 

I've recently moved house - and my Beogram 6500 has blown two fuses. It was working when I moved in, but every night when I come home the turntable won't power up and fuse blown. The first time I replaced fuse it played fine all evening.. but then tonight I come home and the new fuse is gone. Is this a power / surge issue in my apartment block.. or something problematic with the electronics?

 

any advice appreciated!

steve

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kimhav
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Right, taking a closer look now so the regulator is the IC1 7812 and the C3 1000μF is the one you're ref to Martin that most like is the issue here

While looking at the caps they in general looks good; no leakage or any other indications that they're bad but still; if one should pick together a capkit for this BG6500; any recommendation of additional caps to be replaced and as well other components if I'm doing a full overhaul of it?

Dillen
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kimhav:

Right, taking a closer look now so the regulator is the IC1 7812 and the C3 1000μF is the one you're ref to Martin that most like is the issue here

Yes.

kimhav:

While looking at the caps they in general looks good; no leakage or any other indications that they're bad but still; if one should pick together a capkit for this BG6500; any recommendation of additional caps to be replaced and as well other components if I'm doing a full overhaul of it?

No. Just the one
- If it's bad. Check it with an ohmmeter.
You cannot always tell if a component is bad by looking at it.

Martin

kimhav
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Martin you wouldn't know where one could order Vishay 1000uF 40V mounting ring based caps since neither Farnell och TME stocks them.

skolesen
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kimhav
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Yes I saw that it's possible to get these on eBay but kind of reluctant to get NOS which still could be bad so kind of rather go for Vishay (old Philips) caps (who still makes this mounting ring based cap) or I'll most for Panasonic caps.

Dillen
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The ring is not necessary as long as you use the right holes and solder pads for the positive (center pin) and negative (circumference pins) respectively.
Any standard type (perferably not low-ESR) type will be fine.

Did you confirm that the capacitor is the problem?

Martin

kimhav
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Dillen:
Did you confirm that the capacitor is the problem?

Manage to remove the clip that holds down the regulator and disconnected the power cords going to the RIAA and main PCB. About the capacitor, I would say that it most likely is alright, while I don't have any multimeter to measure the capacitance, it does seems to load and discharge when measuring with high ohm range. Also, checking the power supply the output to PCB2 is 19.3V and the output from the PCB2 is 12.03V. Next I connected the power to the RIAA PCB again to see if the fuse would hold - it did. Next connected the power to the main PCB and pressed the play button - the fuse didn't blow this time and the platter started to spin and the tone arm indicated 33rpm. So suddenly everything seems just fine. Short term: Yay! But, hey what did cause my init problems and why? So open for suggestions here.

 

Menahem Yachad
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I agree that buying old NOS capacitors is akin to taking a chance with "a cat in a sack", regarding reliability.

I have brand-new stock of the EXACT Vishay replacement part MAL212047102E3 , 1000uF 40V 125C, with the ring.

Contact me off-line.

Menahem

kimhav
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kimhav replied on Sun, Jul 12 2020 9:32 PM

@Menahem I'll send you an email on the topic.

kimhav
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kimhav replied on Sun, Jul 12 2020 9:37 PM

@Dillen I did got around to re-connect the BG6500 to the BM6500 today and it worked as a charm but sitll not happy with that it blew some fusses after the 400km journey home to Malmo. It might be nothing or it might be something. But, the idea is still to re-cap the unit.

So for now only thing that I had to replce was the needle which sounds totally rusty but have spare needles so once the switch was done is sounded great again.

Also about the regulator on the PSU-board; how on earth to you re-attach the heat clip again to the bottom of the beogram?

Dillen
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Dillen replied on Mon, Jul 13 2020 6:21 AM

Not easy.
Clip it to the bottom plate before inserting the PCB.
I seem to remember the easiest way is to slide the clip in, little by little, lifting its leading edge with a small screwdriver as it goes over the regulators housing.

Martin

kimhav
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Got around to look into this turntable again after that I finally got around to play couple of records yesterday and after couple of hours it died on me.... blown fuse again. So checked the PCB2 board so checked the 7812 which is alright and replaced C3 (1000u); so have a good 12V out from the board - but still fuse blows and only blows when PCB1 is connected. So beside checking the BC337 and other tips on what to check?

Menahem Yachad
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Looking at this problem as you describe it, this would be my procedure - cheap and quick enough to do, without getting into in-depth troubleshooting..

1. On the PSU PCB, Replace the 4 Si rectifier bridge diodes, with a 1.5A unit - perhaps the 1N5393 or similar.

2. Replace the 12V regulator with a L78S12CV - more robust 2 Amps

Connect a 60W incandescent bulb across the fuse terminals - saves fuses.

If the problem still happens, then disconnect the output of the 12V Regulator from the circuits down the line.

Connect an AMMETER (not a voltmeter) between the 12V Regulator output, and all the other down-line circuits.

The objective is to monitor the Amperage, and when the Bulb illuminates (instead of blowing the fuse), check the Amperage at that EXACT time.

That will tell you where the problem is, and is not.

kimhav
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kimhav replied on Sat, Apr 10 2021 3:21 PM

So finally weekend again and due to the nice weather today the garden got it's fair share of TLC as well today after the winter :-) So moving over to the BG6500. So based on your suggestions Menahem I've replaced the bridge diodes including the 12V regulator; so the PCB2  should be in the clear now based on that I've replaced all of the caps and diodes.

Well, fuse still blows. Right, so started check the diodes on the PCB1 and D1 (IN4002) didn't pass, so this one needs to be replaced as well. So question here why would would cause D1 on PCB1 to go bad; transistor leakage?

Dillen
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Dillen replied on Sat, Apr 10 2021 3:48 PM

Is D1 open or shorted?
Can you take an ohmmeter reading across C2 and another from IC1 pin 9 to ground?

Martin

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