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Where to get F-6013 boards for 5000a

bberkom

bberkom

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I have a Sansui 5000a that is in excellent cosmetic and electrical shape. I love the way it sounds, however it has the 1040 driver boards. I know these are prone to failure, so I'd like to replace them with the 6013 boards.

I haven't had any luck on ebay so far. Is there anywhere else I can get ahold of these boards? Or do I just need to wait it out until some come along on ebay? Thanks.
 
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I would also be open to making my own F6013 driver boards. I have seen a really good schematic and file created for this purpose, but I have never etched a PCB before. Is there anyone I could contact on AK who could make the PCB's for me that I could add components to to make the 6013's?
 
ghazzer said:
You are probably better off to modify your existing F-1040 boards.
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Hyperion said:
I agree. :thumbsup:
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Yeah I guess if I am going to do that much soldering, I'd might as well perform the mod that is so well-outlined here. I have a question you guys may be able to help me with (see photos). I know that one of the 1040 boards has already been replaced (I think the left channel). The right channel board has a bunch of diodes on the back of it. This channel also does not have the little black box on the transistors, which I guess is part of the diode mod on that channel?

Seems like the mods would be different on each of those boards?

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I am not sure where to find the details of the modifications to the F-1040 boards, but make sure they are done as per the instructions and illustrations in that thread (?) wherever it is. And if that means removing those diodes on the back of the board (as I suspect it will), then so be it - both boards should be exactly the same when you have finished.

This is what I have found so far - but there is a much more detailed thread somewhere...
http://audiokarma.org/forums/index....-driver-boards-or-f-6013.698177/#post-9387688

This one is better (further links in the thread)
http://www.audiokarma.org/forums/showpost.php?p=4347793&postcount=55

Good pictures - take more as a record for you to use during the modifications.
 
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Thanks for your help. I know which thread you are talking about, and I will just stick to those instructions and match the boards there.
 
Yes. That is the one that Hyperion pointed him to in his last post. There doesn't seem to be an index into the Sansui FAQ, so specific posts are often hard to find.
 
Ah, didn't see that. This reminds me that I've got to try this mod myself. I found a good 5000A with F6013 boards but no case. Then I got a parts unit with a wood case and F1040 boards that turned out to be in restorable condition.
 
I've come into possession of a 5000a recently and I've been loving this receiver. I haven't heard too many (881, 771), but this is really one of the best Sansui receivers I've heard yet. Or any receiver for that matter, the sound quality is a whole other post of rapture. But needless to say, I dig this one..

I took it into my local electronics guru and his reply about the faulty boards was - if it survived this long, it will probably be fine. This is the same guy who, back in the 70's, figured out the issue before they sent out the notice offering the free upgrade.

I'm no expert but your boards look like they've been through some stuff. Here's mine, 100% original I believe.

Question is : if your boards have already been repaired, are you doing any good modifying them further? Maybe you're looking for replacements after all.
 

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Not sure we can say his boards have been repaired. They've been worked on, but with the diodes on the back of the board there is no thermal connection to the drivers. The Skippy mod restores the thermal connection to prevent thermal runaway.
 
I agree with you, maybe I should have switched my words - it definitely has been modified, who knows if it's been repaired. Also, I noticed the heat damage to the VR and the capacitor. In any case, it's cause for concern. Hope the pics I posted assist in some way.
 
darkhosis said:
I agree with you, maybe I should have switched my words - it definitely has been modified, who knows if it's been repaired. Also, I noticed the heat damage to the VR and the capacitor. In any case, it's cause for concern. Hope the pics I posted assist in some way.
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Thanks for your replies. The diode-modified board is the one that has been replaced previously. When they replaced the board, it seems they got a little too close to the left channel and singed those parts. They still check out okay, however. The left channel board looks all original and seems to be pristine (minus the heat damage) like the rest of the receiver with no corrosion at all. The right channel has been modified with the diodes to get around the thermal protection.

I am still trying to decide whether to modify versus try to look for 6013's. Because of the discrepancies that already exist between the boards, I have been leaning towards just replacing the boards with a matching pair of 6013's if I can be patient enough to wait. I'd hate to modify the existing boards only to have one fail because of some other fault.
 
I'll tell you my plan for my 5000A. If I can find F6013 boards cheaply, then I'll buy them and install. If not, then I'll just mod the F1040s. Modding the 1040s isn't really any more difficult than making the changes to install the 6013 board (they aren't plug/play).

With the original 1040 boards, the big square diodes that clamp onto the driver transistors are supposed to provide temperature compensation. As the drivers heat up, the bias current tends to increase - so they get even hotter and bias increases even more until you have melt down. The diodes are supposed to heat up as the drivers heat up, in order to limit the current flow and keep the bias at the correct level. However, the original diodes aren't reliable and the thermal coupling to the drivers isn't good. On my 5000A the diodes have completely detached from the drivers. The Skippy mod replaces the diodes with reliable parts and provides a good thermal attachment.

Don't worry about the fact that your two driver boards are different. One of the first steps of modding the 1040s is to remove the diodes - once you've done that your two boards will be identical again.
 
two.dogs said:
I'll tell you my plan for my 5000A. If I can find F6013 boards cheaply, then I'll buy them and install. If not, then I'll just mod the F1040s. Modding the 1040s isn't really any more difficult than making the changes to install the 6013 board (they aren't plug/play).

With the original 1040 boards, the big square diodes that clamp onto the driver transistors are supposed to provide temperature compensation. As the drivers heat up, the bias current tends to increase - so they get even hotter and bias increases even more until you have melt down. The diodes are supposed to heat up as the drivers heat up, in order to limit the current flow and keep the bias at the correct level. However, the original diodes aren't reliable and the thermal coupling to the drivers isn't good. On my 5000A the diodes have completely detached from the drivers. The Skippy mod replaces the diodes with reliable parts and provides a good thermal attachment.

Don't worry about the fact that your two driver boards are different. One of the first steps of modding the 1040s is to remove the diodes - once you've done that your two boards will be identical again.
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That's a really good summary. Its not at the top of my project list so I'll probably keep an eye out for new boards until it's time to work on it. If I can't find any by then, I'll go with the mod probably.
 
Thats exactly what I'm doing. We'll be bidding against each other on the Bay! Kidding. I'm not actively looking at the moment. Also I think it might be fun to resurrect some 1040 boards so thats the way I'm leaning unless some 6013s fall into my lap.
 
Two 6013s just sold on November 8 with a buy it now. $50 for the pair.

On a side note, I left mine on at work overnight. Came in the next day, a little panicked when I felt the back and how hot it had got just by being on. How much is peace of mind really worth?? hah
 
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