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ETI 477 resurrected but with problems.
ETI 477 resurrected but with problems.
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Old 12th December 2018, 03:31 AM   #41
Ian Finch is offline Ian Finch  Australia
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Join Date: Apr 2010
Location: Coffs Harbour, NSW
Quote:
Originally Posted by Leinster Lad View Post
........Would these be direct "drop in" replacements for the BF's ?? .........
Also, I notice that the 2SC3505 and the KSC3505 are noted on the data sheets as the same.
Is this correct or is there actually a difference ??
Sadly, you are looking at history there. Sanyo's 2SC/2SA types and Philips/Siemens BF4xx type parts were all developed for old picture tube type TVs. Look at availability and the seller's credentials as the prime indicators of suitable replacements. Those parts were obsolete long ago and Fairchild then made single KSC/KSA replacements as a "one size fits all". Both Sanyo Semiconductor and Fairchild Semiconductor are now owned by On Semi so theirs are the appropriate datasheets and selling agencies to check.

Unless you are prepared to buy stock quantities of obsolete or NOS parts, don't buy those which you may find on Ebay etc. in China or various electronic parts traders around the globe. Buy from authorised sellers of genuine parts. Otherwise, you are stuffed again when if they turn out to be fakes, there is a meltdown or you need to buy more for other purposes.

Yes, they should be drop-in replacements but I have only performed the surgery once for another ETI 5000 owner and checked with another repairer in correspondence. AFAIK, three examples still work after at least 7 years but it may not be so for all builds, perhaps where the capacitance of different PCBs and wiring layouts provokes instability. You cannot guarantee DIY results with that, only make suggestions.
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Old 13th December 2018, 05:32 AM   #42
janusz is offline janusz  Australia
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Join Date: Oct 2004
I bought my Sanyos long time ago, Fairchild's ksa1142, ksa992 and ksc3503 are still available, unfortunately ksc2682 is now obsolete. B+D Enterprises still has Sanyo's 2sa1209 and 2sc2911 but they are expensive. Also, apparently, digipart has them. You can write to both and ask if these are genuine Sanyos.

In the 1980s there was some problem with BF availability in Australia so kit makers such as Jaycar later supplied their kits with mje340/350. I got such a kit but I managed to get BFs and used these. I don't have this amp anymore.

Several years ago I got another eti5000 amp and preamp, rebuilt eti477 as well as my original eti5000 preamp. From the latter I kept only the case and its display.

Anyway, my current eti477 has single filter at the input (820/1nF), no cap on 22k nfb resistor, non-inductive 220 ohm resistors in gates, 470pF caps gate to source, non-inductive 0.15 ohm source resistors, 10 ohm caddock in zoebel and "non-inductive" cap, Sanyos in VAS and 220pF there and no oscillations with ancient but genuine Hitachis.

cheers,
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Old 13th December 2018, 09:34 AM   #43
schillg11 is offline schillg11  Germany
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Join Date: Dec 2011
Location: near Stuttgart
BF469 up to BF472 are still available here in Germany at trustworthy dealers (Bürklin, Micros,..) from CDIL. The prices are about 0.55 €/each. So this could be worth a try??


BR
Gunni
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