not my experience
My experience is different with utsource.
Bought 10 FDH44N50 mosfets which were counterfeits of the lowesst quality!
Not only badly manufactured (imagine the legs were obviously filed with sandpaper or something(virtualy impossible to attach solder on these), but also exploded in my face risking my eye a great health hazard. After replaced with original parts the equipment worked as it should.
Not only that but utsource refused to take any responsibility as it happened to use the mosfets 5 months after purchase and their rediculous response was : "Thanks for your email, but for this order, you already bought for about 5 months, we have no guarantee from our supplier, if any quality problem, you should let us know in 2 months. Sorry we do not have change or refund for this item."
Great company!!!
My experience is different with utsource.
Bought 10 FDH44N50 mosfets which were counterfeits of the lowesst quality!
Not only badly manufactured (imagine the legs were obviously filed with sandpaper or something(virtualy impossible to attach solder on these), but also exploded in my face risking my eye a great health hazard. After replaced with original parts the equipment worked as it should.
Not only that but utsource refused to take any responsibility as it happened to use the mosfets 5 months after purchase and their rediculous response was : "Thanks for your email, but for this order, you already bought for about 5 months, we have no guarantee from our supplier, if any quality problem, you should let us know in 2 months. Sorry we do not have change or refund for this item."
Great company!!!
Suitable Transistor Replacements for Rotel RA-870BX Amp
Hi Folks
I have a RA-970BX which has unfortunately been very little used over the last 2 decades.
I can get replacements for leaky capacitors here in South Africa for these caps at RS Components but it also appears that two transistors - 2SD600KE/KF) and 2SB631KE/KF is faulty. My problem is that I cannot find direct replacements at all, RS included. Can anyone kindly recommend an alternative pair(s) that will be suitable and available at RS or similar site.
Thank you very much...
Hi Folks
I have a RA-970BX which has unfortunately been very little used over the last 2 decades.
I can get replacements for leaky capacitors here in South Africa for these caps at RS Components but it also appears that two transistors - 2SD600KE/KF) and 2SB631KE/KF is faulty. My problem is that I cannot find direct replacements at all, RS included. Can anyone kindly recommend an alternative pair(s) that will be suitable and available at RS or similar site.
Thank you very much...
I investigated these a while back to simulate a Rotel RA-820AX that I was going to mod. I found that the widely available KSC2690/KSA1220 were a good match, compare datasheets though because good enough for simulation doesn't necessarily mean good enough for straight replacement.
Cheers,
Cabirio
Cheers,
Cabirio
Technically speaking they may not be be counterfeit components and some parts I bought from UT source several years back were indeed the real thing but times and markets have changed......Utsource .net.....No counterfeits here!!
What you find is that because discrete through-hole transistors are fast becoming obsolete, only a handful of largely generic replacement types is being manufactured to cover thousands of long obsolete original parts - the sort of generics you buy cheap from hundreds of stores on Ebay etc. Then there are also 2nd source parts from other manufacturers like ISC, KEC, Fairchild and dozens of reputable Chinese fabs using their own identifiers or simply no marks at all. These parts will be genuine according their datasheets if they exist but you may have your doubts when their numbers and graphs are obviously just copied from the originals. e.g. Savant IC datasheets. This means trouble for DIYs and if you are a repairer, it means a bad rap, returns and demands for expensive refunds.
It also means you have to wise-up when specifying and buying some semis from careless and unauthorized resellers. General purpose parts and even some power transistors may be non-critical and replacing these successfully may give the impression of a good quality parts but that will not always be the case, particularly with matched duals, VAS, driver and output transistors.
FWIW, I agree with cabirio's suggestion of Fairchild KSC2690A/KSA1220A in the "O" Hfe range as drivers in that Rotel series.
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Thank you Suresh, Cabirio and Ian! I appreciate your suggestions.
I checked all over the place but according to RS, Mouser and Digikey, as far as I can see - the components you suggest are also unavailable and/or scheduled for extinction.
Someone suggested I must try the 2SD669A/2SB649A combination. Do you think this can work or do you perhaps "big please!" have more suggestions?
I checked all over the place but according to RS, Mouser and Digikey, as far as I can see - the components you suggest are also unavailable and/or scheduled for extinction.
Someone suggested I must try the 2SD669A/2SB649A combination. Do you think this can work or do you perhaps "big please!" have more suggestions?
Yes, Digikey/Mouser listings show EOL and no stock of those old TO220 Toshiba parts. The genuine parts are occasionally available but you would have to be constantly searching for them and the proof that they are bona fide components. There are always reasons why people sell off valuable old parts but I found one guy was just off-loading the fakes he got stuck with earlier. If you are looking for good quality, second-source audio semis, go to Profusion plc in the UK. They list enough stock parts, including Taiwanese Unisonic branded copies of 2SD660/B649 to cover most power amplifier needs. However, check delivery costs to your location for small quantities - I learned to keep small stocks of parts and only order when the quantities are economic.
Medium Power-Driver online at Profusion
However, if your repair is a 1-off, take cabirio's suggestion and use global, authorized suppliers like Mouser and Digikey. The originals are Sanyo 2SD600/B631 but these are very low saturation voltage types, probably with no direct equivalent and the amplifier uses 3 pairs of 2SD1047/B817 output transistors - a somewhat heavy load for small T0126 drivers at full rated power. This is tricky if generic parts or bad copies are used for both output and driver transistors so I would still stick with cabirios suggestion of Fairchild's copies of 2SC2690/A1220 drivers as already stated and yes, they are stock items in full production. The key to good repairs is to use genuine parts and avoid the attractive offers of what looks to be genuine parts shown in fuzzy pics that could really have anything that measures like a transistor inside, even with the wrong pinout.
I think you have enough suggestions to get moving but don't[/I] try to use Chinese reseller generic parts in order to save a little money. They will be fairly new looking, maybe unbranded or have counterfeit logos and marks looking like the old Hitachi logo (for example) which has been obsolete for many years. The amplifier will probably even work OK on modest loads with these but only one party or a careless fool who keeps turning up the volume to see what happens, is enough to burn out the fakes and do collateral damage. They may be cheap and easy to buy because they're not worth much but you may still have to make excuses for incompetence, replace them with decent quality parts and repair it - all over again!
Medium Power-Driver online at Profusion
However, if your repair is a 1-off, take cabirio's suggestion and use global, authorized suppliers like Mouser and Digikey. The originals are Sanyo 2SD600/B631 but these are very low saturation voltage types, probably with no direct equivalent and the amplifier uses 3 pairs of 2SD1047/B817 output transistors - a somewhat heavy load for small T0126 drivers at full rated power. This is tricky if generic parts or bad copies are used for both output and driver transistors so I would still stick with cabirios suggestion of Fairchild's copies of 2SC2690/A1220 drivers as already stated and yes, they are stock items in full production. The key to good repairs is to use genuine parts and avoid the attractive offers of what looks to be genuine parts shown in fuzzy pics that could really have anything that measures like a transistor inside, even with the wrong pinout.
I think you have enough suggestions to get moving but don't[/I] try to use Chinese reseller generic parts in order to save a little money. They will be fairly new looking, maybe unbranded or have counterfeit logos and marks looking like the old Hitachi logo (for example) which has been obsolete for many years. The amplifier will probably even work OK on modest loads with these but only one party or a careless fool who keeps turning up the volume to see what happens, is enough to burn out the fakes and do collateral damage. They may be cheap and easy to buy because they're not worth much but you may still have to make excuses for incompetence, replace them with decent quality parts and repair it - all over again!
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