mosfet replacements please help!!!
Printed From: Speakerplans.com
Category: General
Forum Name: General Forum
Forum Description: Open Discussion / Questions
URL: https://forum.speakerplans.com/forum_posts.asp?TID=98538
Printed Date: 19 April 2024 at 10:11am
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: mosfet replacements please help!!!
Posted By: young simba sounds
Subject: mosfet replacements please help!!!
Date Posted: 15 May 2017 at 8:16pm
 doing my head in trying to find these fets i dont think i am but is there an alternative i can usenumbers on fets are as goes sml buz908d and buz 903d any help would be much appreciated thanks!! ------------- scoops...yes scoops the only SUB for me |
Replies:
Posted By: Dub Specialist Sound
Date Posted: 15 May 2017 at 11:48pm
|
I take it you have checked RS or Farnell? ------------- Musical Roots Reggae Vibration is Life! for music is sound...sound is vibration...vibration is energy... and energy begets life. Therein lies my passion!...MUSIC IS LIFE... |
Posted By: kedwardsleisure
Date Posted: 15 May 2017 at 11:57pm
|
dont think you'll get any other than ebay as Hitachi who made them are no longer, they merged with mitsubishi to form Renesas, but AFAIK never made them at that time. Magnetek (now TT) made them for a while too. The nearest equivalent would've been an exicon ECF20N/P25 but I dont think they make those any more either. If you find new ones they're likely to be around the £20 mark each. You could buy a scrap Chevin or old Matrix or similar as they usually have this sort of thing in there. ------------- Kevin North Staffordshire |
Posted By: _djk_
Date Posted: 16 May 2017 at 1:20am
|
What is the ±V on the amp? If it's higher than ±100V you may be SOL, the only part available now is the 200V ECF20N20 at GBP15 each------------- djk |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 7:54am
|
yeah i feared this aswell, i have found one of each for around 18 quid each on ebay thanks for the replies guys!!! ------------- scoops...yes scoops the only SUB for me |
Posted By: VentureSound
Date Posted: 16 May 2017 at 5:53pm
|
Try cricklewood electronics |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 6:00pm
|
thanks everybody, also would anybody no a close value to the small ceramic capacitor next to the mosfet? the little orangy brown ones have no numbers or any values on them at all?? ------------- scoops...yes scoops the only SUB for me |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 6:16pm
|
it also took that out on its way ------------- scoops...yes scoops the only SUB for me |
Posted By: kedwardsleisure
Date Posted: 16 May 2017 at 6:48pm
|
could you ask the manufacturer maybe? ------------- Kevin North Staffordshire |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 6:55pm
|
thats where it gets complicated, the amps are complicated (psl) yes i no, i heard the stories they go bang but ive had a fair few and none failed miserably even when pushed beyond there limit, there is no info anywhere, all else is now good i have some tracking to bypass apart from that its just that last ceramic capacitor now ------------- scoops...yes scoops the only SUB for me |
Posted By: APW
Date Posted: 16 May 2017 at 7:30pm
|
NOS BUZ90x http://dalbani.co.uk/catalogsearch/result/?q=BUZ908D" rel="nofollow - http://dalbani.co.uk/catalogsearch/result/?q=BUZ908D £12.99 each inc vat, half the price of Cricklewoods. |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 8:03pm
 peerfect thanks, gnna order these in!!!------------- scoops...yes scoops the only SUB for me |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 8:13pm
 between the resistor is the two brown little ceramic http://www.ebay.com/sch/Consumer-Electronics-/293/i.html?_nkw=capacitors" rel="nofollow - capacitors thats the last thing, i have one that has gone, any info on what would be the best as there is no indication on them? ------------- scoops...yes scoops the only SUB for me |
Posted By: young simba sounds
Date Posted: 16 May 2017 at 8:15pm
between the resistor is the two brown little ceramic capacitors thats the last thing, i have one that has gone, any info on what would be the best as there is no indication on them? also this is a pic of the board in repair  ------------- scoops...yes scoops the only SUB for me |
Posted By: simonp1100
Date Posted: 16 May 2017 at 8:16pm
|
young simba sounds wrote:Posted By: young simba sounds
Date Posted: 16 May 2017 at 8:18pm
|
perfect, this is more a project for me so will get them ordered thanks again for quick replys!!! ------------- scoops...yes scoops the only SUB for me |
Posted By: odc04r
Date Posted: 16 May 2017 at 9:55pm
|
Do yourself a favor and buy one of these little doodads - http://www.ebay.co.uk/itm/New-All-in-1-Component-Tester-Transistor-Diode-Triode-Capacitance-ESR-Meter-0W77-/201493269992?hash=item2ee9ef4de8" rel="nofollow - http://www.ebay.co.uk/itm/New-All-in-1-Component-Tester-Transistor-Diode-Triode-Capacitance-ESR-Meter-0W77-/201493269992?hash=item2ee9ef4de8 I promise you will find it more then useful enough to warrant the price tag for applications of unknown components. |
Posted By: kedwardsleisure
Date Posted: 16 May 2017 at 10:42pm
|
good sounding amps when working properly. ------------- Kevin North Staffordshire |
Posted By: _djk_
Date Posted: 17 May 2017 at 12:18am
|
DALBANI !!! Have had a huge problem with them in the past with counterfeit parts. Buyer Beware. ------------- djk |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 8:16am
odc04r i will do, i just havnet really thought about getting into amp prepair im very very novice, dont no much but do no a couple little basics, been lurking on this forum for years and years learning and takng in points. after further looking at this amp on the secondary board all the fets are unmatched anyway  so looks like either somebody has been in there before (could be within 20 years) as they are old now as i doubt they was made that way, this is more of a practice amp for me anyway so if it goes wrong it does------------- scoops...yes scoops the only SUB for me |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 8:22am
|
thanks for heads up djk!!!! ------------- scoops...yes scoops the only SUB for me |
Posted By: odc04r
Date Posted: 17 May 2017 at 9:40am
That's why I recommended that gadget :) Like a budgie it is very cheap for the help it can provide. Maybe it would be worth drawing out the schematic and simulating it, then seeing what other FETs might work well in it? I have no idea if they exist but I bet you could get somewhere close and you'd learn an awful lot. Plus simulation is free and quite powerful for the audio frequency range if your device models aren't hopeless. |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 9:45am
yeah thanks again, we all have to start learning somewhere, everything i am good at apart from circuits and amplifiers, its the last part of audio im yet to learn so now is time to start i think   i have orderd all parts so far ill keep you updated when all come to see if the amp fires properly, (it did fire when i aquired it) but ive only just realised these parts had gone, i heard amps will still run without some fets anyway??------------- scoops...yes scoops the only SUB for me |
Posted By: VentureSound
Date Posted: 17 May 2017 at 1:38pm
+1 Beware Dalbani. Quite well known for selling fake parts.
|
Posted By: jbl_man
Date Posted: 17 May 2017 at 1:48pm
Out if interest,what amplifier is this from? Those individual heatsinks look like they would be a dust-trap! ------------- Be seeing you. |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 1:57pm
|
out of a please ka2401!!! ------------- scoops...yes scoops the only SUB for me |
Posted By: simonp1100
Date Posted: 17 May 2017 at 6:44pm
Sorry i am confused, your asking for the above FET'S yet in the board that you posted a picture of they are BUZ901D & BUZ906D as well as BUZ903D & BUZ908D ?????  i am sure these need to be ALL BUZ901D & BUZ906D throughout both channels (the last one i repaired had ALL 906D & 901D). |
Posted By: ceharden
Date Posted: 17 May 2017 at 6:47pm
| IMO the cost of the replacement FET's will be much more than the value of the amp. |
Posted By: simonp1100
Date Posted: 17 May 2017 at 6:48pm
 |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 6:49pm
|
thats what was in there, i got another two of these amps all fets are buz903d and 908d but i was just going to put back in what i took out ------------- scoops...yes scoops the only SUB for me |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 6:50pm
|
in the long run this amp was a spare anyway just incase i needed parts but i thought id have a shot at it to learn on basically so money is not much of an object but rather more of a learning amp ------------- scoops...yes scoops the only SUB for me |
Posted By: simonp1100
Date Posted: 17 May 2017 at 7:00pm
|
I would make sure that you replace all the BUZ906D & BUZ901D with BUZ908D & BUZ903D as the 906D & 901D are rated at 200V devices & the 908D & 903D are rated at 250v devices. These amplifiers were well known for FET'S exploding hence why they may have changed / up-rated the output FET's due to the high supply rails. Do not mix the two together (either all 200v devices or all 250v devices). |
Posted By: young simba sounds
Date Posted: 17 May 2017 at 7:05pm
|
thanks simon, this must be an older model to the other two then as this one also has different capacitors also not as well built as my other two, i might just put this one to rest lol ------------- scoops...yes scoops the only SUB for me |
Posted By: _djk_
Date Posted: 17 May 2017 at 10:25pm
|
"Do not mix the two together (either all 200v devices or all 250v devices)." Does not matter. If the ±V is 100V or less the 200V parts will be fine The difference between the 200V and 250V parts is the 250V parts are obtained on a selection basis. They start out with the same die . The ones that test better than 250V become 250V parts. Then they lower the test spec to 200V, and the ones that pass are sold as 200V parts. Hitachi did the same with the 2SJ48/49/50 series rated at 120/140/160V. ------------- djk |
Posted By: simonp1100
Date Posted: 18 May 2017 at 5:25am
Because of the past record with these amplifiers having FET's blowing with the 906D & 901D fitted and with the supply rails being OVER 100v, stick with the higher voltage FET's for longer long term reliability. Repaired quite a few of these in the past and have seen many PCB's damaged beyond repair due to FET's blowing and taking out the board as well. By the way these amplifiers were made in Bristol (Flowers hill). |
Posted By: odc04r
Date Posted: 18 May 2017 at 10:45am
|
Tbh an amplifier with +100V is not a great idea for a learning project anyway. As the FETs are valuable then you're probably better off stripping it for parts or selling intact as spares second hand, then investing in a more sensible amplifier for learning with. The P3A on ESP audio is a great starter to build, and as long as you have a half decent dual DC power supply then you won't have to build any mains power supplies to be able to have a listen at low levels. If you simulate the design first you will learn a lot as you build it and test it out, mechanical as well as electronic with regards to construction and biasing. It's a good way to start learning vs jumping right in at the deep end with an unknown quantity. |
Posted By: young simba sounds
Date Posted: 18 May 2017 at 10:52am
|
im going to take your adice on this one anyway (last night during a power up one of my mid range amps blew) so money will be going to an engineer to fix this one instead, so...... i have a small quantity of various buz906 901 and 903 fets if anybody wants lol ------------- scoops...yes scoops the only SUB for me |
Posted By: kedwardsleisure
Date Posted: 23 May 2017 at 10:57pm
|
they're great for learning about holes in the tops of transistors, holes in the soft start part of the pcb and holes in your wallet. I once had some new transistors (not lateral fets) from a supplier mentioned in this thread and they were short circuit out of the box. Got a refund however. I've also had fake parts although they were very good fakes...the Crown amplifier knew better though. ------------- Kevin North Staffordshire |
Posted By: young simba sounds
Date Posted: 24 May 2017 at 9:14am
yeh i no, ive scrapped the amplifier for spares now, i also have a behringer ep4000 that i had switched on after a while which got extreme hot to the touch then smoke, though on inspection the only damage i can see is one of the hitachi transisters has completly cracked in half!!!  ------------- scoops...yes scoops the only SUB for me |