Hello all, I’m really needing assistance in finding replacements (equal to or superior) for MTP8N10 and MTP8P10 n and p channel mosfets.
I picked up a fairly rare amplifier, a Superphon Maxx 806 which was designed by Stan Warren of PS audio. Unfortunately it’s so rare that I can’t find any service or schematic info on it anywhere. It uses two of each in the output of each channel, so the amp has four of the N channel and four of the P. One channel has had the outputs destroyed.
Before I opened the amp I saw that they were TO-220 device and was praying for BJTs, but no luck. I know that matching for fets can be trickier and I’m having no luck finding cross reference online. I was hoping for maybe RFP8N10, but no.
Can anyone point out available devices that should work as drop in replacements for these two devices? Hopefully someone is familiar with them as I can’t find much info on them at all.
I really appreciate any help.
Dan
I picked up a fairly rare amplifier, a Superphon Maxx 806 which was designed by Stan Warren of PS audio. Unfortunately it’s so rare that I can’t find any service or schematic info on it anywhere. It uses two of each in the output of each channel, so the amp has four of the N channel and four of the P. One channel has had the outputs destroyed.
Before I opened the amp I saw that they were TO-220 device and was praying for BJTs, but no luck. I know that matching for fets can be trickier and I’m having no luck finding cross reference online. I was hoping for maybe RFP8N10, but no.
Can anyone point out available devices that should work as drop in replacements for these two devices? Hopefully someone is familiar with them as I can’t find much info on them at all.
I really appreciate any help.
Dan
100V 8A mosfets, N and P channel, TO 220
Look at major selling sites.
10A may be suitable, also up to a slightly higher voltage.
But first check what caused the failure.
Look at major selling sites.
10A may be suitable, also up to a slightly higher voltage.
But first check what caused the failure.
Those are obsolete Motorola devices, and a 10A TI equivalent is also obsolete.
Look for equivalent substitute amp modules using same supply voltages, more reliable, and easy fix, just change the power amp section.
Think of Class D if voltages permit.
Look for equivalent substitute amp modules using same supply voltages, more reliable, and easy fix, just change the power amp section.
Think of Class D if voltages permit.
Great, thank you, I’ll definitely be looking for cause of failure, just wanted to make sure failed parts could be swapped.
I guess that’s an option if nothing else was an option. Would like to at least keep it as close to an original design as I can.
Excellent, thank you!
So like IRF520PBF (what’s the BE3, IRF520PBF-BE3?) and IRF9520PBF sound good?
Out of curiosity, what are your thoughts on the IRF540 as a replacement? I have 20 Vishay IRF540PBF-BE3 that I bought some time back for a project, if those would work just as well I could grab some IRF9540PBF-BE3. Would it be good to have IRF520 on hand, or would the 540 be better usually. Other than higher current and power dissipation, not sure of the effects of the different rise time, fall time, drain-source resistance, etc has.
Thank you again,
Dan
Sorry, not in my experience level...
Wait a day or so for the more experienced members to respond
Wait a day or so for the more experienced members to respond
Thank you I appreciate it. If I don’t hear from anyone then I can grab some IRF520 and IRF9520. I’m guessing the 540/9540 will work, but of course thats just a guess. When matching for BJTs it seems easier lol.
Dan
520/9520 are readily available and inexpensive at Mouser and they will certainly work.
Those MTP are basically the same, only they used old style naming conventions, as in : MTP (current) Polarity (voltage) which was enough when there were only a few around, now we need individual "assigned" part numbers because of the wide variety.
But of course they are all very similar inside.
Those MTP are basically the same, only they used old style naming conventions, as in : MTP (current) Polarity (voltage) which was enough when there were only a few around, now we need individual "assigned" part numbers because of the wide variety.
But of course they are all very similar inside.
Thank you for confirming that the 520/9520 combo will work. So that I can better understand the most important specs to match, what do you think about the 540/9540 combo being used, since I already have half of the combo needed. Looks to be pretty much the same except for being rated for higher current and power dissipation. Would it be similar to something like using a 1N4007 instead of 1N4004? Meaning just using a higher powered device.
I’ll certainly grab the 520/9520 combo, but if it’s possible to use what I have that would be cool.
Thank you,
Dan
If you already have them (or half of them), yes, use them.
These are higher current rated which is a bonus.
Sadly we don´t have original schematic, but that board should be able to drive them fine.
Audio use is not as critical as very high frequency high current switching they are designed for, so they have a relatively easier job here.
These are higher current rated which is a bonus.
Sadly we don´t have original schematic, but that board should be able to drive them fine.
Audio use is not as critical as very high frequency high current switching they are designed for, so they have a relatively easier job here.
Awesome! That’s great to hear. I went ahead and placed my order earlier and grabbed 20 of the IRF9540, but wanted other items on my order since I’m paying the shipping so grabbed 20 each of the the IRF520 and IRF9520. So if I run into an issue I’ll have both.
Dan
Please find the fault first...at least you have a working channel to compare. So some things can be done without a schematic.
Take pictures of both the track and component sides, as a record.
And use a dim bulb in series the first time you power up, for safety.
There are many threads here and on other forums for repairs to Mosfet amps, a read will be helpful.
Take pictures of both the track and component sides, as a record.
And use a dim bulb in series the first time you power up, for safety.
There are many threads here and on other forums for repairs to Mosfet amps, a read will be helpful.
That´s classic combination, I used tons of them, but apparently unavailable (or hard to find) today, while higher rated ones ara available by the thousands at Mouser and certainly at similar "safe" places.
Oh yes I absolutely will. I’ll check further down in the circuit such as the drivers for faults. I will definitely be using my DBT as well. I remember reading that fets aren’t fans of variacs, is that correct? I’ll continue reading. I’ll come back to this thread when it’s time for firing it up. There being no instructions maybe you folks can assist with setting bias.
Thank you again!
Dan
Oh great another one on the list. On my next Mouser order I’ll add 30 of each just to have them on hand. Since I bought 30 of each of the 520/9520 and 540/9540 I’ll probably use the 520/9520. I’ll save the 540/9540 for when the higher current is needed. I do like buying components so that in the future I don’t have to wait on parts.
Dan
Oh, same here.
I commercially make Guitar amps, so I will certainly use more in the future, it´s never "wasted money" by any means, specially if those are general purpose components such as power transistors, ICs, supply caps, etc.
Top boot, being in Argentina, I pay somewhat expensive freight all the way from USA so I try to cram as much as possible inside a single, "fixed price" box.
Not to mention I have to fight and waste time at Customs "just once", if at all possible.
I commercially make Guitar amps, so I will certainly use more in the future, it´s never "wasted money" by any means, specially if those are general purpose components such as power transistors, ICs, supply caps, etc.
Top boot, being in Argentina, I pay somewhat expensive freight all the way from USA so I try to cram as much as possible inside a single, "fixed price" box.
Not to mention I have to fight and waste time at Customs "just once", if at all possible.
Question for this design, I don’t need to match these fets for the outputs correct? There are two N channel and two P channel per channel. I have the bad side replaced, the P channel measured just fine and the N channel were exploded. Still aways from powering it up as I still need to take a peak into the circuit, but wanted to check on the need of matching.
Dan
Oh that’s awesome, I build cabinets for a local guitar amp maker, but also love repairing and restoring vintage audio equipment. I agree with you whole heartedly as for it not being a waste. I purchased my KSC1845, KSA992, BC550C, BC560C, 2N5551, 2N5401 at 4,000 for each device. I’ll likely never use them all in my lifetime, but they’re used so often that for the ones that are EOL’d I’ll be set. All the other transistors, diodes, and capacitors I use are bought hundreds at a time, just need to make sure the electrolytics don’t sit for too long lol. I’m constantly on the hunt for broken gear though so hopefully won’t be a problem.
Dan
Cool.
In principle, same polarity Fets in parallel should be matched, I´ll post my MosFet Matcher circuit if I find it.
That said, 2 points in your favour, looking at the above picture:
1) if both transistors come from the same batch/order, same brand, from one of the "big ones", say Faichild, ST, etc. , they will be incredibly close to begin with.
Marvels of modern tight spec production Technology.
2) I see emitter/source/ballast resistors.
What value are they?
At high current drop across them will SWAMP little transistor to transistor differences.
In principle, same polarity Fets in parallel should be matched, I´ll post my MosFet Matcher circuit if I find it.
That said, 2 points in your favour, looking at the above picture:
1) if both transistors come from the same batch/order, same brand, from one of the "big ones", say Faichild, ST, etc. , they will be incredibly close to begin with.
Marvels of modern tight spec production Technology.
2) I see emitter/source/ballast resistors.
What value are they?
At high current drop across them will SWAMP little transistor to transistor differences.