Availability of lateral MOSFETs for repairs

[agedhorse]

I expect similar problems to valves in the future.

In the moment I have a Mesa Walkabout 350 with melt powertranni and defective powerstage. A very expensive repair, if you want to use original parts (in Europe in addition).

I installed an IcePower 700AS1, the output signal of the ECC83 is connected via an impedance converter, and constructed a powersupply 12,6V DC 300mA and DC 385V 10mA.

It's not finished yet, but preamp and powersupply are working, lack of time to finish it due to Christmas.

May be, this can be a (inofficial, only for me) solution to save the sound of the preamps for the future. There is enough space inside the housing and and the weight drops a lot.

Waiting for the storm of indignation...

Christian

Not that it’s impossible, but even this probably costs more in parts and labor ultimately, because of the economies of scale.

The other reason we couldn’t do this is that it negates the existing UL safety certification (and CB safety in the EU) as well as all EMC compliance requirements.

You mention “older Walkabouts”. Does this include the last all-black version?

Yes, unfortunately.

 

[Ethix4]

All of our legacy MOSFET bass amps, none of the Subway amps.

Other manufacturers have used them too, including some models by EBS (Fafner), TubeWorks, Hartke (3500 MOSFET), HH Electronics, Marshall IBS & 3500 series, Trace Elliot, and others that I have not seen firsthand.

Does the marshall DBS series apply as well?

 

[agedhorse]

Does the marshall DBS series apply as well?

I recall those using a bipolar output stage, but there may be exceptions. Those were pretty advanced designs too.

 

[dbflats]

Sounds like maybe my 1991 Hartke mosfet 7000, which I use every day, might, like Wiley Coyote, be over the edge of a cliff and just not know it yet.

 

[agedhorse]

Sounds like maybe my 1991 Hartke mosfet 7000, which I use every day, might, like Wiley Coyote, be over the edge of a cliff and just not know it yet.

That would be the same series.

Ampeg used a different MOSFET part in their SVT-Pro amps that was not a lateral process part. These are kind of still available, but they have different quirks like a higher Vgs (by a factor of about 5 or 6) and had some difficulties with stability in some designs. That's exactly the reason why the lateral parts were so attractive in the first place.

 

[dbflats]

So riddle me this; said Hartke amp performs well, has no current ( ba dum bum ) issues, and key factor, I'm into geezer territory at 69 yo. I don't tour these days or anything like that. How likely is it to......never mind friend, I already know the answer, there's no way to tell how long old, and now evidently parts-obsolete iron, will keep chugging. I'm not worried about it and as a matter of fact, it gets used for guitar more than bass these days, in my corner -of-the-living-room studio and for duo gigs, again on guitar. Any bass I record is bass to pedalboard to interface/DAW.

Interesting discussion.

 

[agedhorse]

So riddle me this; said Hartke amp performs well, has no current ( ba dum bum ) issues, and key factor, I'm into geezer territory at 69 yo. I don't tour these days or anything like that. How likely is it to......never mind friend, I already know the answer, there's no way to tell how long old, and now evidently parts-obsolete iron, will keep chugging. I'm not worried about it and as a matter of fact, it gets used for guitar more than bass these days, in my corner -of-the-living-room studio and for duo gigs, again on guitar. Any bass I record is bass to pedalboard to interface/DAW.

Interesting discussion.

As long as it keeps working, there’s no need to worry or bother. When it breaks, you can worry then. It may outlive you, but hopefully you are lucky enough to outlive it.

 

[InkCow]

We’re entering Porsche 996 IMS bearing territory for these amps, I suppose.

 

[Jeff Scott]

We’re entering Porsche 996 IMS bearing territory for these amps, I suppose.

I'd best go check on the bearings in mine.

 

[cfortner]

Not that it’s impossible, but even this probably costs more in parts and labor ultimately, because of the economies of scale.

The other reason we couldn’t do this is that it negates the existing UL safety certification (and CB safety in the EU) as well as all EMC compliance requirements.


Yes, unfortunately.

I know that, it's my private solution. Material costs some 400 Euros.

 

[pepj]

That's likely my SWR400..not S, and Fafner on borrowed time then. My best two amps, as it happens...

 

[baxter_x]

Anyone know if the Ampeg SVT 4 pro uses those lateral MOSFETs?
Looks like it doesn't. It seems to use IRFP240 & IRFP9240 MOSFETS

 

[Milo Spleen]

My old Peavey Mark VI is looking better all of the time.

 

[darev]

Anyone know if the Ampeg SVT 4 pro uses those lateral MOSFETs?
Looks like it doesn't. It seems to use IRFP240 & IRFP9240 MOSFETS

I got a hitch in my throat when I looked up and saw that the IRFP240 was listed as “obsolete”. Once I read a bit more I realized the versions made with lead are obsolete.
For now there are still lead-free versions still made. IRFP240PBF (dig the suffix as well)

So far, I haven’t had to have a service call made on my 20 year old SVT 4. Thank goodness.

 

[Balog]

Would this apply to the GB Streamliner and Shuttle lines as well?

Edit: and if it does, would it make sense to send mine in for the flat rate check up now?

 

[J Wilson]

@agedhorse:

Where/how does this affect your GenzBenz program ?

 

[agedhorse]

Anyone know if the Ampeg SVT 4 pro uses those lateral MOSFETs?
Looks like it doesn't. It seems to use IRFP240 & IRFP9240 MOSFETS

I got a hitch in my throat when I looked up and saw that the IRFP240 was listed as “obsolete”. Once I read a bit more I realized the versions made with lead are obsolete.
For now there are still lead-free versions still made. IRFP240PBF (dig the suffix as well)

So far, I haven’t had to have a service call made on my 20 year old SVT 4. Thank goodness.

Different type, but availability is shrinking on these as well. They are used in other applications which helps with this. The lateral parts are pretty much only used in audio.

Would this apply to the GB Streamliner and Shuttle lines as well?

Edit: and if it does, would it make sense to send mine in for the flat rate check up now?

@agedhorse:

Where/how does this affect your GenzBenz program ?

Doesn’t affect it at all, entirely different switching MOSFET process. I have plenty of parts for repairs.

 

[agedhorse]

My old Peavey Mark VI is looking better all of the time.

There are parts that are no longer available (obsolete) for these as well…

 

[J Wilson]

Different type, but availability is shrinking on these as well. They are used in other applications which helps with this. The lateral parts are pretty much only used in audio.




Doesn’t affect it at all, entirely different switching MOSFET process. I have plenty of parts for repairs.

Great news, I was afraid this might have affected you and Jeff's wonderful service of those amps.

Thanks, Andy

JW

 

[baxter_x]

So far, I haven’t had to have a service call made on my 20 year old SVT 4. Thank goodness.

They are pretty reliable, except for the ones made while de LOUD period. They had soldering issues. I faced that issue with mine.