Memphis PR 2.150 Outputs

[Randy62]

I have a Memphis PR 2.150 amp that has 3 pairs of MP/MN2510 output transistors per channel.1 of each are shorted in the left channel.
I have been searching and I found an obscure data sheet in Chinese.From what I can tell the specs are very similar to the TIP35/36(which I have plenty).
Does any one know if they are interchangeable?
Or a better sub?
Obviously I would replace all 3 pairs in the bad channel and try to leave the right channel stock(if possible).

 

[Perry Babin]

This will vary by the design of the circuit you're using them in. I have not tried substituting them in any memphis amp. If you do, you need to bring the amp up to the point where it goes into thermal shutdown to confirm that the bias is holding. There are some amps that will not hold the bias and will go into thermal avalanche which will cause the amp to fail.

When you're testing it, you need to check the idle current cold (no audio), then drive it into a load to heat it up. Check it every few minutes to confirm that the idle current has not increased. Do this until it goes into thermal protection. When it goes into thermal protection, remove the signal source and watch the idle current as it comes out of thermal protection.

When doing this, have all covers installed.

 

[Randy62]

I just realized this amp has been repaired before.
It looks like all 12 outputs were replaced.All production codes match.
Who knows?Maybe they arent the originals to this amp.Could be why it failed.
I will take your advice and give it a shot.
Thanks,Perry.

 

[Perry Babin]

Looking at photos of two amps with similar model numbers, the 2.75 used 2SA1693 and 2SC4466. The 4.50 used the MN/MP transistors. If the originals were the 2S transistors, the FJA4213 and FJA4313 would be the preferred subs.

 

[Randy62]

I put the TIP35/36c pairs in the bad channel.The temp got to 208f on the audio side and 155f on the PS side when it went thermal.
I could only see about 1-2 amp increase in hot idle current compared to cold idle current.
Looks good to go to me.
Do you think thats acceptable?

 

[Perry Babin]

On a class B amp, I wouldn't have expected to see any increase but 2 amps overall is probably safe.

 

[Randy62]

Thank you Perry.
Randy.