Help with Memphis 1000D's

Perry Babin · 2011-09-15 10:15 am

Don't drive it hard. This is just to see if any of the drive circuit is damaged.

If it works properly, you'll need to replace all of the output transistors in the group that had shorted outputs.

project pat · 2011-09-15 10:51 am

Perry Babin said:
Don't drive it hard. This is just to see if any of the drive circuit is damaged.

If it works properly, you'll need to replace all of the output transistors in the group that had shorted outputs.

If the drive circuit is damaged I assume it will be distorted. You think it would blow the fuse too? I won't push it.

Perry Babin · 2011-09-15 5:23 pm

It could cause either problem.

project pat · 2011-09-16 5:12 am

I'm ready to power this thing up. I brought everything I needed but I didnt bring the metal end plates with me. So now I'm not sure which terminal is positive and negative for the speaker connection. Can anyone help? Nevermind, found the manual

project pat · 2011-09-16 5:48 am

It powers up and plays clean!! Now the easy part is done, because I have burned circuit boards before.

project pat · 2011-09-16 5:59 am

Perry Babin said:
It could cause either problem.

From your repair page--In class D amplifiers, you should not make any substitutions. In some cases, the new replacements will vary enough from the originals that the same part number component will not work properly.

So what would you recommend. I need four IRF640's and eight IRF9640's. I read that you should buy a full stick of parts and I "plan" on fixing at least one other amp. They came out of the same vehicle I'm hoping the repair is similar, I'll be sure to test first before I order anything.

Perry Babin · 2011-09-16 6:07 am

The IRF64s and IRF9640s are readily available so there's no need to make any substitutions.
IRF640PBF Vishay/Siliconix MOSFET Power
IRF9640PBF Vishay/Siliconix MOSFET Power

If you buy 10 of each part, you should get enough matching transistors to complete the repair for this amp. If you order by phone, you may be able to request matching date codes.

timwebb · 2011-09-16 6:09 am

u can get all those parts there available.make sure to get extras.

project pat · 2011-09-16 6:29 am

This site/you guys are awesome. I've had these amps in the basement for over 5 years. I can't thank you all enough. I'm a member of a site like this for my car repairs and the fact that people are willing to share their knowledge and help out regular ol' people that they don't even know has saved me so much money and so many headaches. I'll say it again, you guys are awesome. I'm not sure when I'll be able to fork up the cash for the parts but I will surely keep you posted. Thanks again. In the meantime I'm sure I'll be surfing the site. I've been building speaker cabinets since I was about 11. I have some fiberglass 3-way loudspeakers I made. I'm probably gonna post pics soon.

project pat · 2011-09-16 7:17 am

I also have a class ab rockford amp laying around that works but sounds distorted. Could that mean the fets are good but theres a driver problem?

Perry Babin · 2011-09-16 7:23 am

Start a new thread if you have questions about a different amp. Include the amp make/model in the subject line with the symptoms.

project pat · 2011-09-16 7:56 am

Perry Babin said:
Start a new thread if you have questions about a different amp. Include the amp make/model in the subject line with the symptoms.

absolutely

project pat · 2011-09-17 5:43 am

project pat said:
From your repair page--In class D amplifiers, you should not make any substitutions. In some cases, the new replacements will vary enough from the originals that the same part number component will not work properly.

So what would you recommend. I need four IRF640's and eight IRF9640's. I read that you should buy a full stick of parts and I "plan" on fixing at least one other amp. They came out of the same vehicle I'm hoping the repair is similar, I'll be sure to test first before I order anything.

I've tested the other 1000d, I got readings of 1.0 and lower on a couple of leg combo's from two transistors.. Luckily it's only on one output side this time so "if" it's just the transistors it's gonna be less to buy. I'm gonna set it up to test for sound clarity in a few minutes.

project pat · 2011-09-17 7:15 am

Oh my perry it worked!!

project pat · 2011-09-17 7:45 am

timwebb said:
u can get all those parts there available.make sure to get extras.

Probably an obvious answer, but why?

timwebb · 2011-09-17 4:34 pm

cause u will blow new parts very easy during testing.so always have enough on hand.

project pat · 2011-09-18 6:58 am

Perry Babin said:
Don't drive it hard. This is just to see if any of the drive circuit is damaged.

If it works properly, you'll need to replace all of the output transistors in the group that had shorted outputs.

I want to be sure I'm not doing more than I have to. Each group of of output transistors has 6 total. Four 9640's and two 640's all in parallel. If only one of the 640's is bad, do I only need to replace both 640's? And vice versa with the 9640's? If only one of the 9640's is bad, I replace all four and I can leave the two 640's that are good?

Perry Babin · 2011-09-18 9:14 pm

Replace all 6.

To clarify, the 640s are in parallel. The 9640s are in parallel. The 640s are not in parallel with the 9640s.

project pat · 2011-09-18 10:41 pm

Perry Babin said:
Replace all 6.

To clarify, the 640s are in parallel. The 9640s are in parallel. The 640s are not in parallel with the 9640s.

Ok, but if their not in parallel with each other and of adifferent value, why replace if not burnt? Because they could be damaged but not totaly at fault?

Perry Babin · 2011-09-19 2:58 am

Didn't you state that one of the two 640s had failed and one of the 9640s had failed?

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