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This TRIO-KA 9900 has been sleeping for 10 years! Let's wake her up!!

Ok, do you have the same pics of the left channel.

Comparing this with photos of a ka907 the boards look the same at first glance but look carefully the layouts are different
 
reddish75 said:
Ok, do you have the same pics of the left channel.

Comparing this with photos of a ka907 the boards look the same at first glance but look carefully the layouts are different
Click to expand...

Yes I do. I have just taken them. I will be uploading to this post and the very next one in a few moments
 

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reddish75 said:
Ok, do you have the same pics of the left channel.

Comparing this with photos of a ka907 the boards look the same at first glance but look carefully the layouts are different
Click to expand...
Agreed, I noticed a few differences but I assumed it was due to versioning not a difference between American and Japanese specifications
 
Reviewing the pictures of the left channel posted above, I notice Q10 was not very visible, so I am posting two new pictures that show Q10 clearly
 

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One of the first things I was told was to use heat shrink tubing to fix the splicing.

I was wondering since I have isolated the problem to the power amp PCB assembly, what if I disconnected this white connector for the right channel would that be ok? to then power on the rest of the amplifier?
 

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OK, the layout is different than the 907 on the power amps even though the board numbers are the same, at this moment there are to me at least an unknown number of differences between them, do not use the 907 service manual as a guide for the 9900, use the left channel as a guide. This said i'll redo the transistor list board by board.

First thing those boards need a good clean.

Resistors maybe different values make sure you take note of the them.

The power amp pcb transistors should be replaced by,

Q7 c945 - Ksc945
Q9 a733 - Ksa992, this is because the new version of the 2sa733 the ksa733 is not rated with the same dissipation (625mw to 250mw) the 992 part is rated to 500mw which will be be fine in this application.
Q8 a733 - ksa992
Q10 c945 - ksc945
Q1 change to 2SC2344
Q2 change to 2SA1011
 
reddish75 said:
OK, the layout is different than the 907 on the power amps even though the board numbers are the same, at this moment there are to me at least an unknown number of differences between them, do not use the 907 service manual as a guide for the 9900, use the left channel as a guide. This said i'll redo the transistor list board by board.

First thing those boards need a good clean.

Resistors maybe different values make sure you take note of the them.

The power amp pcb transistors should be replaced by,

Q7 c945 - Ksc945
Q9 a733 - Ksa992, this is because the new version of the 2sa733 the ksa733 is not rated with the same dissipation (625mw to 250mw) the 992 part is rated to 500mw which will be be fine in this application.
Q8 a733 - ksa992
Q10 c945 - ksc945
Q1 change to 2SC2344
Q2 change to 2SA1011
Click to expand...

Those differences between the service manual and the amp made me suspend the repair.

Thanks for the updated transistor list.


My ultimate satisfaction would be to make it work again.

What's the recommended way of cleaning up those boards, I did use an air blower but much of the dust is like caked, if I use my bare hands, I can get it off. But what of the hard to reach places?

The left channel appears to be virgin. So it is a very good reference. I appreciate your input.

Once again let me say this, I cannot begin to thank you enough!
 
reddish75 said:
Splicing wires

Click to expand...
Thanks for the video. Splicing wires is an art.
It was wrong to splice several close wires at the same place. I am seriously considering doubling the heat shrink tubing as a consequence.

Once again thanks for holding me by the hand as I struggle to restore this amplifier
 
I would use a thin dry paintbrush first maybe an inch to an inch and a half see how you get on with that, use a lightly damp cloth to wipe over transformers and metal parts. Here's a good read as well,

https://www.audiokarma.org/forums/index.php?threads/tutorial-deep-cleaning-an-amplifier.258899/

There is Rs components in South Africa for some parts but I tend to find Rs expensive and they have minimum part orders.

https://za.rs-online.com/web/?cm_mm...VC553Ch2ZLwlnEAAYASAAEgKsEPD_BwE&gclsrc=aw.ds

For the bulk of the parts I would use Mouser or Digikey, when I order from them delivery takes around 48 hours from the states to the UK maybe make a list of all parts to be replaced pcb by pcb then make just one order.
 
reddish75 said:
I would use a thin dry paintbrush first maybe an inch to an inch and a half see how you get on with that, use a lightly damp cloth to wipe over transformers and metal parts. Here's a good read as well,

https://www.audiokarma.org/forums/index.php?threads/tutorial-deep-cleaning-an-amplifier.258899/

There is Rs components in South Africa for some parts but I tend to find Rs expensive and they have minimum part orders.

https://za.rs-online.com/web/?cm_mm...VC553Ch2ZLwlnEAAYASAAEgKsEPD_BwE&gclsrc=aw.ds

For the bulk of the parts I would use Mouser or Digikey, when I order from them delivery takes around 48 hours from the states to the UK maybe make a list of all parts to be replaced pcb by pcb then make just one order.
Click to expand...

Thanks for the deep cleaning tutorial.
Tearing apart the unit appears to be an overkill for now, but it's good to know it can be done and safely too.

I will most likely order from Digikey or Mouser as recommended.

I have a way of shipping from the US that takes about 3 weeks, and it should be cheaper than from SA I believe
 
Good luck with the repair - I'm glad someone mentioned cleaning because just looking at those boards made me cringe. Also there's a whole bunch of components installed at really weird angles too - some of your photos show transistors bent over and all kinds of other strange things - check that none of the component legs are touching each other - especially those bent transistors where the leg spacing is marginal at best.
 
Markoneswift said:
Good luck with the repair - I'm glad someone mentioned cleaning because just looking at those boards made me cringe. Also there's a whole bunch of components installed at really weird angles too - some of your photos show transistors bent over and all kinds of other strange things - check that none of the component legs are touching each other - especially those bent transistors where the leg spacing is marginal at best.
Click to expand...

I know the boards needed cleaning, I just didn't know how to clean them without causing more problems until today.

I guess you are referring to pictures of the left board, I did adjust some of the transistors so I could get clear pictures with the details for @reddish75.

If there are other components that are improperly installed, I would appreciate pointers so I can rectify.

Thanks for the good wishes.
Edit:

Just seen that a toothbrush can help with the cleaning.
 
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reddish75 said:
OK, the layout is different than the 907 on the power amps even though the board numbers are the same, at this moment there are to me at least an unknown number of differences between them, do not use the 907 service manual as a guide for the 9900, use the left channel as a guide. This said i'll redo the transistor list board by board.

First thing those boards need a good clean.

Resistors maybe different values make sure you take note of the them.

The power amp pcb transistors should be replaced by,

Q7 c945 - Ksc945
Q9 a733 - Ksa992, this is because the new version of the 2sa733 the ksa733 is not rated with the same dissipation (625mw to 250mw) the 992 part is rated to 500mw which will be be fine in this application.
Q8 a733 - ksa992
Q10 c945 - ksc945
Q1 change to 2SC2344
Q2 change to 2SA1011
Click to expand...
Did you intend that Q1 be replaced with 2SC2344 or 2SA1011?
Did you intend that Q2 be replaced with 2SA1011 or 2SC2344?
 
I cannot find the drivers 2SA1011 and 2SA2344 on Digikey or Mouser.

I'd appreciate pointers to suitable substitutes.

Thanks in advance

Edit:
Available on BDent!
 
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