This KENWOOD KA-907 needs total overhaul!

[KA907nKA9900]

I bought a Trio KA-9900 and when it failed, I sent someone to get me a KA-907.

The idea was to use the KA-907 as a mirror image to restore the KA-9900.

Here is the story of the KA-9900 https://audiokarma.org/forums/index...leeping-for-10-years-lets-wake-her-up.918566/

It turned out to be a bad buy.

A picture is worth a thousand words, so I will let the pictures tell the story.

Heads-up: The KA-907 was cannibalized and bastardized, the noise/hum it generated was so much that I couldn't stand it playing since purchase.

With your help, I maybe able to decide if it can be restored, how to go about the restore and most importantly at what cost.

 

[diepbtt]

You make the informations very confused as i read.

You firstly bought a Trio KA-9900 -japanese version- and it was bad, then you bought further a KA-907 -Europe/ USA version for comparation?

Now your KA-907 is also bad and you cannibalize it ?

And what do you want to restoration? KA-9900 or KA-907? they are the same, just different AC voltage supply.

For KA-907 you can read Echowars restoration: http://www.cdkands.com/ka907_1.html or a german site: https://www.amplifier.cd/Verstaerker/verstaerker/bolide.htm using google translate or

For Trio KA-9900 you can find some advices from a japanese blog: http://gt2500jzz.livedoor.blog/archives/2013-01.html?p=3 also
using google translate

Good luck

 

[KA907nKA9900]

You make the informations very confused as i read.

You firstly bought a Trio KA-9900 -japanese version- and it was bad, then you bought further a KA-907 -Europe/ USA version for comparation?

Now your KA-907 is also bad and you cannibalize it ?

And what do you want to restoration? KA-9900 or KA-907? they are the same, just different AC voltage supply.

For KA-907 you can read a german site: https://www.amplifier.cd/Verstaerker/verstaerker/bolide.htm using google translate or

For Trio KA-9900 you can find some advices from a japanese blog: http://gt2500jzz.livedoor.blog/archives/2013-01.html?p=3 also
using google translate

Good luck

I bought a perfectly working TRIO KA-9900.

One channel died due to I assume a power surge. That's the only problem the TRIO has.

Then I bought a Kenwood KA-907.

I bought both sight unseen.

I didn't cannibalize the Kenwood, recently I took it apart and saw why it sounded so bad. It was cannibalized prior to my purchase. Outside it looks like a KA-907 inside, it is not a KA-907.

I need to restore both. But I wish to separate the restore process hence two threads.

I assumed they were internally the same save for the power supply.

Thanks for the links.

Hope it is clearer now.

I'll let the pictures tell the rest of the story.

 

[KA907nKA9900]

Sorry for the long break in transmission.

Life happens but I got some spare time.

Front and rear pictures.

 

[KA907nKA9900]

View from the top

 

[KA907nKA9900]

View from below

 

[KA907nKA9900]

I cannot get two screws out despite everything I have done. I would appreciate suggestions on what works

 

[KA907nKA9900]

One of the boards has been totally stripped. Looks like the power amp PCB assembly

 

[KA907nKA9900]

Pictures of the other channel that I was able to take apart.

Pictures before and after dusting.

I know I can clean them better and I will in the course of its restoration.

This one I don't mind take apart for the purpose of practice.

Vast improvement over initial pictures in the TRIO KA-9900 thread

 

[KA907nKA9900]

pictures of the outputs taken out of the KA-907

 

[Watthour]

That is in very poor condition. It will require a lot of effort to restore. Fortunately, the parts are not expensive if you can get them. The time you invest may be high, however.

 

[KA907nKA9900]

That is in very poor condition. It will require a lot of effort to restore. Fortunately, the parts are not expensive if you can get them. The time you invest may be high, however.

Agreed.

It will an interesting exercise.

I don't mind taking my time.

I plan to go very slow.

About that stripped PCB what are my options?

I am thinking of replacing both transformers as well

 

[reddish75]

I be honest on this one, you have NO CHANCE of restoring that.

One transformer is not original, providing the other is in good working order you could get a new one made bespoke for what would be an enormous cost, probably getting on to be half the amps value

The rust looks so bad once sanded down they'll be next to no material left

The PCB's are toast.

The original wiring loom looks completely hacked away.

My advice on this would be to strip it for parts and ebay them.

 

[reddish75]

I cannot get two screws out despite everything I have done. I would appreciate suggestions on what works

If the heads are in good condition, you could try penetrating spray with graphite or if rusted in rost off which is a wurth product, which works by freezing the rust making it easier to back the screw out.

If the heads are stripped try cutting a new slot with a dremmel type tool if no joy cut the head off pop the parts out and drill the rest out.

 

[KA907nKA9900]

I be honest on this one, you have NO CHANCE of restoring that.

One transformer is not original, providing the other is in good working order you could get a new one made bespoke for what would be an enormous cost, probably getting on to be half the amps value

The rust looks so bad once sanded down they'll be next to no material left

The PCB's are toast.

The original wiring loom looks completely hacked away.

My advice on this would be to strip it for parts and ebay them.

The easiest way to repair it is to get new PCBs, but I never find them online.

Seems I am better of cutting my losses and selling what can be sold.

Then buying another 9900 or 907 from a more reputable source

Thanks for your insight

 

[reddish75]

My advice on selling it, strip the pcb's that haven't been molested, the pots, the knobs faceplate if in good condition, speaker terminals, powerswitch etc, anything that's salvagable the put the money to getting the 9900 working properly.

 

[KA907nKA9900]

My advice on selling it, strip the pcb's that haven't been molested, the pots, the knobs faceplate if in good condition, speaker terminals, powerswitch etc, anything that's salvagable the put the money to getting the 9900 working properly.

Lovely word: "molested"

I would also add "raped"
Confirmed what I suspected, the KA-907 was a bad buy.

Thanks again

 

[KA907nKA9900]

No longer going to restore this amp.

I will be stripping it and attempting to recover my losses.

There is no way to change the thread title.

Will focus my time and efforts on https://audiokarma.org/forums/index...leeping-for-10-years-lets-wake-her-up.918566/

After stripping this amp, its parts are headed for eBay.

Thanks again @reddish75. You have been immensely useful to me.

I would rather spend $500 to get another one with minimal repairs like the 9900 than go this route anymore

 

[reddish75]

Just one more point on this, you could possibly use some of the wiring on your 9900 if the specs printed on the wire matches up.

 

[reddish75]

After stripping this amp, its parts are headed for eBay.

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