TA-100W follow-up "work around"

[Bfox]

This link http://www.suwa-koubou.jp/repair/ka_7500/ka_7500_2.html worked for my ka-9100. As mentioned in the thread just be sure to swap the position of the trimmer vr1(2k) and r1(2.7k) with r2(1.2k). Those values work great.

I also swapped the 2sd2012 for a MJE15032 cause it was all I had laying around

ALSO do not forget to check for bad transistors and capacitors on the kenwood amp board, I had 3 bad/blown transistors q6, q8 q12. Plus r26 was open.

ALSO ALSO, you should first adjust trimmer VR2 on the amp board to achieve a balanced bias, I got about +-1.1v. Then fine tune it with vr1 from the new circuit. Don't have a distortion analyzer, but sounds great to me.

 

[EchoWars]

Cool. I love confirmation.

 

[SicMan]

Thanks for posting that info.
JM

 

[dlucy]

I'm opening up a KA-9150 (Eurpoean version of the KA-9100 that is all over AK) and I'm doing researching on the awesome threads already here. There was an AK system update last year and some of the links provided don't work any more. I've updated the below quote with links that do work, a at least right now.

My personal email should NOT be posted in the open forum. If it is, I wish you would point out the specific thread so I might edit it.

The Sanken S-100W is lacking the current limiting circuitry that is built into the stock TA-100W. Strictly speaking, it is NOT necessary for operation...the circuit just pulls back on the drive to the output devices when it detects the current is too high. Without it, a shorted speaker or wire will kill the module very very quickly (and it obviously had limited effectiveness, judging from the number of dead modules I read about on the web from shorted speaker cables). Anyway, a few members have noted (correctly) that many high-end amps have no such circuitry.

At any rate, you may want to take a look at this thread. I detail the pinout of each here.

I have not done the swap, but I can describe how it should go...

Pin1 and Pin2 on the S-100W are fine on the PC board. Pin3 on the PC board gets cut, and routed to Pin4 on the Sanken chip. Pin4 on the PC board is left disconnected. Pin5 is the output and is OK. Pin6 on the PC board is cut and routed to Pin7 on the Sanken chip. Pin7 on the PC board is cut and routed to Pin9 on the Sanken chip. Pin8 and Pin9 on the PC board are left disconnected.

It appears that this would work. No promises. The hard part is finding a Sanken S-100W chip.

Another member claimed to use the Sanken SAP16 and SAP16N to replace the module. These parts were 5-lead Darlington devices with internal temp compensation and built-in thin-film emitter resistors. This would also have worked well, and is the way I would have gone, except that these parts are discontinued. Sanken has replaced these with the STD01N & STD01P (150V 10A), and the STD03N & STD03P (160V 15A). There is very little difference between these new devices and the old, EXCEPT the new devices do not have the internal thin-film emitter resistor, so the emitter resistors would have to be mounted somewhere else, which complicates the install a bit. Besides that, the bias pins of these devices simply have to be joined with a 200 ohm trimpot for bias adjustment. If I were to tackle a dead 9100, I'd try to find the STD03 devices and make it work. They are apparently current production Sanken devices, but finding a reseller in the US is not easy. Profusion in the UK can source them, but I don't know what the minimum might be.

 

[SicMan]

FYI: TA100's bought from China:
I posted a a bunch of posts back that I got a couple TA100's from Alliexpress or whatever the name is in china and they worked. Well I just got the unit back and both failed in the same way, Neg side of the sine wave under load was cut off, distortion audio.
Also just checked a unit under heavy load that was going back to someone with one of those similar parts in, stays on for 10 mins under load and kicks out.
So 3 out of 4 TA100's I bought from China go bad quickly. Also I noticed that the ones from China have a sticker over the original sticker, same part number
but all the ones I bought from China have this..The case looks like it was opened up by the marks around the edges if you look closely. I'm going to open these up and take a look and compare to another that was original and went bad.
So be warned peeps.
MY .02
John M

 

[pjrengineer]

Anyone have a link for purchasing the transistor components for this mod? I have a bad ka-8300.
Thanks
Patrick

 

[Vickey]

Greeting all,
I modified my Kenwood KA8300 with the darling-ton Pair Quasi-Complementary amp design from this website (http://www.suwa-koubou.jp/repair/ka_7500/ka_7500_2.html ) and it seems to have a major bias problem.So Here is a picture with some of the voltages measured on the board. I have in on an on bulb tester so none of the parts do not get hot.

The Voltages in red are real time voltages measured whiles its running and it has no sound. If I was to take it off the on buld tester it would fry the darlingtons. If I reduce the resistor #27 circled in red by 1/2 its resistance to output circuit starts working but the transistors qe3 and qe4 start burning up.

So can someone please help me with an idea to help get it running corectly.
Thank you

 

[pjrengineer]

That’s disappointing to hear. Where did you get the transistors from?

 

[Vickey]

That’s disappointing to hear. Where did you get the transistors from?

Thank you for your reply,
I had ordered them from China and the source called out from the page. I had matched the transistors to make sure they were ok and also I have replaced all of the other transistors on the PC board including the long tail matched set. I also made sure the long matched set were matched gain to achieve a current mirror. So I'm really confused why its not working.

I am curious,
per a note above.
Do I have the position of the position of the trimmer vr1(2k) and r1(2.7k) with r2(1.2k)
in the correct order?

Audio Path-page-001

• Vickey
• Feb 28, 2020

 

[SicMan]

Well just took these out of a KA-9100 that had bad damage on the front panel.
They ran for 2 years in a bar driving a set of 4 ohm speakers I sold him this unit and did the work.
. And they still work. The SAP16N & P are obsolete. And we’re replaced with the STD03N & P.
No emitter resistor. I have one with the std03’s in it and it works fine.
The down side is don’t short the output.
Or if the speaker shorts it will fry the speaker.

Also have these in a KR9600 running for over 6 years..

 

[sregor]

Thank you for your reply,
I had ordered them from China and the source called out from the page. I had matched the transistors to make sure they were ok and also I have replaced all of the other transistors on the PC board including the long tail matched set. I also made sure the long matched set were matched gain to achieve a current mirror. So I'm really confused why its not working.

I am curious,
per a note above.
Do I have the position of the position of the trimmer vr1(2k) and r1(2.7k) with r2(1.2k)
in the correct order?

Audio Path-page-001

• Vickey
• Feb 28, 2020

vr1 and r2 positions are fine.
Based on voltages, looks like you have problems with the outputs (darlingtons). -.6 on base should not cause current draw.

 

[gort69]

I think the SAP16N & P had built-in emitter resistors

 

[SicMan]

I still have some of those SAP16’s. got them from a uk distribution house. About 4$ apiece. Should have bought more. They don’t have anymore. Got the STD03’s from them too.
good source for power stuff.
Jm

 

[SicMan]

rjsalvi: theres an extra pin on the sap16's that comes right off the emitter before the internal resistor,
so you can use an external emitter resistor.
YES: the std03's are better I'd say.

 

[SicMan]

This is a trusted supplier of power transistors and more
30 years in business I've been dealing with them for 12 or so.

https://www.profusionplc.com/about/aboutus.html

 

[johnhoef]

I currently am confronted with this TA-100WA dilemma. Interesting ideas mentioned here, but they all require some time to get installed and working, driving up the cost to the customer. What do you all think of this:

https://www.ebay.co.uk/itm/125159684482?hash=item1d24193982:g:5zsAAOSw5IBgCuD5

It's not exactly cheap, but considering it's a drop in replacement with no dealing with adding emitter resistors, etc, the cost to the customer may actually be cheaper? Has any of you tried this module?

 

[gort69]

I bought one - works perfectly and worth the money.

 

[johnhoef]

gort69, cool! Was it a simple drop in replacement?

 

[gort69]

I guess you shouldn't assume that the driver board is up to snuff. I replaced all of the transistors, electrolytics and the offset trimmer at the same time.

 

[johnhoef]

gort69.....standard procedure to check the rest of the amp before power up.