STK3042 STK3044 STK3062 STK3082 STK3102 STK3122 STK3152 II III IV V looking for reliable Substitute

[tiefbassuebertr]

Regardless of whether you are dealing with the original versions from Sanyo or with various replicas and various fakes - it just remains unreliable after any replace. An incredible amount of wasted time has already been accomplished (alone in my circle of acquaintances) by this bad design of STK front ends (in order to get low thermal stress).

The reason for this is obvious - simply too weak cooling in the voltage amplifier stage. This means, lokal hot spots and thus premature malfunction. The higher the supply voltage, the greater the power loss and the higher the thermal stress.

I still have a large number of defective amp devices equipped with these STK front end resp. pre-driver modules.
In particular, I would like to get the Sony power amplifier TA-N55ES and the Luxman R5030 so as various Marantz models up and running again permanently.

For a replica I would prefer a 3-transistor LTP (differential amplifier with current source without current mirror) and for the VAS-stage only 2 transistors and 2 heat sinks - one for the gain stage and one for the current source (no SMD resp SMT parts). The loss of sound resulting from this simplification should be negligible.

Maybe someone has done it in this kind.

According to the attached images, the solution in image No and under
https://www.diyaudio.com/community/threads/stk3152-stk3102-clone-for-aluminium-back-pcb.380947/
and post #30 under
https://www.diyaudio.com/community/threads/fake-stk3152-stk3102.268473/page-2
seems to me to be the best.
But it's still not good enough from my view, because one can't mount a BCP56 SMD transistor in the SOT223 outline onto a heat sink (disadvantage is the not good thermal conductivity between PCB and metal/aluminium plate).

Maybe there are even better solutions.

some URL's
http://epicbeardquest.blogspot.com/2016/09/exploring-sanyo-stk3122-iii.html
https://www.diyaudio.com/community/threads/fake-stk3152-stk3102.268473/
https://old-fidelity-forum.de/archive/index.php/thread-41061.html

https://www.diyaudio.com/community/threads/any-modification-for-replacing-stk3102-iv.69472/
https://www.diyaudio.com/community/threads/sanyo-chip-amps-v-ii-xi-differences.170525/
https://www.diyaudio.com/community/threads/i-need-a-information-about-stk3152.4607/
https://www.diyaudio.com/community/threads/connecting-stk-hibryds.187226/
https://www.diyaudio.com/community/threads/amp-crackling-sound.338876/
https://www.diyaudio.com/community/...-amp-module-for-marantz-pm80-amplifier.36425/
https://www.diyaudio.com/community/threads/alternative-for-stk3102-iv.177898/
https://www.diyaudio.com/community/threads/stk3102-iv-manantz-pm-80se-amplifier.55376/
https://www.diyaudio.com/community/threads/stk3062iv-substitute.164588/
https://www.diyaudio.com/community/threads/stk-series-type-amp-bias-adjust-how-is-it-done.26710/
https://www.diyaudio.com/community/threads/marantz-pm-52-no-sound-speakers-or-headphones.309626/

 

[davidsrsb]

I designed the STK3102 clone on alumina substrate.
My constraint was to fit the original dimensions

The real issue with these modules is the lack of protection.
Thrash them into 4 Ohms or short them and the output transistors or module will blow and take the voltage amplifier with it

 

[NareshBrd]

Space permitting, an external populated transistor board may be used for a one-off repair, that would be easier and more reliable.
Many ready to use transistor boards are sold, you can search by voltage, or output.
If possible, the 7294, 3886 and other chip amps may be also considered, though purists may scoff at Class D topology.

Simply use a ribbon cable to connect from the pin location for the old STK module to the new board, maybe mount it higher on the heat sink.

An added stage for speaker protection may be considered.

Some STKs have died after killing the power supply and the speakers, so I at least would be very cautious in replacing them with equivalent circuits.
There are equivalent circuits available, but as noted above, heat dissipation and speaker protection are sometimes not fully implemented, those will remain a weak point.

I have a Sony HCD BX3/DX3 set awaiting repair, the service manual says +45.5V and -46.7V for the STK 403-90 / 100 (two models exist for different regions for the same Sony model number).
I paid US$ 1.50 at the flea market, the display works, and it has been lying in storage for about 5 years (!). No remote was provided, or available.
I have spare amps, as I investigated the repair needed, and put it on the low priority list of things to be done.
At worst, I will part it out, and use the transformer in another amp.

 

[NareshBrd]

An alternative way is to make your own amplifier boards, using your choice of components and custom made (or trusted ready made) boards.
Then you can set it up as per the layout and space available inside the unit that needs repair.

 

[tiefbassuebertr]

Currently I'm toying with the idea of using a circuit that only consists of one voltage gain stage for the replica as a replacement for this STK module.
So instead of LTP+VAS (two voltage gain stages like in use on the NE5534) a folded cascode with differential input (only one voltage gain stage like in use on AD817/AD797/AD825).
Front-end examples therefore are to find in the attached schematics of NAD's 3240PE and AVM's M1 so as in the simplified schematic of AD817
I guess, that the difference in sound character is very similar to those between two line preamps equipped with NE5534 in one preamp device and AD817 resp. AD825 in the other.

 

[NareshBrd]

I think the STK modules ran at much higher voltages than the ones you intend to use as substitutes, that also has to be considered during replacement.
The STK 3152 is described as a differential amplifier, I did not check the other part numbers listed above.

The common op amps, like 5532 / 4558 / TL072 have output voltages proportional to supply voltage, please heck that the output of the STK and substitute are similar.

Unless I am mistaken, and you will drive transistors with the op amps to get the desired output level.
There are low noise versions in the AD series, and OPA2134 was also said to be of good quality, though that is stereo I think.
Their sonic character comparison is unknown for me.

 

[chinoy]

Guys I have an akai amp which uses the STK3042 with STK2250
Can I replace the STK3042 with the STK3062.
I found in my notes that the 3062/ 3082 are compatible with the 3042.
Have a friend flying out of Auz in 3 days so needed to know before he pulls the trigger on it.

 

[NareshBrd]

No need unless faulty.
New will be fake...

 

[tiefbassuebertr]

The common op amps, like 5532 / 4558 / TL072 have output voltages proportional to supply voltage, please heck that the output of the STK and substitute are similar.

Unless I am mistaken, and you will drive transistors with the op amps to get the desired output level.
There are low noise versions in the AD series, and OPA2134 was also said to be of good quality, though that is stereo I think.
Their sonic character comparison is unknown for me.

Probably also a good approach - go to
https://www.diyaudio.com/community/...-amp-in-the-front-end-overview-wanted.286589/

 

[chinoy]

Here is another intresting read on the STK
http://epicbeardquest.blogspot.com/2016/09/exploring-sanyo-stk3122-iii.html
Here is the sanyo STK datasheet with schematic. Which I need to compare to the schematic used in the creation of this board.
So far its looking good.

 

[tiefbassuebertr]

what about Andre Andrea Ciuffoli's cool follower if voltage gain isn't necessary ??
https://www.diyaudio.com/community/threads/quality-in-a-cool-follower-99.12542/
http://www.audiodesignguide.com/my/
What about PSRR and thermal stability of quiescent (idle) current ?

 

[JPI33600]

I designed the STK3102 clone on alumina substrate.
My constraint was to fit the original dimensions

The real issue with these modules is the lack of protection.
Thrash them into 4 Ohms or short them and the output transistors or module will blow and take the voltage amplifier with it

Hi everybody,
I'm trying to repair my brother's Sony audio amp (TA-F630ESD) which blew its STK3152, and I'm very interested in the possibility to fit a substitute for this IC. Apart from the protection issue, one member of the forum (Lars71dk) who built davidsrsb's replacement module reported some oscillation problems when applying signal. I'm not sure if he managed to work it out, but unfortunately I can't PM him since I just registered on diyAudio and am currently prevented to do so. Did anybody else meet this kind of issue with davidsrsb's module, and if so, how did you solve it?

 

[davidsrsb]

I thought that he did solve it with the correct compensation capacitor.
The challenge is that you are probably also changing the output transistors with something very different to the originals.
The original transistors in the voltage amplifier module are completly undocumented, but probably in the same ball park as what I suggested for my substitute.

 

[JPI33600]

Thanks for your reply davidsrsb, much appreciated. You suggest to adapt the "compensation capacitor". Which one would it be on the attached schematics? I suppose we're talking of C303 / 68p (and C353 for left channel)? As far as you can say, other motherboard components could possibly need some kind of tuning?

 

[davidsrsb]

Yes C303/C353 is involved, along with C308/C358 15pF
The 470R in series R327/R377 provides a feedback zero - this makes me think Sony might have been struggling with stability, a common issue with these THD zeroes obsessed designs
And C305/C355 in the overall feedback is involved

 

[JPI33600]

Thanks David, that's precious info! I will have a closer look then. At the moment, I can say all capacitors/resistors values involved with feedback in the Sony (except R303/C304 which set the overall gain) follow the recommended values of the test circuit included in the original STK3152 datasheet, so these values (including R327) are probably not Sony-specific.

 

[tiefbassuebertr]

PCB on aluminium plate for stk3152 and stk3102 clone
https://www.diyaudio.com/community/threads/stk3152-stk3102-clone-for-aluminium-back-pcb.380947/