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Unfortunately no progress. I asked a friend of mine who is a test engineer (electronics engineer) to take a look at it at work at his spare time, but he didn't yet have the time for it.

Thank you tarior, I'll do that! I was checking the resistors as a last resort and meanwhile I checked the diodes again. D548 conducts in both directions so it should the troublemaker!

The output transistors are not connected. I checked the diodes and they also all seem to be fine (I did test them in circuit, which were suspicious were desoldered). The destroyed traces were for one the 2SA1360 were bridged. After putting the diodes back I did a test power on with DBT, and it...

I tested the all transistors (based on this) out of circuit except the 2 FETs (TR502, 504), replaced the optocoupler. Still the voltages are not ok. The solder rings of one 2SA1360 are pretty much destroyed and also the traces were lifted by a previous failure or someone else's soldering...

Thanks for the info Ray and tarior! I'll check the small signal transistors. For preparation I might just order them in advance, thus I'm looking for a suitable replacement part for the following types: 2SC3334 - 2SC3467? 2SA1321 - ? 2SA968 - ? 2SA988 - ? For the rest I can order the exact...

Just found a suitable replacement for the TLP521-1, which is a TLP621-1. It should arrive soon, I'll post the results.

Recently I got my hands on this amp however when I turn it on the led 4/4 blinks while the others stay lit, with DBT. No input or speakers are connected. The service manual says "DC offset voltage for Right channel exceeds set level". So I checked some voltages on the board KU-9143-3 and found a...

Hello Dan! I'm not fluent at all in German but I'm repairing my POA-2400, and by the looks the procedure is the same, just with different values.

I have the Talema version, on the PCb there is XMOS U208 V1.1. There are 4 1500uF 16V elcos, 1 47uF 25V (on the PCB the marking shows 100uF), these are black and gold labels, unknown brand. There is also another 47uF 6.3 or 16V Oscon looking elco. I replaced the 1500uFs with Nichicon KA 2200uF...

Sorry to revive this old thread. I'm looking for speaker terminals for these speakers. Is there a drop in replacement for these, have someone changed it? Thank you in advance for any suggestions!

Hello again! It's been a while since anyone posted in this thread, so I shake it up a bit. Since my last comment here I've changed a lot of the FC caps to Elna Silmic IIs. It didn't sound as good as I thought it would but after a few weeks with them, I can say it was worth it! If anyone...

Indeed, one is neg the other is positive. I checked the resistors you mentioned today and found them to be ok. When soldering back 1 of them I noticed the cause of all this "mystery". One of the leg of the outputs came loose from the pad.....I just don't know how I missed it for so long. After...

Yes, bias adjustment works on Rch, but nothing happens on the Left. The voltages are 45.5V for TR128, 45.3V for TR124 these are on the good channel. The same voltages are on the other channel exactly: 45.5V for TR127 and 45.3V for TR123.

I was not able to identify the cause, could you please suggest what should I check next?

I checked those resistors and they were ok, I replaced them with new ones though. I also tried switching the VRs, the good side with the bad but it had no effect. TP2 to ground 11mV

Hi James! So after a few hours of listening yesterday, there is a noticeable difference! There are a lot more details in music, and the bass is improved quite a bit. I don't really believe in cap burn-in so I don't expect more improvement but I think I just don't need anymore :D For me it is...

World Peace! :))

More pics.

More pics.

Meanwhile I'm done with the recap of the AX-700. Took me about 10 hours to disassemble the amp, clean the boards of the glue and dust, grime, clean the pots and of course to change the caps, plus take some pictures and reassemble. It was fun, I've enjoyed working on this amp, it is very easy to...

The parts arrived finally. I replaced the burnt resistor, plugged in with DBT, relay clicked yaay! :) Time to set idle current: Rch set to 15mV, Lch 0.0, turning VR107 has no effect, TP2 to ground 10.3mV. Should I replace VR107 or something else is still not ok?

Thank you James! I will just order the pots with the rest of the stuff form the site here, but I appreciate your offer! :) "C303 and C304 are shown in the schematic as 47µF/16v but what I found actually installed on the board(s) were 4.7µF/16v. I've been replacing them with Wima MKS-2 film...

Thank you James! This was exactly what I was looking for! :) One last thing, do you know if the trim pots which are in my list will fit? That is the last thing I'm not sure about.

I've modified the part list to my preference. I would like to ask for your opinion if the parts I've chosen will be a good decision, especially the trim pots which I have no idea if they will fit or not. Some of the caps I've chosen are a few millimeters bigger in diameter but the board has a...

Yes I enjoy it a lot, it has the bass and clear mid-highs that I really like with my Pioneer S-910s! :) Now I just need a suitable pair of speaker stands for these monsters, it is the last piece of my equipment that is missing. First I will try the deoxit method a few times, if that wont't...