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Almi's Logitech Z-5500 Mod (High-End upgrade for the speaker system) - Page 8

post #106 of 378
thanks for picture. my regs are only hot wen using the pod... you said yours are running hot when by passed aswrll? mine run cold when by passed. mine do get hot when running the pod but i am also running a 200ma fan on the pod aswell.
post #107 of 378

ok... tda-amps turned up today... and well well... after 3 million op-amps later it turned out to be a tda that had snapped... the sub is working again and sounds mint... got all opa1612's in... elna silmic ii 50v 47uf & 22uf ... got the 0.22uf's on the underside... it int looking like a showcase model as i have been messing about with these op-amps and getting very annoyed... i have broken quite a few tracks but i have patched stuff up (two caps laying down) but hey... whos gunna see it? i will just epoxy everything in place and i will know for the other board... i will take more time and know my errors from this last one. two 47ufs are layed down because i broke the solder point on underside but the connection is topside anyway.. so i lent it over and soldered the two caps in place (more epoxy). so in the end... i have all six channels back online at equal volume and the sub works... so its a big relief for me as it got to the point where i dint think it would work again and kept glancing at the other board thinking "should i start using that one instead" lol... but i got there in the end... i will just change the two main filter caps and the pod cap and call it a day with that board... its all working again and i dont want to have more headaches with it... the second board will be the main focus now. the problem with the other channels was tda amp related aswell... as all i did was put 4 new tda's in where the old worst ones was and everything is good... sounds good just to hear it going again never mind the upgrade :)


here is


a pic of it... looks like a bad job (and it is) but i just wanted it to work again whatever it looked like in the end... and it does :)


i have not added thermal paste yet... i also broke two ferrite rings off the rear speakers... but i took an old inductor with same size from another board and re wound (three times) the ring... all works fine.


all that messing about with op-amps and that was not the problem... will take more pictures when i have it out again... but for now... i want to listen to it (not for long tho as no thermal paste) everything is sounding pretty good :)


thanks @ramachandra for this thread :)








for the underside of the board... i have some shielded cable sat here... just have not put it in yet... will do that when i change the last three caps... the blue cap in the middle i broke both holes for the cap legs and the connections was on that side so that was not nice to fix... had to use single strand telephone cable which i soldered to the track and then made little circles where the cap legs go in... i then soldered the cap to these rings and epoxied it in place... alot of this mod is not nice but mostly because i was impatient and getting annoyed with the op-amps. still... it works lol.

Edited by jayjayuk - 6/25/14 at 1:46pm
post #108 of 378
Thread Starter 

I know some work still ahead, but I'm already happy to see an upgraded board what i have not touched. You have done a serious job on those OpAmps to make them work, and i think the rest of the mod will not be a challenge for you to complete. I'm really looking forward to see the rest. Well done! :smile:

post #109 of 378

i know it does not look great... but it works... it would not of turned out like that if i caught that tda amp a little sooner... oh well... on the next board it will have all new tda's and new op-amps... i know on the first board i will have had them in several times working it was just the tda. on the second board there is only about three tracks broken so that one will look better but i dont know how far i will go with second one... maybe just keep it stock and compare... then if this board i have just done goes down i will just transfer the caps and stuff to the second board as the first board is not really going to take another hit.


them op-amps took time with the little wires (still managed multi core though... was going to go single strand at first) and i wanted the ends to turn 90 degree so i could get the most contact area to the solder joint on the smd's then epoxy in place (waiting for more epoxy lol). i am going to change that bottom v-reg aswell... the contact pressure is not great as i put thermal paste on then epoxied the sink to the board... the top v-reg i mixed epoxy with a bit of thermal paste and held it down for 10 mins as much pressure as i could... the top one gets hotter quicker probably because of the better contact so thats why i want to change the bottom one (when i do the big caps). i am just putting thermal paste on the tda's right now... i want to go set it all up in the house and test it out on something... will be blasting it most of tomorrow :)


learnt alot from it... for a start that i am not nearly careful enough lol... and about the way it works... i kept thinking i was blowing them op-amps with either heat or static... so i switched to a gas soldering iron and earthed myself to the socket... dangerous option but i dont have anti static stuff and i was on the edge with this amp so i did what i could.


again @ramachandra thanks for this thread.. would not of even attempted any of this if not for reading this thread. Cheers.



it made it alot easier with the second board sat next to me... if i forgot anything or was not sure of something... i could just look at the second board to see what i wanted to know... also good for testing one board then the other.

Edited by jayjayuk - 6/25/14 at 3:10pm
post #110 of 378

Hmmm.... took it in the house last night and set it up... had it running for about 15 minutes and the rear left just producing audio and started doing the suck/pop thing again... annoying... i will just leave it for now... i am not messing about with op-amps again just yet... i have one brand new one left... it could be that as when i put the one in for the rears i did not use the gas soldering iron... the rear right works fine its just the left... all other channels work fine and upon the initial few tests all channels work... it just went bad? i will investigate when my tda's turn up and just change the tda for the rear left and if it is still bad i will pull the op-amp and check smd's ... if everything is ok i will put the last op-amp in that i have to see if that sorts it... sounds like an op-amp as when i first changed one (because the front left was quieter than the front right) it sorted the front left out and made it level with the front right... but the center produced no audio and just this suck and pop sound (the cone moves deeply in and out slowly then gives a loud pop now and then) that was the first time i saw this behavior and it was when i changed the op-amp... nothing else was done... for now i will just use the system. it is strange how it worked at first on a few tests running for longer than 10mins and its like it just goes down and then thats it... i wont hear audio out of it now untill i open it up and change something.


Damn... but i am now on the right path... at least it is one problem with one channel that is one op-amp to one tda... before its like i had multiple problems with everything... least i am on the right path and should be an easy quick fix once i have the parts and open it up again... the other tda's are not clever anyway... i have bought in total 14 X tda7294's enough for two full boards so i might just have all new tda's in both boards.




@ramachandra do you know what the three transistors are for on the pre-amp panel by any chance?


@andro6600 hows your system holding up? still running ok?

Edited by jayjayuk - 6/26/14 at 7:22am
post #111 of 378

@jayjayuk, hi! Why don't you just put everything in the new board you have, seems like there is quite a problems in the old one. And  about the problem with rear left channel, don't thing it is in op-amp. And it is just one opamp for both rear channels, and if you say that everything was running for a while, then maybe, something overheat and make a mess. And if the opamp is broken, in my case there is almost no sound, barely audible. BTW, i like the bottom side of your board, seems clean and elegant. Good job!  :smile: I've had problems too. This board is likely very crappy and the tracks rip off very easy, if i go too over with the heat. But the f@cking taiwans, made every cap legs bend to the track, and i can't heat them properly with heat pump, and got to apply a little more force pulling, and then the track is almost goner. I changed almost every cap in the control pod, besides that ones that @ramachandra said to be replaced. For them i considering either Nichicon FG, or KZ. Also for the TDA caps. I have heard recently one AV receiver Sony,with my speakers, and it turns out, that the Sony was much more mud sounding in high range, with a lot less clarity and definition, but mid-low end was much better then mine. Overall i liked the sound(just sats, no sub) and Sony was entirely with FG caps. So, now i am wonder witch ones will fit better - FG or KZ. Datasheets said that KZ is premium grade, but FG got very good bass. Here my system for now, the bypass caps will be putted back after i decide what caps to place in that position.




The main filter caps are now replace with Nichicon KG.  Now i am in auditioning the results with elnas and KG. I know that they need some time to settle, but my first impressions are very positive! It is amazing how precise and defined sound became, The lows are good, deep, hitting absolutely correct, very tight and with fast response, witch however, in some occasions results in some lack of the... how to put it, maybe sustain of the bass, to fill the sound gaps between sats and sub. Like the notes are damped very fast after they hit. But all and all, i am very satisfied. That's why i amd considering FG series instead of elna or KZ, because i am afraid that over detailing of the sound will become not so peasant. I need to add some mid-low present to the sats, because they are more of the transparent side, and sounding more like in surround, i want them more direct.


Also wonder this- the pre amp 5 caps are for speakers. What if i increase the capacitance of the, i red that this may give a better lows? Is that correct? Also i replaced the two caps that are separate with MKS2, cause with axials, the brightness was over and needed some round and smoothness. @ramachandra what will be, if i use the MKT, that i have bought for bypass, for that position? Because you recommended  MKS,MKP films?

post #112 of 378

yes this board does seem to have some problems... but i am not just here to mod... i am here to learn as well... so if i brake something i will fix it and make it work again (in the end). i think this time it is actually in the op-amp as i had this issue before and all i had changed is the op-amp for center / front left and the center channel did this then when i changed first op-amp... now the center is working and i did not change the center tda amp.


looks like your mods are coming along nicely... i know what you mean about the bent over cap legs... i use a small point tip and let the solder melt and then flick the leg to the upright position but every now and then this goes wrong and grabs the solder point and pulls it up with it. i broke alot of tracks on op-amps but i will do the next one better.


i currently have mine open again and have bypassed the pod so just the amp is running on its own with rca's connected to the rear channels... i will test to see if it happens now and if so i might start looking at the pod.



post #113 of 378
Thread Starter 



All 3 transistors are the same and as i remember 2N4401 is the code printed on them. (Better to check) If you can not get them there are similar alternatives like BC337, BC338, BC547, 2N2222.





I think you need to wait to get the rest of the components, because it may bring the results you looking for. Many people says the Nichicon caps have brilliant mids and nothing else realy, so they are not the path for better bass or decrease the brightness. I do not know your sound preference, still i think you may like the Silmic II more instead of FG.


I have not played with capacitance in the Zobel network, so i can not tell the result. As far is i know it is exactly designed for the original speakers and require some calculations to set it right. I can imagine it is not the best setup for your new speakers. One function is the circuit is to protect the TDA Amps from feedback suppression (I'm not sure i found the proper English translation) so technically you can use the system without it. Not included in most TDA DIY Kit so I will not be surprise if everything turn out better if you live it out of business.

Edited by ramachandra - 6/26/14 at 1:09pm
post #114 of 378

ok... so the problem seems to have gone away... i took the amp off the back and thought about changing that op-amp... but first i used a d-sub connector i got from ebay and linked the correct pins and attached my rca's to that instead of soldering to the board... then i can just plug it in the back of the amp and change the d-sub when i want to test different channels. bypassing the pod all was running ok so i decided to try the pod again... everything was running fine for about an hour... took it back in the house again and everything is working... so i guess i will solve that problem if/when it resurfaces. all is running good now :) just have a graphic and tv to look at now while my tda's turn up for the second board... i will post back in when they turn up.


@ramachandra yes 2n4401 is correct... but as the problem as gone for now... i will wait... could just be dodgy conection on pins in the d-sub... i tightened it in the first time and now it is not... just slotted in with weight of wire pulling down. if the problem comes back i will look at changing them and some other stuff before i have to go at the op-amp.



post #115 of 378

now a new problem has come to light... been reading alot about it... as i have moved the op-amps away and used wires to connect to the board... i think the op-amps are to far away from the caps and is causing oscillation (i think) all op-amps stay sort of at the same temp... around 40c... one off them for the sub heats up quicker than the others but settles around the same temp... after an hour off running the system the audio cut out on me... then i turned it off for 20 seconds and turned it back on and the sound came back on for about 5 seconds... so i opened it up... the two 47uf's on the v-regs are getting very warm 40+c and rising (so i turned off) i am not sure as of yet why the system is killing the audio or specifically which device is thermally cutting out... but most of the caps on the modded op-amps run warm/hot while the caps for the rear speakers are nice and cool... at first i thought maybe the op-amp is oscillating because the system is not tuned for these op-amps but then why would everything around the rear speakers be ok... seems more like an issue with me moving the op-amps.. i have read online to put a 0.1uf cap between the rails or two caps on a rail each to ground (the original setup has that cermaic smd very close to the op-amps legs that go straight and it has one on each rail... so the first thing i will try is one straight across the rails... if that is the same then i will try one per rail... if still no luck there is not much more for me with this board as i dont have an oscope and even if i did... i would need to do alot of learning with it anyway... so after this it will be all focus on second board when the parts arrive... i though everything was fine :( oh well.

post #116 of 378

Ok, i checked the v-regs again today, because this thing bothers me a lot. And for my big surprise, they became hot even without pod connected, just power switch on!!! At least the problem is clearly not in the pod. And all the caps for op-amps and V-regs are warm too, when playing, the TDA caps are cool however? Now that is not normal in my opinion. And is it normal, the power supply to make that little buzz noise, just in standby mode? I am guessing that there is really some short circuit here, but don't know how to find it. It is suppose to be somewhere in the spots that i solder new components, but can't really see anything wrong with them. Is it possible some of the diodes to be faulty after the short i made? How to measure them properly? And what values they need to be?  What to do now? :confused_face:  


EDIT: Little update info, i checked the voltage of the regulators, and on the input i got 35-36V, and for output -18V! Isn't this a too big of a difference between input and output, and perhaps the reg dissipate the extra voltage difference in heat? If my understanding is correct, this means under load (36V-18V)x0,5A=9W that reg is absorbing and dissipate in form of heat. What are your values guys? If i put the bigger wattage resistors for the v-regs, do the help to dissipate part of the heat? Maybe heat sink is needed for that ? And this empty places for the capacitors, do they meant to be for the input of the regs, and if so, can i solder there also 1uF 100V film caps? In the v-reg datasheets, they say, that input capacitor is needed when there is appreciable distance from the main filter caps, for stability, and in my case, it is just like that?

Edited by andro6600 - 6/29/14 at 5:30am
post #117 of 378

I am going to order the 3 op-amps for the analog output of the pod. I am thinking of TI OPA2134   http://www.farnell.com/datasheets/1762538.pdf   because it is much cheaper than OPA1612, but looks like the differences are very minor, in the same time looks better to R4580.  Also considering LM4562 http://www.farnell.com/datasheets/1814389.pdf  But as i can see, there is a difference in schematics of the two? Is it compatible?  @ramachandra, @jayjayuk what you thing of it. 

Edited by andro6600 - 6/29/14 at 5:31am
post #118 of 378
Thread Starter 



Make a shield from paper and aluminum food wrap on top, than connected to the ground with a wire and cover the critical area(s) It will decrease the noise if it coming from the outside.

Or do the "Third Mod" and save yourself from all the headache :wink_face:




Just wait for the new regs to arrive. Of course not doing harm to check the surrounding components meanwhile. The diodes have a number printed on them for identification, and the diode tester function on the multimeter is suitable for checking. Standard diodes conduct electricity to one way only. Most of the transformers are not dead silent, nothing to fix. The LM4562 is a noise bag in the circuits i tried, the sound is is ok. I do not know the OPA2134, it is also from the SoundPuls family so you can not go too wrong with it.

post #119 of 378
Thanks ramachandra

The new reg TS7818CZ and TS7918CZ are already in, and running! I took the risk to put the negative one, soldered with pin 2 (in) to the plate. I checked every manufacturer datasheet, and everyone is configured with pins 1 ground, 2 in, 3 out. I thought that must be at pin 2 ground. But everything is working for now, and, don't know if i am just fooling myself, but there is a difference in sound after changing them. Became more linear and rich, especially in the low mids. Sounds somehow modern. But, maybe my Elnas starts to "sounds" better. Don't know! :-) But the regs still are hot, even on standby. I don't know if this is normal, never checked them before mods, but from the calculations is obvious, that the dissipation power is quite a lot. My logic tells me, that something draining current from regs, even on standby. What that could be? Aren't just op-amps, that could be draining?!Isn't they suppose to have build in mute function? If that is true, how to find which one is faulty? BTW,ordered the two big heat sinks with 4C/W resistance.At least now i can put them in TO-220 package. Hope this helps.

Just checked what current is leaking trough the system. Without the pod, just switched on it is 0.05A. In STANDBY with pod connected it is 0.12A. With pod switched on it is 0.18-0.19A. Are these values the normal? @jayjayuk, could you please check your system what values reading? Calculations tells, that in that case, there is about 2W dissipating power in standby, and that is too high for such small device, and obviously heat sink is needed. Also, these two resistors, are they before the inputs of the regs, and if so, can i just put there bigger resistance, to lower the input voltage? And what value is needed to lower with 6V for example?

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Edited by andro6600 - 6/30/14 at 10:51am
post #120 of 378

i will be back to this thread soon... i dont want to mess about with it anymore until the new tda amps turn up and i get some caps for the op-amp bypass (the third mod) i have had enough messing about with it lol i just want it back up and running again... i will report back in when the parts arrive

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