[jayjayuk]

So i got back on this about a week ago, things are starting to go alot better now. i was being stupid and not using anti static equipment and not cleaning the tip, the problem was the tda amps i was soldering right/carefull enough. i focused on one and threw about 8 in one position (front left) and they keep running hot for 10 secs then would shut down (no sound) after which they just shut off without getting hot at all, i got past this problem with new equipment and clean tip and they have gone in one after another on both boards i have and all work fine... except for the sub on the second blown board i have but that will get worked out.
 
on my main board i started to rip the track up for the voltage feed to the op-amp, in the end it got so bad that it was either transfer to the other board and work on that, or take a chance on the op-amp bypass for the sub (U15) where i got up the data sheet and joined the + inputs to the outputs, i also remove one shunt resistor R618 and R617+R619 - at first the volume was low for the sub so i lost something... then i removed R617 and R619 and put a bridge across all the terminals for those two resistors (this is the input signal being dropped so is ok for op-amp) the volume improved but it is still low and does not punch as much as it once did, also for people soldering in op-amps. you can use what i said on U15 to bridge it first, then you know if U14 is in correct (this is what i am going to do with second board) then remove the bridge and work on U15 until it works. i am upset about the loss but i have a plan for that, and i am glad everything is working again as it should, all the sats sound fine and good, i have designed a board to be able to put an op-amp back on U15 which i broke as i think it needs to be re-amplified after it has gone through the first part of the signal filter for the sub.
 
i have also been drawing schematics for this amp board, they will be separate and not professional as they are the first ones i have drawn but i hope that they will help someone if they become stuck like i have and will be able to trace things better. i am still working on a full schematic for the sub (i have done one full op-amp, i am at the point where it runs over to the second op-amp then towards the tda amps) all diagrams will have the components values and codes (except the very small caps, i need to get a new meter to read the low values) but so far i have ready real pics of the board, then a diagram that i have drawn showing the connections for the op-amps and surrounding components for all the sats, thats what i will be posting here today, and also the board i have drawn up for repairing the U15 with components on the board using wires to connect back to the original board, but all the fussy stuff will be on the secondary/break-out board like the 0.1uF caps for the power rails as close as possible to the op-amp rail pins (4&8). so here goes...
 

 

 

 

 

 

 
Those are for the sat speakers... this next one is for the sub, which i took a camera pic and drew directly on the camera pic to show where the connections go on the top side of the board, the full sub schematic will have all the component values in.
 

 
 
in the end i will have full schematics for this amp board (not control pod lol) they will all be separate for each separate channel except the sub which splits into two but this has to be done as one anyway so in total there will be 6 different schematics for the 6 channels starting from the input at the D-Sub connector right up to the output terminals for the speakers and subs so i am going to do full schematics but also littler ones like the ones posted so can focus on just that area at a time if needed. i will also post fixes that i have had to do. here is one fix that i will be building to replace my broken U15 area which as of now i have bypassed... (i think if i removed some inline and shunt resistors down the signal path from U14 to U15 then i could get the voltage back up and have the power back, but i want to draw up some schematics before big changes happen lol)
 
 

 

(EDIT: Take note of the Negative (N) marker for the electrolytic caps)
 
took some time to do just this what i have posted and there is lots more to do... hope someone finds it useful.
 
Cheers

 

[jayjayuk]

@andro6600 sorry i did not comment on your mods, i have been looking through the forum now and then and keeping track but i have been using these pages for info while i have been frustrated with my own dooings lol.
 
great mods you have applied there, i like those heatsinks and those regs, in a word... BEAST. hopefully mine will go that way aswell, still alot of work to do but it is now finally getting there. i have another amp which i am very hopefull to get running soon aswell and i have the box and no sub for it... how much did you pay for that sub if you dont mind me asking? i want a good sub driver but i have never really looked at different drivers to know what is good or not so i ask advice what i was thinking was keeping one with the logitech sub in and another one with a different sub, i want to do the schematic for the board and then study it over the datasheets and see what i can change to really push those tda amps, once i have the schematic i will not really be bothered about hard experimenting with it as i will know better where to look and replace the components once i know the values.
 
good to see you overcame your problems with it and all is working fine and to your liking.
 
Cheers

 

[andro6600]

Hi again 

 
@jayjayuk, you have done incredible work on schematics man! Respect! Seems that you've got some pretty good knowledge in this, i am sure it will be extremely helpful, if someone want to mod or just repair something broken in the system! Meanwhile, i made little more upgrade on the pod, with Elna Cerafine at 50V, for the op-amps, and Nichicon LF(polymer) for volume control. Just wanted a bit more "live stage" feeling in the sound, and Cerafines seems to meet my needs, from what i've red. At the moment they are not break-in, but initially impressions are just i expected. And the effect from this polymer cap is, bringing highs a little more in front, maybe adding little sharpness to them, but i like it! 

 
I had to cut a bit of the back cover of the pod, because the Elnas are too big, but no worries. 
 
About the sub driver Pioneer, i got it for 70 euros, in my country, and with little playing with the cotton wool, as i said before, the results are amazing! Hope, everything will turn right for you too, man!
 
Cheers

 

[jayjayuk]

thanks, it is taking some time to do them, i did a little more on the sub schematic last night, got upto the U6 tda amp, done most of the pins on the U6, i have found how the system works the amps together... the U6 is the positive feed (non inverting on pin 3) which uses the wire on the back of the board to go from the bootstrap cap on U6 and takes it straight to the negative feed (inverting input pin 2) on U7 then pin 14 on U7 is bootstrapped to pin 6 and you get the negative feed for the sub. i am learning alot from tracing a drawing it. like the op-amps, they just loop in and out of each other while passing through the capacitors then one out feed on U15 is fed to pin 3 on U6, i thought it was going to split the signal before and let one tda invert and the other non invert, but i was wrong.
 
cool mods on the pod, i will eventually go that way aswell of replacing the caps in the pod but my pod rarely gets used at the minute, i just attach rca's to the pre-amp panel pins to where i want the signal, and trace audio using an earphone and meter probe, this is how i knew op-amp U14 was working which is why i took a shot on the U15 bypass as i knew it was that area that was the only problem.
 
i will have to keep my eye out for a sub to go in the other box i have and get that board up and running... all is coming together and what seemed hard for me to get working is now very easy.
 
i had to cut a bit of the back of my pod to give the fan more air flow, it works perfect and with the fan off the pod gets very hot after about an hour or two, but with the fan on it is constantly cold, i hope i dont have to loose the fan to get big caps in there .
 
keep checking in with the new mods you have done, your system must be sounding  
 
Cheers

 

[jayjayuk]

Here is the next one, i got carried away chasing the mute and standby pins of the tda7294 amps so i started at pin 8 on the pre-amp panel, pin 8 leads to most of the pre-amp board so i just did the pre-amp board now, will carry on with the sub schematic next.
 

 
EDIT : some things i cannot test right now, like the smd capacitors as my meter is not good for capacitors with low values, so the two things missing from the schematics will be smd cap values and zener diode ratings as i can not see the markings clear enough to tell what the zeners are.

 

[A-Force]

Hi!!!! I have a big problem with the sub woofer from the beginning with z5500. I think that the sound of the sub woofer isn't flat at all.. so many years i ve tried everything from eq settings to all the different places in the room in all rooms of the house...even in a different house...and the only place where you get the most accurate and deep bass is when you put the woofer to the one corner of the room and your listening position is on the opposite corner. So i bought and a second z5500 system in order to have two woofers because i 've read with two the bass is better and more accurate all across the room and not only in the corner...BUT... with two the bass was even worse.. full boooooomm and the low range was missing..the bass was terrible. the same happened and to the outside where there are no room resonance. so i decided to go and buy 2 proper woofers(i was thinking of 2 crystal audio thx-10subs) and have at last good bass. before i do this i was hoping maybe there is still hope with this mod. i ve read somewhere here that the opa2228p will result in deeper and nicer bass... i found that there are some models like opa2228u that they are soic(D) and not pdip(p) and probably they don't need an adapter. Do you think the mod with this chip would be better instead of the opa1602aid for the two op amps of the sub?? do you have another recommendation maybe for the deepest bass without booooom? thanks in advance and i hope to find a solution at last... :-/

 

[jayjayuk]

@A-Force i am new to this and have not done much experimenting with op-amps so it would be better for @ramachandra to answer your question
 
 
 
Here is the next schematic... it is of the power supply area, from the transformer's outputs to every point that supplies power to the sub and pod... i have terminated them stating that they are the COMMON for wherever they will go to the circuit board. i have done the sub schematic which includes the power supply area and the pre-amp board, but i have not double checked the sub part yet so i will post it after i have double checked everything is ok... here is the power supply...
 

 
 
 
EDIT:
 
i have a new test meter on the way so when it turns up i can check the values of the smd capacitors and make the changes to the schematics and change the pictures here... what i thought was zener diodes are actually normal diodes but they are the glass signal type diodes, still have to get the codes for all diodes aswell, so diodes and smd caps are missing, but as i said, i will fill these in as and when i find them out

 

[ramachandra]

A-Force
 
During the years Logitech made some big or small changes like switching mostly from Su'Scon capacitor brand to Tbor, and i found boards where the OpAmps for the Sub is not connected to each other on the PCB (maybe the latest PCBs) so the bass is a bit different. I had OPA228UA Soic only as sample a while back and I was not impressed, certainly not the same as the OPA2228P or PA. This far the OPA2228p have the best Sub-bass i have ever heard. One of my friend is also confirmed, this chip is without competition for the modified Sub for his other project. If you lucky the space near the wires let you use adapters for the OPA2228P chips. (The OPA228P is the mono you need the stereo OPA2228P)
 
jayjayuk
 
I see you take it seriously. Probably no better schematics on the Internet yet for the system or i have not found it.

 

[jayjayuk]

@ramachandra i have not found and as of yet either, the most i have found is for the pre-amp board, and parts of the pod for the signal coming into the pod and through the relevant circuitry and out of the pod to the sub (but no full schematic for the pod either). the schematics i have drawn are not the best lol as these are the first ones i have actually drawn like this so there is alot of room for improvement... but least from these you will be able to see clearly how the components are connected and what values they are (in the end) so hopefully they will help anyone working on this sub.

 

[jayjayuk]

OK... so i have double checked it and everything seems to be ok, missed one resistor (R627) but i corrected it this is the full schematic for the sub circuit which includes the power supply section and the pre-amp panel all in one. when my new meter turns up i will go over smd caps but they will be exact readings of the ones on my board as there are no smd markings (is the best i can do) then just the diodes, but it is getting there. was a lot quicker to check it as i have it in this picture to find my place from the schematic to the board so it quickened the checking up.
 
the TS|BS  and BS|TS indicate when the track runs from one side of the board to the other (i have missed some in some places but it was mainly for me when doing it, as the board markings are also in the schematic so you just go from one marking to the next)... gets a little hard to follow if just looking at it but once you start following tracks on the board it all makes sense
 
SUB CIRCUIT SCHEMATIC
----------------------------------------
 

 

[A-Force]

Thank you very much for your answer!!!!! 2228p it is then!!! do i need only two of these in the sub or should i replace the sub op amp in the control panel and the sub op amp in my audio card(sb x-fi titanium) as well in order to get the proper result? Should i prefer mouser or eBay is fine?     http://www.ebay.com/sch/i.html?_from=R40|R40|R40|R40|R40&_sacat=0&_nkw=%22opa2228p%22&_sop=15     eBay has many different looking chips as you can see with different writings on it.. i dont know what to pick :-/

 

[A-Force]

Thank you very much for the answer!!! 2228p it is then should i buy only two of them for the sub or i have to replace also the op amp belongs to the sub in control panel and in my audio card in order to get the proper result?  mouser or eBay is fine? i saw e bay has many different writings on the chips...i don't know what to pick.  any recommendations?  http://www.ebay.com/sch/i.html?_from=R40|R40|R40|R40|R40&_sacat=0&_nkw=%22opa2228p%22&_sop=15 (sorry for the second reply...)

 

[ramachandra]

http://www.ebay.com/itm/2pcs-OPA2228-OPA2228P-ICs-/180575202092?pt=LH_DefaultDomain_0&hash=item2a0b1eeb2c
 
If you upgrade your soundcard, Pod, Sub with better OpAmps it is certainly result more accurate bass, crisp clear more musical sound. The only thing is OpAmps is alone about 40% improvement for the bass you really need to work on the caps too. The caps is the real badass for the bass and dynamic but the stock OpAmps unlikely let it happen so they must go first than you can do more later if you like. My advice is to star a full mod on your Titanium card and leave the rest after that. If you buy in bulk Mouser is preferable, at least to my location no shipping cost beyond 70€ and take no more than couple of days to receive.

 

[A-Force]

thanks for the reply my friend!!! you are the best!!! That s what i am going to do...   (you didn't understand my question although) i meant on the titanium instead of 4x opa1602aid maybe i should put 3, and 1 opa2228p for center/sub channel, and the same to control pod for the best result? or i only need to put them only in the sub (replace the 2 op amps of sub with 2228p) and the others(titanium, control pod) 1602 :-/  i was thinking to do the 3rd mod but i cant find the military caps k73-16...is there an other recommendation to buy? my priority is the deepest bass from the sub woofer. as for the control pod cap.... is this cap play role for the bass or only the main filter caps(Elna for audio 10000uf 80v) and the 4 caps of the sub op amps (silmic ii of course ) for the titanium the tcxo 0.1ppm is the best because i know the 0.3 is better from 1ppm for a bit more money. sorry my friend for many questions. it is because i don't want to make any mistake with the choices :-/ Thank you again.
 
p.s. the modifies titanium.. you think it would be better than the new asus stx ii 7.1 or at least comparable, for the z5500?

 

[ramachandra]

I have never had any ASUS card, but i have some experience about the components on the STX and i do know what not to expect. The Nichicon FG is good, still not the league of the Silmic II, the PCM DACs are refined and gentle with a nice 3d touch compared to the Titanium's Cirrus Logic what is a rough beauty in comparison. When i see the JRC letters on OpAmps i always sure replacing them is essential, the rest of the National OpAmps usually ok. The ASUS card have a DAC chip for every single channel so it result better clarity but do not have an ultra precision clock so it is going against it if not good enough. The modified Titanium is my pick unless you ready to work on the STX.
 
For a complete mod i only recommend the OPA2228P in the Sub of the Z5500 or on the Titanium (if the speaker can handle it for both

)  Better to not use it in the Pod by 3 reasons.
 
The eBay's search engine is playing the fool today, still i fund them:
http://www.ebay.com/itm/0-47uF-160V-PETP-Mylar-Capacitors-K73-16-Lot-of-10-/201120413110?pt=Vintage_Electronics_R2&hash=item2ed3b5f5b6