Hi there... i am new to this forum and modding electronic equipment. i bought a z5500 from ebay (broken) and fixed the d-sub connector to make it work again.
At the minute i have one full z5500 system (all working except center speaker) and another sub box with the amplifier (which i got from my brother)... the sub driver is missing as he blew it up driving the sub from an external amp... which beforehand he blew the plate amp up for the sub... just the sub was not working so he removed the board and tried swapping a tda7294 for another one and forgot to put the mica sheets back in... alot of smoke later and it went into storage which i now have... so i have two projects here... an upgrade for the full system... and a fix for the blown amp. so lets get started...
the full (main) system i have all works fine except the center (i messaged you @ramachandra about front left... but i swapped an op-amp out of the broken system to see what would happen... the front left works fine but now there is no sounds/just popping from the center speaker) anyway i have 5 X opa1612aid on the way to fix that... all other parts from my main system will be transfered to the blow amp when they arrive.
the second blown amp is just about fully stripped down apart from smd's alll the tda7294's are out... i have 10 of them on there way. i am also about to purchase 16xelna silmic ii 47uf 50v & 16xelna silmic ii 22uf 50v which will go in my main system... so the old caps will then go to the blown system... if the blown system will come back to life then i wil upgrade it aswell (eventually). and the old r4580i out of my full system will go into the blown amp... i will add two tda's and one op-amp at a time to the blown board and power on and test as i go... i know i will need another op-amp (because my center doesn't work) but this will have to wait as i want to get my full system upgraded first and slowly fix the blown board. the blown board has some smd resistors missing 3 x 81A but i will just use 1/4w metal films to get it running and the replace with smd after i know it works... i also have a few bad/broken tracks on the blown board which are for the tda's most of which are broken don't go anywhere anyway... some of the ones that do (2 of) i can fix quite easily... there is another problem though... when i had it turned on testing it with only one op-amp in... and only two tda's in to check the center... on one of the op-amps tracks it was arcing to the board... i had removed the op-amp from this position and i could see small blue flashes so the only thing i could do was to lift that pad from the board... now it is lifted i cannot put it back down without it arcing... is there something i can do with that? if there is not some kind of insulation i can put under the pad then the only thing i can think of is to rip the track up which goes to an smd cap and solder a wire stright from op-amp to cap... or i might try your cap mod to remove op-amps as that would get round it aswell.
at the minute i have all WIMA cap's on the underside of the board 250v+ and i have replaced all 1/8w carbon resistors with 1/4 metal film and replaced the v-regs resistors and 1/2w with same wattage but metal film. i have replaced 220nf on the preamp board with 630v axial caps and one on the underside of the board (green cap) with a 630v axial but i had to go through the top of the board and solder on the underside... its no problem i just used some epoxy on the cap to hold it.
i will keep you posted on how my modding goes... the control pod will be the last thing that i do... but i might change the op-amps in the control soon(ish) aswell (those opa1612aid's start really totting up when you need many of them... the cheapest i found on ebay was £3.50+£3.00 P&P i have bought 5 so far. i will be getting the nichicon KA 4700uf 25v for a direct size replacement for the 4700uf pod cap... and i will be using nichicon 10000uf 50v for the main filter caps... as i dont really want to mod the board in the same way you have done just to get big caps in... plus it cheaper and i have a few other mods on at the min aswell... a graphic equalizer to mod and another graphic i need to fix... so cost cutting is essential for me at the minute.
@ramachandra i see you have some modded boards on ebay... i assume you took those boards from the actual heatsink (plate) which leads me to my next question... the blown board i have has got the heatsink plate but i dont have the bars to secure the tda7294's and i dont have the mica sheets or the screws for the bars... do you have any of these items spare that you are willing to sell? please PM me about that if you want to sell them... thanks.
i will check in after each new mod i do to the full system and progress on the blown board
If someone here has one of these with a control pod... the next time you open it up could you check to see how hot the +18 & -18 volt regulators are? i was showing my amp to someone and turned it on with the pre-amp board out and it grounded the d-sub connector and would not play sound... it popped a resistor on 79m18a went from 36R to 30R ... i have replaced the resistor and everything works again... but these two voltage regulators seem to be running hot... as in after it has been turned on for about 1 min you cannot keep your finger on them for longer than 5-10secs (its becomes uncomfortably hot not instant blister hot) i was just wondering if any one elses ran this hot? if not i have a couple of these v-regs i can throw in but i wanted to be sure there was a problem there before i change anything... any info anyone can give would be appreciated... these v-regs are near the two 10000uf filter caps... Cheers
Edited by jayjayuk - 6/6/14 at 5:35am