the big white caps you see next to the outputs is decoupling of 1mfd rated at 600V ( ????) any comments on that ??
Some manufacturers prefers film filter caps in the power supply rated at high voltage. Is it possible that they are more stable? less microphonic?
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I think the answer is that the larger 600V capacitor will handle higher current ripple. I think that the capacitors larger size will act as a heatsink.
Kenwood/Trio Model 600 halfway through restoration
Huge, heavy, difficult to work on but extremely well built 1970's intergrated, developed around the time some designers left kenwood to set up accuphase, some say the one to beat pre 1990.
Huge, heavy, difficult to work on but extremely well built 1970's intergrated, developed around the time some designers left kenwood to set up accuphase, some say the one to beat pre 1990.
SERVICE SANSUI T500
IS THERE anything to do in such a machine ? obviously not much ...replace capacitors add a few in local stabilization and a bit of tuning ....
Loved the analog knob and also found the tuner sensitive quite and warmish from sound aspects
here is a couple of pics
IS THERE anything to do in such a machine ? obviously not much ...replace capacitors add a few in local stabilization and a bit of tuning ....
Loved the analog knob and also found the tuner sensitive quite and warmish from sound aspects
here is a couple of pics
service sansui a500
obviously and like wise will be for the same series amplifier ....very few things to be done and a bit of cleaning done most of difference.
Machines like those could be made to work a lot better but i wonder why the manufacturer make them so bad. Often other issues like marketing define the coarse of making an amp .
here is a few gut pics
obviously and like wise will be for the same series amplifier ....very few things to be done and a bit of cleaning done most of difference.
Machines like those could be made to work a lot better but i wonder why the manufacturer make them so bad. Often other issues like marketing define the coarse of making an amp .
here is a few gut pics
service revox B 251
extensive threads around the B251 say that is bad equipment ...Revox done miracles in other machines but this i will agree is bad ....
German schematic is available and one may notice that there is a mixture of various of technologies inside and to my understanding even though this a machine that is possible to operate , the mixture of so many technologies and the complexity that is made actually produce an everlasting but after all bad result .
all controls are touch ,no actual switches ( or very few ) huge amount of various ttl , one amplifier with loads of CCS and loads of transistors just to produce less than 100w .... add to this the futuristic freon heatsink ...and on the top of the above the shelf oscillating power supply ....
Problem wise there was very few ...4 trimmers all small capacitors and a lot of soldering to be done ...
Real problem was one cup of coffee inside the power supply ...thank god all was in the primary and a bit of cleaning and a few capacitors bring the machine back to life ..
I will not bother to say anything about the sound of it ...though the explosive pictures of the power supply
extensive threads around the B251 say that is bad equipment ...Revox done miracles in other machines but this i will agree is bad ....
German schematic is available and one may notice that there is a mixture of various of technologies inside and to my understanding even though this a machine that is possible to operate , the mixture of so many technologies and the complexity that is made actually produce an everlasting but after all bad result .
all controls are touch ,no actual switches ( or very few ) huge amount of various ttl , one amplifier with loads of CCS and loads of transistors just to produce less than 100w .... add to this the futuristic freon heatsink ...and on the top of the above the shelf oscillating power supply ....
Problem wise there was very few ...4 trimmers all small capacitors and a lot of soldering to be done ...
Real problem was one cup of coffee inside the power supply ...thank god all was in the primary and a bit of cleaning and a few capacitors bring the machine back to life ..
I will not bother to say anything about the sound of it ...though the explosive pictures of the power supply
Thanks Sakis
You made me 50 euro richer, helps to pay for the austerity. I had a bet with a designer about the topology and where they got the idea from.
You made me 50 euro richer, helps to pay for the austerity. I had a bet with a designer about the topology and where they got the idea from.
Single ended input amps have a particular sound, especially in the midrange, excellent on vocals, after listening so many type amps I can sometimes (more right than not) guess the topology used.
For another example of a very good single ended amp with good sound see Renardsons designs, no need to chase thoes THD figures he does though.
For another example of a very good single ended amp with good sound see Renardsons designs, no need to chase thoes THD figures he does though.
It would be a chore to put up all the restoration pics but here are a few links to whole threads. It is a croatian forum but the pics are self-explanatory.
Luxman L530
diyaudio.com.hr • Pogledaj temu - Luxman L530
This one came from a Luxman service, declared unfixable after it blew the original NEC RETs on one channel. In the mean time they stripped the knobs to fix another one. Then the original output modules were removed and replacmenet MOSFET modules were installed, new knobs were made out of turned aluminium, copies of the originals. This is how it came to me.
It was restored with original modules, the knobs were modified to fit properly, the wireloom was redone, etc etc (as per pictures), output connectors changed to more modern ones and finally the woodwork was renewed. It has been restored to factory spec and more (the few electrolytics in the signal pat were changed to foil caps).
Sansui BA-2000/CA-2000
diyaudio.com.hr • Pogledaj temu - Pogodi tko sam...
The power amp was used in a disco and put in a rack, burned several times until finally something in the rack under it caught fire. The preamp was in better shape but had some 'tweaks' like gold painted bottom cover (?!) and removed accessory plugs.
Everythinng was stripped, chasis re-painted, even screws were replaced, all electronics overhauled including new semis, all wirelooms redone, front panels and heatsinks de-anodized, nicks and scratches grpund outm reanodized and lettering redone.
Everything restored to factory specs +...
Sony TA-F830ES
diyaudio.com.hr • Pogledaj temu - Sony TA-F830ES: ru?na pri?a sretnog kraja?
Suffered a 'tweak' by replacing original electrolytics with cheap elna's held by rubber bands (!!!) original cap holder lost forever, output stage transistors stolen and replaced with lesser units due to (probably) one output stage failure, also the rest was fixed with recycled components. Thief also initially installed one of the filter caps backwards resulting in PCB traces burning (left + and - inscriptions on the PCB, wrong way around).
This unit is intended for 220V and puts close to maximum voltages on it's caps in high 230V mains condition, a small autoformer was installed to shave off up to 20V from the mains to correct for this.
Everything restored to factory specs, complete resolder job, also completely washed from dust and tar / tobbacco smoke residue, cover repainted.
Luxman L530
diyaudio.com.hr • Pogledaj temu - Luxman L530
This one came from a Luxman service, declared unfixable after it blew the original NEC RETs on one channel. In the mean time they stripped the knobs to fix another one. Then the original output modules were removed and replacmenet MOSFET modules were installed, new knobs were made out of turned aluminium, copies of the originals. This is how it came to me.
It was restored with original modules, the knobs were modified to fit properly, the wireloom was redone, etc etc (as per pictures), output connectors changed to more modern ones and finally the woodwork was renewed. It has been restored to factory spec and more (the few electrolytics in the signal pat were changed to foil caps).
Sansui BA-2000/CA-2000
diyaudio.com.hr • Pogledaj temu - Pogodi tko sam...
The power amp was used in a disco and put in a rack, burned several times until finally something in the rack under it caught fire. The preamp was in better shape but had some 'tweaks' like gold painted bottom cover (?!) and removed accessory plugs.
Everythinng was stripped, chasis re-painted, even screws were replaced, all electronics overhauled including new semis, all wirelooms redone, front panels and heatsinks de-anodized, nicks and scratches grpund outm reanodized and lettering redone.
Everything restored to factory specs +...
Sony TA-F830ES
diyaudio.com.hr • Pogledaj temu - Sony TA-F830ES: ru?na pri?a sretnog kraja?
Suffered a 'tweak' by replacing original electrolytics with cheap elna's held by rubber bands (!!!) original cap holder lost forever, output stage transistors stolen and replaced with lesser units due to (probably) one output stage failure, also the rest was fixed with recycled components. Thief also initially installed one of the filter caps backwards resulting in PCB traces burning (left + and - inscriptions on the PCB, wrong way around).
This unit is intended for 220V and puts close to maximum voltages on it's caps in high 230V mains condition, a small autoformer was installed to shave off up to 20V from the mains to correct for this.
Everything restored to factory specs, complete resolder job, also completely washed from dust and tar / tobbacco smoke residue, cover repainted.
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I just got a Luxman LV92, works and sound great. Do you think it worths the effort of a full recap?
I would say, if you really like the amp and want to keep it, then yes. A refurbished old amp will keep up with modern offerings.
As electrolytic capacitors, like the feedback capacitors and other signal path caps, dry out they can change the gain and frequency response to an audible level. Plus some older parts can go bang in the end...
As electrolytic capacitors, like the feedback capacitors and other signal path caps, dry out they can change the gain and frequency response to an audible level. Plus some older parts can go bang in the end...
I agree you might also wana change coupling capacitors with MKT in various stages that will also help to a better amp Use Wima with 5mm pitch nothing bigger than that in size