petehall347
the brandy coffee man
bd139 bd140 might be better choices .. you will need to attach heatsinks to them .
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Short circuit connecting preamp with amp (RCA)
- Thread starter elgrillo
- Start date
elgrillo
El Grillo
So You think this are good substitutes for Q209 an Q210? what type of heatsink do you recommend?
BTW Q210 in left channel its not original, i can read b649 in it , and it has a crew in it as a heat sink. Q209 looks to be original motorola.
So i should replace all 4 , I think ? To keep the amp balanced.
Thanks !
petehall347
the brandy coffee man
i am confused about the transistor placement on the boards .
and it looks like at least one is maybe in the wrong way round .ss47
and it looks like at least one is maybe in the wrong way round .ss47
petehall347
the brandy coffee man
will look into it later .. i have work to do shortly .
they are better as complimentary pairs .
2sb649 datasheet here ..http://www.datasheetcatalog.com/datasheets_pdf/2/S/B/6/2SB649.shtml
they are better as complimentary pairs .
2sb649 datasheet here ..http://www.datasheetcatalog.com/datasheets_pdf/2/S/B/6/2SB649.shtml
elgrillo
El Grillo
Peter what photos are you looking at? i will put new fotos here better.
elgrillo
El Grillo
Tomorrow morning Im going to buy the bd139 and bd140 to replace the Q209 and Q210. The cost about .45 Euro each and I can find them near my house.
And some small heatsinks also.
I hope the Diodes are good that are the only things I didnt checked.
Tomorow I will update the info.
Gonzalo
petehall347
the brandy coffee man
i used them in a similar situation and they worked just fine . .
just be sure you put them in the correct way around .
just be sure you put them in the correct way around .
elgrillo
El Grillo
Ok peter i will be carefull.
could you give me some advice for the heatsinks? and do you think the other to126 that I have replaced need also heatsinks?
Thanks!
petehall347
the brandy coffee man
i think it best to use heatsinks .
i salvage my heatsinks from old equipment .
you can of course buy new ones . i fasten the transistor the heatsink and use hot glue to fasten them down .
there are a few styles . just pick one that suits the job best .
i salvage my heatsinks from old equipment .
you can of course buy new ones . i fasten the transistor the heatsink and use hot glue to fasten them down .
there are a few styles . just pick one that suits the job best .
elgrillo
El Grillo
Ok now its runs again, Dim bulb light (120W) , dims like it should and relay Clicks.
Im going to check the AC and DC voltage from chassis to chassis.And from chassis to ground (outlet). Ans post the readings. This sould be zero ? or a really low numberer?
By the way the black/white and white wires from primary (trafo) are soldered together and isolated with isolation tape. Not soldered to the chassis like before. I hope this fixes the hot chassis.
Gonzalo
petehall347
the brandy coffee man
did someone say the wires should be attached to chassis ?
it should be zero yes .
you could check the dc offset ... do you have a current meter and variac to set the bias ?
it should be zero yes .
you could check the dc offset ... do you have a current meter and variac to set the bias ?
elgrillo
El Grillo
In the manual , in the first pages, there ara the indications for changing the voltage operation. And in one part says: "attach the standoff terminal to the chassis using the ... supplied. 5) Unsolder the white wire from the fuse holder. Unsolder the black/white wire from J3 pin 2. 6)Solder the white and Black/white to standoff terminal.
Whith that I assumed that both wires where grounded. But in the diagram dont appear a chassis ground.
I dont have a Varic. But I can try to set the bias with the dim bulb tester (just for precaution). I think the bias have to be set across one of the emitter resistors with 4.2mV as suggested here in the post #30: http://www.audiokarma.org/forums/showthread.php?t=364223&page=2
That is Ok?
petehall347
the brandy coffee man
if you set with dim bulb tester you will need to reset with it plugged in directly .
turn it down in-between as it will rise the current when plugged in directly .
try first with bulb tester .
4.2mv looks like it will be safe .
you could maybe get one of these afterwards to final check it.make sure it will do the job as there are different ones with different features
turn it down in-between as it will rise the current when plugged in directly .
try first with bulb tester .
4.2mv looks like it will be safe .
you could maybe get one of these afterwards to final check it.make sure it will do the job as there are different ones with different features
elgrillo
El Grillo
if you set with dim bulb tester you will need to reset with it plugged in directly .
turn it down in-between as it will rise the current when plugged in directly .
try first with bulb tester .
4.2mv looks like it will be safe .
you could maybe get one of these afterwards to final check it.make sure it will do the job as there are different ones with different features
I conected the DMM to the chassis (red) and to the earth in the outlet (black). And without turning it on I got 1.286V (AC). And when I turn on the Amp (via a power bar) . I got OL .
Is this OK? I think not. What could be the problem?:scratch2:
Thanks
petehall347
the brandy coffee man
OL is overload .means you need to use a higher setting on the meter .
but it isn't right there is leakage somewhere from the mains to the chassis . i am wondering if you connect them wires to chassis it may cancel it out ? i am not too sure about this though ..
first things first see what the high voltage reads when you set your meter to high AC volts .
or better still unplug the amp . set your meter on ohms and check resistance from the power lead to the chassis .
and also check from secondary side transformer to ground and also to primary ..
i am thinking it has a short in the transformer or one of the wires shorting to ground .
will study the schematic now
but it isn't right there is leakage somewhere from the mains to the chassis . i am wondering if you connect them wires to chassis it may cancel it out ? i am not too sure about this though ..
first things first see what the high voltage reads when you set your meter to high AC volts .
or better still unplug the amp . set your meter on ohms and check resistance from the power lead to the chassis .
and also check from secondary side transformer to ground and also to primary ..
i am thinking it has a short in the transformer or one of the wires shorting to ground .
will study the schematic now
elgrillo
El Grillo
The DMM is auto range but I found a yellow button for changeing the range.
The value is 106V (AC) :thumbsdn:.
I dont understand what you said here :"set your meter on ohms and check resistance from the power lead to the chassis.
and also check from secondary side transformer to ground and also to primary "
Could you axplain me that a little bit. So sorry to bother
Thx
petehall347
the brandy coffee man
The DMM is auto range but I found a yellow button for changeing the range.
The value is 106V (AC) :thumbsdn:.
I dont understand what you said here :"set your meter on ohms and check resistance from the power lead to the chassis.
and also check from secondary side transformer to ground and also to primary "
Could you axplain me that a little bit. So sorry to bother
Thx
i don't know where this came from [COLOR="black"
ok it looks like its at half the mains supply potential .. first check voltage from the black white / white wires ..keep them connected and measure voltage from earth in your power socket and to amp chassis .
elgrillo
El Grillo
119V (AC) . Conecting RED to wires WHITE and BLACK /WHITE; and black to ground on the outlet.
petehall347
the brandy coffee man
just had a thought .. try swapping live neutral ..hot/cold .. at the power plug . this will hopefully make it zero volts on the chassis