I think it's ready to go full power. See updated voltage with the outputs hooked up in post one.
http://www.diyaudio.com/forums/pass...d-4000-repair-need-some-help.html#post4267129
http://www.diyaudio.com/forums/pass...d-4000-repair-need-some-help.html#post4267129
Only thing I see is a typo -
17E of working side should be -2.17v, not +2.17v.
Bias current will be lower on rebuilt side initially.
Good to go!
17E of working side should be -2.17v, not +2.17v.
Bias current will be lower on rebuilt side initially.
Good to go!
I fixed the typo. Thanks for the help. I will try to get it going this weekend.
Tony
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It's playing music and sound good!!!! I will work on the bias now. Thanks for the help James.
Tony
Tony
Could this crossover have something to do with the problem? The amp played fine until I hooked up one of these.
B&W CM1 https://www.flickr.com/photos/85302162@N06/
https://flic.kr/p/vEY6wmCM1 parts https://www.flickr.com/photos/85302162@N06/
B&W CM1 https://www.flickr.com/photos/85302162@N06/
https://flic.kr/p/vEY6wmCM1 parts https://www.flickr.com/photos/85302162@N06/
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Never seen anything like this before. My only concern would be the relay opening and closing while current still flowing through inductors. Maybe a voltage spike could be developed on amp output which breakdown amp output transistor.
I did a quick look and found the 1N4004 on the plus side shorted. I have some ON Semiconductor 1N4004RLG. They should work I would think.
Sorry I guess I should have specified. The bad 1N4004 is in the amp. I never know the speakers had a protection circuit in them. I think the relay open up and things when to hell fast. the relay was welded in the open position and the woofer was smoked. I had the woofer repaired and removed the protection parts from the crossover and they sound really good now. Thanks for the input.
Tony
I think I may be back in business.
1N4004 replaced https://www.flickr.com/photos/85302162@N06/
A picture of the relay from the speaker for fun
Relay
1N4004 replaced https://www.flickr.com/photos/85302162@N06/
A picture of the relay from the speaker for fun
Relay
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Bias transistor matching
I have gotten tired of looking at this sitting in pieces so I am trying to get it back together. I have read that these transistors need to be matched. I would think the L51s would need to match each other and the L01 would need to match each other. Do the L51 need to need to match the L01? How close should they match?
Thanks
Tony
I have gotten tired of looking at this sitting in pieces so I am trying to get it back together. I have read that these transistors need to be matched. I would think the L51s would need to match each other and the L01 would need to match each other. Do the L51 need to need to match the L01? How close should they match?
Thanks
Tony
Attachments
I wouldn't loose my sleep too much over it
once when in temp. equilibrium , I can't see much of importance in matching
once when in temp. equilibrium , I can't see much of importance in matching
So I have the first channel back together and hooked up to the power supply run through a 150 watt DBT. +61.3/-61.9 on the rails. Draws .4 amps at 115 volt ac and .73 volts on the output. It does produce sound. The transistor I have marked 4 gets hot pretty fast. There is 9.4v at emitter, 10v at base and 29.5 at collector. Does these sound right? Should I go full power?
Tony
Tony
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730mV at output - that's DC offset?
if yes , that's too high
say that 100mV is highest you can allow, in temp. equilibrium
replace all old electrolytics, same as these nasty tantals - use modern electrolytics instead
regarding transistor you marked as 4 - which one is it on schmtc (it's too small in resolution , so I can't de-cypher)?
if yes , that's too high
say that 100mV is highest you can allow, in temp. equilibrium
replace all old electrolytics, same as these nasty tantals - use modern electrolytics instead
regarding transistor you marked as 4 - which one is it on schmtc (it's too small in resolution , so I can't de-cypher)?