Yamaha A-1 Repair and restore: beyond Deoxit

[DaaDaa]

are these choices for replacements ok? specially for the TIP41F im not sure if the choice is sutable.


TR-133: 2SC1913 -> TIP41F
TR134 same
TR135 : 2SA913 -> MJE15033
TR136: same
TR137: 2SC1213A - > kSC2383

S5151 -> no idea, no info i think these are toshiba parts
S5151R -> no idea
1S1555 -> 1N4148

I would like to replace all of these and would appreciate suggestions. all for the A-1 power supply.

 

[avionic]

S5151 -> no idea, no info i think these are toshiba parts
S5151R -> no idea

Dual diodes. One is common anode and tne other is a common cathode.

 

[clinic-audio]

Why do you try to replace everything ? and why looking for TR differents from original type ? Because you don't know where to buy original TR or specific diodes ?

Why replacing things if they are working ?

 

[DaaDaa]

the power supply board:

glue gone and the two transistors will be replaced tomorrow.

the green BP cap is in place of a 100 mf 16 volt cap which was not BP. is that a problem?


ill also do the 0.1 mf metal film caps when they arrive from china.

edit: in the picture there is a little residue glue left but since the picture was taken, ive cleaned it up more and now other than under the carbon resistors, there is none left that i can see.

 

[amr2]

Those green BP are not the most suitable for power supplies...

 

[avionic]

the green BP cap is in place of a 100 mf 16 volt cap which was not BP. is that a problem?

Most likely not going to be a problem.

Those green BP are not the most suitable for power supplies...

In PS's. I use Nichicon EP or VP hi-temp bipolars where needed.

 

[avionic]

S5151 -> no idea, no info i think these are toshiba parts
S5151R -> no idea

If they are still serviceable. Leave them alone.

 

[DaaDaa]

Most likely not going to be a problem.

In PS's. I use Nichicon EP or VP hi-temp bipolars where needed.

i took the nichicon muse BP 16v 85 degrees out and used a 50v 105 degrees instead. same value but 50v is all i have.

 

[DaaDaa]

first board is ready:

 

[DaaDaa]

are those transistors correct? TIP41 AND tip42

 

[DaaDaa]

I used TIP41 for 476A
and TIP42 for 566A

there has got to be a mistake there. maybe i need to swap the two?

 

[clinic-audio]

Sorry but why did you replace them if original are working ??

 

[DaaDaa]

41 and 42 seem to both be npn.

 

[avionic]

I used TIP41 for 476A
and TIP42 for 566A

there has got to be a mistake there. maybe i need to swap the two?

2SA/B ------ PNP ----- TIP42
2SC/D ------ NPN ----- TIP41

 

[avionic]

41 and 42 seem to both be npn.

Not !!!!

 

[clinic-audio]

ooooh la, la

 

[DaaDaa]

Sorry but why did you replace them if original are working ??

no it was not working and i coudnt figure it out. also you didnt post the pictures so that i can take the board out and send it to a professional like you to be repaired so i decided to replace all components that i can in the power supply and see how it turns out. i basically tried to follow the steps of mr., yamaha and repalce almost all compoents that he replaced iun his restoration project of 2010. now i am in deep ooooh la la but ill figure it out.

 

[DaaDaa]

upon further inspection, it looks to me like around the emitter of tip 42 the conductor ring around the leg is gone so that it doesn't make a connection. what is there to do in this situation? i only noticed it because realized that the solder joint looks suspect and when tried to reflow i saw that the solder does not stick. removed it and see that there does not seem to be any copper/trace there.

 

[DaaDaa]

yes it was gone. i scraped off a bot of the pcb to expose some copper and connected it with solder. now i have continuity.

 

[avionic]

Some of those old boards are getting to the point where desoldering damages the solder pads.