Yamaha REV 1 with a broken psu

[dreamix]

Something in the psu died, fuse is alright!

Anyone know who could fix these things, or have a schematic over the psu, please pm me!

All the best / Mattias

 

[Rob Flinn]

If it's anything like a lot of the yamaha reverb/delay processors from that era the first thing I would do is recap the PSU.

 

[NoisyIndividual]

If it's anything like a lot of the yamaha reverb/delay processors from that era the first thing I would do is recap the PSU.

 

[Rob Flinn]

PSU is a bit more beefy than some of the other units, but I would still recap the psu.

 

[NoisyIndividual]

I had to replace the 2 main switching transistors in one of these a while ago.
They are BJT's and very difficult to find equivalents for at those rated specs.

 

[dreamix]

Thanks for the answers,

Ive taken out the psu, and disconect the switchboard from the psu mainsboard, looks like a nightmare this psu,

 

[dreamix]

I had to replace the 2 main switching transistors in one of these a while ago.
They are BJT's and very difficult to find equivalents for at those rated specs.

Did you found an equivalent that worked and care to share

 

[NoisyIndividual]

I believe the originals are 2SC2937.

Mouser sell the BUV48A which I seem to recall are rated the same or better.

https://www.mouser.co.uk/ProductDetail/STMicroelectronics/BUV48A?qs=JV7lzlMm3yIoXBpWz6h6ag==

 

[dreamix]

I dug inside to check whats wrong, this was broken, think its a fuse kinda thing, some safe network there with also a temperature fuse, which was fine. I took one of the big caps out, 470uf, I never seen one like this, why is it vented or what is it?

 

[Rob Flinn]

I dug inside to check whats wrong, this was broken, think its a fuse kinda thing, some safe network there with also a temperature fuse, which was fine. I took one of the big caps out, 470uf, I never seen one like this, why is it vented or what is it?
View attachment 140666

It's a wire wound resistor !

 

[dreamix]

These 2 im not sure how to measure, they show nothing in my transistor tester, multimeter show 0 ohm between B-C C-B , nothing values at alot between.others

 

[dreamix]

It's a wire wound resistor !

Ye I have a bag of those so switched the bad one out

 

[Rob Flinn]

These 2 im not sure how to measure, they show nothing in my transistor tester, multimeter show 0 ohm between B-C C-B , nothing values at alot between.others

View attachment 140667

That might be telling that they're dead ...