RM KL 500 linear amp does not work

[Pelltom]

HI


problem- when i turn transformer on (even amp is off) it takes over 30 amp of current -> final transistor start to heat quickly.

So it is like shortcut somewhere ?

Have any one play with same problem? Are final transistor burn out or is it control malfunction ?

 

[mackmobile43]

Sounds like a shorted transistor conducting, pull the 2 transistors in that stage and test for short.

Place leads of you VOM to the base and collector tabs in both directions meaning switch the positive and negative leads between those tabs and if it shows continuity both ways you'll have found your shorted transistor.



Happy hunting.

 

[Pelltom]

:glare:

i remove final (4 pcs) transistor and i make measurements of them it seems to be that all of them are burn out.

Transistor model is NPN MS1051 now i need to find somewhere a new ones..
i think these are not cheap..

 

[mackmobile43]

:glare:

i remove final (4 pcs) transistor and i make measurements of them it seems to be that all of them are burn out.

Transistor model is NPN MS1051 now i need to find somewhere a new ones..
i think these are not cheap..

Replace them with the SD-1446

 

[eagle1911]

You'll need 2 matched pairs or better yet a matched quad.

Item SD1446-MP is available from rfparts for$79.90. It consists of a matched pair, and SD1446-MQ is a matched quad for $159.80.

Here's the link: PT - SD - TIP Transistors at RF Parts Company

 

[PU8WWW]

.

 

[Pelltom]

Hi

Thanks for the answers... yes i find that in older models of KL 500 have that SD1446 transistor.. so i think it will also work on these new model.

I ask for these MS1051 from asia markets and best offer so far is 30 us $ pcs and 35 $ shipping...

that price for sd1466 79$ sound too expensive

 

[mackmobile43]

$31 each with free shipping, beats your price by $31
Transistor SD1446 ST M113 | eBay