soundstream ref300 problem

marko

Member
2004-05-08 11:40 am
donnyuk
i'm trying to fix a ref300 and not sure what's wrong with it, when i power it up i have sound but it "blips" if that makes sence and some of the big resistors near the outputs are toasty hot! all outputs and resisters seam to be ok as i've ohmed them out so a bit stumped :confused:

any help would be appreciated...

mark.
 
The large transistors on the driver board are the driver transistors.

VERY carefully compare the readings of the driver transistors on both the new and the used boards. Sometimes the drivers are leaking (not completely shorted) which makes it difficult to determine if they're defective. You will have to pull the boards to get accurate readings (unless something is completely shorted or completely open).

I don't know if you've removed the driver boards before but if you haven't, be very careful. The main boards are easily damaged. I generally recommend using ChipQuik solder alloy but it's not always readily available. Try to find the problem without removing the driver board.

You probably only need to be concerned with the channel that has the overheating resistors.
 

marko

Member
2004-05-08 11:40 am
donnyuk
i shall go and check them then, it's the left side channel that gets hot, i've never pulled those boards before but i know the soundstream boards seam very fragile compared to pg m and ms boards....

i need to invest in some kinda de-soldering equipment but i don't know what, i'm slowly learning how to fix amps but having trouble desoldering at times :bawling: it's a fun hobby though :)
 

marko

Member
2004-05-08 11:40 am
donnyuk
think i may have found the problem, going over the outputs again i noticed the top 3 devices are only reading 81ohm compared with the rest this is considerably lower and it's this section getting quite hot!

i think they are tip102's under that section so will see if i have any spares and try it out!
 
If this is your own personal amp, replacing the single TIP102 may be acceptable but if you do this for a paying customer, you need to replace all of the transistors that are operating in parallel. In this case, you should have replaced all 3 of the 102s in that channel. Having matched components increases reliability.

A good soldering iron, a good desoldering pump and good quality desoldering braid is all you need to desolder most components. I like the WES51 iron. The edsyn DS017 is the best desoldering pump I've used. Chemtronics Chemwick braid is the best I've used.

For times when you need to work on sensitive boards you need to use special solder. ChipQuik solder is a low temp alloy that allows you to remove components at very low temperatures. This helps prevent damage to the board. It's most effective if you have a variable temp soldering iron. If you don't have a low/variable temp iron, you can apply it quickly with a hot iron and then use a heat gun to desolder the components.
 

marko

Member
2004-05-08 11:40 am
donnyuk
i just repair amps for my own personal collection and a hobby, i will be replacing all the units at some point but for now it's up and running and sounding superb :)

i need to put a big order in with jandrelectonics as i've got a faulty continuum on it's way and this will have everything done right 1st time!! (i'm guessing this has tip102/107 combo too?)
 
The continuum is based on the reference 705 which uses the 102 and 107. There were a few amps that used the TIP142T and TIP147T (which were rated at higher current). Since the continuum was a special edition amp, you may want to wait for it to arrive before ordering parts. It may have used the 142T and 147T.

Justonemoreamp knows more about the SS amps than I do, maybe he can tell you which ones they used.