[xTr3Me.aka.Chris]

Well my meter should work. Its not the best one but I got a new battery in it and it should be good enough to messure this..

I tested on a 9V battery and messured 9.5V...

I already tested the 12V points without and with jisbos and I always have the higher voltage

with opamp:
22 at +12V
20 at -12v

with jisbos
22,1 at +12V
19,7 at -12v

I read the the 100k ohm resistors can cause "noise"?

mb its because of that?

---

the heater voltage is -12,59V

the transformer is an avel lindberg 30va

--

the sj74s and sk170s are on their right place.. also the bc 550 and 560 are ok

 

[Pars]

Quote:

Originally Posted by xTr3Me.aka.Chris /img/forum/go_quote.gif Well my meter should work. Its not the best one but I got a new battery in it and it should be good enough to messure this.. I tested on a 9V battery and messured 9.5V... I already tested the 12V points without and with jisbos and I always have the higher voltage with opamp: 22 at +12V 20 at -12v with jisbos 22,1 at +12V 19,7 at -12v

OK, we'll say your meter is probably working. These voltages are just wrong... which regs are in for these, 12V or 15V? This portion of the circuit is really simple... a bridge feeding a pair of regulators with input and output caps on them. Are the regulators in the right way? Cuz they sure aren't regulating (sorry). You might check around the regulators and make sure that you actually have connections where you are supposed to (ohm function). I am trying to recall if the SOHA board is 2 sided or not? Replacing the regs you may have damaged the thru-hole plating (easy to do)? Ohm all the reg pins out to the appropriate caps, etc. Something isn't right here.

Quote:

Originally Posted by xTr3Me.aka.Chris /img/forum/go_quote.gif I read the the 100k ohm resistors can cause "noise"? mb its because of that?

No, at least not directly. These resistors should have no effect on power supply voltages...

Quote:

Originally Posted by xTr3Me.aka.Chris /img/forum/go_quote.gif --- the heater voltage is -12,59V the transformer is an avel lindberg 30va -- the sj74s and sk170s are on their right place.. also the bc 550 and 560 are ok

That all looks good.

 

[regal]

Somehow you are bypassing the regulators, 22V is the pre-reg voltage of the board. Possibly you have the regulator installed backwards, or there is a short between in/out of the reg.

 

[xTr3Me.aka.Chris]

Quote:

which regs are in for these, 12V or 15V?

15V, but 2x 1.0A - but we already got that this isnt the problem

Quote:

Are the regulators in the right way?

well they are installed the same way like the old ones.. its marked on the pcb which way to install them, so this should be ok


i will the check soldering of vr1 and vr2 again now



---

i messured r3 and r4 and they are 650 ohms(?) and not 820 or 825.. mb jeff put the wrong resistors in my package

 

[regal]

R3 is adjusted by the pot this should cause no harm.


Use you DMM to check for shorts between the pins of you 15V regulators, sounds like you have solder jumping the pins.

 

[xTr3Me.aka.Chris]

well i have little success:

i soldered a bridge between vr1 and vr2... to be exactly between both pins leading to the top of the pcb

its the middle pin of vr1 and right pin of vr2 (seen from the heatsink-side)

now i have -14,9V on the -12V point. so this is right now

so I only have the +22V at the +12V point left.. I will go bowling and bb in 2-3 hours

here is a good view of the pcb:
mb3k.com the place to be

mb you can understand my explanations easier with it :X


_______

well it really seems that I bypass the VR1 regulator! But I cant find the problem. If I would totally remove the VR1 nothing should work right? So I must have done a bypass.. strange thing.

Well I noticed that I more or less destroyed 2 of the VR1 and VR2 soldering points. But Ive tried to solve the problem with soldering bridges to C7 for example but it didnt help

now Im think of how to solve this problem.. I dont know what know.. mb think about it tomorrow again++#

__

well, can I damage the soha when using it with +22V on +12V point?


__

when I totally remove the VR1 and solder some cables to its legs and solder them to the + of C7, C9 and on the ground it should work right?

http://www.mb3k.com/pics/SOHA/cavalli2_fig5.png

 

[Pars]

I wouldn't totally remove VR1. If you have some small gauge solid wire around (24ga, maybe some Cat5 or something) you can just jumper the pins on the back of the board. Try to lay the wire down tight on the board (don't leave it flopping around).

 

[xTr3Me.aka.Chris]

and jumper them like I said? would this fix the problem?

 

[Pars]

Quote:

Originally Posted by xTr3Me.aka.Chris /img/forum/go_quote.gif and jumper them like I said? would this fix the problem?

It should, but you need to use your meter and a print of the schematic, and check (thoroughly) what is actually connected to what. And more importantly what is NOT connected to where it should be as this is what you should jumper.

Here is a pic of a Musiland MD10 I fixed for a guy on HF that a transistor had tried to burn thru the board, showing a jumper wire. I only jumpered what I had to.

 

[xTr3Me.aka.Chris]

well im not that kind of a electronic specialist to make the connections myself

when I look at the schematic here:
http://www.mb3k.com/pics/SOHA/cavalli2_fig5.png

I would say I have to connect vr1 with c7 and c9 and then it should also be connected with c8,c10 and so on right?

 

[synaesthetic]

If you're messing up the PCB when desoldering you might have an iron that's too hot. I've never used anything above a 15W pencil iron on any of this kind of work, though I'm getting a variable soldering station soon to make soldering jacks and stuff easier.

 

[Pars]

Quote:

Originally Posted by xTr3Me.aka.Chris /img/forum/go_quote.gif well im not that kind of a electronic specialist to make the connections myself when I look at the schematic here: http://www.mb3k.com/pics/SOHA/cavalli2_fig5.png I would say I have to connect vr1 with c7 and c9 and then it should also be connected with c8,c10 and so on right?

Yes. Look at the schematic and compare it to the board traces, etc. Use your meter and verify the connection from the actual device pins to the board traces, to the next component, etc. Not that much to check. Look at both sides of the board as they may run traces to a via then to the other side of the board.

 

[xTr3Me.aka.Chris]

well is it possible that the regulator is damaged so it doesnt change the voltage and I have the 22V after it?

cant understand the fault... i bridged everything and still it doesnt work

---------

i have made interesting messurements ... regarding ohms between in and output legs of the regs

when i messure between in and output leg of the working reg i have very very high ohm

and beteween not working one i have 1-2 ohms.... there must be a bridge or someting.. mb i soldered the reg too hot and so it got soldered inside xD

 

[Pars]

Quote:

Originally Posted by xTr3Me.aka.Chris /img/forum/go_quote.gif well is it possible that the regulator is damaged so it doesnt change the voltage and I have the 22V after it? cant understand the fault... i bridged everything and still it doesnt work

Yes, regulators can blow. Got any spares? Even the 12V?

 

[xTr3Me.aka.Chris]

well the 12V should be ok.. but when i remove the 15v again and change back.. the pcb .. errrr :C


-

ok lets think the VR is damaged and just has something like an internal bypass (xD) .. what would happen if i solder the older 12V VR parallel to the 15V one on the backplate without removing the 15v one.. if there is a bypass i should at least have a lower voltage than 22V .. or not?