[bloodhawk]

I assembly back to simple setup and just got all the voltage reading now, seem like something error on right side output.
Read from picture above shown:
Red first left to right : (151.5) (-108) (-108) (151.5) (151.5) (1.0) (1.0) (151.5)
White left to right : (149) (-105) (-94) (149) (149) (1.0) (1.0) (149)
Yellow left to right (213) (213) (214) (214)
Help needed for the negative reading, thanks

First think would be to double check and reflow the joints in this region -

Next double check the tube socket solder joints and reflow those

(Be careful with the heater wiring, as it loves to come right off if you dont hold it down while reflowing the solder joints) - These are the 2 thick grey wires coming from the transformer at the back and then branching off to the second tube socket.

 

[baronbeehive]

I assembly back to simple setup and just got all the voltage reading now, seem like something error on right side output.
Read from picture above shown:
Red first left to right : (151.5) (-108) (-108) (151.5) (151.5) (1.0) (1.0) (151.5)
White left to right : (149) (-105) (-94) (149) (149) (1.0) (1.0) (149)
Yellow left to right (213) (213) (214) (214)
Help needed for the negative reading, thanks

Not sure what's happening here, you should be getting 100v on the B+ and a 25v drop across the 330R resistors.

Check the voltage drop across the 330R's, put one probe of your multimeter on one side and the other probe on the other side of the 330R's to check the voltage drop.

Also could you post a pic with your resistor values like I have done.

Edit: How many 330R resistors have you installed? I can only see 4.

 

[klnglim]

Not sure what's happening here, you should be getting 100v on the B+ and a 25v drop across the 330R resistors.

Check the voltage drop across the 330R's, put one probe of your multimeter on one side and the other probe on the other side of the 330R's to check the voltage drop.

Also could you post a pic with your resistor values like I have done.

Edit: How many 330R resistors have you installed? I can only see 4.

There are 8 150R mills resistor, that's the different between mk6 & mk8se

 

[bloodhawk]

There are 8 150R mills resistor, that's the different between mk6 & mk8se

@baronbeehive

There seems to something wrong with the PSU side feeding the right channel anode as well. Some sort of short around there .



Also.. anyone know what value of resistor is being in the ampmeter lighting circuit ? I measured it as 68Ohm.. but on my friends amp where the left meter is busted , with a new replacement ampmeter the light doesn't seem to be turning on.

 

[baronbeehive]

@baronbeehive

There seems to something wrong with the PSU side feeding the right channel anode as well. Some sort of short around there .

Yes, somewhere between anode and cathode something's up, I leave it to someone else to fathom that one out. When the problem there is found it might rectify the other wrong readings I mentioned.

If we can have the resistor values, that might point to something unless you say they are correct, otherwise you will have to check connections and components in that area on the trace between anode and cathode, both circuits right side.

BTW, sorry I forgot the MKViii has 150R's, not 330R's.

 

[bloodhawk]

Yes, somewhere between anode and cathode something's up, I leave it to someone else to fathom that one out. When the problem there is found it might rectify the other wrong readings I mentioned.

If we can have the resistor values, that might point to something unless you say they are correct, otherwise you will have to check connections and components in that area on the trace between anode and cathode, both circuits right side.

BTW, sorry I forgot the MKViii has 150R's, not 330R's.

yeap!

Ill look into this more tonight after work and try to help him out.


Onto the next thing, any idea what the rating for the amp meter lighting is? I found a 68Ohm in series with the positive lead going to the amp meters. Was wondering if those are super necessary or can be removed as its super hard to solder those on.

 

[baronbeehive]

yeap!

Ill look into this more tonight after work and try to help him out.


Onto the next thing, any idea what the rating for the amp meter lighting is? I found a 68Ohm in series with the positive lead going to the amp meters. Was wondering if those are super necessary or can be removed as its super hard to solder those on.

Right! My guess is a short or a grounded connection somewhere, difficult to know when you don't know what has been done.

Re: the meter, sorry I do't know about that.

 

[bloodhawk]

Right! My guess is a short or a grounded connection somewhere, difficult to know when you don't know what has been done.

Re: the meter, sorry I do't know about that.

Yeah my guess right now is that the wiring on the B- transistor.


On another note, i have a crap ton of extra PNP and NPN transistors that @SonicTrance had recommended, mouser had goofed my order and thought they sent the wrong pair even though i received the correct ones. A week later 4 more pairs showed up lol.

 

[SonicTrance]

Onto the next thing, any idea what the rating for the amp meter lighting is? I found a 68Ohm in series with the positive lead going to the amp meters. Was wondering if those are super necessary or can be removed as its super hard to solder those on.

I don’t understand what exactly it is you mean? Where did you find a 68R resistor?

 

[bloodhawk]

I don’t understand what exactly it is you mean? Where did you find a 68R resistor?

The amp meters positive terminal for the yellow lamp.

 

[SonicTrance]

The amp meters positive terminal for the yellow lamp.

Ok, I didn’t know there was a resistor there. Where is it? On the board, soldered on the wire or inside the meter? Sounds like a current limiting resistor and is there to prolong the life of the bulb.

 

[bloodhawk]

Ok, I didn’t know there was a resistor there. Where is it? On the board, soldered on the wire or inside the meter? Sounds like a current limiting resistor and is there to prolong the life of the bulb.

My bad i should have specified. Its heatshrinked between the wire and the meters terminal. I didnt even know it was there until i took out the old meter out .

Ahh that would make sense.. im guessing to drop the voltages from 12V to about 8-10V?

 

[SonicTrance]

My bad i should have specified. Its heatshrinked between the wire and the meters terminal. I didnt even know it was there until i took out the old meter out .

Ahh that would make sense.. im guessing to drop the voltages from 12V to about 8-10V?

I don’t remember how much current the bulbs draw. Therefore I don’t know how much voltage a 68R resistor would drop. I would definitely use some resistor there though as to not cook the bulbs at turn on when voltage is higher.

 

[klnglim]

Yeah my guess right now is that the wiring on the B- transistor.


On another note, i have a crap ton of extra PNP and NPN transistors that @SonicTrance had recommended, mouser had goofed my order and thought they sent the wrong pair even though i received the correct ones. A week later 4 more pairs showed up lol.

Hey Guy! I just find out what's the problem when double checked the NPN & PNP , although both nothing wrong but I notice those transistor's Collector touching ground, I guess that's the reason why the amp short circuit after 2nd VU meter light up.
I will change some problem circuit and confirm again later

 

[baronbeehive]

Hey Guy! I just find out what's the problem when double checked the NPN & PNP , although both nothing wrong but I notice those transistor's Collector touching ground, I guess that's the reason why the amp short circuit after 2nd VU meter light up.
I will change some problem circuit and confirm again later

Sounds like that could be the problem. That would probably explain why the headphone protection circuit kicked in too, you were getting very high voltages in the other circuit but I think this may right itself when you've fixed the ground issue.

I would like to know what voltage triggers the protection circuit.