New to me 610II - Distortion

[Kapco]

TR497 seems to test OK.
Can't seem to get a good read on the FR491. I think I'll have to remove it to check accurately....
Trimmers seem to change resistance smoothly across the range.

 

[Kapco]

Took FR491 out....toast. Seems like these fusistors are hard to come by. Any chance a guy can use a 220ohm 1/2w resistor?
If the value is 220ohm (although it actually said 45mA-220∆k. Triangle being ohm symbol) I calculate needing 0.4455watt
I doubt its 220k ohm as would be super high watts at that spec if doing my math correct.

 

[Kapco]

Just because I'm trying to learn here...I'm assuming that because the fusistor was open, all the current flow out of TR497 is now flowing into the base of the TR501 and over driving it?

 

[avionic]

Just because I'm trying to learn here...I'm assuming that because the fusistor was open, all the current flow out of TR497 is now flowing into the base of the TR501 and over driving it?

Something along those lines..

 

[avionic]

. Any chance a guy can use a 220ohm 1/2w resistor?
If the value is 220ohm (although it actually said 45mA-220∆k. Triangle being ohm symbol) I calculate needing 0.4455watt

Precisely !! .. 220 Ω 500mw-1/2 watt is what you need. With flamproof/resist coating - Fusible if you can find one.

I found one at Mouser.Pick up a few of them . Just in case.
https://www.mouser.com/ProductDetail/Vishay-BC-Components/NFR25H0002200JR500?qs=4g6zCjIpOKgMD9AQRjQWfQ==

Ω being the omega symbol

Alt key code 234 Ω -- 220Ω --
Alt key code 230 µ -- 220µf --
Alt key code 248 ° -- 220°F --

 

[Kapco]

Well....saga continues lol.
Managed to swap the 10kohm caps today along with the 470s. Put in the 220ohm 1/2w resistor...... And drum roll please.... .no difference lol.
Powers up with no release of smoke from anywhere but after about 6 seconds of waiting for the relay to click...which it doesn't....I turn it off....transistor 501 is very hot.....the other 3 cold.....perhaps time to pull out OT and test it again.....

Side note...tried the Alt-234....I get a U with 2dots on top. Probably my keyboard language setting....

 

[avionic]

.tried the Alt-234....I get a U with 2dots on top.

... I get Ω..

https://www.alt-codes.net/

 

[avionic]

Managed to swap the 10kohm caps today

10,000 µf ?

 

[Kapco]

10,000 µf ?

Yes...duh...10k microfarad (10,000) not ohm. I'm honestly smarter then this lol

 

[Kapco]

Been studying this schematic trying to figure out how OT 501 can be dumping lots of current and why. And why no others are.

 

[Kapco]

Also swapped TR497 &498 from each channel just to see if the problem followed...nope...501 still heats up.

 

[avionic]

How much voltage are you seeing on the base of TR501 ?

 

[Kapco]

I'll see if I can check before it gets too hot....only get about 6-8 seconds and too hot to touch

 

[Kapco]

-35 v at the base.
Supposed to be .3v?

 

[Kapco]

I can't figure out what current is flowing where with all these damn transistors connected to each other...lol

 

[avionic]

Do you have another output transistor ? That one looks like toast.

 

[Kapco]

I checked base of T503 ...I get -38v also???

 

[Kapco]

On the bases of the other set I got .-.5 and +.6

 

[Kapco]

That would suck....all these are new. Can I remove them and check voltage at the bases when removed....I guess not idea is they should be flowing and almost no voltage drop?

 

[Kapco]

These were the pair that was missing when I got it.......