CR-2040 hot resistor issues.

[avionic]

after a few moments.

How long does it take to stabilize ? A few seconds ?

 

[avionic]

How long does it take for the protect relay to " click " ?

 

[Vince1966]

Not yet, waiting for them. I see where they are tied into the protection circuit. I have a bunch of LED’s but decided against them for that reason, also they would be too bright.

 

[Vince1966]

How long does it take to stabilize ? A few seconds ?

About 2 min to come down to normal. It’s always off from where I set it, up or down in mV, that’s why I was thinking dirty trimmers.

How long does it take for the protect relay to " click " ?

3 seconds for the relay to click.

 

[avionic]

About 2 min to come down to normal. It’s always off from where I set it, up or down in mV, that’s why I was thinking dirty trimmers.

2 min.. Thats really nothing to worry about.. TR702 and 703 would be the prime suspects.. I don't think a new trimmer will make much of a difference.

 

[avionic]

TR702 and 703 would be the prime suspects.

These are dual transistor
2SA979's are no longer available
Replace with (2 each) 512-KSA992FBTA (must be gain matched )

https://www.mouser.com/ProductDetail/onsemi-Fairchild/KSA992FBTA?qs=BiJXFBt7cx0C7PSFUPmr1w==

 

[Vince1966]

Are you referring the TR-703-704 pairs? I have a bunch of KSA992 FB’s, the bulbs will be here tomorrow and I’m finishing the veneer replacement on the cabinet. I’m going to put together a BOM and eventually recap this unit, new trimmers and the 979 transistors.

 

[avionic]

Are you referring the TR-703-704 pairs?

Yes.. I see that typo now on the shematic.. Good catch..

 

[Vince1966]

Thanks, I’m putting the bulbs in now and will see how it effects the DC.

 

[Vince1966]

Well, new bulbs definitely straighten out the DC fluctuations at start up, stabilizes much faster and a smaller spike at start up. Now I need to fine tune it. Working on the cabinet now.