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CA610 II Protection Relay Slooooooooow

Farducci

Farducci

New Member
Hey All,

Looking at a CA610 II Amp for a friend as they said it's taking longer and longer to "turn on" as they use it.

I've looked into it a bit and have noticed the protection relay does take about 2-3 minutes to activate with the power on, then the amp operates normally. Once warm, if I turn the amp off then back on within 30 sec. or so, the relay operates normally within a few seconds. Sound coming from amp is crisp and clean once operational.

I'm somewhat of a novice on fault tracing, but have replaced a few caps and resistors on occasion (mostly through forum's helpful recommendations).

I'm considering two things here:

1. Removing Relay and cleaning contacts. Theres just no way to remove the cover and clean in place. Too tight on the CA10 II IMHO. SO I'll do a quick removal/clean/replace and see if that helps.

2. I can see there are TWO 470uf / 50V Caps right next to said relay that appear to be shot judging by the caramel colored goo they are surrounded with.

So I'm going to replace those 2 caps as well, BUT just wanted to know IF the failure of those two caps could be the culprit in the slow relay response as I had read "The time delay is controlled by a RC time constant in the protect circuit- Resistor-capacitor = RC--Could possibly have a electrolytic capacitor going south." Just trying to learn some cause and effect type troubleshooting on these old dogs.

Thanks in advance. Ryan
 
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Look at C584 a 47µf/16vdc electrolytic. It is part of the time delay circuit for the relay.
 
The fact that it takes longer and longer to power up would point to age related deterioration in the electrolytic caps. The contacts on the relay are not the issue, and as avionic stated the caramel goo is just the glue used to hold the caps in place during production. Even if replacing the caps in the time delay circuit solves the immediate issue, I would bet that many other caps throughout the unit are also going high esr at this stage of life.
 
I would take voltage readings around the power supply section and see if any are trending toward the low side, which would also indicate age related deterioration of the electrlytics.
 
Thank you all for the input. New cap on order and will replace along with taking some voltage readings... see what I come up with. Thanks! R
 
Happy Presidents' Day everyone! Had some time to replace the cap in question today. C584 was indeed the Lilac Matsushita. The good news is... it is no worse. But, upon first start it did take some time to fire back up. Once everything warms up the relay clicks within a few seconds of startup. Left my voltage meter at work, but this unit will probably be beyond my skill set to bring back to 100%. Its for a friend so at least I tried. Thanks for all the insight to this point. Ryan
 
Trying a different tact. The relay wont set if there is excessive dc voltage, that's what the protect circuit does.
Suggest monitor Vdc (to GND/chassis) at one of the bias test pins, repeat for the other channel, you should
see less than 100mV (depending on test pin used). Monitor voltage 5 sec after power up (there will be swings/transients
during power up, 5 sec to settle)
 
Farducci said:
Happy Presidents' Day everyone! Had some time to replace the cap in question today. C584 was indeed the Lilac Matsushita. The good news is... it is no worse. But, upon first start it did take some time to fire back up. Once everything warms up the relay clicks within a few seconds of startup. Left my voltage meter at work, but this unit will probably be beyond my skill set to bring back to 100%. Its for a friend so at least I tried. Thanks for all the insight to this point. Ryan
Click to expand...

Sorry to hear that cap didn't take care of the problem, they are very often troublesome. mbz has the next step covered for you in his above post.
 
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