G-22000 - protection circuit time delay problem

[w1jim]

Eight and a half years later, here’s a little update.
I found that the pre-amp out / main amp in Slide switch on the F-2096 PCB was prone to intermittent operation. Its a bespoke 3 position switch with no standard replacement.
I decided to bypass the switch with the orange jumpers in the picture which can easily be cut or removed.

I brought the G22K to our Fall “FrankenFest” this past weekend - the attendees were suitably impressed with both its Sonics and its enormity.
Research with the Sansui Database suggests that this is the first G-22000 built!
Still crazy after all these years!

 

[kevzep]

How cool is that, the old #0001 unit!!


I removed, and dismantled my CONNECTED/SEPARATED switch for proper cleaning.
Its not been a problem ever since.
I am a big believer in getting access to those silver plated contacts and removing all the black tarnish.

As for the original topic of the thread, my G22000 does this thing occasionally where there is no delay on power up from the Protection circuit, it might happen one out of 20 times, I have no idea why its doing it.

My G22 is completely rebuilt, and I am suspecting there may be a state where it shuts down where there may be some residual power stored in that timing cap so that when power is applied, it releases that protection circuit way earlier than it should.
One day I will check it out when I have time........!! At this point its not an issue for me, it doesn't cause any unwanted cracks, bangs, and or other damaging sounds......although its a bit scary when it fires up and it goes Klang!! straight on!!

 

[JOMARK911]

Kev have you recap the Protection circuit and it still does this?
If it does , there is a solution, double the soft start resistor's value to increase the time delay a bit. I don't remember where i read about this.

 

[kevzep]

Kev have you recap the Protection circuit and it still does this?

My G22 is completely rebuilt

Remember, I am a technician, I wouldn't post a description of a fault like that without rebuilding the circuit, and in this case the entire receiver. I did spend a few hours looking at it and trying various things...

Also remember, it works perfectly as it should most of the time, but occasionally it turns straight on, the protection circuit has nothing to do with the soft start circuit.

If it does , there is a solution, double the soft start resistor's value to increase the time delay a bit.

That will have absolutely no effect on how long it takes the Protection circuit to engage the protection relay.
Its done by a timing capacitor in the protection circuit.
The soft start is simply to limit the inrush current as the main capacitors charge up.

 

[w1jim]

Likely related to rotational issues due to your location in the Southern Hemisphere.
Send it to me and I’ll test it out in the northern hemisphere.

 

[kevzep]

Likely related to rotational issues due to your location in the Southern Hemisphere.
Send it to me and I’ll test it out in the northern hemisphere.

Seems reasonable......!!

 

[LBPete]

To illustrate how rare having a 0001 serial number is, we have just over 8,700 serial numbers on file. Only 14 serial numbers with 0001 in the last 4 digits. It will take a little more research to see if any of these 14 were from the first month of production. The G-22 in this thread is the first confirmed as the first built.

- Pete

 

[JOMARK911]

Wow lucky you . Having the FIRST G22K is very very extraordinaire .
Hold on to it like a precious jewel that it is.

 

[tobyj17]

Speaking of protection circuits, mine does this odd thing once in awhile where I get sound before it clicks off of protection.

 

[w1jim]

Speaking of protection circuits, mine does this odd thing once in awhile where I get sound before it clicks off of protection.

Mine had been well behaved for quite a while - then the other day it came on with no delay.
Clearly an undiscovered feature.

 

[kevzep]

Mine had been well behaved for quite a while - then the other day it came on with no delay.
Clearly an undiscovered feature.

Right!! thats it, I am going to find out why they do that!! Mine has not done it for over a week now and I have used it quite a bit.
I know one day I will walk in and flick the switch, and it will all come on with no delay!!

 

[LBPete]

It typically means the speaker relay contacts are sticking. My G-9000DB would continue to produce sound with the speaker switches off! Replacing the relays fixed it. The speaker switches on the G22 also turn the speaker relays on and off. Turn them off and see if you still get sound.

- Pete

 

[w1jim]

It typically means the speaker relay contacts are sticking. My G-9000DB would continue to produce sound with the speaker switches off! Replacing the relays fixed it. The speaker switches on the G22 also turn the speaker relays on and off. Turn them off and see if you still get sound.

- Pete

I was thinking that - but I replaced my relays during the resurrection.
Also, I don’t ever notice the sound still on (decaying) when shutting the unit off.
That being said I don’t doubt that there’s something in the circuitry that is activating the relays prematurely.

 

[petehall347]

flaky relay driver or timing capacitor .

 

[kevzep]

flaky relay driver or timing capacitor .

Nope, been there done that, its some kind of circuit instability.
I have already spent some time on this and it seems to be a common problem with G22/33000, its all pointing back to some weakness in the design.

 

[kevzep]

It typically means the speaker relay contacts are sticking. My G-9000DB would continue to produce sound with the speaker switches off! Replacing the relays fixed it. The speaker switches on the G22 also turn the speaker relays on and off. Turn them off and see if you still get sound.

- Pete

ALL new relays in my G22K, it used to do it before the new relays, and after the new relays.
I have completely rebuilt the entire protection circuit, replaced what is known to be a Flaky SCR, its not a component issue, I believe it to be something overlooked in the design.

I will be getting to the bottom of it when I can find the time.

 

[kevzep]

It would be more helpful of people would read the thread a few posts back, otherwise we keep going round in circles.
My protection circuit has had>
>New E-Caps
>New Zener diodes
>New SCR, twice, but that has nothing to do with the "no delay at power up".
>New Transistors
>New Relay driver transistors

The various protection features such as over current, thermal etc etc have nothing to do with the turn on protection delay.
This feature is determined by a E-Cap charging up which in turn, when the voltage is enough to turn on the relay driver transistor for the PROTECTION DELAY (not the speaker relays), then the Protection relay pulls in which in turn then allows the speaker relays to pull in if the speaker switches are engaged.

I will get to the bottom of it, I am an E tech, but a busy one, I will get to it and find out why when I have the time.....

 

[LBPete]

It looks like power is supplied to the speaker relay through the speaker toggle switch. The relay is grounded through the protection circuit. Monitor the voltage on the ground side during the incident. If it is low (~ 0V) during the incident it's a circuit problem. If it's high (~ 24V) during the incident, you have sticking contacts.

- Pete

 

[kevzep]

It looks like power is supplied to the speaker relay through the speaker toggle switch. The relay is grounded through the protection circuit. Monitor the voltage on the ground side during the incident. If it is low (~ 0V) during the incident it's a circuit problem. If it's high (~ 24V) during the incident, you have sticking contacts.

- Pete

Its not sticking contacts Pete.
Upon powering on, as soon as the soft start relays have engaged, instead of the protector indicator flashing for its 6-10sec, it goes straight to "everything on" with no delay and no flashing indicator, you might get a few milliseconds of protector flashing, but nothing more. Mine does the same thing occasionally, its got nothing to do with the speaker relays, its to do with the triggering of the Protection relay upon power up, its like the timing cap is charging up too quickly, or is holding a residual charge, so the voltage comes up too soon to trigger the relay driver transistor.
I have observed this by monitoring the voltage going to the protection relay driver transistor, and there is an inconsistency in how the voltage builds up to turn on the transistor.
I do not know why yet, but I will get to the bottom of it.

 

[Ronald.C]

Funny, my G-22000 usually gives this problem when the weather is wetter and colder, who knows!