G6000 protection problem.

[anderslober]

I just got another g6000.......I will compare the ps boards. I took a quick peek inside the new one......I can already see that the 2 big resistors in the middle are different.........they ar smaller than the unit I am working on.

Time to measure voltages.................

 

[anderslober]

Ok guys....I have the other g6k.....it works fine. I measured voltages at the 2 big resistors on the ps board. The good unit has 48vdc on one sode....and about 23vdc on the other.

The bad unit has 48vdc both sides of both resistors. The resistors are tested good, as I swapped them. What could be giving me these 48vdc where there should be about 24vdc.

Zd605 is a 1n4749a....24v zener........tested good.

 

[Hyperion]

The bad unit has 48vdc both sides of both resistors

Can you give the circuit reference (Rxxx) & board number (F-xxxx) for these resistors Anders?

 

[anderslober]

Yes ...r602 and r603. You have to look at a g7k scat. On a g6k scat there os only on e resistor, r603. The actaual unit has 2. Also the new unit.

Anyway...I have some good info. When I measure voltages on the good unit, BEFORE the relay clicks, they are the same as the bad unit. 48vdc both sides of zd605. All is good in that circuit.

I pulled the driver board from the good unit...powered up...relay click....all good. I then measured voltages on the main outputs.......on the good unit the voltages at TP are zero....on the bad unit the volatges are almost 300mv both test points. This seems high.

The bad unit has brand new mj21193/94.....are these the best subs?

I intend to take the main outputs out and power up....will this be ok?

 

[Hyperion]

The bad unit has brand new mj21193/94.....are these the best subs?

Yes they are.

I intend to take the main outputs out and power up....will this be ok?

Yes, that's ok.

 

[Hyperion]

48vdc both sides of zd605. All is good in that circuit.

Well, 48V on BOTH sides of the zener (and by implication the relay coil) means that TR609 isn't turning on, OR you have a lost ground from the emitter of TR609 to the negative of C609 (47µF 63V).

If the relay isn't firing, try temporarily shorting the collector of TR609 to ground - this should fire the relay, in that case you need to check TR609 and examine the circuitry around TR610 & TR611.

 

[anderslober]

John...awesome...I will do as you say.

I did take the main outpouts out...and powered on......still no relay.

Funny problem this...........

When I compare with the new unit......all volatges are basicallt the same.....until the relay clicks on the new unit....then the relay volatges change.......

The bad units main power supply tr`s all test fine and give the correct volatges.......

 

[anderslober]

John......c609 is 10/63.....and the emitter og tr609 goes to the positive of c609..........

 

[anderslober]

Could I have reversed a cap?..?.+.?.

 

[anderslober]

I was looking at the g6k scat....c609 has positive to ground......on the g7k scat c609 it is reversed(correct).

 

[Hyperion]

Could I have reversed a cap?..?.+.?.

Yes, negative should go to ground - I notice C609 is wrong (reversed) on the G-6000 schematic but correct on the G-7000 schematic. Hopefully it should be correctly orientated on the PCB itself?

So the emitter of TR609 should go to ground AND the negative of C609.

 

[anderslober]

Yes...all is checked......with continuity meter......cap orientation is correct.

Tr609 is a new ksc2960a.....is ksc2383 better suited?

Nothing is burning or frying........circuit is otherwise stable....

I will try to short tr609 emitter to ground......

 

[Hyperion]

I will try to short tr609 emitter to ground......

Collector - not emitter - the emitter should already be grounded.

This will mimic TR609 turning on - and you should hear the relay activate/fire.

ksc2960a is fine, you won't gain anything by changing it for another type.

 

[anderslober]

Ok...gotcha!.....collector ground .....I reread your post.....

If this works and the relay clicks......then what?....

 

[Hyperion]

If this works and the relay clicks......then what?....

Re-read the second para of post #46

 

[anderslober]

Collector to ground......relay clicked..........

Is this a grounding problem then.??

 

[anderslober]

I did replace tr610/611 with ksc1845`s. Originals were 2sc1400`s. The ksc1845...is it an adequate replacement in this circuit?
I will check all zeners and diodes. 1s1588 replaced with 1n4148.
Zd605/605 replaced as appropriate..... eqa01-24 replaced with 1n4749a........and rd6.2e replacedwith 6.2v zener.

 

[anderslober]

Darnnnnn....I am conundrummed. On the cathode of zener zd606, I have `only` 3.9v. On the good unit this voltage is 6.8v...as it should be I guess.

Something dragging down the voltage?

 

[anderslober]

YYYYYYYAAAAAAHHHHOOOOOO......... .!!,!! I changed the SCR back to the original.......and the friggin relay clicked!!,!
I had put in a new 2n5064.......apparently this was not a good idea........or it was defective.

ON WE GO!

 

[Hyperion]

ON WE GO!

Nice - well done! - sometimes its not such a good idea changing everything in sight, especially in the 'non-audio' sections.