voltages are NOT right help

[najo49]

On the left side c4s I have the lover  leds glowing top 2 dimmmer other voltages
lA 220.9 V
OB 218 V
BA  0
OA 132 v
Kreg 5.7
On the right c4s bottom leds on top 2 come on and off at start up
1A 220.9
OA 218v
Breg 182
OB 181 The top 2 leds come to life on and off when taking this measurement..... Kreg is  4.9

 

[Paul Birkeland]

220V at IA/IB is a bad sign.

Did you test the power supply Pc board?

You have two different voltages listed for OA...

 

[najo49]

Paul thanks for the reply yes i tested the power supplya per the manual. I will go get the voltages again. First the top 2 leds on the left c4s are not glowing all others are.
Kreg 5.25/b reg 215/Ob  218/ba 0/ OA  117/1A 220v That the left one top two led not working
Kreg 4.93/Breg 184v/OB 218v/ba 0/IA 225v/OA 218v  all leds are lit on this the right c4s as you look from front. top 2 led are dimmmer. Could you give me a starting point for trouble shooting I have checked the location of the Resistrs and the caps and solid state stuff. Jann Olsen

 

[Paul Birkeland]

Now you have two different voltages listed for OB...

Can you try writing these in a vertical list?

The same voltage between I/O (input output) terminals can mean a short, but for some reason you're sucking so much current through the power supply that your input voltage is 50V down.

This would also suggest a short.  Can you check the +275 pad on the power supply PCB to verify this reading?

 

[najo49]

Paul doing more checking neither of the A or B tube filiment are on so that is paramount. will check back when thats fixed.

 

[Paul Birkeland]

They are difficult to see, if the 6922 glows, then the EF86's are more than likely OK.  Even if they are out of the circuit, the regulated power supply should be working.  I would recommend starting there.

 

[najo49]

paul, I am getting at the power supply 4.9v for the positivve, and a few m/a on the black for the filiment supply as you say when I checked the power supply I was getting 6.3 v but you should know that I blew the 10uf tantalum on the power supply do you think this did more damage that just the tantalums

 

[Paul Birkeland]

You may have damaged a diode, or another component on the power supply board.  You can heat up the joint on the + pad and slip the red wire out, then remeasure the DC supply.  The 6.3V supply is generally an all or nothing component - either the supply is shorted out and producing no voltage, or it's right up at 6.3V.

You can also measure the output of the FWB, which is the silver end of either 1N5820 closest to the +6.3V pad.  You should see a good margin more than 6.3V (I don't remember what it was last time I measured one, but you may find your 4.9V there).

-PB

(PS - with no tubes heating, your IA/OA/IB/OB should all be ~275V)

 

[najo49]

paul, going to the power supply I get 370 v dc as per the power supply test. but the plus pad of the 6.3 v i get 12 .1 v DC.What do you think. something got damaged when the tantalum went out .on the lead closest to tje 6/3 pad I get 9.75 volts and 12 volt at the 6.3 pad. J

 

[Paul Birkeland]

paul, going to the power supply I get 370 v dc as per the power supply test. but the plus pad of the 6.3 v i get 12 .1 v DC.What do you think. something got damaged when the tantalum went out .on the lead closest to tje 6/3 pad I get 9.75 volts and 12 volt at the 6.3 pad. J

So you have 370V on the power supply PC board, but 225 at IA/IB (these are supposed to be wired together, making that very unlikely)?

9.75V is a good place to be on the diode bridge.  Getting 12V at the +6.3V pad is very unlikely, can you double check that? 

-PB

 

[Grainger49]

Paul is saying either you didn't check both points at the same time or that the wire isn't functioning as a wire.

 

[Paul Birkeland]

Jan - it will help to stick to the back power supply C4S board for now.  You can run the Eros with just a 12BH7 plugged in, and no other tubes.  These voltages need to be stabilized before it makes sense to continue with other troubleshooting.

For terminology - the rear PC board is the power supply shunt reg PC board.

The left and right PC boards up front are the C4S boards for the amplifier, on the A side and B side. 

Calling them out in this manner will help us narrow down which voltages you're referring to.

-PB

 

[najo49]

Thanks paul and grainger. I did some good trouble shooting this afternoon. Here is how things are now. All LEDs are lit on all boards glowing brightly.. All voltages on all boards are good except two. The kreg on both c4s boards is low about 300mV. and the filiment is low at about 5.3 volts. since this is regulated I do not see how I could be getting a lower voltage at all. I am running it thru a varic so I match your manual voltage at 117. Anxious to hear what you think. J

 

[Paul Birkeland]

and the filiment is low at about 5.3 volts. since this is regulated I do not see how I could be getting a lower voltage at all.

Did both the 10uf's pop?  Did you replace the 1085 regulator?

 

[najo49]

Paul, I am not sure what the z5us are. And i did not replace the 1050 regulater . But I did get the kreg in one channel to measure 1.1 volts. and I hooked it up and one channel works great. The other has a faint signal.I am making progress! But the kreg in the other channel I have traced back to and cant find the problem. Your thoughts would be appreciated. Jann O

 

[Grainger49]

Jann,

The Z5Us are the mustard yellow caps on the center tube socket.  At least I remember them being on the center socket.  Looking you will see what I am talking about.  There are a lot of wires and component leads where they are. 

 

[Paul Birkeland]

Jan,

You're kinda all over the road. Without 6.3 on the heater supply, I wouldn't hook the amp up to your system. 1 1V at kreg tells me that the regulator isn't working.

I have made suggestions and asked questions, when you're ready to answer those, I'll be here to help.

-PB

 

[najo49]

Paul, I have not done anything to the caps that go to ground on the center tube, but I will call eileen this morning and order at set of them there are 3. But please be understand that they were not blown, just the 10uf tantalums in the power supply.I will also order a 1050 at the same time then replace all the above. sound good to you?

 

[Paul Birkeland]

A replacement 1085 would be the next step, provided you are still getting a low voltage at the output of the regulator, but through your posts, you have called out that voltage as both being low (~4V) and high (~12V), so without being confident about which of those voltage is correct, is very difficult to properly advise you.

-PB

 

[najo49]

paul,thank you for your reply. After checking things this am,this is how things stand. i swapped the tubes and found the low kreg follows one of the ef 86 tube. put it in the right side and everything measures fine. put it in the left side  is fine.The other tube is bad in both sockets The kreg is 1v which is right on.so I ordered a new tube. The filiment voltage is 5.3 volt at the power supply now. it is only a1volt low so do you think that it is the regulator,any way I ordered a new 1085 regulator.