So, here I go. Phase Linear 400

[VSAT88]

Looks like I did not install C3, C8 or C9.

 

[VSAT88]

As I recall yes, it did flash over and over with the relay clicking the whole time however I cannot be 100% on this without checking it out again. Accept for the fact that C3, C8 and C9 were not installed....

 

[laatsch55]

Ok, I would suggest the next step to be to unhook all wires from the DC protect board, tape up the bare ends of all wires so as not to short anything out and bring it up again.....

Mouser had the IC for that board or did it come with it?

 

[VSAT88]

Just ran out to the shop. All fuses are intact. The IC was sent to me with the board from Mr. Don.

 

[laatsch55]

Good night Sir, gotta go....

 

[VSAT88]

OK. I will do just that and check back in as soon as I do. I think I am beginning to finally understand what is going on. I appreciate your help.

 

[laatsch55]

I don't think the DC protect board is the problem, we just need to eliminate it's influence...

 

[VSAT88]

Ok, I would suggest the next step to be to unhook all wires from the DC protect board, tape up the bare ends of all wires so as not to short anything out and bring it up again.....

Did just that a few minutes ago. Took all the wires from the protection circuit loose, taped them up, brought it back up on the veriac using the DBT inline. No problems that I see. Went to 115 V or so and no smoke. The DBT flashed just a tiny bit as I brought it up, dim then bright then dim again as the filters charged. Left it at voltage for about 30 seconds. Stopped there for further instructions. Had to make time tonight late to get in the shop and have to get up early tomorrow for an appointment then I will be back in the shop right after so let me know what you would have me do next when you have time. Thanks ! Jim.

 

[laatsch55]

Measure DC offset and Bias......to see if things look normal...

 

[Northwinds]

Welcome Jim, hopefully soon you will be enjoying your amp!!

 

[VSAT88]

Welcome Jim, hopefully soon you will be enjoying your amp!!

Thanks, however I think I got a while to go !

 

[VSAT88]

Measure DC offset and Bias......to see if things look normal...

Oh no, things do not look normal. On the DBT last night I noticed that the 100W bulb never completely dimmed. I have had amps do this before (B&K) without issue. Anyway, I went to check bias today and what I found was not so great. At 45-50 VAC (without the DBT, just the veriac) the left channel bias went well above .35 DC. It went to .100 without a problem. The more I turned the veriac up the larger the number. On the right side I get no bias at all. Another big time issue...When I hit 50 VAC on the veriac the left front panel meter pegs all the way out. Cant recall DC offset but do not think it matters too much considering the problems I have now. Thanks, Jim.

 

[laatsch55]

Yes , it does matter, we need to know if the offset is in the millivolt or volt range...

 

[laatsch55]

And it's OK to use the DBT, when you are dealing with a current problem, it's nice to have a current limiter in circuit...

 

[VSAT88]

OK, still without the DBT, just the veriac. ( from now on I will use DBT untill I am told differently). At around 50 VAC the right channel DC offset is .008 The left channel DC offset is .002 At the same AC voltage of 50 VAC the left meter starts pegging intermittently just like the relay/DBT bulb did when I was testing with the relay board/protection in circuit.

 

[laatsch55]

Could you take a pic of the driver board and post it. Close enough so we can see the component orientation...

 

[VSAT88]

Sure. I also sent a shot of the row (at the bottom) of 150 Ohm resistors that I replaced near/on the drivers. That is the only component I replaced in that area . All the rest was on the driver board. I took the driver board out when doing the re cap so all of the wires were de soldered and soldered back.

 

[laatsch55]

In the middle of pic #3, there is a green mylar cap just south of the 40327 TO-39 transistor, is it burnt?

 

[VSAT88]

In the middle of pic #3, there is a green mylar cap just south of the 40327 TO-39 transistor, is it burnt?

No Sir, just checked it against the other one on the other side.

 

[laatsch55]

Before going further, you should clean the solder flux off the backside of the board. A small chemical brush, or small paint brush and some isopropyl alcohol, and if that won't do it, try some acetone. Keep the board at a pretty good angle so it runs off, but it might take a little scrubbing too...