Silvertone 1484 Weird Issue

[dorrisant]

I measured 5.6vac at the first node. It does not change no matter if there is signal on it or not. Also, volume makes no difference to the ac ripple.

I have never had this much trouble from a 1484 or ANY other amp. I am beginning to hate this POS.

[sluckey]

Have you replaced C26, C27, C28, and C29? If not, do so.

[martin manning]

Microphonic tube?

[dorrisant]

Have you replaced C26, C27, C28, and C29? If not, do so.

Already did that.

Microphonic tube?

I've tried 3 different sets of known good tubes.

Seriously, if it were mine, I'd stop right now and part it out. I have another one on the shelf. I just ordered all of the caps for a re-cap. If that one works, I'll give it to the customer and part this turd out.

[Stevem]

Are you sure you are reading FIVE point SIX volts?

If so the amp should have a massive overwhelming hum to it!

Normal ripple voltage at the plate resistor on V1 should be well less then 1/4 ( .250 ) vac.

Also as I look thru your photos here for the first time, I can’t make out if the positive end of one of the bias filters is going to ground?
The one to the right of the bias trim pot.

[sluckey]

I measured 5.6vac at the first node. It does not change no matter if there is signal on it or not. Also, volume makes no difference to the ac ripple.

Are you sure you are reading FIVE point SIX volts?
Normal ripple voltage at the plate resistor on V1 should be well less then 1/4 ( .250 ) vac.

He ain't talking about the plate resistor of V1! He's talking about NODE 1. That's the node that feeds the OT and it's very common to read several volts ripple, even up to about 10V at that point.

[Stevem]

Well I asked specifically for him to test the supply at the first preamp node if you go back and look at my post.

I guess we need to wait for his reply.

[sluckey]

Well I asked specifically for him to test the supply at the first preamp node if you go back and look at my post.

I guess we need to wait for his reply.

Looks like you were the only one that was not confused.

[dorrisant]

Well I asked specifically for him to test the supply at the first preamp node if you go back and look at my post.

I guess we need to wait for his reply.

Sorry Steve... That was the measurement at the B+1 node. I'm busy again today but I will get that measurement tomorrow or as soon as I can.

[Stevem]

No rush, just real darn curious about what’s taking place .

[Stevem]

How’s it going with this?

[dorrisant]

Haven't had the time to put it on the bench... Very hectic at the moment.