Still no break-up. 2x 5F1's.

[Enzo]

I just want a normal 5F1 & I dont think 9/10 5F1 builders will have or need to consider buying an oscilloscope to get their simple amp working as it should.

Yes, you are correct, 9/10 5F1 builders will not need a scope. I am sure I could service one without a scope, but I also have a lot of experience in doing so. Buy a scope is a powerful tool, and would probably help spot a tricky problem. You don't need a scope because it is a 5F1, you need a scope to find out why we can;t see the problem with your unit

I am convinced you are missing something. I think you have made an internal assumption about the amp, and you cannot see past it at the moment. This can happen to anyone, experienced or not. But if you look at something long enough it becomes familiar, and some circuit anomaly disappears to your eyes. Once you find what is wrong, you will be able to see why you missed it.

"Oh, I checked that" is a killer. For example, a guy checks his resistors and finds the 1.5k and 100k he expects, OK those are OK. The guy moves on, checks his grid stoppers and tone circuits, all OK. Finds no issue. Starts over tomorrow, and says to himself. "OK< I know those resistors are OK, I tested them yesterday," and he moves on down the circuit. And right there, any mistake he made the previous day is sealed into history, because he "knew" those resistors were OK. A friend comes over and suggests checking those resistors, and the guy says "Oh those are OK I checked them yesterday." Now I do not know what you have here, but I tend to think something you "know" is OK probably is not. THat makes the problem all the more mysterious. Until we find the answer.

[Jazz P Bass]

How about if we 'start' with the Vac voltage that your guitar is capable of outputing.

Hook your volt meter (set to read Vac) up to the guitar signal cable that would normally be inserted into the amplifier input jack.

Turn the volume & tone controls full on, select the neck pickup & bang away on an E chord.
What is the Vac reading?

Do the same test but select the bridge pickup.
What is the Vac reading?

[Chuck H]

How about if we 'start' with the Vac voltage that your guitar is capable of outputing.

Hook your volt meter (set to read Vac) up to the guitar signal cable that would normally be inserted into the amplifier input jack.

Turn the volume & tone controls full on, select the neck pickup & bang away on an E chord.
What is the Vac reading?

Do the same test but select the bridge pickup.
What is the Vac reading?

Sea Chief is "110%" certain that there is nothing wrong with the guitars. Though he could only site perception as his reasons, not measurements. I asked him to check twice and he refused both times.

Enzo is likely right in his last post and there is no way for us to do any testing for ourselves. It's possible the problems we are trying to solve for have nothing to do with amps or guitars.

[Jazz P Bass]

Personally, I am growing weary of this post.

Seeing that we have a Vac 6V6 grid measurement from another poster, I wanted to start at the beginning.

Having the guitar signal as a reference we can go from there.

I am not after 'checking the guitar', as I feel that what is needed is some solid data points.

Up until now (post #124!!) this post has been an excercise in dancing with fairies.

[Sea Chief]

Sea Chief is "110%" certain that there is nothing wrong with the guitars. Though he could only site perception as his reasons, not measurements. I asked him to check twice and he refused both times.

Argh ! I am 1000% certain the guitars are fine. I know this because I have 2 other amps. They sound as they should thorough these. I have had a total of 3 other amps in the past few years. They sound as they should through these too. In all of the 30 years Ive had guitars, not once has one not been correct. Gtr 1 is a 5 year old gibson sg, I am the 2nd user. It sounds exactly as it should. Gtr 2 is wired exactly as instructions dictated (by me/ correctly) and sounds exactly as it should.

Can everyone- please- stop going on about the gtrs. If you cant help me, then you cant help me but please dont make spurious assumptions about such basic stuff as "have you got the vol up?" or "are you sure gtrs are not defective". It is driving me insane tbh.

The guitar (s/ plural) are not defective. This is the last time I will say it/ I will not address anything re the gtrs.

[Sea Chief]

How about if we 'start' with the Vac voltage that your guitar is capable of outputing.

Hook your volt meter (set to read Vac) up to the guitar signal cable that would normally be inserted into the amplifier input jack.

Turn the volume & tone controls full on, select the neck pickup & bang away on an E chord.
What is the Vac reading?

Do the same test but select the bridge pickup.
What is the Vac reading?

Ok I have somewhere to go. Thanks JazzP. The VAC reading is 0.1. This doesnt change between pickups or whether banging a chord or strings not touched.

Im not sure what this is all about at all. Does my MM not go low enough to read? isnt a gtr output in millivolts? (MM has 2 settings 750 and 200 only).

[Sea Chief]

Can someone close this thread? As JazzP suggested in another thread, it makes sense to simply start another if nothing is happening on here after #125. It would clear my head as well.

Thanks, Sea Chief.

[g1]

No, you can't just close the thread and start another. There is pertinent info here and it needs to be followed to it's conclusion.
Was your meter on the 200VAC range? It doesn't seem to have enough resolution to measure low voltages.
You are measuring from tip to shell at the other end of the guitar cord?

Edit: I think when JazzP said "start at the beginning", he meant at the input, not ditch this thread and go through it all again.

[Jazz P Bass]

And now, ladies and gentlemen, we find out that we have measurement equipment issues.

[Sea Chief]

No, you can't just close the thread and start another. There is pertinent info here and it needs to be followed to it's conclusion.
Was your meter on the 200VAC range? It doesn't seem to have enough resolution to measure low voltages.
You are measuring from tip to shell at the other end of the guitar cord?

Hi g-one. I was just gonna start new saying "Got no break-up/ why please. My V reading are * * and *. Thanks" surely that simplifies things? I cant be done with this insistance by folks that both my gtrs are bad/ Im just not getting anywhere.

Yes it was in the 200 Vac range. Yes I am measuring across the tip and shield/ shell(?) of guitar plug. No it doesnt have resolution low enough then. I think I should be looking at * mV should I not? I have mA but not mV on the MM.

[g1]

isnt a gtr output in millivolts?

It should be hundreds of millivolts, probably around .5VAC. The meter should be able to detect some change between no signal and a heavy power chord.
The first thing we would normally do here is try another guitar cord.

[Sea Chief]

And now, ladies and gentlemen, we find out that we have measurement equipment issues.

How patronising.

[Sea Chief]

It should be hundreds of millivolts, probably around .5VAC. The meter should be able to detect some change between no signal and a heavy power chord.
The first thing we would normally do here is try another guitar cord.

2 cords test same. Both gtrs test same. MM reads 0.1 VAC whether no signal or whacking strings, every pickup selected.

[g1]

Can you beg, borrow or steal another MM?
Meanwhile, with your current MM, measure VAC at 6V6 pin 5 (with black probe grounded to chassis). Plug the guitar in and hit a power chord. What does the meter read?

[Dave H]

A DMM like that with only 750V and 200V AC ranges probably doesn't compensate for the diode ie. it can't measure AC voltages with a peak of less than a diode Vf. It won't be AC coupled either so it can't measure AC riding on a DC voltage. It's cathode biased so pin 5 of the 6V6 should be OK (no VDC).