American Bass 1100.1

[Deadly Sones]

I'm not sure where you mean by "Why isn't the vertical amp set to 'cal"

Here are the current settings.

 

[Perry Babin]

You had the vertical amp off of cal previously. It's on cal now.

Did you check the probe calibration?

You need to remember to state 1/10x when displaying waveforms.

When you go back to waveforms, only post 1 so we can get everything as it should be.

 

[Deadly Sones]

It seems to be reading 12v source close. 5v/d it deflects 2.5 divisions. So I might be a little high. How do a adjust it a bit lower?

 

[Perry Babin]

That's not probe calibration. The loop on the bottom of the scope is to calibrate the probe to the scope.

Go to item #26 on the Generic Repair Techniques page (GRT in quick links at top of directory).

 

[Deadly Sones]

This is what I get with the settings displayed

 

[Perry Babin]

Did you have to adjust the probe?

 

[Deadly Sones]

I did not touch anything yet. Just switched it to AC coupling so could see wave better, and the time/div and volt/div to try and match yours in the pic.

 

[Perry Babin]

It's OK.

Do you have another probe to see if it gives a better signal when probing the amp?

 

[Deadly Sones]

No sir. I want to buy a pair... but always been leary of getting wrong ones. Do you have a preference that won't break my bank I can buy a pair of? This one came with the scope when I bought it used 7 years ago

 

[Perry Babin]

Most people (myself included) use the $5 a piece probes. You can buy 4 for $20.

 

[Deadly Sones]

lmao.. that's sort of what scared me... too cheap to be true, lol

So, something like these would be fine?

RioRand 100 MHz Oscilloscope Clip Probes with Accessory Kit (Pack of 2): Amazon.ca: Gateway

Then I just need to adjust them to the scope via the trim pot in the probe?

 

[Perry Babin]

Yes but most people buy from ebay. The brand isn't important. They're all the same. Buy the cheapest ones you can find from a seller with good feedback.

Yes on the calibration.

 

[Deadly Sones]

OK.... I'll order in a pair. Should be here next week.

Any ideas on this amp issue. At least it's not kicking in and out of protect until it pops now. With high power it shorted all 4 banks low side fets. also damaged one of the ICs, but I replaced them all again. On low power I get what I showed you on the fets.

 

[Perry Babin]

Can you order a longer piece of wire so you can incrementally increase the voltage? I would think that would be easier than replacing all of those parts.

 

[Deadly Sones]

I brought home more wire last night. I can do more wraps now.

 

[Deadly Sones]

right now I'm making +/- 18.75v

 

[Perry Babin]

Each time you go up, try all of the mechanical tests on the boards and inductors.

Look at the drive signals to see if anything changes. MAke sure that the drive to the FETs never goes above 20v (with reference to the source leg -- don't ground your scope to the negative rail).

You may want to read up on using your scope in differential mode. Tech Tips 8, item #8.

 

[Deadly Sones]

Ok thanks.

 

[Deadly Sones]

New probes are ordered. I'll come back to this one once they come in, so can do the whole differential thing.

 

[Perry Babin]

Have you seen any pattern in the failure of the components as in one IC or driver failing repeatedly?