Folsom's great little 7297 Chip Amp

indosmokejon · « **Reply #820 on:** 11 Jun 2017, 06:04 am »

I didn't get that far. I hope! Transformer is working properly, and I definitely didn't drill anything out. Rectifiers are definitely shot, as they are no longer one way by testing with my dmm. The 7297 chip may have been contacting the heat sink when I first fired it up? Would this fry the rectifiers? I will order new rectifiers and install and see if I get a repeat performance. I did not install insulated mounts on my last build as it does not seem that the mounts make any contact with anything else on the board? As long as I did not drill them out this would be the case, yes? Thanks for the quick reply Folsom.

Folsom · « **Reply #821 on:** 11 Jun 2017, 06:13 am »

Heatsink to chip doesnt matter.

The holez for the Antipole look drilled on the capacitor side for mounting locations.

indosmokejon · « **Reply #822 on:** 11 Jun 2017, 06:18 am »

Yeah definitely no drilling of any kind into any holes. I know that's a no-no. Well now I am thinking if I replace all the rectifiers they may just pop again as I may have some other problem? Guess I could always try and see. I checked for any type of continuity between the mounting holes and anything else on the board and I wasn't getting any readings from all four corners, so that's def not the problem.

Folsom · « **Reply #823 on:** 11 Jun 2017, 08:08 am »

Ok, well something is probably shorting out somewhere, otherwise that much current simply wouldn't be drawn. The speaker outputs are isolated from chassis, right?

This image shows the hole that looked odd to me, but I guess it's just an optical illusion.

lacro · « **Reply #824 on:** 11 Jun 2017, 01:16 pm »

How about trying a different PS to see if the Folsom board is working?

indosmokejon · « **Reply #825 on:** 11 Jun 2017, 06:23 pm »

I just hooked it up to just under 24v of battery power and everything works just fine. Good to know that I'm not completely dead in the water. I will order 4 new rectifiers and see what happens with the antipole once they are installed. Any way to check the antipole before putting 120v to it and possibly having a repeat? Could I put 12-20VAC to it and test it? Folsom, the pic you are questioning is some sort of cell phone anomoly, here's a better one.

indosmokejon · « **Reply #826 on:** 11 Jun 2017, 06:25 pm »

And obviously, thank you so much for the help!!!

Folsom · « **Reply #827 on:** 12 Jun 2017, 12:55 am »

120v? I hope not directly to the Antipole!

The Antipole is only need 16-18VAC for the amp to get what it needs.

Have you checked the output on the transformer?

indosmokejon · « **Reply #828 on:** 12 Jun 2017, 06:34 pm »

Yeah sorry. Slip of the keyboard. Antipole only sees 16V AC. My toroidal is functioning perfectly. I could try finding a transformer in my pile that steps 120 down to 5 or so and try it first? Not sure it will make a difference.

Folsom · « **Reply #829 on:** 12 Jun 2017, 11:55 pm »

No it won't. Just check for dead shorts.

indosmokejon · « **Reply #830 on:** 16 Jun 2017, 06:52 pm »

Happy to report that with new rectifiers installed all is well and working perfectly. Not sure what the original problem was? Maybe a bad rectifier in the first batch? That's kinda hard to imagine but I changed nothing on the antipole. A couple pics of my finished build with the Nabu case.

indosmokejon · « **Reply #831 on:** 16 Jun 2017, 06:55 pm »

Pics didn't load the first time.

Folsom · « **Reply #832 on:** 16 Jun 2017, 11:04 pm »

Oh good! I'm glad it wasnt so hard to solve

errcl65 · « **Reply #833 on:** 17 Jun 2017, 12:18 am »

Where does one get Folsom's amp board or kit? I would like to build it to replace an old car amp
2 x 40W. Is there is PSU which can run off the car's 12-14.2 VDC?

undertowogt1 · « **Reply #834 on:** 17 Jun 2017, 02:59 am »

Quote from: errcl65 on 17 Jun 2017, 12:18 am

Where does one get Folsom's amp board or kit? I would like to build it to replace an old car amp
2 x 40W. Is there is PSU which can run off the car's 12-14.2 VDC?

I cant find it any where as well, I am interested, itching for a project

BRN · « **Reply #835 on:** 17 Jun 2017, 03:02 am »

Quote from: indosmokejon on 16 Jun 2017, 06:55 pm

Pics didn't load the first time.

Nice looking build.

Folsom · « **Reply #836 on:** 17 Jun 2017, 03:37 am »

Im out of boards.

A PSU for a car? Depends on how much voltage you need. If 12v is enough then its some capacitors. If you need more you need a buck booster.

ebag4 · « **Reply #837 on:** 8 Jul 2017, 07:14 pm »

Just a note about the Folsom amp.

My son is moving to a house where he now has room to take the GR Research V1s so I thought I would go ahead and set him up with a few other components to get them playing rather than have them use a reciever. He and his housemates are all in their early 20s so they all use their phones as a source. To make this work I have picked up the iFi iOne for Bluetooth duty, this will run into the original iFi iTube preamp buffer which will drive the Folsom Amp.

To ensure the amp is is running correctly, I pulled it out of the closet and checked it over. Afterwards I plugged it into my big system, this is truly an excellent amp. It sounds great running my big system and as an added benefit allows me to break in speakers I just completed without burning up the tubes in my regular amp (Bottlehead Kaiju).

I may need to find another set of boards to build myself a summer amp, it sounds great and does not heat up the room like the Bottlehead.

One thing I would like to change on the amp is the transformer, I am using the recommended Hammond and it has a slight mechanical hum. What other currently available transformers have any of you used that have given quiet operation?

Best,
Ed

Folsom · « **Reply #838 on:** 8 Jul 2017, 09:50 pm »

If you don't have DC on your line Antek and others offer toroids that hum less. But hum can often be prevented too, with a little isolation work.

Folsom · « **Reply #839 on:** 10 Jul 2017, 10:54 pm »

In case anyone wants some boards, this just started.