If you want to test it Cold, put the Dvm on Ohms , with the unit unplugged from the mains, and measure points A+ A- , with the on switch turned on, you should see 100 Ohms or less, an open circuit can mean a break in the primary side .

 

I have not read all of your test procedures thoroughly but it appears that you do need some assistance.

1) While having a circuit schematic is very useful, when none is available you have to learn to work without one.

2) As I mentioned before, I would not wait for the unit to be working in order to localize the fault. You want to find the fault while it is not working. Granted, you may be inexperienced at trouble shooting electronics and would prefer to have a baseline to compare. Sometimes this is desirable but I believe it is not necessary in this case.

3) Your assumption in test (B) is not correct. You will not expect to see 120V across the fuse.

With that last observation alone, I would suggest that you STOP right there and proceed no further. Wait for someone with the appropriate knowledge and experience to guide you through with LIVE power testing.

Without proper care you will either kill the unit or kill yourself which would be both unfortunate. If we don't hear back from you we will assume the latter and may you R.I.P.

Thank you. I am not doing anything until a plan is vetted. I am sorry about B). I wasnt thinking. V = IR, so there shouldnt be 120 across the fuse, if I am remebering correctly. Rest assured, I am not doing anything on the AC side unless I have a definitive plan as dont want to kill unit or me. I have popped enough ICs on circuit boards to know what can happen and enough house rewiring (to code) to know that AC feels like a jackhammer. I will be careful. Thank you.

 

If you want to test it Cold, put the Dvm on Ohms , with the unit unplugged from the mains, and measure points A+ A- , with the on switch turned on, you should see 100 Ohms or less, an open circuit can mean a break in the primary side .

I have attached a picture of my DVM settings and the readout after I unplugged the unit, set at 200 ohms, and put probes across A+ and A-.

 

Ok put the meter on Diode beep, and test across the brown wires with the switch turned on, .
Then test on Diode between the terminals E1, E2, E3, .
Test on Diode from A +/- to B+/-.

 

For starters, set your DMM to 200Ω range just as in post #23.
Unplug the AC plug from you wall outlet and measure resistance across the prongs of the AC plug,
With the POWER switch set to OFF you should show the same as post #23.
With the POWER switch set to ON you should read lower than 10Ω.

(Show us a photograph of what your AC plug looks like. Yours may be different from the photo below.)

 

Ok put the meter on Diode beep, and test across the brown wires with the switch turned on, .
Then test on Diode between the terminals E1, E2, E3, .
Test on Diode from A +/- to B+/-.

Okay...I found it...the attached picture shows the terminals for the AC power terminals on the board from the wall service. During probe testing, I must have moved it just right and it uncoupled completely physically...now a loose tooth. If I pinch physically together, it comes up...if I let the pressure go...it powers down...Now I don't know if this is the actual problem or a coincidence as I wiggled those particular wires to test such a thing before and it didn't affect the power on state. But, it could have been decoupled enough electrically then by my physically touching it, it physically debonded and surfaced its problem. Anyway, I am going to sign off for now and heat up the soldering iron cuz I have to fix this anyhow. Let's hope that's the problem.

Thank You.

 

For starters, set your DMM to 200Ω range just as in post #23.
Unplug the AC plug from you wall outlet and measure resistance across the prongs of the AC plug,
With the POWER switch set to OFF you should show the same as post #23.
With the POWER switch set to ON you should read lower than 10Ω.

(Show us a photograph of what your AC plug looks like. Yours may be different from the photo below.)

View attachment 202094

Let me do the resoldering and see if I need to perform this. Thank you.

 

If there was a bad solder connection at the BLACK and WHITE input terminals it should have been obvious with proper visual inspection.

Thorough visual inspection is one of the first steps in expert technical repair.

 

If there was a bad solder connection at the BLACK and WHITE input terminals it should have be obvious with proper visual inspection.

Thorough visual inspection is one of the first steps in expert technical repair.

Mr Chips and All,

Thank you for helping me out. It is up and running now. Let's see if the original problem surfaces again.

Mr. Chips, I will take the blame for not initially physically removing the board and inspecting. I so agree with you. In fact, that is actually how I troubleshot my microwave. The AC power to the microwave board when I took it apart the first thing I noticed was the dull blackish terminal soldered joint...resoldered to fix. The only reason why I did not what to take the power circuit board out this time is I did not want to paint myself in a corner if I placed it permanently into a never comes up mode, because I did not know if I needed to pull voltages etc. with it being in operational mode or not (without a schematic). I have done those things before and wanted to error on the side of caution. That one is on me, but I hope you understand.

I like your guys forum. You all seem to really enjoy this.

I will be back to this thread if my original problem as described pops up again, meaning that those resoldered joints were not the problem.

I run into things like this around the house from time to time as a DIY guy, and I will remember you guys.

Thank You

 

Glad you enjoy the site.
As I said, it would have been best to do all testing while it was DEAD.

We would have been able to trace all the AC supply lines and see if there was a discontinuity. We might have been able to narrow it down to the exact joint.

Now all we can do is wait and see.

btw, when I was a boy I wanted to become a radio repairman. We didn't have TV then. I became a nuclear engineer since then. Same difference.

 

Glad you enjoy the site.
As I said, it would have been best to do all testing while it was DEAD.

We would have been able to trace all the AC supply lines and see if there was a discontinuity. We might have been able to narrow it down to the exact joint.

Now all we can do is wait and see.

btw, when I was a boy I wanted to become a radio repairman. We didn't have TV then. I became a nuclear engineer since then. Same difference.

Wow...my dad when he was a boy at 16 in 19 40s repaired radios and TV and was a HAM and was radio operator in Navy on destroywr in Korea then moved on to AT&T CWA union retired and has since passed. Learned a lot from him. I am Civil Engineer but have had software development companies during 80s and 90s one with patent hibernation. I go back and forth but I love HW and SW development, unfotunately career is CE. Looking to retire soon so I may go SW to supplement.

Thank You again...

 

Forgot to add,
besides being a HAM, I play guitar and bass. I have a Fender Telecaster, Jazz Bass, Fender Super Champ XD, Rumble 100.
I just retired recently after a very satisfying career in HW, SW, nuclear physics.

 

Forgot to add,
besides being a HAM, I play guitar and bass. I have a Fender Telecaster, Jazz Bass, Fender Super Champ XD, Rumble 100.
I just retired recently after a very satisfying career in HW, SW, nuclear physics.

Nice! We share some things in common. I have been doing a preretirement project to take me into retirement...covering Pink Floyd, LZ, Rush. I have been working on DSOTM and have completed Time and Breathe. I cant sing but I did anyway. Love to share but dont know how to share mp3s to you other than email. I do not do much on Internet or social media at all and try to stay away from doing that. I also build projects around RPi Arduino ASM CPP Python...mostly IoT type boxes. What type of music do you do?

 

WOW!
Impressive playroom you have there. I must have counted at least ten guitars, one bass, and a mandolin.
A play with older folks for older audience so we do a lot of 60s-80s music, Beatles, Eagles, Van Morrison, Neil Diamond, CCR, Cold Play, The Tragically Hip, Rock 'n Roll. Our repertoire varies depends on who we get on vocals. I like to sing but been told not to. (I get the message.)

 

WOW!
Impressive playroom you have there. I must have counted at least ten guitars, one bass, and a mandolin.
A play with older folks for older audience so we do a lot of 60s-80s music, Beatles, Eagles, Van Morrison, Neil Diamond, CCR, Cold Play, The Tragically Hip, Rock 'n Roll. Our repertoire varies depends on who we get on vocals. I like to sing but been told not to. (I get the message.)

Nice playlist. I like bands like yours. I would love to hear some of your mp3s. I am a homebody and dont do well playing in front of people. I like puzzles, so breaking out all the parts of songs, tones etc then building them track by track is very enjoyable. I do the synths, bass, electric and acoustic guitars, 12 string, slide guitar, and all synths VSTis. Not drums as I use tracks for those. My favorite guitar is my Fender Strat MIM Gilmour build with heavy string set. David is a master imho.