MiniTiouner Kit MTK1 Instructions.

G4EWJ · Post by **G4EWJ** » Wed Mar 01, 2017 1:08 pm

Is that 9.5v at the north-east pad of PSU1? This should be about 0.7v less than your external psu voltage. What is that voltage and is it what you expect? It can be measured on the top of L5.

If the north-west pad of PSU1 is less than 1v, there must be a problem with PSU1 or a short circuit somewhere. I assume that you haven't fitted LK1 yet. Don't do that until you're getting 5.4-5.6v at the north-west pad of PSU1.

Brian

cashy666 · Post by **cashy666** » Wed Mar 01, 2017 6:03 pm

Hi Brian,
Thanks for your response..
The north east pad is showing 0.7v below (12v) psu , but north west is just under 1v. No not installed LK1 yet. Is there any other test point on psu1 I can check? or would you recommend changing it as I cannot see any shorts!

regards

Dave

G4EWJ · Post by **G4EWJ** » Wed Mar 01, 2017 6:19 pm

With LK1 not fitted, there's nothing connected to the output (NW pad) of PSU1.

Remove the power and look for a short at the output of PSU1. Are you sure that you made the mod to PSU1 correctly, where you take off the pot and replace it with 62k in parallel with 220k?

Brian

G0EID · Post by **G0EID** » Wed Mar 01, 2017 7:15 pm

Hi Dave,
It's worth checking for dry joints on the PSU1.
I had one where some joints around the 8 pin chip were mostly flux.
73
Dave - G0EID

cashy666 · Post by **cashy666** » Thu Mar 02, 2017 10:28 pm

Hi Brian, Dave

thank you for your help....Ive come to the conclusion (with your advise) that PSU1 is faulty.

Ive ordered a new one, should be arriving next week...so fingers crossed.

hopefully be up and running by the end of the week.

thanks again guys!!!!!!!!!!!!!!!!!!!!!!!

regards

Dave
G7MEG

G4EWJ · Post by **G4EWJ** » Fri Mar 03, 2017 1:48 am

If you feel inclined, drop it in the post to me and I'll have a look at it. I'm QTHR.

Brian

cashy666 · Post by **cashy666** » Fri Mar 03, 2017 9:08 am

Hi Brian,

thank you so much for the offer, if you don't mind I would like to bank it for future use. I will see what the new PSU does.

regards
Dave

cashy666 · Post by **cashy666** » Fri Mar 03, 2017 4:22 pm

Hi Brian, Dave,

just an update...

PSU1 is faulty, it just lit up!!!! hopefully didn't do any other damage.

regards

Dave

G4EWJ · Post by **G4EWJ** » Fri Mar 03, 2017 8:31 pm

Whoops!

Check that D2 is still a diode and there are no shorts to ground from it. If LK1 wasn't connected, there won't be any damage downstream.

Brian

cashy666 · Post by **cashy666** » Sat Mar 04, 2017 10:13 pm

Hi Brian,

I would like to take up your offer to look at my minituner. New PSU1 arrived today and still not getting 5.4v...

Ive had my iron on it far to many times...

regards

Dave

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MiniTiouner Kit MTK1 Instructions.

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