Mesa Mark V Power Supplay Question

[boogiegirl]

Hello! I need help! Can someone do measure resistance ( using ordinary ohmmeter*** ) of the primary winding Mesa mark V power transformer, please ? Interesting USA (120v) and Europe (220-230v versions). These data needed to check PT condition of second-hand amplifier.

***Remove the plug mesa mark v from AC power. Connect an ohmmeter to the plug mesa mark v. Turn on POWER switch of the amplifier. Report the ohmmeter data

( sorry for mу english )

[Leo_Gnardo]

Hello! I need help! Can someone do measure resistance ( using ordinary ohmmeter*** ) of the primary winding Mesa mark V power transformer, please ?

I hope I can help, and welcome aboard! I admit I don't have a Mk V PT ready to hand so I can measure its primary resistance, but in general you would see a very low resistance on the 120V setting, certainly less than 10 ohms. Twice that on the 220-230V setting. Also take note, simply knowing the PT's primary resistance tells you almost nothing about the general health of the amp.

FWIW I just measured the PT primary resistance of an amp with similar power, it was 5.5 ohms. 120 V only, this amp has no 220V setting. Your results may, and probably will, vary.

[J M Fahey]

Yes, compare what you have with any similar amp you have available, for example a Marshall 100W or similar.

In any case, what does the back panel say?
It *must* state 120V or 220 or 240 or 100 or whatever, printed right on the panel or in the serial number plate.

Also take note, simply knowing the PT's primary resistance tells you almost nothing about the general health of the amp.

I bet boogiegirl wants to know whether she can actually plug the amp in an outlet to start testing

Just curious: what Country are you in?
How did you get that amp? ... was it bought from somebody who was using it?
Was it bought used and unchecked from USA and brought somewhere else?
It used to work but is now blowing fuses?

IF it´s blowing fuses and you suspect a shorted power transformer, first disconnect all secondary wires , ***label them properly***, and then reconnect primary to mains through a 60 to 100W incandescent/filament bulb, it should blink and almost turn off or give weak orange/red light; if it shines brghtly thebtransformer is shorted.
Search for lamp bulb limitr in this Foru or the Net.

[boogiegirl]

Thank you very much! Perhaps I formulated my question not very clear (too crazy)

Simplify :

Mesa Mark v 120v pt pr=?ohm
Mesa Mark v 220-230v pt pr=?ohm

[Leo_Gnardo]

Simplify : Mesa Mark v 120v pt pr=ohm?
Mesa Mark v 220-230v pt pr=ohm?

Of course you can always call or Email Mesa/Boogie. Where else can you get a simple direct answer? They'll be open 9AM Pacific time Monday.

[Jazz P Bass]

Whatever the 120V setting reads (5-15 ohms) the 220V setting will read double.

[Chuck H]

Ohms schmomes (sorry if that doesn't translate). What is the problem or project?

[boogiegirl]

Ohms schmomes (sorry if that doesn't translate). What is the problem or project?

God knows... Perhaps the lack of a mesa mark v, lack ohm meter, lack telephone, lack of a capable friend who has a phone and a mesa mark v, which you can easily call and say: man, luck your leaky skull!, please don't be mad that I refrain to teach you a course in basic electrical Would you be so kind as just to remove the ohmmeter out of ... yes! and connecting it to the plug on the mesa mark v ? (sorry if that doesn't translate )

[J M Fahey]

Boogiegirl , your post is so amazing that I´ll have to go over it bit by bit, because (at least to me) it does not make sense
Or probably something was lost in the translation.
Start by posting where are you from, answers depend A LOT on that. Really.

For example; if you have a dead PT, the BEST/FASTEST/CHEAPEST solution is to order a new one from the factory, period.
Now I am in Argentina, ordering one would have added at least U$250 to original cost, + 2 Months wait to get it here , mainly trying to get it out of the Customs office without paying too much bribe, so I REWOUND it .
See the pattern?
So again, tell us where are you.

God knows... Perhaps the lack of a mesa mark v,

Do you or don´t you have said Mesa Mark V?
If you have it, measure/read/post what´s been asked from you; if not, what are you asking for?

lack ohm meter,

Just curious how will you use the values we answer you .

lack telephone,

You-must-be-kidding. I don´t believe you.

lack of a capable friend who has a phone and a mesa mark v, which you can easily call and say: man, luck your leaky skull!, please don't be mad that I refrain to teach you a course in basic electrical Would you be so kind as just to remove the ohmmeter out of ... yes! and connecting it to the plug on the mesa mark v ? (sorry if that doesn't translate )

Well, maybe, supposing we are some kind of remote "capable friend" , and supposing we give you some ohms value ... what will you do with that?
You won´t be able to measure the transformer which in any case you don´t have.
And said value , even if you did, won´t mean much because we don´t know what your mains voltage is so ......

So again:
1) where are you now
2) do you have a MBMV near you or not?
3) do you have a multimeter?
4) can you use it?
5) just to save some time: what is the problem you are trying to solve?
Please answer all 5 or none at all, your choice.

[Leo_Gnardo]

Perhaps the lack of a mesa mark v

(That may be our main problem gentlemen, none of us has a Mark V ready to hand so we can measure its PT's primary resistance and help our new friend.)

boogiegirl, that's why I suggested you email Mesa/Boogie for an answer, and an end to your frustration. If you can post here you certainly can send email to Petaluma. Demanding an answer from those that don't have your answer is obviously not working. Ask the place that has the answer, simple enough, no? Good luck!

[HDSarge]

I do have a Mark V in line for repair. The120VAC primary of the power transformer has a full power tap that measures 1.9 ohms and a Variac tap that measures 1.7 ohms. Sorry no 220VAC, but this is not hard to estimate( see post#6).......readings this low are questionable even with a good meter. Hope this helps.

[Justin Thomas]

Check the resistance of the meter leads, too...
Of course, this is why we don't use Continuity to check transformers...

Justin

[Chuck H]

Indeed, as Leo suggested. Mesa has an Email, boogiegirl has a computer and IS on line... Oh, wait a minute.?. It's impossible to locate an Email address for Mesa from their site!?! Have they stopped corresponding via Email? Apparently boogiegirl already looked into this. Ergo her reference for not being able to contact Mesa by phone.

Sorry, I don't have a MKV at hand either.

[nosaj]

Indeed, as Leo suggested. Mesa has an Email, boogiegirl has a computer and IS on line... Oh, wait a minute.?. It's impossible to locate an Email address for Mesa from their site!?! Have they stopped corresponding via Email? Apparently boogiegirl already looked into this. Ergo her reference for not being able to contact Mesa by phone.

Sorry, I don't have a MKV at hand either.

But they do have an online support center
Contact Us | MESA/BoogieŽ

Nosaj

[Chuck H]

Yep. I was going to link it, but it seems clunky compared to just offering an email address. I guess the point is filtering to mitigate the amount of email support necessary. Makes sense. But it's still a turn off when you just want an answer. I get the feeling boogiegirl has already seen this and was put off.