zenith mlt 15 console record player problem - diyAudio
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Old 3rd July 2008, 04:01 PM   #1
tim614 is offline tim614  United States
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Default zenith mlt 15 console record player problem

happy 4th of july every one!

I recently got a zenith console for free from a very nice lady that was cleaning out her basement .the unit work nice and sound great but the only thing was the record player played but not great. so i open the back up and unplug the rca that was conected to the record player and plug the in my stanalone one i have ,it played but not loud at all with volume all the way up.

any help is apreciated.


thanks !!!!
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Old 3rd July 2008, 04:24 PM   #2
kevinkr is offline kevinkr  United States
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Cartridge in the zenith TT is a ceramic or crystal type and has high output, your TT undoubtedly has a magnetic cartridge (unless it is an ancient cheap BSR, Garrard or similar) and needs an RIAA pre-amp to bring the levels up.

By the way is this console a tube unit? If so do you know what sort of risk you took by just plugging it in after it had sat around for years disused? Not a good idea, it's a wonder the power supply caps did not fail.. This thing should be checked by some familiar with electronics.
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Old 3rd July 2008, 10:39 PM   #3
tim614 is offline tim614  United States
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the unit is tube and the lady who had them use it acasionaly she said not sure but it turn on and play beautifuly no hum radio pickup very well record player didnot turn untill i lube it and work fine only when i put in a some what warp record than it realy sounded bad so than i try to plug in my beogram 3000 than here im. i kinda though it was what you said but wasnt sure.

thank again for the help! ,need more info on this model if you could (wattage)( popularity)?
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Old 3rd July 2008, 10:43 PM   #4
tim614 is offline tim614  United States
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By the way is this console a tube unit? If so do you know what sort of risk you took by just plugging it in after it had sat around for years disused? Not a good idea, it's a wonder the power supply caps did not fail.. This thing should be checked by some familiar with electronics.

OOOPS!!!
I TURN IT ON AND PLAY FOR 2 DAYS NOW ABOUT AN HOUR EACH DAY HOPE NTHING GOES WRONG SHOULD I STOP PLAYING IT?
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Old 4th July 2008, 05:50 PM   #5
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by tim614
By the way is this console a tube unit? If so do you know what sort of risk you took by just plugging it in after it had sat around for years disused? Not a good idea, it's a wonder the power supply caps did not fail.. This thing should be checked by some familiar with electronics.

OOOPS!!!
I TURN IT ON AND PLAY FOR 2 DAYS NOW ABOUT AN HOUR EACH DAY HOPE NTHING GOES WRONG SHOULD I STOP PLAYING IT?

Too late now, however you should get it checked out. Is it tubed?
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Old 4th July 2008, 05:55 PM   #6
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Tim,

If the unit is getting regular use, you are past the immediate danger point. Tube based electronics that has been unused for a lengthy period needs to be slowly brought up to voltage, using a variac.

The fact the generous lady used the Zenith console, on an occasional basis, kept the capacitors in reasonable condition.

Given the unit's age, replacing all electrolytic capacitors SOON is something that should be done.

What's the tube complement in the unit? Look for O/P types like the 6BQ5 and 6V6. Provide an exact count. The power O/P can be worked out from that info.

Kevin is undoubtedly correct about the need for RIAA preamplification. Connect the recording O/Ps of another unit to the Zenith. Connect the Beogram TT to the mag. phono I/Ps of the 2nd unit and set its selector switch to phono.

BTW, if you value the condition of your LPs, do not play them on the console's TT. The piezoelectric phono cartridge literally scrubs the high frequency info. out of the records.
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Old 4th July 2008, 08:20 PM   #7
tim614 is offline tim614  United States
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yes they are tubes and the tube are 2 6bq5 and one big one i think it a 5au7 ,how many watt are they they sounded awsom
the speaker in the console are they any good ?
and also changing (cap job) how much does it usualy cost ?and should that improve sound quality?
thanks for all the info "Kev" and every one replyed! this is very very intresting to me and i think its going to be fun to learn about these old technology .

more more please!!!!
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Old 4th July 2008, 10:08 PM   #8
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The big one is more likely 5AU4 (a rectifier). The 6BQ5s are the power output tubes (European version is EL84 and is reputed to be a rather nice tube).

I assume that this is a stereo unit so if there are only two of them then it is run single ended. It is likely that they are run in pentode mode like my RCA and so probably a few watts of output power per channel. The GE data sheet that I looked at has some design examples that run about four to five watts at 10% THD. The speakers are likely to be pretty efficient so it is doubtful that you are ever playing it loudly enough to get to that high of distortion.

If you are willing to do a little DIY the recap should not be too expensive. Since this is not likely to be a golden ear project some decent modern equivalents should be fine. You should get a schematic if you want to play with it. I could see playing around with triode mode and possibly speaker enhancements. Hooking up an external subwoofer should be a pretty easy step.

What model is it?
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Old 4th July 2008, 10:12 PM   #9
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Quote:
Originally posted by tim614
yes they are tubes and the tube are 2 6bq5 and one big one i think it a 5au7 ,how many watt are they they sounded awsom
the speaker in the console are they any good ?
and also changing (cap job) how much does it usualy cost ?and should that improve sound quality?
thanks for all the info "Kev" and every one replyed! this is very very intresting to me and i think its going to be fun to learn about these old technology .

more more please!!!!

Is the console mono or stereo? The 6BQ5 is good for about 5 W., in Class "A" pentode mode. If that's a stereo unit, you get 5 WPC.

Look for identifying numbers on the chassis of the electronics. Such info. will allow a schematic to be tracked down.

Posting links to photos may also help some of the "crew" here in making an identification.

The big tube is probably a rectifier. Look again, as I suspect the rectifier is a 5AR4.

As you are starting to discover, newer technology need not be better. Being open minded also requires recognition of effective new technology. The LARGE corporations that currently make and sell consumer electronics are only concerned with profit. Back in the day that Zenith was made, there was some sense of value for value. New technology is fine, as long as something besides corporate greed is the motivation for its existence.
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Old 4th July 2008, 11:40 PM   #10
tim614 is offline tim614  United States
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the console is syereo,the big tube # i have to duble check and get back with you guy later its the 4th so im not home,anyway insid the cab there,s a stiker with print of the layout of tubes that have a model #ZENTH MLT 15 .
DIY ?I DONT THINK IM QUALIFY YET BUT DEFINATELY WITH ALL THE MASTER IN HERE I THINK IS POSSIBLE I WANT TO LEARN AND TAKE IN AS MUCH AS POSIBLE I THINK THAT IS PART THE FUN SO PLEASE WALK ME THROUGH IM A VERY PATIENT STUDENT THANKS ALOT GUYS!!
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