Author Topic: Motorola Identification - Quality??  (Read 7727 times)

fastdog

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Re: Motorola Identification - Quality??
« Reply #30 on: July 09, 2015, 06:29:05 PM »
Thanks Pat, I need that input. I have serviced the record changer myself as I have done that before... It's the electronics that I'm unable to do. Hopefully, with the changer complete, it would cost less. And I do really love the style of this piece... Forgot to mention that I have the separate right speaker in like new condition too.
Tim

624Magnificent

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Re: Motorola Identification - Quality??
« Reply #31 on: July 09, 2015, 07:44:35 PM »
That's a very nice piece of equipment!!
Tom

Harbourmaster

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Re: Motorola Identification - Quality??
« Reply #32 on: July 10, 2015, 01:28:31 AM »
Super nice!


I love the sweeping curve on the front of that cabinet!!
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AlexanderMartin

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Re: Motorola Identification - Quality??
« Reply #33 on: July 11, 2015, 11:51:28 PM »
If you can't get her going, I doubt any of us would be hesitant to help you by fixing your amp/receiver, I'll happily do it for you if it has to come to that

AlexanderMartin

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Re: Motorola Identification - Quality??
« Reply #34 on: July 11, 2015, 11:55:58 PM »
And no, I certainly wont charge you the stupid price of $300 just to fix a damned right channel.

fastdog

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Re: Motorola Identification - Quality??
« Reply #35 on: July 15, 2015, 02:42:45 PM »
Thank you Alexander!!!!!!
Tim

fastdog

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Re: Motorola Identification - Quality??
« Reply #36 on: July 15, 2015, 02:45:49 PM »
Where are you located Alexander.... Just in case it does come to that?
Tim

AlexanderMartin

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Re: Motorola Identification - Quality??
« Reply #37 on: July 16, 2015, 01:32:29 AM »
Western Illinois.

fastdog

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Re: Motorola Identification - Quality??
« Reply #38 on: July 16, 2015, 06:20:47 PM »
Uggggggggggg... I'm in the DC area but thanks for the offer!!  This is why I love this forum!!!
Tim

spiritofradio

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Re: Motorola Identification - Quality??
« Reply #39 on: July 16, 2015, 08:40:28 PM »
Sorry so late jumping in...Fastdog if you need the amp and tuner rebuilt I can certainly help you out.  I'm in Richmond and I'm pretty familiar with the early stereo amps.   I'm on vacation next week so if you want to try to coordinate something just PM me.
~~~and did you exchange.......
a 'walk-on' part in a war.....
for a lead role, in a cage?~~~

fastdog

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Re: Motorola Identification - Quality??
« Reply #40 on: July 20, 2015, 02:36:23 PM »
Thanks Spirit, great to know you're that close and thanks for the offer. I dropped it off to my guy two weeks ago and he pulled back some on that crazy price he first gave me. I'm not in any hurry for it so he'll cut me a break on it I'm sure.
Tim

Motorola Minion

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Re: Motorola Identification - Quality??
« Reply #41 on: July 22, 2015, 01:54:25 PM »
That is a very nice unit. The electronics are deserving of that fine cabinet. I hope you get it fixed up, the sound is warm and classic High Fidelity. Im personally nuts for these !!!!

I just restored an SK70M, in low-end photofinish mahogany a few years newer but similarly equipped to yours.
I hope to find some wisdom on the V-M record changer as mine plays fantastic but does not cycle even after a good cleaning.   
 
Post the HS-XXX number on your amp chassis if you can. The usual configuration was two single-ended 6BQ5/EL84 output stages for right and left with a center (lotsa bass) channel driven by two 6BQ5/EL84 tubes in a push-pull configuration.

Main issue on mine was dirty controls, loose/dirty tube sockets and of course, capacitor replacement. I did not even plug it in but when straight to work on a re-cap. I had some pops and one channel dropped out but that was cured by cleaning and squeeezing (re-tensioning) tube socket contacts on the amp chassis. All that bass and heat expansion probably loosens them.
There were few wax-paper caps and several electrolytics. The separate mono tuner and also a separate preamp chassis had even fewer caps but it looks like those two components are integrated on yours. 
Tubes - Magical - Tubes

Dave

fastdog

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Re: Motorola Identification - Quality??
« Reply #42 on: July 23, 2015, 07:37:19 AM »
Hey there MotoMinion, thanks so much for your help!!!  Yes, tube layout is just as you said... And the Hs# is HS-711B
                                        12M58
The guy working on it has got the FM up on it now, however, the brand new 6BQ5's installed are still "cherry capping" so he's ordered the new capacitors that lead to them in hopes to stop that issue. Any thoughts on that right channel not working that I can pass on to him?
Tim

Motorola Minion

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Re: Motorola Identification - Quality??
« Reply #43 on: July 23, 2015, 12:29:22 PM »
If the 6BQ5 tubes are getting cherry-plates, check those voltages on pins 2 and 3 carefully during a brief power up.
I agree coupling caps to your grids are a prime suspect
Biasing resistors to the grid (if any) OR a shorted bypass cap across the cathode resistor will lower the voltage difference between grid and plate, causing full-on conduction of teh 6BQ5 and corresponding drop in plate voltage from what the schematic states.
Tubes - Magical - Tubes

Dave

Pat L

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Re: Motorola Identification - Quality??
« Reply #44 on: July 23, 2015, 12:57:40 PM »
It's almost a given that cherry plating in output tubes is caused by bad caps. I have seen a couple of 6BQ5 tubes cherry plate simply because they were bad; but that was a rare occurrence. I wish the gentleman would've just replaced the caps for you in the first place as that is standard practice by knowledgeable techs who work on this equipment. In any case I'm sure your problem is easily solved.