Magnavox Astro-Sonic Console Info Needed

That sounds like it may solve many of your problems. I wouldn't replace just one cap on a unit that old. I don't think those black Nichicon(sp) caps were top of the line (at least that's what is in all my units). Quality has improved over the years and you can get a variety from Digi-Key, Mouser, Parts Express, MCM Electronics (if they still exist) and several other companies that have been mentioned in previous posts. --BB

Bobby Basham
Tucson, Arizona

My tech finally found the main problem (and replaced everything else that was out of spec).
The replacement transistor's on the way from Ohio.
He says it'll be ready Mondy afternoon.
He charged me $130 for the initial diagnosis & 6 cap replacement.
Now he has quite a few hours into troubleshooting and has replaced more buggy components.
When I asked him today "how much is all this going to cost me?" he said "don't worry, not much, I'm taking care of you."
That' sounds scary but he knows I only paid $20 for the Maggie and the $130 hurt like hell.
I think I might get a perfect top-o-da-line '65 Maggie for under $200 when all's been said and done.
After I get it back I'll tell you what got replaced and post the $$ damage so y'all can gloat

It must be nice to be able to troubleshoot and replace components etc.
When I pick up a solder iron I just hurt myself.
I can make fine furniture but it doesn't sound as good as a working Hifi

Although I have both channels playing, I still have some distortion in channel 1 (just not as clean as channel 2). It is not the speakers, because when I run all four speakers off channel 2, it sounds great. Any suggestions as to what could cause this? Would changing the resistors on the audio board help? Or is it a problem in the amplifier? Any help would be appreciated.

Thanks,

Jeff

I'm no help.
I pays my money and takes my turn...the tech does the work.

jfstinnett wrote:Although I have both channels playing, I still have some distortion in channel 1 (just not as clean as channel 2). It is not the speakers, because when I run all four speakers off channel 2, it sounds great. Any suggestions as to what could cause this? Would changing the resistors on the audio board help? Or is it a problem in the amplifier? Any help would be appreciated.
Thanks,
Jeff

It could be a bad pickup cartridge or the tracking force adjustment.

The tech has been swapping components from side to side until he finally found the issue.
Not the most efficient way to do it but he finally found it.
He's waiting for the 2 offending transistors to arrive and expects to have it ready for the weekend
He's not charging me for the past month of swappage so he said I'm not getting any further charges.
He just picked away at it when he had the time in between other jobs.
I'm glad that he finally nailed it and it'll be worth the total cost ~$180 since my specialty is letting the smoke out of electronics but I won't be bringing him any further business.

These previous posts just reinforce the fact that us TECHS are the only ones capable of properly servicing units like these.

A hot soldering iron and a screwdriver cannot ever compete with years of experience and learned theory.

MattTech wrote:These previous posts just reinforce the fact that us TECHS are the only ones capable of properly servicing units like these.
A hot soldering iron and a screwdriver cannot ever compete with years of experience and learned theory.

My point exactly so let me misquote you:

MattTech wrote:These previous posts just reinforce the fact that GOOD TECHS are the only ones capable of properly servicing units like these.
So get your hurtin' electronics to a GOOD TECH

He soldered in the replacement transistors and found that the balance is still screwed.
The frequency response issue is even-Steven now though.

The balance only shuts the opposing speaker down one way.
Turned the other way still bleeds.

Any ideas?

Hmmm....Ideas?

Maybe it could be a resistor issue. I had one simple resistor that was choking a channel, and here I went out replaced a bunch of stuff that should have been left alone. Of course, I'll allways first do a recap of the electrolytics.

It seems that sometimes folks ignore resistors since they seem to hold up better than the electrolytics. I've got a gazillion cap job/projects on the back burner, and I will not ignore the resistors.

To you Techs: Please don't belittle us folks who try to do the best we can with what we have. Many folks cannot afford to package that amp/tuner for shipping and send it to some [questionable] Tech who may charge a ridiculous price, then charge you return shipping, and no guarantee that the thing is going to work properly. Offer your advice and expertise, and to those who don't know a screwdriver from a can opener, please get it to a good Tech.

I, personally, may not have a degree, but I've done alot of research and bought dozens of books and done much studying and downloaded hundreds of postings from seasoned Techs and applied all that knowledge. Reading schematics, testing voltages/bias, cross-referencing components etc. I just don't have the "Formal" training and degree hanging on the wall, but managed to repair all past projects successfully.

It's good that we have some Techs here. I don't know about you guys or your track records, but please don't be arrogant and condescending about the work that the amatuers do. We all didn't fall off a turnup truck yesterday, and some of us amateurs have quite a bit of knowledge.

I apologize about the arrogance and condenscending comment. A lot of folks here know what they're doing, and if the shoe fits, wear it, and it's good that the Techs and other knowledgeable folks keep after those CLUELESS NEWBIES who may possibly destroy/fry a unit beyond repair, or burn down their house.


ON A LAST NOTE: IS THERE A WAY THAT WE CAN ADD ANOTHER [FAQ] SECTION TO THE BOARD THAT LISTS ALL THE TECHS/KNOWLEDGEABLE FOLKS AND THEIR SERVICES, WITH CONTACT INFO, EMAIL, PHONE NUMBERS, FAXES, ADDRESSES, AND MAYBE SOME ADDITIONAL GOOD TECHS WHO MAY NOT NECESSARILY SUBSCRIBE TO THIS BOARD?

THERE ARE ALOT OF TECHS OVER IN MagnovoxFriends.com, Instead of typing in a topic on the web and get on million hits, you may find some info there. Those folks are mainly into the TUBE UNITS...Magnavox Regency, Imperial, Concert Grands, and they have a section that have pictures and schematics, including Astro-Sonics...free for the downloading. That's my story and I'm sticking to it...LOL

I may get flamed for this posting, but I mean no harm and am not trying to slam/bash the Techs who subscribe. I think you folks got our backs and really look out for us, offering advice for some of the simpler repairs. I just pray that there are no predators out there. --BB


Bobby Basham
Sanctified, Holy Ghost Filled Electronics Repair

XXXX East Grant Road
Tucson Arizona
Phone: (520) 234-5678
Fax: (520) 123-45678
Email: ShoutForJoy@yahoo.com
(TOTALL FAKE...THIS INFO IS NOT REAL)

Mowgli wrote:He soldered in the replacement transistors and found that the balance is still screwed.
The frequency response issue is even-Steven now though.

The balance only shuts the opposing speaker down one way.
Turned the other way still bleeds.

Any ideas?

Go find yourself a qualified repair tech.
Sounds like he's putzing around and guessing..... lord knows how much he's already screwed up.
Ask him to show you the proper service documents to this unit.... if not, he's guessing.

I don't have a Maggie chassis in front of me right now, and it's been a few years since I've torn one apart. But, are there a pair of Huge resistors (or caps) attached to or near that balance pot? Transistors are either on or off (hissing if you're using the wrong replacements).

I know on that small board, pre-amp stage, where all the signals pass through, there are about 3 pairs of small transistors, a half dozen electrolytics, and some resistors.

Does the inbalance happens in the phono/radio/aux modes, or is it isolated to one section. Gotta do a process of elimation, not putzing around. Radio/Aux may work perfectly, but you may narrow it down to a bad cartridge or wires. Step back and look at the whole picture. A process of elimination may help, before tearing out a hot soldering iron and screwdriver. --BB

Bobby Basham
Tucson, Arizona

He has the tuner/preamp working better than it did from the factory yay.

The bleeding balance is actually in the amp # a57502

Anyone have the manual with schematics etc?

Thanks

Hey Mowgli,

There are a bunch of schematics posted in the files/pics section of MagnavoxFriends.com. It may be there. Can't afford a scanner right now (can't even afford to replace my cartridges for 3 HP Laserjets right now), but would gladly send you what I have if I had a scanner. If not there, try Sams Photofact folder SET 748 FOLDER 7 for the amp. The radio chassis could be anything like posted below...R207, R216, R218 etc....many to choose from.

You can fix alot of things without a schematic, because caps are labeled and resistors are color coated, but the schematics also reveal voltage values between components and maybe bias settings on newer units. I learned the bias thing by tweaking the wrong pots, thinking they were some kind of gain/output controls....until the amp got abit hot to the touch. Thank goodness I actually had the schematic and a digital multi-meter and corrected that immediately.

I'm not an expert or qualitified Tech by any means, but managed to fashion my own signal tracer. If the balance is off, then do some back-tracking on that amp. Don't overlook a gremlin resistor in the audio circuit. Please don't ignore the resistors, they are not steadfast and unmoveable, and, though they hold up better than electrolytics, can still go way out of tolerance.

I reiterate the fact that I'm no professional (maybe save me some flaming from more qualified folks), and I truly apologize for any inaccurate information that I have shared here. --BB

Bobby Basham
Tucson, Arizona

No help at Magnavox Friends, they had ideas but not relevent.

The amps are seperate left and right.
What actually shares left and right on the amp?
That's the only place(s) it could be bleeding from channel to channel.