Ok my friend who brought me the Disasteradios also had this ugly beast in the box. It's a Magnavox AT-61. Guts are clean, I just need to put a battery case in it. I haven't looked much on these (Never messed with T-radios) but it's a rad color for sure. Now, If I can get it clean enough to get my wife to let me keep it in the baby room! (bout the only space I've got left lol)

Neat Cordless transistor Magnavox ! Haven't seen one of these before...

Looks like it'll clean up fine... Be sure to post a "complete" pic ! And would like to see a pic of its "guts"...

John

Don't worry, It'll be first thing tomorrow. Pulling a late shift tonight so all I can do is stare at it for now. It's missing the battery box so I'll have to slap one together tomorrow to see if it works. But I'll post as I go along.

Sorry about the bad pics before, I've got it cleaned up as much as elbow-grease will do. I've also found a new home for all the spider nest that were inside. I don't believe the knobs are original, and they actually look like AC dimmer switch knobs to me. They match up all right for my taste so I'm not going to stress on that.
I do have two problems (one I'm clueless on the other just lazy)
1) I'm scare to death of warping or hazing the plastic on the outside, but as you can see from the pics, it's gotten enamel over-spray all over it. It's also been fairly close to someone’s welder at some point, as there are slag holes burnt in on one side (pinholes) I haven't used anything stronger than scrubbing bubbles bathroom cleaner and a cotton washcloth on the paint. Does anyone recommend something that might work on enamel but won't damage plastic? I've considered an emery and then buffing the finish back in but I've had some plastic go nuts on me before if you’re not careful with your buffer.
2) here's the lazy one. As you can see from the pics I haven't put a 9v pigtail on this set yet, but I hand wired a 9v up to see if she'd talk. I get volume knob pop when the set first turns on but nothing else. No hum, no static, not even dirty volume knob noise. This things full of polarized caps (that I haven't tested) so I'm guessing that's where I might be in trouble. I'm suspicious of a 30mf 12v (under the clear insulation) that appears to feed T4. If anyone has any ideas on where I should be looking, let me know.

Would be best to replace the electrolytic caps first as they are at the top of list of failure causes on these old
sets...

I've used 91% Isopropyl alcohol with great success on most plastics to remove paint residue, but be sure to try a small area inside or on bottom to make sure it won't "attack" it ! And it can remove lettering or attack the tuning dial plastic...

Have also used automotive brake fluid to remove paint from some plastics, but be EXTRA CAREFUL with it !

Noticed the knobs in latest pics---have you Googled the model # to see if there's a pic of one w/originals ?

Great that you have schematic---you can take a hi-res pic and print an "enlargement"...

Let us know...

John

Lol that's exactly what I just ran to the store for. Alcohol doesn't seem to be affecting the plastic any but I'm gonna give it a min and make sure I'm not going to haze. I've already got the caps I didn't have on order. I've had NO luck finding anything on this radio though. Ebay has a photofact and a manual but neither are color. The best pic I've found is the one below. Was hoping to find the right knobs but I'm not going to hold my breath... I'll post pics after I get the paint removed.

Check out this link---some color pics & info: http://live.universal-collectibles.com/ ... aid=158603

Thanks for the link xr! I've been digging for 2 days now and can't find ANY knobs similar to these. They're made of the same gold plating that the trim is made of so I'm sure they're prone to "plastic flake" like chromed plastic is. If anyone knows who might have repo's, can you steer me in their direction? Thanks for all the help, Oh and it cleaned up very well, I'll post pics this evening.

BTW, do you motocross xrhonda?

Looking forward to pics !

Those dimmer knobs don't look too bad---maybe you can find some w/o the "pointer"...

I'm just an occasional "play-rider", but did have a couple friends many years ago who raced---great fun !
Actually have a '96 XR250L dual-sport which is licensed/insured & street legal---was looking for a '91 when I ran across this "project" at decent price years ago...

John

Hello again! Sorry I've been off this subject for awhile, got WAY too many projects. I finished up the caps on this Mag last week and to my despair, I get the same results I had before the replacements. I tested all of the caps that came out as well and didn't find any leaking or open (even the little turd I thought was my culprit) What I'm getting is an audible "POP" when the set is turned on. But nothing other than that. No volume knob scratch or tune changes. I believe I hear a very low hum but it's so low it's hard to tell for sure.

So I moved on to the case, Alcohol worked for about 80% of the paint and grime. However, it started taking the gold off of the glass ”plastic" dial so I stopped before I lost it all. I was left with the welding "slag" I mentioned before and two large drops of paint that the alcohol wouldn't touch. So I sat down and buffed, and buffed, and buffed, and found that these two drops of paint not only are not coming off, they're actually burnt into the plastic. I stopped where I thought I would only make things worse and I have to say I'm happy with the results. I do have some paint around the tuning knob I have to get out of the grillwork, but other than that I've got it where I want it. Found some smaller white knobs without pointers so they should match up with the cabinet much better now.

All in all its been a fun project, and it looks awesome in my new daughters room!

Quick 'n dirty, place another AM radio next to it, turned on and tuned to 1000 KC. Turn this one on, and rotate the dial. At about 1450 KC it should cause a squeal in the other set, which would indicate that you have power in the circuit, and the oscillator is functioning.

If no squeal, you may want to do some voltage checks on each Transistors elements.

Awesome, I'll give that a try tonight. If I can prove the circuit and oscilator are functioning, where would be my next ave. of investigation be?

Oh and I've worked on a LOT of boards in my life, but this is the first I've ever worked on that had exposed "solder channels" on the printed side of the pcb. I do NOT approve lol.

As mentioned, check the voltage on each Transistor element; generally, each leg should show a different voltage, even though the difference between Base and Emitter may be as small as .1 volt. Collector voltages should approach the supply voltage.
Do you have a schematic for this set? If so, you can compare findings to what should be.

I have the schematic that is in the case, haven't had much luck finding anything more than a pic online. I'll run the math off of it this evening before I get started testing. I'm looking at this pic right now (don't have the radio in front of me) and it appears that all of my trans are PNP type (can't really tell on the speaker side).
Now don't beat me up if I'm wrong but from what I can read I should be checking the base and emitter settings (base being LOW relative to emitter when the curcuit is ON) then the collector should activate. Depending on what the trans is being used for I should see either a relatively close voltage to the base (logic gate on/off) or a HIGH voltage on the collector as an amp signal.

Again if I'm wrong, don't rub my nose in it. But I don't mind being corrected whatsoever lol.

get ready to do some troubleshooting t-radios have been driving Me nuts!

The circuit employs PNP devices throughout. I can't tell by the scan if the arrows on the output Transistors are pointing in on the emitter elements, but Sanyo 2SA and 2SB Transistors are PNP's. Their 2SC and 2SD units are NPN.



I'm the last guy to rub anyone's nose in anything.
As we used to say when I was a Teamster, "no one was born with a steering wheel in his hands".

the outputs are pnp

If your osc. is functioning, try checking audio by touching center pin of volume ctl. with a meter probe or small screwdriver with your fingers on it---if amp okay, you should hear noise/hum from speaker...

You can check detector by putting cathode of germanium diode to input of external amp with ground to radio chassis---touch anode to same point as detector diode anode connected to last IFT... If conv & IF stages okay, you should be able to hear stations as radio tuned...

Of course, first make sure all antenna loopstick & other wiring okay...