Please help me save my Sony TR-1000 Portable Shortwave

[[email protected]]

Greetings,

This unit is a 1960's era (I think) Sony TR-1000 10 Transistor 4-Band
AM/Shortwave Portable. Purchased at a church sale for $2.00. Best
$2.00 I ever spent.

I was listening to talk radio the other day on battery power and the
hosts voice just suddenly cut off. Now all that is audible from the
unit is a very slight static that changes in character (but not really
in loudness) when you rotate the volume knob. I have tried the unit
on DC power and even another set of batteries with the same results so
I know it is not the batteries.

This is my all time favorite radio. The way it pulls in AM stations
is unbeliveable. It also gets TONS of shortwave stations which is
another reason I like it. I have ordered the basic schematic but was
hoping someone out there might have seen this problem before or know
some of the common faults of this radio.

I know it is very old but I was just hoping this radio has came across
someones workbench out there. Other people who have one must love it
like I do. It really has unbelievable sound quality and sensitivity.
Sony knows their transistors... All help or suggestions, even the
most simple ones would be greatly appreciated. I know you probably
can't tell too much from my description of the problem, I am just
hoping that someone has seen a similar problem in another unit. I am
also looking for someone who has the Sams Photofact (TSM-97) repair
manual for this radio for sale (cheap).

I took a quick look in the back last night and there are resistors in
there that look like the color bars are hand painted on each one...so
I am scared.

Also does anyone know if this radio has any value to Sony collectors?
I couldn't find much about it on the Internet or in Google.

Thanks in advance for your help and suggestions!

 

[Sofie]

snipped:

I was listening to talk radio the other day on battery power and the
hosts voice just suddenly cut off. Now all that is audible from the
unit is a very slight static that changes in character (but not really
in loudness) when you rotate the volume knob.

-----------------------------------------------------


Many times with these older multi-band radios, dirty contacts on the
bandswitch can cause the very symptoms you described. Try switching the
bandswitch quickly throughout its full range several times. If this
treatment doesn't help, then you may want to spray some contact or tuner
cleaner (available at Radio Shack) on the switch contacts.
Obviously there could be lots of other faults causing the problem your
reported, but investigating the bandswitch is the FIRST and easiest
troubleshooting procedure.
By

 

[[email protected]]

Hi Daniel,

It's not the bandswitch. It has a sliding type bandswitch and I have
given it a shot of tuner cleaner (best I can anyways) and worked it
through the bands several times. No Dice I have came across table
top radios like this one (only newer) where the AM/SW stage won't work
but the FM stage still does. I have seen more than one radio with
this problem. Is there some common part to this type of radio in the
AM section that is weak or 'wears' out? I know the capacitors go bad
but is there something else common to the AM stage that dies? I was
looking at an RCA portable at a sale a few months ago and I remember
it having weak static for the AM and SW bands but the FM was strong
and working fine. Seems like the FM part would be more complex and
die first if something was going to die. This radio is too old to
have an FM stage so I guess it doesn't matter...but just lookin for a
common component that dies in AM radios like this if there is one.
Anyways, any other suggestions you might have would be great. It will
be a few days before I get the schematic. It is coming all the way
from Canada.

Is there any place online that has the older SAMS photofacts for
download? seems like they might be out of copyright by now?

 

[[email protected]]

Ok, I got the Photofact for this radio. Amazing that you can still
get the schematic for it! Got it from www.justradios.com in about
five days. What great service all the way from Canada..anways.. I
put the batteries back in and checked some of the voltage test points
and they measure .4 to .8 Volts too high for the first four that I
checked using a good digital multimeter. I had the black lead clipped
to the - on the battery holder and just touched the red lead to where
it shows on the PCB photo. Two of the boards are VERY difficult to
get out of this radio and I was wondering if anyone could give me some
pointers as to what components you might suspect with this symptom.
The first test points are coming directly off of and from the power
supply/voltage regulator board so I am hoping the bad component is
there somewhere. That is also the easiest board to remove. Even it
has like a dozen short wires soldered to the back that I will have to
remove and then put back. What type of failed component would cause
the voltage to be higher like that? (A resistor? capacitor?
transistor?). I guess I am asking where to start looking and for
helpful hints. The batteries I am using for testing are old ones so
the test points would probably measure even higher if I used fresh
batteries. Also, do I risk burning out more components by testing in
this fashion (live with batteries)? This radio is a early 60's model
so some of the components will probably be really hard to find. I got
NO clue where to look for the transistors out of this guy. It has 10
of them. I really want to save it though, I have never found a
radio that receives stations like this one and sounds this good.

Please help, I am a real beginner when it comes to radio repair.
Any and all suggestions would be greatly appreciated!

 

[**THE-RFI-EMI-GUY**]

I think I reads somewhere that this model has a DC-DC inverter to boost
the battery voltage. If so, I would check to see if that circuit is
running (oscillating), if not, suspect a bad capacitor first, then look
for bad solder, broken resistors and lastly semiconductors.

 

[G. Skiffington]

Hello Sir. Before you get too involved with checking voltages and
wondering about parts and board removal, I'd suggest you review,
research
or at least think about your method of troubleshooting. Although you
"might" fix any problem by replacing an obviously burned/broken part or
by "trying this or that", I'll tell you that the ONLY way to
successfully troubleshoot anything (and it almost doesn't matter what)
is to work from OUTPUT back to INPUT....in other words, ask yourself
"what does this piece of equipment SUPPOSED to do.....and what is
missing"....always keep this in mind no matter what - If you're looking
at the equipment as a whole make a note of all the operations that work
or don't AND any interactions which work correctly or have now become
apparent - THEN look at your information and/or diagrams and see if you
can isolate what subsections (not individual parts at this point) would
cause the overall
symptoms AND THEN delve into the individual subsections (stages etc) to
see why they behave as such. IF BY CHANCE one of the first things you
discover is that the entire unit appears dead (similar to your problem)
then you might start by checking for battery voltage at different points
in the circuit (as you've done) FROM OUTPUT BACK TO INPUT (important so
as to not waste your time) - with a receiver which appears nearly or
completely dead, I'd start with some basic battery voltage checks
according to your diagram (or experience if troubleshooting blind) and
work on the audio amplifier first (OUTPUT)....see if its powered up and
can you inject a signal into it OR see if you can see signal input using
your scope (all this depends on what you have to work with). Sometimes
finding a "signal" to inject (which can be just noise) into the audio
amplifier can be done by touching the audio pot wiper with your finger
(you'd be surprised at the noise you can generate!). Without going on
forever at this, suffice to say what it appears you're missing is just a
good method of troubleshooting and in this light I'd recommend that you
read up on troubleshooting receivers in general AND/OR get some
assistance from a local technician/radio amateur who repairs etc. These
people can really help you make sense of troubleshooting and will make
the best use of your time. Hope this helps in a small way.....sounds
like you're on the right track but just need some help. By the way,
when you've gotten some confidence in troubleshooting methods, you'll
often be able to answer the question "why did it fail" as you effect
your repairs OR see that because you haven't answered this question,
that you may have more work to do yet.

Have fun - Gord

 

[[email protected]]

Hello again,

I want to thank everyone for the excellent suggestions and
troubleshooting tips. Here is what happened with my radio. It is not
exactly fixed yet but it is working and my ear hurts.

I was reading here:

http://www.vintage-radio.com/repair-restore-information/transistor_faultfinding.shtml

and attempting to follow the operation of the different stages of the
radio as one poster suggested and was probing around the 2nd IF Amp
transistor with my multimeter. Initially the collector was showing
the specified 3.4 V but the base and emmiter were reading pretty close
to no voltage. I accidentally shorted across from the 3.4V supply to
the base with my mutimeter probe and the radio boomed into life and
Dr. Laura started yelling at me from the speaker and my mini-macaw who
was watching the whole operation bit my ear then flew off my shoulder
yelling because she scared him.

What the heck?

It then faded out after two or three seconds of operation. Not to
mess with success, I shorted back across from the 3.4V supply to the
base pad again and whammo..back to life it came..this time it stays on
a little longer. I had to do it a couple more times and then it
stayed on permanently and has been operating just fine for a few hours
now.

The 1st and 2nd IF AMP transistors are 2SC404's in plastic cases.
Most of the other transistors in the radio are sony's of the 2SC
variety in metal cans.

Did I somehow shock the junction in the transistor back to life. Did
I wake up an old electrolytic cap that was asleep? Anyone have any
theories for what happened here? Pretty strange stuff to me. Why
did the 3.4V electroshock bring it back to life?

One lesson I have learned is don't leave your radio tuned to Dr. Laura
with the volume maxxed and a bird on your shoulder when
troubleshooting. Other than that, I am just really confused.

 

[Sofie]

Look for cracked solder connection ..... gently move things around near the
affected area with a toothpick? Also might be a leaky or shorted
electrolytic around the circuitry of the transistor.... look in your
schematic for electrolytics not too far electrically removed from the base
or emitter.