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 Post subject: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Mar Mon 29, 2021 11:08 am 
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Joined: Dec Sat 19, 2015 12:06 pm
Posts: 27
Hello all! It's been a while but thought I'd share a new project. I've recently started a small collection of pocket transistor radios and would like to get them all working!

I have purchased both the Toshiba 7TP-352M and 7TP-352S, however the 7TP-352S is currently on it's way. When I saw these radios I just fell in love with the look. :o I plan to display them but I also want them working to.

The Toshiba 7TP-352M seems to be in very good condition. No major discoloration or scratches on the shell. Although one top tab on the inside has broken off. The back shell still stays on but the broken piece is missing. :( I was surprised to find an original battery inside! :shock: It's a Mallory M-1600 9V cylinder battery and from the looks of it there are no signs of leakage. This battery is dead of course but has zero signs of leakage and looks brand new! I know old batteries can spell doom if left inside equipment and I consider myself lucky that this didn't explode inside the radio.

I won't power it up until I can remove the board and get a closer look. I hope I can put a normal 9v inside but I haven't measured yet. I assume all the electrolytic capacitors need replacing. The band selector switch doesn't seem to latch when pressed and I hope this will be an easy. One of the transformers seems to be broken off the board. I can move it quite easily with my finger. Feels like it's being held on by only one wire! This is strange because I see no signs that the radio has been dropped. Atleast I see no physical damage so I'm not sure why the transformer would have broke off.

I see the service manual is available on Ebay but was hoping it was available online somewhere if anyone knows.

Anyway I will post pics of the 7TP-352S when I get it. The pics from the seller look promising so I'll keep my fingers crossed.

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I circled the broken transformer.
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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Mar Mon 29, 2021 11:27 am 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 16428
Location: Mountains of Mourne. Ireland.
Shoot me your e-mail address via PM (private message) and I will send you the service manual.

Greg.


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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Tue 06, 2021 11:58 am 
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Joined: Dec Sat 19, 2015 12:06 pm
Posts: 27
Thought I'd post an update. Spoiler alert! Both radio's are now working! Long story is that the 7TP-352M was pretty clean and didn't need much help other than the two electrolytic caps and a cleaning of the volume pot. It looks like the 7TP-352S had at one time been "services". I have little idea of how this radio has been treated in the past but it looks like it was converted to a standard 9v and a "fixing" of a possible broken antenna.

Just a heads up. My plan was to restore then to working order and clean then up so I can display them. My skills are limited as far as expert restoration goes. Meaning I may show things here that might upset someone who would want to preserve the originality of the radio's . I'm sure some would rather I had not done this and displayed them as is. However these were my chooses and I liked how they turned out.

First the 7TP-352M.

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Having not previously handled these kinds of radios I would have to say this one was in reasonably good shape. A little dirt here and there and a few minor scratches. The first hitch was removing the PCB. There are two screws holding the board in but it wouldn't come out! I tinkered with this for a few minutes until I found the magic screw! This was a very well hidden screw. The board will not come out while the band selector is up and the little button cap is removed!

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Of course the two caps had to go. Both measured way out of spec. One had measured in the picofarads!

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The band selector switch wouldn't latch when I got it. I found out quick that the holding spring had jumped the little groove and needed to be reset.

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The volume pots of both radios were very scratchy so I removed both and cleaned with contact cleaner.

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I did my best to clean the front panel. It was a little dirty so I carefully used soap and water to clean. Then I used a little polishing compound to polish the surface a bit. The scratches are still visible but I didn't want to go to hardcore on it.

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I decided to convert both the run regular 9v batteries so I removed the old terminals.

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Last edited by Tevian on Apr Tue 06, 2021 1:02 pm, edited 3 times in total.

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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Tue 06, 2021 11:59 am 
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Joined: Dec Sat 19, 2015 12:06 pm
Posts: 27
Next is the 7TP-352S.

This radio has seen some use and repair! As you can see the battery terminals aren't original. At some point the battery has leaked causing some corrosion. Nothing too bad but the antenna has seen better days. It must have broken at some point and someone tried to fix it. The tip has been broke off and crimped onto the top of the smallest available stem. The bottom looks like it's been cut and soldered on. I didn't take a picture of it but the largest outer part is gone and doesn't fill in the top hole in the casing. Not sure what brake the antenna suffered but it must have been bad! If someone knows of a replacement or possibly has one laying around I'd be interested!!

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Another weird part is the metal grill seems to have needed to be removed. All the tabs inside are broken off and missing. Someone tried to reattach the mental by using wire wraps and glue! I wonder if this radio was assembled from parts of other radios back in the day.

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This glue didn't fully come off but I made progress with the polishing compound! The front panel got the same treatment. It has very deep scratches but cleaned up well. Here's a before and after.

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One more minor thing was broken speaker clamp. This may explain the need to remove the front metal cover. There is a screw attaching the post from the front. I decided to epoxy it back into place.

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The caps in this one were bad. Although the 50uf cap was reading about 120uf so I guess that one might be working. The other was a complete dud.

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I used some vinegar and water to clean the inside and antenna. It doesn't look pretty but it's on the inside. The 9v does fit into the casing as long as there are no wires under the battery and the connector doesn't stick above the battery!

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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Tue 06, 2021 11:59 am 
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Joined: Dec Sat 19, 2015 12:06 pm
Posts: 27
These radio's look so awesome together. The both are fully working now. The AM reception comes in nice and clear! Both radios pick up the 5mhz time signal nice and clear. I was afraid I might need to do some tuning but thankfully I didn't have to. I have very little experience with that. Although I'm sure I'd have to if the radio's weren't functional beyond my attempts to restore them. Next will be a display case for the radio's I've recently acquired. I have six in total but I like these the most. I can't wait to get them on the wall.

Here's a before and after. Externally these radios were in pretty good shape to begin with. Both had at least one outer shell tab broken off inside but this old plastic is very brittle so I consider myself lucky.

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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Tue 06, 2021 3:24 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 16428
Location: Mountains of Mourne. Ireland.
Very nice... :)
Thanks for taking the time to document your work.


Once or twice when the speaker post was missing, I have used a bridging blob of hot-melt glue (sticks).

Yes, those little grill-tabs are often a one-time-deal with regards to bending. I heat / warm them up pretty good with my soldering iron first - - not sure if it helps, I've lost a few over the years!

At times I have reattached with small pieces of grey 3M double sided foam tape 0.8mm thick.
https://www.ebay.co.uk/itm/152796786306
Watch-out, 3M make a bazillion sticky tapes. lol


Another obsolete battery can be seen here, albeit a 3.6Volt Ni.Cd
viewtopic.php?p=2712380#p2712380

Greg


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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Tue 06, 2021 3:50 pm 
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Joined: Oct Mon 26, 2009 10:02 pm
Posts: 6806
Location: Indianapolis, IN
Great work---radios look excellent !

I've wet-sanded plastic (including clear) with 2000-grit to remove deeper scratches and glue staining with success---just be careful to do it evenly. Then a few rounds of Novus-2 brought back clarity & shine...

Now that those two are beauties, you may be hooked on the hobby and that six may become 60 or more !

John


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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Tue 06, 2021 4:52 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 16428
Location: Mountains of Mourne. Ireland.
Dating Japanese capacitors and Toshiba serial numbers.
Alan Kastner→ http://tabiwallah.com/radiowallah/dating101.html

Greg.


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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Thu 08, 2021 6:42 am 
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Joined: Dec Sat 19, 2015 12:06 pm
Posts: 27
Ya this probably won't be the last one I buy! :wink:

Thanks for the link Greg. My Toshiba has a serial number 00207343. So I'm guessing February 1960?

I forgot the mention but I also have the original leather case for both. In the model M case was a brochure and inside that was a little slip that has a circuit diagram! I should have looked closer when I got the radio but I missed that completely. :oops:

One quick thing. The model M volume pot is still a bit weird. It's very difficult to adjust for a medium volume. It's either super soft or ear piercing! I've seen in inside of another older Toshiba radio and they look identical to the 5k volume pot with switch. I'll keep my eye out for an old Toshiba for parts. The antenna might be harder. Does someone know if that antenna was used on other radios? Possibly something like a little desk radio?


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 Post subject: Re: Toshiba 7TP-352M and 7TP-352 restore
PostPosted: Apr Thu 08, 2021 7:32 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 37958
Location: SoCal, 91387
Tevian wrote:

One quick thing. The model M volume pot is still a bit weird. It's very difficult to adjust for a medium volume. It's either super soft or ear piercing! I've seen in inside of another older Toshiba radio and they look identical to the 5k volume pot with switch. I'll keep my eye out for an old Toshiba for parts. The antenna might be harder. Does someone know if that antenna was used on other radios? Possibly something like a little desk radio?


You did nice work on restoring those sets, congrats! Neither the volume control nor telescoping antenna are anything unique or special. Any 5K VC should work, and any antenna with the same connection on the bottom and approximate same height of the first section would work.

You might look for these parts on eBay. The antenna would most often be found on another AM/FM pocket radio.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


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