UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Closed Thread
 
Thread Tools
Old 26th Mar 2023, 11:19 pm   #1
trellis
Pentode
 
Join Date: Mar 2010
Location: Ipswich, Suffolk, UK.
Posts: 136
Default Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

Just bought this little thing on eBay on a whim, and from the moment I took it out of the box I was smitten! It's the cutest little thing!

The seller claimed the unit was working until they accidentally reversed the polarity on the power supply, after which it stopped working.

I would really, really love to get this thing working - it's such a gorgeous little thing - but I'm not sure whether reversing the power supply polarity would have done catasrophic damage.

I found the circuit diagrams, and there doesn't appear to be any reverse polarity protection. The -ve of the power supply is connected directly to ground, so in a reverse-polarity scenario, that would obviously have become +ve, which I'm thinking could have had far-reaching consequences.

Worryingly, the unit is not totally dead. It shows signs of life:
  • The clock and alarm work (when set to buzzer). The alarm buzzer sounds through the speaker
  • When the unit is switched on, I hear a pop, and then a very faint hiss from the speaker, suggesting the audio amplifier is working.
  • Intermittently, I can hear a very faint 50 Hz-ish buzz from the speaker - possibly from the frame oscillator? (I'm powering the unit on batteries so it's not mains hum.)

Having looked inside the unit, it looks like a bit of a nightmare to disassemble to even gain access to the main TV PCB (where the power supply is located).

Is it worth even trying to fix, or is it likely to be a lost cause after suffering a reverse polarity power connection?
Attached Thumbnails
Click image for larger version

Name:	sanyo_mini_tv.jpg
Views:	116
Size:	71.1 KB
ID:	275838  
trellis is offline  
Old 27th Mar 2023, 8:58 am   #2
marceljack
Pentode
 
Join Date: Apr 2021
Location: Paris, France.
Posts: 235
Default Re: Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

Hi trellis,
I would first have a look to the power supply part (voltage regulation), it's possible that damages are limited to this part, especially the semiconductors.
Attached Thumbnails
Click image for larger version

Name:	Sanyo PS.jpg
Views:	67
Size:	53.3 KB
ID:	275839  

Last edited by marceljack; 27th Mar 2023 at 9:15 am.
marceljack is offline  
Old 27th Mar 2023, 9:20 am   #3
agardiner
Octode
 
agardiner's Avatar
 
Join Date: Sep 2020
Location: Thetford, Norfolk, UK.
Posts: 1,731
Default Re: Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

Agree totally. Q701 and Q702 are likely damaged, but personally I think the rest will be just fine.
agardiner is offline  
Old 27th Mar 2023, 10:04 am   #4
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
Default Re: Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

As an aside, where did you find the complete circuit diagram of this unit? I have one but the only service manual could find was missing the last page which is the circuit of the main board.
TonyDuell is offline  
Old 27th Mar 2023, 12:51 pm   #5
trellis
Pentode
 
Join Date: Mar 2010
Location: Ipswich, Suffolk, UK.
Posts: 136
Default Re: Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

Thanks folks. It looks like a major disassembly job to even get to that corner of the board where the power goes in - basically the whole thing has to be taken apart and everything removed from the chassis including the tube.

Yes, I found the same manual online with the missing back page - however, someone was selling a manual for the 2170 on eBay, and helpfully one of the pictures on the listing was a high-res photo of the circuit diagram.

That photo isn't particular clear, but it's clear enough to be able to see that the circuit is the same as that for the TPM-2140, for which there is a full service manual available.
Attached Thumbnails
Click image for larger version

Name:	05.jpg
Views:	50
Size:	82.8 KB
ID:	275849  
trellis is offline  
Old 27th Mar 2023, 1:32 pm   #6
marceljack
Pentode
 
Join Date: Apr 2021
Location: Paris, France.
Posts: 235
Default Re: Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

Hi Trellis,
This a recomposition of the diagram I made from two PDF parts available at radiomuseum.org.
The SM is also available on electrotanya, with a lot of miising pages but at least there is an exploded view, part list and other interesting infos.

However the resolution of images posted here is reduced compared to the original.
Attached Thumbnails
Click image for larger version

Name:	sanyo-tpm2170-p1&2.jpg
Views:	49
Size:	126.6 KB
ID:	275850  
marceljack is offline  
Old 27th Mar 2023, 3:59 pm   #7
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
Default Re: Sanyo TPM-2170 Mini TV / Alarm Clock / Radio

Thanks, I've now downloaded the TPM-2140 manual.
TonyDuell is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 8:34 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.