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 Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players

Notices

Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

Reply
 
Thread Tools
Old 3rd Jan 2023, 8:03 pm   #121
Borderer
Tetrode
 
Join Date: May 2009
Location: Hereford, Hereford and Worcester, UK.
Posts: 92
Default Re: Fidelity transistorised Playmaster - reverse engineering?

Ben, Following this with interest, although I no longer have the machine.

Diagram in post 18 is for a different machine. Not sure it is the same. From memory, the Fidelity was positive to chassis but someone else will be able to confirm.

Photos in post 1 and 105 show the rectifier location at the RH end of the board and you can make out the rectifier connections.

The 16 volts that you have must be at the input to the rectifier - the heater and HT of course come direct from the transformer.

Last edited by Borderer; 3rd Jan 2023 at 8:22 pm.
Borderer is offline   Reply With Quote
Old 3rd Jan 2023, 9:03 pm   #122
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 7,463
Default Re: Fidelity transistorised Playmaster - reverse engineering?

Thanks. Replaced missing rectifier bridge, 1000uF smoother (+ve gnd), replaced missing 1000uF cap on output stage. Replaced 1x 25uF/25v cap which had leaked and had leg hanging off.

Now there is hum and a slight crackle from speaker if volume adjusted.
If REC selected green segment in magic eye lights up, but just as one dull blur.

So, some progress but still not operational. Will keep at it.
__________________
Regards,
Ben.
ben is offline   Reply With Quote
Old 3rd Jan 2023, 9:13 pm   #123
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,550
Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by Chris55000 View Post

I've just checked "up top", & I'm thinking you'll find the "Playmaster TR8" or the "Playmaster TR9", both of which you can buy "up top" will meet your needs
Should not Playmaster above have read "Playmatic ?

David
DMcMahon is offline   Reply With Quote
Old 3rd Jan 2023, 9:27 pm   #124
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,550
Default Re: Fidelity transistorised Playmaster - reverse engineering?

Quote:
Originally Posted by ben View Post
Perhaps someone reading this could confirm something. From the diagram in post 18, am I to assume that the positive output from the rectifier is in fact fed to chassis and the negative to the output stage? Or is that diagram for a different setup?

Since the entire rectifier was removed and there are no board markings, I'm largely in the dark.
+ve ground and -ve to the supply rail on the Fidelity Playmatic TR8/TR9 schematic, with -24V at reservoir capacitor C27.

The TR8/9 are a 2 valve hybrid with EM87 Magic Eye and ECH83.

David
DMcMahon is offline   Reply With Quote
Old 3rd Jan 2023, 9:41 pm   #125
Chris55000
Nonode
 
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,820
Default Re: Fidelity transistorised Playmaster - reverse engineering?

. . .Oh dear, I'll have to get those Playmaster remains out from under my bed and get on with some more drawing–out me thinks – (it got put on one side because of holidays, eye–surgery, repair work for another Member, now complete), and the panel I got being only part–complete, hence me having to puzzle some of it out still!

Chris Williams
__________________
It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!
Chris55000 is offline   Reply With Quote
Old 28th Nov 2023, 11:15 pm   #126
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 7,463
Default Re: Fidelity transistorised Playmaster - reverse engineering?

I recently looked at my moribund unit again. A dodgy design to begin with and an example which had missing parts and had been got at -a glutton for punishment am I!

One of the output pair was s/c, I replaced the AC128 and AC176 with an AC187 /AC188 pair which I had to hand, now there's quite a strong output but the signal is of terrible quality, very distorted/fuzzy and a bit of buzz. The winding for track 1 of the R/P head is o/c, so am awaiting a suitable replacement. Erase does not work. For all I know the erase head may be open too!

The odd display on the EM87 was due to a green (signal?) and a yellow wire having detached themselves from the pcb. Now when Rec is selected the display is a bit jittery, but not blurred.

I will do some more tests on the resistors and erase head if/when I get a new R/P head.
__________________
Regards,
Ben.
ben is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 9:01 pm.


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.