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 Post subject: Restoring Grundig TK64 R2R, Blowing Fuse
PostPosted: Nov Wed 14, 2018 12:38 pm 
New Member

Joined: Nov Wed 14, 2018 12:33 pm
Posts: 1
Hello to everybody from Sydney,

I am restoring a Grundig TK64 and if there are experts please comment.

1) it is blowing the 250mA fuse

2) I disconnected the B+ at the Rectifier, and measured the voltage at the DC output of the Rectifier. OK ! about 220v and the fuse is not blowing.

3) I disconnected the Power amp, which has a single connector. fuse still blowing.

4) I replaced the main 50uF + 50uF filter capacity with a new unit, fuse still blowing



What is the big red capacitor (?) with a large bolt to mount it to the chassis ?



Should i remove ALL valves and test again ? I dont think valves will cause a high current short...??

There are many wax capacitors in the unit ?

There is also a 2nd 50uF + 50uF filter capacitor which i have not replaced.



Any suggestions on what i should try next ? maybe change the 50uF + 50uF capacitor ?

Thank You.


Attachments:
small TK64.jpg
small TK64.jpg [ 68.28 KiB | Viewed 496 times ]
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 Post subject: Re: Restoring Grundig TK64 R2R, Blowing Fuse
PostPosted: Nov Wed 14, 2018 4:12 pm 
Member

Joined: Jan Mon 16, 2012 4:15 pm
Posts: 5523
Location: Near Brandon, Iowa
(1) Find a schematic for the unit (see link below) and identify all of the power supply filter electrolytics and all of the B+ bypass caps. It appears that there are four 50uF electrolytics, two each in parallel on either side of the filter reactor.

(2) Replace ALL of the remaining original electrolytic caps and ALL of the B+ bypass caps. A shorted cap in either case can take down the power supply. Don't parallel old caps with new; cut out the old ones so that they are no longer electrically in the circuit. You can leave the other foil/paper caps in place until after you get the unit nominally working- then they should all be replaced, as well.

https://elektrotanya.com/grundig_tk64.pdf/download.html


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 Post subject: Re: Restoring Grundig TK64 R2R, Blowing Fuse
PostPosted: Nov Fri 16, 2018 3:17 am 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 11418
Location: Powell River BC Canada
After getting the HT system operable and before you do a general recap,
test the machine to see if the mechanical functions work, and the heads
have enough life to play and record properly.

I repaired them when they were current. They can drive you batty.
Attachment:
Grundig TK 64    Find an English service manual.jpg
Grundig TK 64 Find an English service manual.jpg [ 174.17 KiB | Viewed 439 times ]


edit added

Here are pages from the parts list Grundig wanted American shops to know about.
Attachment:
GRUNDIG T   K  M 64  SPECIAL PARTS.jpg
GRUNDIG T K M 64 SPECIAL PARTS.jpg [ 184.88 KiB | Viewed 416 times ]
Attachment:
GRUNDIG  T K M 64 SPECIAL i.jpg
GRUNDIG T K M 64 SPECIAL i.jpg [ 193.59 KiB | Viewed 416 times ]

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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