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My old grundig is semi-dead

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t0nito
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Oct 27, 2013, 12:22 AM

Post #26 of 76 (1447 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

Ok, thank you for your patience :) I'll order it it's a cheap part anyway :D

Funny you say that because I do hear a high pitched pulsating noise from the set when I plug it in, but it has always done that even when it worked, instandby I could always hear this high frequency, but it is not the same as the 15KHz whine.

(This post was edited by t0nito on Oct 27, 2013, 12:25 AM)

Ron.M
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Oct 27, 2013, 12:33 AM

Post #27 of 76 (1445 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;......

Put the negative lead (Usually the black wire) from your meter on either side of R521 ...
If you can't find R521 , connect your meter to the emitter pad on the board with the red wire from your meter...

Quote

This schematic is from this flyback but it's confusing as pin A (1) doesn't look like ground to me.

According to the schematic , it's NOT !!!
Pin "A" is the collector of "T661" the primary driver transistor...

Later...Ron.M... Cool

..
Veteran & Retired TV technician

t0nito
User

Oct 27, 2013, 12:38 AM

Post #28 of 76 (1441 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

with the red on the emitter pad pin L M and N shows 14V

Ron.M
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Oct 27, 2013, 12:46 AM

Post #29 of 76 (1435 views)
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Post deleted by Ron.M [In reply to]

t0nito
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Oct 27, 2013, 12:48 AM

Post #30 of 76 (1431 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

I did that Ron, I put the red lead on the emitter pad and used the black one on L M and N also switching between on and standby made no difference.

(This post was edited by t0nito on Oct 27, 2013, 12:50 AM)

Ron.M
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Oct 27, 2013, 12:52 AM

Post #31 of 76 (1425 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;.....
You are correct !!!.. Smile

...
I screwed up.... Crazy

...
I'll see you when you get the replacement....
Do not install it in the set till you post back...

Later...Ron.M... Cool

...
Veteran & Retired TV technician

t0nito
User

Oct 27, 2013, 12:54 AM

Post #32 of 76 (1422 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

Ok, thanks Ron I'll be ordering one right now.

See ya ;)

jts1957
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Oct 27, 2013, 1:11 AM

Post #33 of 76 (1420 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

NOT the typical voltage regulator / horizontal drive / output that we're used to Ron. Cool

-------------------------
Location: Far, Far Away

(This post was edited by jts1957 on Oct 27, 2013, 1:24 AM)

Ron.M
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Oct 27, 2013, 5:26 PM

Post #34 of 76 (1406 views)
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Re: [jts1957] My old grundig is semi-dead [In reply to]	Can't Post

jts1957;....

Yup , yup , yep...
I'm usually pretty good on the uptake...
Methinks (& hopes) that the transistor will fire up the power supply IF all is well there...

Later...Ron.M... Cool

...
Veteran & Retired TV technician

t0nito
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Nov 5, 2013, 1:57 PM

Post #35 of 76 (1388 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

Hi Ron, the transistor arrived today, you told me to tell you before I install it.

Ron.M
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Nov 5, 2013, 6:26 PM

Post #36 of 76 (1383 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;...

OK...

Is it the same number as the original ???

What I'd like you to do is compare readings with the new transistor against the original as follows;=>...
New transistor;=>..
Collector to base;=___
Collector to emitter;=___
Base to emitter;=___
Base to collector;=___
Emitter to collector;=___
Emitter to base;=___

Original transistor;=>...
Collector to base;=___
Collector to emitter;=___
Base to emitter;=___
Base to collector;=___
Emitter to collector;=___
Emitter to base;=___

Fill in the blanks...

Thanks.... Smile

...

Later..Ron.M... Cool

..
Veteran & Retired TV technician

t0nito
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Nov 5, 2013, 8:08 PM

Post #37 of 76 (1371 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

New: BU508D - (S0335 in smaller numbers)
Old: BU508D - (S9524 in smaller numbers)

Damn, I think I screwed up, it seems like the old transistor is good after all, I was using the Ohm setting last time, this time I used the diode/continuity mode and comparing to the new one ot seems to be quite close.

New transistor;=>..
Collector to base;=476
Collector to emitter;=504
Base to emitter;=44
Base to collector;= infinite
Emitter to collector;=infinite
Emitter to base;=44

Original transistor;=>...
Collector to base;=471
Collector to emitter;=500
Base to emitter;=48
Base to collector;=infinite
Emitter to collector;=infinite
Emitter to base;=48

Ron.M
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Nov 5, 2013, 9:15 PM

Post #38 of 76 (1360 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;....

My bad... Crazy

...
I wanted ohms !!!.. Unsure

....

Quote

(S0335 in smaller numbers)
(S9524 in smaller numbers)

Where are these numbers from/at ????

I'll be offline for about 3~4 hours due to computer repair... Unimpressed

...

Later..Ron.M... Cool

...
Veteran & Retired TV technician

t0nito
User

Nov 5, 2013, 10:36 PM

Post #39 of 76 (1357 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

That's OK, it's a little late here.

The numbers are written on a second line under.

Like these (the on the right is the same as mine)

t0nito
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Nov 6, 2013, 7:31 PM

Post #40 of 76 (1341 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

So what's the next step?

Ron.M
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Nov 7, 2013, 3:49 AM

Post #41 of 76 (1335 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;....

I'm still waiting for you to finish up posting info I asked for:=>....

Quote

My bad...

...
I wanted ohms !!!.. Unsure

....

What I'd like you to do is compare readings with the new transistor against the original as follows;=>...
New transistor;=>..
Collector to base;=___
Collector to emitter;=___
Base to emitter;=___
Base to collector;=___
Emitter to collector;=___
Emitter to base;=___

Reverse meter leads;...

Original transistor;=>...
Collector to base;=___
Collector to emitter;=___
Base to emitter;=___
Base to collector;=___
Emitter to collector;=___
Emitter to base;=___

Thanks.... Sly

....

Later...Ron.M... Cool

Veteran & Retired TV technician

(This post was edited by Ron.M on Nov 7, 2013, 3:50 AM)

t0nito
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Nov 7, 2013, 2:10 PM

Post #42 of 76 (1326 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

I feel really dumb now. I had the meter leads broken so in the first reading before I ordered the transistor I was holding the meter wires with my fingers and that must have caused bad readings.

Now I resoldered the leads back and measured without touching.

Anyway the resistance results are:

(Black lead = From, Red lead = To)

New transistor;=>..
Collector to base;= 6 MOhm
Collector to emitter;= 6MOhm
Base to emitter;= 0 Ohm
Base to collector;= Infinite
Emitter to collector;= Infinite
Emitter to base;= 0 Ohm

Original transistor;=>...
Collector to base;= 7 MOhm
Collector to emitter;= 7 MOhm
Base to emitter;= 0 Ohm
Base to collector;= Infinite
Emitter to collector;=Infinite
Emitter to base;= 0 Ohm

(This post was edited by t0nito on Nov 7, 2013, 2:25 PM)

Ron.M
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Nov 7, 2013, 8:32 PM

Post #43 of 76 (1317 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;...

Well , the original transistor IS & WAS good...

Now lets do this;=>...

Put either a new transistor or the original transistor back in the TV...
Have your meter ready to go on +DC volts (to read about +125 vdc)...
Connect the "-" lead to either side of R523 or the emitter of T521...
Locate pin "M" or pins 16 or 17 on TR665 (HV Transformer)...
Set the chassis in a safe position so you can put the red "+" lead to that connection when the set is turned on...
Please note that I want the leads hooked up AS you turn the TV on to see IF there is a brief start up pulse...
Turn the TV on & read volts...
Post reading & pulse info.......

Later..Ron.M.... Cool

..
Veteran & Retired TV technician

t0nito
User

Nov 7, 2013, 8:52 PM

Post #44 of 76 (1314 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

Hi ron.

Result 0V no pulse whatsoever.

Tried while plugging the tv on, and while turning on with the remote.

t0nito
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Nov 7, 2013, 9:07 PM

Post #45 of 76 (1308 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

Don't know if it helps but looking at traces of solder flux on the primary side of the board, it looks like the main switching transistor T661, r641, C667 maybe even IC655 have been replaced before.

(This post was edited by t0nito on Nov 7, 2013, 9:08 PM)

Ron.M
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Nov 7, 2013, 9:16 PM

Post #46 of 76 (1302 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;.....

Time to start looking at the power supply....

With the TV off & unplugged , find T661 (On the primary side of TR665)..
Read ohms across all 3 legs as you did with T521...
E,B & C.....
Post readings...

Later...Ron.M... Cool

...
Veteran & Retired TV technician

t0nito
User

Nov 7, 2013, 9:24 PM

Post #47 of 76 (1299 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

Don't know if it's because of residual charge in the capacitors but resistance isn't stable.

The longer I hold the leads the higher the resistance goes, should I remove the transistor from the board?

It's my meter, it seems to be charging some capacitor, after releasing for a while the reading lowers again, LOL I'm such a noob.

(This post was edited by t0nito on Nov 7, 2013, 9:28 PM)

Ron.M
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Nov 7, 2013, 9:36 PM

Post #48 of 76 (1290 views)
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t0nito;...

Yeah , remove it from the board...
Your meter is changing possibly from some voltage that was there from the last test..

Later...Ron..... Cool

..
Veteran & Retired TV technician

t0nito
User

Nov 7, 2013, 9:45 PM

Post #49 of 76 (1289 views)
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Re: [Ron.M] My old grundig is semi-dead [In reply to]	Can't Post

So I ran out of patience with my meter so I took it off the board.

Emitter to Collector = INF
Emitter to Base = 1.2 MOhm
Base to Collector = INF
Base to Emitter = INF
Collector to Base = 742 Ohm
Collector to Emiiter = INF

with it still on the board was 98 Ohm between Emitter to Base and also Base to Emitter

Measuring the pads/foils on the board:

Base to Emitter and Emitter to base 98 Ohm
Collector to base, base to collector, collector to emitter and emitter to collector the value just keeps rising as long as I keep the meter there as before.

(This post was edited by t0nito on Nov 7, 2013, 9:46 PM)

Ron.M
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Nov 7, 2013, 9:50 PM

Post #50 of 76 (1286 views)
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Re: [t0nito] My old grundig is semi-dead [In reply to]	Can't Post

t0nito;...

There's a problem with this reading....
""Collector to Base = 742 Ohm"....
Please recheck that reading....
Thanks....

Later...Ron.M.... Cool

..
Veteran & Retired TV technician

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