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Yamaha CR-600 and Cr-800 help and ideas needed!

The values on fusible resistors have been measured out of the board.
Unfortunately I cannot find new fusible resistors with 500mWatt, so they have to go back.

Can you recommend any alternate for these fusible resistors just in case if they go bad?
 
Question for Avionic:

I'm a little dumb when it comes to wattage and paralleling resistors. Does the wattage double?

I ask because if pa_200 can't find any 3.9 ohm 1/2 fusible I have some Yageo and TE Connectivity 4.7 ohm and 10 ohm 1/4w. One of each soldered in parallel measures 3.8-3.9 ohms (bounces between) with my Fluke 79 True RMS.

Any chance this would be useful? Because I'm not all that far from pa_200 and can send him some if needed and they work.

All this because I was searching and not finding any 3.9 ohm 1/2w in fusible or flameproof.

Cheers,
James
 
Two quarter watts in parallel will handle 500mw
pa_200 said:
Today I recheck the power circuit board and measured the 8 Fuse resistors. Seven of it are hat good values but there was same change on der FR807.

According to the manual it should be 3,9 Ohm 1 Watt, but it on the board there was a sticker saying 3,8 Ohm 500mW. The resistor was down to 2,73 Ohm.
View attachment 1431636
I can order the same value or would one of you recommend an increase from 500mW to 1 Watt like it is in the manual?

The FR804 and 805 still have 3,8 Ohm but I will change them as well for new ones.
Click to expand...
Thats not 500mw Thats 3.9Ω at 500ma...(Milliamp);)
 
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Those resistors are much larger than 1/2 watt !
Use a 3.9Ω at 1 watt...fusible or flame proof..:thumbsup:
 
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A 3.9Ω resistor at 500ma will need to be capable of withstanding .975 watts before it burns open. Closest common value is 1 watt.
 
Avionic, that sounds very good. After which formula did you convert the value?
I would like to convert the values from the other FR also.
 
In the meantime I could ask a friend to help my with the calculation and he gave me the two “magic formula” U= R x I and the second one P = U x I

With that the calculation is quite simple like (R) 3,9 Ohm x (I) 0,5amp = (U) 1,95volt

Since we want the value for watt, than the second formula is needed.
P = U x I, (U) 1,95volt x (I) 0,5amp = (P) 0,975 W

With that formulas I could calculate for all the fuse resistors the values in watt!

3,9 Ohm 500mA = 0,975 W
3,8 Ohm 500 mA = 0,95 W
47Ohm 100 mA = 0,47 W
100 Ohm 70 mA = 0,49 W
220 Ohm 45 mA = 0,4455 W
470 Ohm 30 mA = 0,423 W

So we have to take allways the closest common value like 0,5 and 1 watt
 
pa_200 said:
In the meantime I could ask a friend to help my with the calculation and he gave me the two “magic formula” U= R x I and the second one P = U x I

With that the calculation is quite simple like (R) 3,9 Ohm x (I) 0,5amp = (U) 1,95volt

Since we want the value for watt, than the second formula is needed.
P = U x I, (U) 1,95volt x (I) 0,5amp = (P) 0,975 W

With that formulas I could calculate for all the fuse resistors the values in watt!

3,9 Ohm 500mA = 0,975 W
3,8 Ohm 500 mA = 0,95 W
47Ohm 100 mA = 0,47 W
100 Ohm 70 mA = 0,49 W
220 Ohm 45 mA = 0,4455 W
470 Ohm 30 mA = 0,423 W

So we have to take allways the closest common value like 0,5 and 1 watt
Click to expand...
http://www.ohmslawcalculator.com/ohms-law-calculator
To use the calculator you only need to insert two parameters. ie. 3.9Ω and 500ma and press calculate.
 
Brilliant that is a link I was looking for. Thanks and many happy landings for the Eagle
Roland, as well Ret. GAF 1978-1998
 
Now I have change all the capacitators on the power board.

Unfortunately we all have a very bad SM-scan which makes it hard to find out the correct number and position on the board, so I made a picture after removing all the old ones and use it now as a nice layout and marked every position with its value. You can find all the values without the layout as well in the beginning of this threat at post nr. 15.
Hope it will be a help as well for every other CR-800 owner
CR_800_Power_circuit_board_position_and_values_of_all_capacitors_according_to_the_service_manual.jpg
 
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pa_200 said:
Now I have change all the capacitators on the power board.

Unfortunately we all have a very bad SM-scan which makes it hard to find out the correct number and position on the board, so I made a picture after removing all the old ones and use it now as a nice layout and marked every position with its value. You can find all the values without the layout as well in the beginning of this threat at post nr. 15.
Hope it will be a help as well for every other CR-800 owner
Click to expand...

Nice work.

Cheers,
James
 
pa_200 said:
Brilliant that is a link I was looking for. Thanks and many happy landings for the Eagle
Roland, as well Ret. GAF 1978-1998
Click to expand...
https://en.wikipedia.org/wiki/Roland_(missile)

I was stationed at Bitburg 1980-82
bitburger_logo_BWV.png
1d3801e229037d6a4b027b6f40febb3b.jpg
 
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After the successful recap on the power board I still have problems when I use the radio on my Cr-800.
With the selector in tuner mode, the radio starts at a lower volume and sound like mono, after around 10 seconds comes a small blob and the volume gets a bit louder, sometimes it feels like moving a little bit in the frequency, but the tuner is stable in the middle.
Then after about 2 minutes I get a second or third “blob-sound” and it feels like running now in stereo. Waiting another few minutes of warmup time, suddenly everything is fine and die Cr-800 runs without any further problem.

Does anyone here know the same problem and can give me an idea where to look at?
 
I have no experience with any of those CRxxx amps or with tuners, so I can't do much to help other than to bump this thread to place it in view again.

I suppose that if the amp were in front of me I would be checking all of the solder connections in the rest of the amp first.

Cheers,
James
 
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