HELP WANTED to locate Diode

G'Day to all at VC,
I'm hoping someone may be able to help me find a BB 3H diode for a Multi-Channel analyser c.1973 Model.
We have looked in catalogues, parts supplier websites and googled the codes to no avail.
We recently had a power surge and lost the unit. My collegue has performed checks and found one of three of these diodes on the board is dead - this is most likely our problem and we would dearly love to get it going again.
If anyone could please help us in our search we would be very appreciative.
Some other useful info:
Model # of the MCA is Matsushita M-9004NA Deflection Yoke Part # Panasonic TLY80339A .
Model # of CRT: 240AKB4(N)
Chassis family # is FA3520248
Thank you to anybody who tries to help :D:D:D

diodes

diodes

It looks like they're damper diodes in a snubber circuit. Is the CRT fairly small ? You might be able to use something like a 1N4007 (1A/1000V) or a NTE558 (1A/1500V) (Datasheet for NTE558 attached.
The plug on the pic is where the deflection yoke attaches, right ?
patscc

I looked through my component reference books.
All I could find is the diode series of: BB1, BB2, BB4, BB6, BB8, BB10
Described as "high speed, general purpose".

The book suggested the following replacements:
BB1 --> RGP10B or NTE506 .......... where (RGP10B=1A/100V/150nS)
BB2 --> RGP10D or NTE506 .......... where (RGP10D=1A/200V/150nS)(NTE506=2A/1400V/500nS)
BB4 --> RGP10G or NTE552 .......... where (RGP10G=1A/400V/150nS)(NTE552=1A/600V/200nS)
BB6 --> RGP10J or NTE552 .......... where (RGP10G=1A/600V/250nS)
BB8 --> RGP10K or NTE506 .......... where (RGP10G=1A/800V/500nS)
BB10 -> RGP10M or NTE552

If (repeat: if) your BB3H is in the same series, the above 'replacement' info suggests for BB3:

Max. forward current = 1A
Max. reverse voltage = 300V (based on the RGPxxxx replacements)
Recovery time = around the 200nS mark

EDIT: I did also look for variations of 3HBB

We really, really DO have an amazing range of talented people hanging out around here. There appears to be so much knowledge that if there were only one person, instead of billions, their head would explode or melt or something.

I vaguely remember someone saying something about designing radio receivers on scraps while sitting on the can. Like I said, amazing.

OMG U Guys are Tops THANX a MILLION !!

OMG U Guys are Tops THANX a MILLION !!

Thank you Very Much for your Help.

Patscc - yes that is where the yoke plugs in - yes the CRT is fairly small. Thank you for the data sheet this is very helpful, you guys are amazing, my boss is :mrgreen:.

Modem7 - thank you, we appreciate your time and effort. That component book is gold !! What a legend.

THANKS PPL :-D:-D:-D
I'D LOVE TO BUY YOU A BEVERAGE - ONE DAY WE JUST MIGHT

amazing

amazing

We're not that amazing. If we were amazing, someone would have had the diode in their junk box.
Post back if you guys get it going.
patscc

HOT & Vertical

HOT & Vertical

Just to throw out something else, in case the diode blew for a reason, did you guys check your horizontal & vertical output stages to make sure they're not shorted ?
patscc

belairjo said:

I'D LOVE TO BUY YOU A BEVERAGE - ONE DAY WE JUST MIGHT

Click to expand...

You can...it's cyberspace, anything is possible!...<T tips a virtual pint>...Hell! A round for the house, wench!

--T

Slop Slop Slurp Slurp

Slop Slop Slurp Slurp

:toast:
Here ya go ! Cheeeers to yaz all !!

:drunk:

Hot n Vertical

Hot n Vertical

Yes my colleague assures me he has checked those; although he just commented that without the diode he cannot test them?

He thought it was the deflection yoke blown at first because there is a very fine yoke wire loose - not sure where or if it should be attached.

static test

static test

Not test under power, a static test. Just a check to see if the HOT and/or vertical out is shorted or not.
Just to be nosy, how did the diode fail ? Did it open up or short out ?
I guess you guys don't have the schematics ?
What are the DC resistances on the yoke's coils ?
Can you post a picture of the loose wire ?
While you're at it, and if you're so inclined, some pictures of the doohickie in general would be appreciated. Nothing like ogling someone else's problem.
patscc

DC Resistances & Pics

DC Resistances & Pics

GDay Patscc,
Appreciating your ogling very much. Thank you, sorry havent got back to you before now.
Apparently the old diode is still conductive both ways. We have replaced the diode and still not getting the screen up.

The DC resistance is 1.9M ohms btw the inside wires (Blue/ Grey) 1.9M ohms btw the outside (Yellow/ red) No registration btw Red/ Grey. Not getting reading on the lower settings (4M or 40M).
Please see pics attached.
You might be best to use pic 60 to zoom in.
Thanks again for your assistance. Good luck.

The depopulated look of the PCB makes me wonder if this thing is nothing more or less than a generic monochrome PC display. (Hey Pat, I wonder if the FBT is an 8-lead model...)

I've got a schematic for a Panasonic OEM monocrhome display, but it's considerably more complex than this one. You're welcome to it if it'll help.

Stop Looking !!

Stop Looking !!

CRT Solutions Solves our Restoration Puzzle!

Thank You Modem7 for referring us to CRT Solutions

http://www.crtsolutions.com/

They were able to provide us with a circuit board and replacement yoke.

Thanks to all who offered assistance and advice - very much appreciated.
:mrgreen: