Author Topic: 25K7400 / 25K7401 Cap Kit List / Blows H.O.T (Read 9725 times)

Kevin Mullins · « **on:** March 10, 2009, 08:22:05 pm »

Anyone have a typical cap kit list for the K7401 handy?
(P763 main board)

I have one that needs done and I have several standard K7000 kits and was just going to piece one together from those and other kits I have around for this K7401 if I have enough.
(just trying to turn it around quickly)

If not, I'll just make one up from the WG parts listing.

Kevin Mullins · « **Reply #1 on:** March 13, 2009, 04:03:13 pm »

In case anyone else goes looking for one:

P763 Main chassis -

C105 - 270uf 400v (main filter cap, not included in kits)
C107 - 33uf 200v
C115 - 100uf 200v
C117 - 22uf 63v
C126 - 1uf 50v
C127 - 470uf 35v
C304 - 1000uf 25v
C305 - 2200uf 35v
C310 - 10uf 200v
C507 - 100uf 16v
C600 - 47uf 16v
C602 - 10uf 25v
C605 - 100uf 35v
C607 - 470uf 35v
C610 - 2.2uf 50v
C613 - 100uf 35v
C615 - 33uf 16v
C616 - 1500uf 35v
C700 - 220uf 16v
C701 - 10uf 25v
C706 - 1uf 50v
C709 - 1uf 50v
C712 - 1000uf 16v
C713 - 4.7uf 25v
C716 - 1uf 200v
C729 - 10uf 50v NP or BP (non-polarized or bi-polar)
C730 - 4.7uf 25v
C731 - 10uf 25v
C732 - 10uf 25v
C805 - 2.2uf 200v
C808 - 2.2uf 200v
C812 - 2.2uf 350v

P719 Neck Board

C501 - 10uf 25v
C502 - 10uf 25v
C503 - 10uf 25v
C504 - 4.7uf 160v
C530 - 10uf 25v

Pincushion board on 23" & 27" models only

C770 - 100uf 25v
C771 - 10uf 50v
C772 - 10uf 50v

Needless to say there were only a few caps that were common with a standard K7000 kit, so don't bother trying to do that like I thought I could get away with.

BTW - Symptom was dead monitor with ticking (shutdown mode)
Cure was Q704 (2SC3686) H.O.T.
Re-capped for good measure.

B+ voltage at TP202 is 117V DC.

Kevin Mullins · « **Reply #2 on:** August 06, 2009, 10:46:52 pm »

Ok...... suggestions, pointers and the like needed.
This 7401 is about to kick my tail, continuously keeps blowing the H.O.T.
Doesn't blow immediately or anything like that. Anywhere from a couple days to a couple weeks. But inevitably it's always a blown HOT. It's in a true gameroom enviroment, so it's on from opening to closing, etc, etc. (10-12 hours daily or so)

Just re-capped it the other day.
B+ is about spot on as it gets. (117-122v)
No whistling or any other unusual noises.
Absolutely beautiful picture when on.
Doesn't do much of anything when off.

I guarantee ya if I go in tomorrow, throw another HOT in it, it'll fire right up and look awesome.
Of course, for how long, who knows.

Have an identical monitor right next to it (dual monitor cab) that hasn't had a problem yet.
Both were NEW about the same time.

Ken Layton · « **Reply #3 on:** August 06, 2009, 11:19:37 pm »

Frequent failure of a horizontal output transistor can be from a bad damper diode.

Kevin Mullins · « **Reply #4 on:** August 06, 2009, 11:37:07 pm »

Would it show as open or shorted ? (guessing if it were shorted I'd have immediate problems)
Or is it going to be one of those iffy ones?

grantspain · « **Reply #5 on:** August 07, 2009, 01:55:54 am »

i have had transistors blow when the high voltage cap on the collector of the HOT has shorted
Maybe its a dodgy batch of transistors-phillips bu2525 springs to mind

Kevin Mullins · « **Reply #6 on:** August 07, 2009, 02:03:26 am »

Definitely open to all suggestions.
It's a 60 mile round trip, so would rather check anything possible next trip down there.

Does D117 sound right on the damper diode location ?
(I was just trying to browse the schematics)

SirPeale · « **Reply #7 on:** August 07, 2009, 09:51:03 am »

Quote from: Kevin Mullins on March 13, 2009, 04:03:13 pm

In case anyone else goes looking for one:

Is that a complete list?

edit: I took that list and made a Mouser project list. Please look it over and see how it looks.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=aee0d8b906

Kevin Mullins · « **Reply #8 on:** August 07, 2009, 11:28:30 am »

Quote from: SirPeale on August 07, 2009, 09:51:03 am

Is that a complete list?

Yes, pretty sure I didn't miss anything. I bounced it off the schematics as well as a Zanen cap list I just got.

Note: The voltages in MY list were from the schematics. Zanen's kit did have several higher voltage caps.

I can scan Zanen's sheet too if you want it.

SirPeale · « **Reply #9 on:** August 07, 2009, 11:36:48 am »

Sure, why not.

Ken Layton · « **Reply #10 on:** August 07, 2009, 11:38:51 am »

Diode D707 in the K7400 monitors is the damper diode. This one's kinda special. It's a Sanyo # DD54RC (Wells-Gardner # 066X0150-001). This sucker is in a TO-220 case and has the center lead cut off (specs: 1500 PRV @ 5 amps! ).

Here's the datasheet:

http://www.datasheetcatalog.org/datasheet/sanyo/DD54RC.pdf

I could not cross this to an NTE replacement.

Kevin Mullins · « **Reply #11 on:** August 07, 2009, 11:53:28 am »

Quote from: SirPeale on August 07, 2009, 11:36:48 am

Sure, why not.

Done.

Quote from: Ken Layton on August 07, 2009, 11:38:51 am

Diode D707 in the K7400 monitors is the damper diode. This one's kinda special. It's a Sanyo # DD54RC (Wells-Gardner # 066X0150-001). This sucker is in a TO-220 case and has the center lead cut off (specs: 1500 PRV @ 5 amps! ).

Thanks a bunch Ken.... I was way off base then on that one.
I'll take a look into it some more.
I do happen to have several parts chassis's, so I may just yank one off those if need be and see what happens. (50/50 shot of it being good)

SirPeale · « **Reply #12 on:** August 07, 2009, 01:36:05 pm »

I'm noting that I do not see the 270UF 400V cap on that Zanen list. That's the main power filter cap, right? If so I'll remove it from the Mouser list since it's /very/ expensive.

Kevin Mullins · « **Reply #13 on:** August 07, 2009, 01:40:48 pm »

Ken - Do you think D708 would have an impact on the H.O.T. as well ? (MUR460)
It's in series with the D707 you pointed out.

I'd just assume change both if there's even a remote possibility.
Especially if I recall correctly those won't check very well with a standard DMM. (?)

Peale - Yes, that's the main filter cap.
I usually make a note of those, guess I missed it this time.
I just like to add them to my lists for reference.

EDIT: Just noted it on my list.
Also note that this list is for the K7500 as well.

SirPeale · « **Reply #14 on:** August 07, 2009, 01:59:21 pm »

Updated the Mouser list to remove that cap. Thanks.

Ken Layton · « **Reply #15 on:** August 07, 2009, 02:13:40 pm »

The MUR460 is a high speed diode which crosses to an NTE577. I would change that out too in addition to D707.

Kevin Mullins · « **Reply #16 on:** August 07, 2009, 02:47:36 pm »

Thanks Ken...... That's kinda what I was thinking too.

qrz · « **Reply #17 on:** August 16, 2009, 10:46:23 pm »

u may wish to also check the "snubber circuit" in the smps.
d107 and r104.

couple of months ago , had the same issue caused by a leaky diode and out of tolerance resistor .
had found NOTHING amiss in the output stage ...... just kept randomly shorting the hot

qrz

Kevin Mullins · « **Reply #18 on:** August 17, 2009, 12:30:10 am »

Swapped the D707 and D708 with ones from a good chassis. Gonna keep an eye on it and see what it does for a little while.
If it continues to happen I'll check out the D107 and R104 qrz mentioned.

Kevin Mullins · « **Reply #19 on:** August 20, 2009, 01:21:41 pm »

Wanted to note that while looking over some parts chassis I came across two K7500's (P793 boards)....

One had the DD54RC for D707, the other had a FMPG2FS for D707.

Haven't looked up the datasheet for the FMPG2FS, but figured it may be an alternative.


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