Sony CPD 420GS

[weirdlookinguy]

Hey everyone, my Sony CPD-420GS (19" CRT Computer Monitor) lost Horizontal Deflection the other day. I can't find any burned resistors or components inside, and I swapped out a few bad caps. Didn't help.

Can you guys help me? Tossing it and buying another used one or an LCD is not an option. I have the repair manual.

Thanks,

-weird

[Krankshaft]

Re: Sony CPD 420GS

Check the HOT (Horizontal Output Transistor) with the diode function of your multimeter.

It will be on a big heatsink near the flyback.

[weirdlookinguy]

Re: Sony CPD 420GS

There are two, I will check both. One is a IRFI9634G (Labeled Q901) and the other is a FS7KM-18A (Q902). Q902 is a cross for NTE 2960, I couldn't find any crosses for IRFI9634G. Can you tell me what readings I should get? Neither looks burnt or damaged in any way. Also do you think bad caps could cause this? I've replaced a few bad caps on the neck board and the left side of the chassis, but haven't checked any caps on the right side (side w/ the flyback). Could they be the cause? I ask because I can't get either Q901 or Q902 locally, so I don't want to replace them unless I know for a fact they are the cause of the problem.

Thanks a ton. I was starting to lose hope on this monitor.

[weirdlookinguy]

Re: Sony CPD 420GS

OK, Q902 looks to be bad. I googled how to test transistors and on a normal transistor, you should get a value (like 0.980 for example) when you test it one way and no conductivity when you test it the other. On Q902 (FS7KM-18A) I get 0.908 one way and 0.600 another, according to the guide I read that is bad.

One thing though, the schematics in the repair manual clearly state Q902 as being a FS7KM-18A. The Q902 that's actually on the board is a FS5KM-18A. Does it matter which one I replace it with? FS5KM crosses to NTE 2959, and FS7KM crosses to NTE 2960.

Are there any other replacements I can use? I pulled apart an older 15" Trinitron but to my dismay there was no FS7/5KM in there. I can't get NTE 2959 or 2960 locally, all I have is Radio Shack and Fry's. Fry's stocks a lot of NTE but they don't have anything in the 2900 range. I's rather not buy anything online, buying online is nearly impossible for me.

EDIT: According to this: http://www.anatekcorp.com/faq/monitor.htm, Q901 and Q902 drive the flyback in a Dell P991, which uses the same chassis as my monitor. I still have HV, just no horizontal, so Q901/Q902 can't be the problem, right?

[weirdlookinguy]

Re: Sony CPD 420GS

OK, big update: The HOT is a Hitachi 2SC5530-01, Part # Q505 inside the chassis. It is SHORTED, according to my multimeter. I'm pretty sure this is the source of the problem. The only problem now is finding a replacement. There is no NTE cross for this. I doubt radio shack will have it, and I don't think Fry's will have one. I must buy locally. Can you suggest a replacement? Also I have a 15" Trinitron monitor made in 1996 (the 420GS is a 1999 model). Do you think it will have the same HOT, maybe I can pull it from there?

Thanks a lot, waiting on your reply.

[kc8adu]

Re: Sony CPD 420GS

where are you?
i know i have gotten these from cei
www.ceitron.com
they are local to me and great to deal with.
be warned that there is abuck converter that feeds the h-out stage that will have a shorted fet.
you MUST repair it or the new hot will die in seconds.
also resolder the h-drive transformer.
that seems to be the most common cause of hot death.

[tvtech]

Re: Sony CPD 420GS

Kc8's right there will be another shorted fet,I forget on which heatsink the fet was on,Try not use any NTE replacements for power trans. or FET's they don't last very long,go with an original part.And since your HOT is shorted it may be a good idea to check the flyback for burns or signs of arcing,look close to where the anode lead exits the fly.Also do as suggested and resolder the HDT and connections surrounding it.As for pulling the HOT from your other monitor,Probabaly not as it may be a different chassis but you can check.

[kc8adu]

Re: Sony CPD 420GS

the fly on these is driven independant of h-out.
and nte is not much better than the crooks that remark lesser speced parts for a quick buck.
its surprising how many counterfiet parts are out there.
warning signs can be a too good to be true price on an expensive or hard to find part.
large monitor hots and stk's top the list.high power audio and rf transistors not far behind.

[weirdlookinguy]

Re: Sony CPD 420GS

The 15" Trinitron did not have the part. It was unlikely that it would but it was worth a shot. Anyway, I have found the HOT online:

http://www.bluestar-online.com/2SC55...FQ6NHgodr0oAFQ

I don't know if it's an original. I've bought stuff from these guys before and they are trustworthy. I didn't mention this before, but before it died, the image kinda flinched a few times every few minutes before it gave up. Immediately after Horizontal collapsed, I shut off the monitor. Upon turning it back on, the vertical line would appear for a second or two before the monitor shut itself off and the power line started blinking. Now, I don't get the vertical line, but that's probably because the tube doesn't have enough time to warm up before the monitor shuts off. Do you guys think that points to bad soldering on H Drive, shorted FET, or is it insignificant?

[tvtech]

Re: Sony CPD 420GS

Yes probabaly shuts down before the tube can warm up.Yes you probabaly have bad connections and that was causing you to lose deflection,I would inspect the entire horizontal section.Resolder the drive transformer and carefully inspect all other conections in the horizontal section.Don't be surprised if you have to resolder almost every connection,some of the older sony tv's and studio monitors I worked on I had to resolder nearly all of the connections in the set,especially the studio monitors that had run 24/7 for 7-10 years due to the heat.As for the replacement transistor you found,iv'e never heard of that reseller before but they look reputable,but I would browse around and see if you can find the original hitachi part first.The worst part is about the bogus parts is that most of the parts suppliers that sell the parts to you dont even know that they are knockoffs.The best way to know if you have an original part is look at the markings,most of the major japanese manufacturers,st,toshiba,hitachi,fairchild will laser etch the part number and their logo or name on the part not use an ink stamp.BTW-kc8 what kind of python is that in your avatar?

[weirdlookinguy]

Re: Sony CPD 420GS

I think I'm going to have to go with the bluestar one, I really didn't want to have to order online since I have to get my dad to order it for me, but I am going to try and see if I can send them a money order or something. I don't know if it's an original but right now it looks like it's the only one I might have access to. I will replace and resolder everything, as well as check any FETs I can find. FET's are three-pin devices on heatsinks that look similar to the HOT, right? There's one right next to the HOT.

[tvtech]

Re: Sony CPD 420GS

I think I'm going to have to go with the bluestar one, I really didn't want to have to order online since I have to get my dad to order it for me, but I am going to try and see if I can send them a money order or something. I don't know if it's an original but right now it looks like it's the only one I might have access to. I will replace and resolder everything, as well as check any FETs I can find. FET's are three-pin devices on heatsinks that look similar to the HOT, right? There's one right next to the HOT.

Yes FET's are three pin transistors and are usually mounted on heatsinks,just check the large transistors on the board or that are mounted on heatsinks,dont worry about the small half-circle shaped ones yet.As for trying to find your FET I may have a good used one here as I have scrapped some newer sony CRT monitors due to obselecence and may have saved the HOT from them.Here I couldn't even get 10-15 dollars for a 19" CRT monitor so most of them get scrapped.

[weirdlookinguy]

Re: Sony CPD 420GS

I appreciate that tvtech. I'm leaving on a two week vacation in a couple hours, so I won't get back to this monitor until after new years, but I will revive this thread once I get back. Thanks a lot for the help everyone, talk to you in 2 weeks.

[weirdlookinguy]

Re: Sony CPD 420GS

Well guys, looks like it ends here. When my dad found out it would take $20 to (maybe) fix the Trinitron, he told me to trash it and offered to help me pay for a new LCD, if I get decent grades and use some money saved from my summer job. I tried to convince him to let me fix the Trinitron but he said he wouldn't let me keep pouring money into a nearly 10 year old monitor (I already put about $20 worth of new caps into it). I wasn't really convinced at first but I found this really nice HP at Fry's that I really liked. Looks like I'll be scrapping the board, saving the new caps I installed, the flyback, coils, etc. Kinda sad but at the same time I wouldn't mind a 16:9 display, so...

Thanks for helping me try to save this monitor.