22nd Feb 2023, 12:48 pm | #21 | |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
Quote:
yes i have the EW circuit repair guide, 59P7A isn't listed on it however parts wise it is the same as the 51K5 with the exception of CL48 being a 11n instead of a 10n5.
__________________
Cheers, Luke |
|
22nd Feb 2023, 12:48 pm | #22 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,932
|
Re: Horizontal Output Transisor Question
Is it not BU208D with the diode protection?
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
22nd Feb 2023, 3:54 pm | #23 |
Octode
Join Date: Dec 2019
Location: Owston Ferry, North Lincolnshire, UK.
Posts: 1,701
|
Re: Horizontal Output Transisor Question
The 51K5 circuit diagram shows the horizontal output transistor as being either a BU508A or an S2000A3. Now if memory serves the BU508AF is entirely plastic encapsulated, whereas the BU508A has a metal rear tab for joining to the heatsink. If that is the case then I would fit the BU508A version with insulator. Also might be worth hooking up a voltmeter to monitor the HT that should be at 158v, as it could be creeping up. Other things to check are the secondary supplies coming from the LOPTX, incase any are putting excessive load on the LOPTX due to leaky diodes and or caps.
Dave
__________________
Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica) |
22nd Feb 2023, 4:55 pm | #24 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,932
|
Re: Horizontal Output Transisor Question
The whole BU508A is metal.
__________________
G8JET BVWS Archivist and Member V.M.A.R.S |
22nd Feb 2023, 9:18 pm | #25 |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
I changed two more parts, CL44 and DL46 and let it run again, this time it made it about 25 mins and then shut down again, this time i had the back off, nothing noticable happened, but when the set tripped the first time and attempted to come on again the whole screen flashed white before it tripped again thats when i powered it off to save the HOT from dying again.
The heat sink the HOT is mounted to is quite warm but not too hot to touch, the other components in that area appear to be reasonably warm also nothing id be overly concerned about, CP41 in front of the LOPT is very warm but not to hot to touch, the line drive transformer windings are quite hot, as in after a second or two i had to remove my finger as it was too hot? is that normal? this is gonna be a frustrating one to figure out, the set behaves completely normal until the trip happens but if i let it trip and go dead and immediately attempt to start again it tries to start as normal then goes into trip condition and then it will kill the HOT, if I let it cool down, it'll run normal for about 20 mins and then do the same thing. anyone have any more suggestions?
__________________
Cheers, Luke |
22nd Feb 2023, 10:11 pm | #26 |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
actually turns out its no heat relaed, i let it fully cool down and attempted to start again and just as the picture appeared it tripped off again.
Could it be the Loptx?
__________________
Cheers, Luke |
22nd Feb 2023, 10:55 pm | #27 | |
Tetrode
Join Date: Dec 2019
Location: Bergen op Zoom, Netherlands
Posts: 65
|
Re: Horizontal Output Transisor Question
Quote:
Is the picture really perfect? No fuzzyness on vertical lines ? (Bad B+ indication). is black real black or do you see diagonal lines very softly? You said the picture flashed white when trying again, did you saw flyback lines? Bright white with lines can indicate a missing +200V (or so) for the RGB amplifiers. A short in the RGB amplifiers can trip the set (check the caps/diodes in this supply). A faulty/shorted/arcing tube can cause these kind of problems too. Last edited by 3CX15000A7; 22nd Feb 2023 at 11:01 pm. |
|
22nd Feb 2023, 10:59 pm | #28 |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
the picture is pristine on it no indication of any fault. When it flashed white, there was no flyback lines (it was like an older tv turning off)
the issue now is it wont even get to display a picture, when i turn it on, it begins to start, eht starts up then the set trips, I cant let it trip more than once because if i do it will cook the HOT. I've changed the loptx too and same results, also changed CP41 and IL14. I'm gonna close it up for now and leave it be for a few hours, i'll attempt to start it later and see how far it gets before tripping.
__________________
Cheers, Luke Last edited by IKC2E51R8; 22nd Feb 2023 at 11:17 pm. |
22nd Feb 2023, 11:30 pm | #29 |
Tetrode
Join Date: Dec 2019
Location: Bergen op Zoom, Netherlands
Posts: 65
|
Re: Horizontal Output Transisor Question
Be very sure there are no bad solder joints, also in the main psu and around IL14.
If the state it is in now (no picture, tripping after ETH) remains, try to measure all the secondary voltages of the LOPT in the short moment it's on. See if one of them is missing. |
23rd Feb 2023, 9:00 am | #30 |
Heptode
Join Date: Oct 2005
Location: Olympia, Washington, USA.
Posts: 664
|
Re: Horizontal Output Transisor Question
Check the solder connections of the driver transformer. often ring cracks can cause problems like this. Also if there is a low value 'lytic on the primary of the driver transformer, (.1-1mfd typically) it may be bad.
When I serviced for a living I always replaced that cap as a PM procedure, and resoldered the leads on he driver transformer. |
23rd Feb 2023, 9:48 am | #31 |
Tetrode
Join Date: Dec 2019
Location: Bergen op Zoom, Netherlands
Posts: 65
|
Re: Horizontal Output Transisor Question
Don't forget to check the connections at the yoke!
Btw, a bit off topic, did you fix your GR2.2 meanwhile?(just curious) |
23rd Feb 2023, 12:44 pm | #32 |
Tetrode
Join Date: Jun 2008
Location: Stratford upon Avon, Warwickshire, UK.
Posts: 80
|
Re: Horizontal Output Transisor Question
Dear Luke,
I would check again for dry joints in the power supply, line driver, line stage and scan coils and change the line driver transistor which I have had problems with in the past. The line driver transformer could also be faulty, is it possible to compare the inductance readings with someone else's transformer? Any resistors feeding the base of the transistor may have changed value, sometimes they are only an ohm or two. I would monitor the temperature of the Line Output Transistor using a K type probe to see how hot it is getting. I have a distant memory of only certain makes of transistor being suitable and others overheating, I might be confusing your set with the TX10 or TX100, it was a long time ago. I used to use a battery powered Tektronix oscilloscope to monitor line drive etc, be very cautious if you use anything else. Best wishes, Geoffrey. |
23rd Feb 2023, 1:55 pm | #33 |
Dekatron
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 7,498
|
Re: Horizontal Output Transisor Question
This might be a bad mica insulator between the transistor and its heat sink.
Double check all the heatsink jojnts to the main pcb earth. I once had this tripping off problem with a latter ICC set and it was the line o/p transformer at fault
__________________
Regards, Ben. |
23rd Feb 2023, 3:05 pm | #34 |
Heptode
Join Date: Mar 2011
Location: Dorset, UK.
Posts: 521
|
Re: Horizontal Output Transisor Question
Might be worth checking components around line driver transformer (LL32) primary.
First candidate would be the 2.2μF electrolytic capacitor (CL26). Replacement should be low ESR and designed for high frequency operation. Driver transistor BC639 (TL29), depending on manufacturer but usually Telefunken, has often been known to develop an intermittent open circuit base-emitter connection. Sudden cessation or intermittent drive will destroy the HOT. Timing of the horizontal drive mark space ratio is fairly critical. Really need a 'scope for tracking down this type of fault. Also worth checking that 150Ω resistor (RL29) or 33nF (CL29) have not gone open circuit. Rich
__________________
To an optimist a glass is half full; a pessimist half empty; an engineer twice as big as need be! |
23rd Feb 2023, 3:22 pm | #35 |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
original fault is probably irrelevant at this stage as the current status of the set is dead. on power on the LED flashes on once, the set makes a slight 'click' sound then completely dead. the led will flash again when i push the power button to turn the set off.
I've changed all the usual suspects in the stock fault list for this fault and same result. The HOT may have been killed again but its not measuring short anyway. I'm 100% lost at this point, i dont know what's up with it.
__________________
Cheers, Luke |
23rd Feb 2023, 3:27 pm | #36 | |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
Quote:
It will be brought out of retirement soon if I cant get this ICC5 going again.
__________________
Cheers, Luke |
|
23rd Feb 2023, 4:26 pm | #37 |
Tetrode
Join Date: Dec 2019
Location: Bergen op Zoom, Netherlands
Posts: 65
|
Re: Horizontal Output Transisor Question
I think the first step now would be getting a scope . .
For around 100euro you can find a basic one on the second hand market. It will be a good investment when collecting/saving vintage equipment. Good to hear the gr2 works again fine! |
23rd Feb 2023, 5:46 pm | #38 |
Octode
Join Date: Dec 2019
Location: Owston Ferry, North Lincolnshire, UK.
Posts: 1,701
|
Re: Horizontal Output Transisor Question
If it's totally dead in standby have you checked CP44, IR73, DP45, TP15 and possible dry joint on RR30. Dead and or tripping TL31, RP43,DP44, DL51, IR81,CL21, CL16, IL14, DL51, o/c print between RL18 and base of TL17, CP23, CL48, CP29, IL14, IR73. Check LOPTX for s/c in windings eg between pins 11 to 3 and pin 9 to earth.
All the above was listed in the HRS fault finding guide, perhaps something there is relevant. Dave
__________________
Quote "All is hyperthetical, until it isn't!" (President Laura Roslin, Battlestar Galactica) |
24th Feb 2023, 12:28 am | #39 |
Hexode
Join Date: Aug 2018
Location: Dublin, Republic of Ireland.
Posts: 493
|
Re: Horizontal Output Transisor Question
most of those components ive either tested or replaced.
now the strangest thing, i left it alone for a few hours, and ive just tried to start it now. First attempt, rush of EHT and tripped off (more than it had been doing) Second Attempt, EHT started up, set appeared to be turning on 1 displayed on the front, tripped off after about 3 seconds third attempt, EHT started up, set appears to be on, 1 displayed on the front, No picture Nothing, no attempt to light the screen, i let it run for close to a minute then i turned it to standby just in case something dies. set is still in standby with standby LED lit as i type. I've two Questions, 1. why all of a sudden is it doing more now than it had been doing 3 hours ago 2. Why no picture - there is deflection, i can hear it, but nothing at all on the screen
__________________
Cheers, Luke |
24th Feb 2023, 1:03 am | #40 |
Tetrode
Join Date: Dec 2019
Location: Bergen op Zoom, Netherlands
Posts: 65
|
Re: Horizontal Output Transisor Question
It seems to make all different kind of faults. Are you really sure their are no bad solder joints around the lopt?
Are there voltages missing secondary of the lopt?(heater?) |