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Old 26th Mar 2010, 4:31 pm   #41
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Default Re: Tv62

F1 is the HT fuse which you need to pull. If you're not sure which is which, do the resistance test across the mains again. When you pull F2 the resistance will go high, when you pull F1 it won't.

Give it 5 minutes around 150V, then wind it up to full mains. All valves except the EHT rect will light up and the dropper will get nice and hot. Don't worry about a small amount of smoke and a horrible smell. It will pass.

Then you can plug the set in directly and use the variac on HT only as I suggested. Do make sure your variac is wired corectly with common neutral. It should always be done this way but it really matters this time.

Do you have a 405 line source yet? If not, see if one of the kind TV guys in the Newcastle/Durham area will lend you an Aurora. Makes life much easier and it's nice to hear sound and see a picture.
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Old 26th Mar 2010, 4:36 pm   #42
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Default Re: Tv62

No Aurora yet it's on order should be here around April
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Old 26th Mar 2010, 4:48 pm   #43
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Default Re: Tv62

Ok
Filter cap snipped
F1 pulled
Variac at 150V
I can Hear a Humm from the speaker, sounds like smoothing Humm
Will wait 5 mins now
hmmm i love that warm dusty valve smell, heaters lit

Ps.
Can't see how I can do the second part of your process as My Variac does not have outputs other than the 3pin socket (see photo)
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Old 26th Mar 2010, 5:04 pm   #44
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Default Re: Tv62

I wouldn't expect a hum from the speaker at this stage. You need a working audio amp for that which needs HT.

For part 2, plug the TV directly into the mains so the heaters get full volts. Make yourself a nice lethal mains plug to croc clip lead. I usually use a Safebloc and a couple of flyleads or an IEC male with a length of flex rather than the traditional mains to croc clip lead. Plug that into the variac, connect the neutral to chassis and live to the end of F1 that's connected to the anodes of V18/V19. Make sure that both TV and variac are running from the same RCD otherwise you'll have funny trip problems. Make sure that variac neutral is the same as mains neutral - use a meter with power off - otherwise something will complain.

Be aware that there is no single point of isolation with this setup. Make sure both plugs are unplugged before you go delving.
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Old 26th Mar 2010, 5:06 pm   #45
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Default Re: Tv62

Ok I'm at 190V the humm is loud and it does sound like smoothers. Should I stop now.
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Old 26th Mar 2010, 5:19 pm   #46
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Default Re: Tv62

The smoothers aren't even in circuit with F1 pulled! All that should be energised is the heater dropper, L47 and the heaters themselves. Do some measuring to check that mains really isn't getting to the HT rectifiers.

Possible longshot problem of C111. I think this injects a bit of antiphase hum into the HT and could be short circuit. If it is then some valves will be lit up rather brightly while others may be hardly lit at all. Clip out C111 just to be sure.
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Old 26th Mar 2010, 5:24 pm   #47
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Default Re: Tv62

Hi Jeffrey, thats exactly the scenario, Some are bright the PCF80 and EB91 nearest the back of the case are faint , I swapped the PCF80 as I thought it was dead (old one back in place now). Turned out the lights and it could be seen.

When you say measure mains is not getting to the rectifiers do you mean C95,96 & 97

Last edited by oldticktock; 26th Mar 2010 at 5:47 pm.
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Old 26th Mar 2010, 5:39 pm   #48
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Default Re: Tv62

Quote:
Originally Posted by oldticktock View Post
Hi Jeffrey, thats exactly the scenario, Some are bright the PCF80 and EB90 nearest the back of the case are faint , I swapped the PCF80 as I thought it was dead (old one back in place now). Turned out the lights and it could be seen.

Do you mean measure on MR1 & 2
This set has valve HT rects! V18 and V19, both PY82. Can't even find MR1 and MR2 on the circuit at the moment.
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Old 26th Mar 2010, 5:55 pm   #49
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Default Re: Tv62

Oh I see, to be honest I'm having a nightmare reading this Trader sheet. Up until now the radio ones have been easy to read circuit description identified valves and cap functions. This TV one is hard to figure, no mention of py82 being a rectifier, Components diagrams don't reflect actuals........

This is going to take me ages to figure out.

forget the MR1 & MR2 thats to do with sync pulses and me clutching at straws to find rectifiers
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Old 26th Mar 2010, 6:03 pm   #50
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Default Re: Tv62

Just took the set off the bench and there was wax on the mat. Looks like it came from C73, who knows what that function is. its on the tuner side. Seems to do something around V15a V15b the EB91

Last edited by oldticktock; 26th Mar 2010 at 6:09 pm.
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Old 26th Mar 2010, 6:07 pm   #51
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Default Re: Tv62

V18 and V19 are diodes connected directly to the mains via a fuse which is a bit of a clue that they are rectifiers. I suppose it's a matter of familiarity with TV circuits but it's not really any different to a UY41 or whatever in a DAC90A. Just a lot beefier.

I've dragged out one of my TV62s. I've had them for a while and never touched them. I've clipped out C98 and C111. Now trying to get continuity through the heater chain. Not sure I'll be able to spend much time on them but if I can get power on then I can probably help you a bit more.

PS: After seeing your last post don't worry about C73. It's just a decoupler and if it's SC it'll just burn R81 which really doesn't matter at this stage.
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Old 26th Mar 2010, 6:12 pm   #52
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Default Re: Tv62

Cheers Jeffrey, see above re leaking wax, don't know if thats just a side effect and just a componet failing not related.
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Old 26th Mar 2010, 6:24 pm   #53
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Default Re: Tv62

Chris, Just one thing I would be extremely cautious of when firing up an unknown set like this. Does it have any waxxies decoupling any of the heater chain?

I ask as when I rebuilt my first TV22 half the valves suddenly went out and the remainder lit up like floodlights!

Not having the TV62 circuit I can't say if it applies. If it does just snip one end of the waxxies for now.

Dave
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Old 26th Mar 2010, 6:37 pm   #54
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Default Re: Tv62

Dave,

To be honest as I mentioned above, the circuit sheet is taxing me greatly. Having only worked on radios, and having descriptions of components and their function,

e.g.

C20/C21 HT smoothing
C15 AF Coupling
half wave rectifying valve (V5 Mullard etc )

this has always helped me in the learning process.

This is a whole new ball game for me, guess the component, guess the location....... I know it's second nature to the TV guys and I will get there in the end but certainly thinking bitten more than I can chew at this stage as I cannot tell my derriere from my elbow.

Those other DAC90a's on the shelf waiting work suddenly look inviting

Currently following Jeffreys lead.

Chris
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Old 26th Mar 2010, 6:52 pm   #55
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Default Re: Tv62

The component locations are all given in the parts list. For example C111 (the wax nasty on the heater chain) is at location E10. Look at the mech drawings and see that it's on a tag baord just below V10. Fairly easy to find a part number on the circuit as it's sort of logical, left to right increasing numbers.

Right, found the badly seated valve, ran up the heaters without hassle. Nice hot muck smell - this set is still full of cobwebs. Direct maisn to set. Apply HT via variac as I suggested using clip lead to top of F1. Up to 150V, leave it for a minute, no distress. Up to 180V and I can hear faint buzzes and line whistle. Up to 200V and the main line whistle kicks in. I can draw a small spark from the LOP anode with an insulated screwdriver. Don't earth the screwdriver when you're doing this! Drat - nasty purple glow from the EHT rectifier V11 which is on top of the LOPT. Either the rect is faulty or the heater winding has a short. I'll change the rect and see. If it's the heater winding I'll abandon it for now. Pull anode cap off EHT rect and run it up again. Line whistle sounds healthier. There's also a lead dangling from the scan coil assembly. It's got a sort of plug on the end but the socket isn't obvious. Worst that can happen is that I'll get a bright line rather than a raster though the frame output transformer may not be too happy. It's a bit like a valave audio amp without a speaker connected.

Curious. Trader says EHT rect is a wire ended EY51. Mine has a B9A valve. Probably EY86 but marking is faint. Same valve as EY51 but in different package. Maybe it's a production change or a replacement LOPT with different fittings.
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Old 26th Mar 2010, 7:10 pm   #56
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Default Re: Tv62

Hi Jeffrey,

I followed the component locations (grid refs) that was not the issue, the issue is my paxolin strip board seems to vary from the schematic. I've taken a photo of it and its orientated as per the schematic diagram. the components don't follow exactly

for example at the bottom R64 next up should be C111, its not there!

likewise C79 not there just a gap, unless they are hidden under, in which case this is going to be tricky and loads of potential to make mistakes as I will have to unsolder 12+ connections

Chris

P.s. An indirect benefit in helping me is you've started on one of those 62's which have been calling you for some love and attention.
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Old 26th Mar 2010, 7:16 pm   #57
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Default Re: Tv62

Are all the valves lit? if not could be cathode heater short or a wax decoupler on heater chain u/s.

David
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Old 26th Mar 2010, 7:21 pm   #58
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Default Re: Tv62

All valves lit although I did leave the cans on the back two (chassis still in case at mo) so hard to tell on those
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Old 26th Mar 2010, 7:23 pm   #59
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Default Re: Tv62

I'd say somebody has already removed C111. Have to say my tagboard looks very different to the picture. Probably a design change. I've found some bits of the printed Bush official manuals and there are certainly variants. Need the TV53 manual as well as the TV62. Some TV62 stuff downlaodable from http://www.thevalvepage.com/tvmanu/bush/bush.htm at bottom of page. Not anything like all you need but it might help.

Replaced the EY86 and it was the valve. Now getting EHT but nothing on screen at all. Probe around the CRT base. No first anode voltage (pin 10, should be 380V). MIght be R68 o/c or C57 s/c.

I'm probably going to stop now.

Has anyone got all the TV53/62 Bush manuals scanned?
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Old 26th Mar 2010, 7:28 pm   #60
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Default Re: Tv62

Great stuff Jeffrey, safe bet yours is going to be up and running before mine. Thanks for all you advice today, much appreciated. I've downloaded the document and shall digest

The figure showing underview of the main deck matches mine in the bush document. Some extra useful info there especially the picture centering device. I wondered what that was as it was very loose and moved around.

Last edited by oldticktock; 26th Mar 2010 at 7:40 pm.
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