Mtc9000 ? I think ..

[gunblade]

polarity don't matter on those caps
the reason I dummy load at the HOT collector first is to see if there are any shorts in deflection circuit, all you did was prove b+ is ok
i would not be too confident in that flyback either as i know where its from
Do you have an eht probe so you can see if you get initial HT and what level it is?

 

[Retroman839]

Nah I don’t have one yet

I mean I’m going round the houses because I can’t prove the flyback is knackerd ..
By proving everything els is ok ..
Which I don’t mimd Doing because it’s good practice for me.


I will try to get a eht probe

It’s all pointing to a short in flyback
Case has HR embossed .
I thought right from the get go that even good flyback can still be bad right ? 1 in 100 or the like
1 in 1000 maybe

I have a flyback tester hr diemen but for 31khz only ..

 

[gunblade]

you are taking quite a risk doing chassis repairs without one

 

[Retroman839]

👍 I will get one

 

[Retroman839]

I will wait for esr meter to arrive
Then Check this cap ..
Will try to get eht probe asap also thanks

 

[gunblade]

i bought a batch of 7215 some years ago from that supplier and all of them failed after 10 to 20 hours of use

 

[Retroman839]

i bought a batch of 7215 some years ago from that supplier and all of them failed after 10 to 20 hours of use

Yeh I remeber lots of talk regarding dodgy batches

 

[Retroman839]

Regarding loading the collecter of the hot to prove vertical deflection circuit is oporational ..

Do I just do as you’ve mentioned ..
Clip positive of bulb on to collector , Gnd to heat sink ? Nice glow
Vertical ic and circuit is good ?

 

[gunblade]

loading on collector of HOT on this chassis will not prove the 26v for the vertical as chassis has to be fully running. if lamp is super bright then flyback has a short, if lamp is at a level you would expect then likely flyback is ok but not always
if r94 is good then in general you should expect the vertical ic to be ok
things to check when you have good b+ but no chassis start up
D27,C36,r94,zd1,ic2, flyback

 

[Retroman839]

Not checked d27 or zd1..
Ic2 do you check it has the input voltage first ?

12vdc, I should
Check that!…
That’s the leaky zd1 then if no 12v

 

[gunblade]

another issue which is common with this age chassis is corroded diodes, i pick at every diode with a screwdriver to check their integrity

 

[tb2000]

By the way you can't change the B+ on the MTC9000, it's set automatically by the psu section. Yours looks ok though as said.

 

[Retroman839]

another issue which is common with this age chassis is corroded diodes, i pick at every diode with a screwdriver to check their integrity

I will do that ..
What kind of eht probe should I get

 

[gunblade]

Test Equipment SAT 40KV - HIGH VOLTAGE PROBE 40KV DIEMEN... - UK (GBP)

sat 40kv, high voltage probe 40kv diemen eht measurement/screen (g2) and focus voltage

www.donberg.co.uk

 

[Retroman839]

Test Equipment SAT 40KV - HIGH VOLTAGE PROBE 40KV DIEMEN... - UK (GBP)

sat 40kv, high voltage probe 40kv diemen eht measurement/screen (g2) and focus voltage

www.donberg.co.uk

I will try rhat again
Last time.. It was out of stock

Also does that require a bench meter ?
Some have a built in meter

 

[Retroman839]

Can I run this chassi with r11 leg lifted out to rule out xray protection being sensitive ?

 

[M K L]

I will try rhat again
Last time.. It was out of stock

Also does that require a bench meter ?
Some have a built in meter

Standard multimeter is fine. Here's the SAT-40KV in action:

 

[big10p]

Can I run this chassi with r11 leg lifted out to rule out xray protection being sensitive ?

Grant already mentioned that this older version doesn't have x-ray protection. I didn't know this until he said.

 

[Retroman839]

Grant already mentioned that this older version doesn't have x-ray protection. I didn't know this until he said.

Yeh I did think about that .
But I thought that maybe r11 was still doing something even though some other componants still missing .

I only ask because if it’s pointless i can solder the leg back

 

[Retroman839]

Standard multimeter is fine. Here's the SAT-40KV in action:
View attachment 68003

Ah that’s cool ..
Will see if it’s in stock