First time capacitor replacement

balford · October 2013

Thermally challenged users should upgrade to a toastrack for best results :D

Edge · October 2013

I prefer the use of a nice toasty power pack :D take it to bed for that hot water bottle feeling after a night of gaming!!

balford · October 2013

I think Rick Dickinson's sketch on this topic is appropriate here :-)

Edge · October 2013

Ok, Rapid gave me the run around....

So I am opting for Farnell.ie
They offer a fair size range of Axial capacitors, so i don't want to pick up the wrong one (not being electronic expert!)

I know you need to keep an eye on the size, max size around 5-6mm in width and 12-13mm in length, Exactly the same uF, voltage close as you can (but higher), both of the below fulfill that, so what other things do i need to ensure to get the right replacement?

With Rapid the codes had been put up, so much easier to navigate :D

for example:-

the below two options are 22uf, 25V replacements (tolerance and temperature differ - I have seen mention of temperature at 105c for near heatsinks)

http://ie.farnell.com/vishay-bc-components/2222-138-36229/capacitor-22uf-25v-axial/dp/2113009
The above is ?1.81 each

http://ie.farnell.com/jsp/search/productdetail.jsp?sku=1165420
The above is 47c each

can anyone let me know or better still explain which i should opt for (will most likely be same for the 1uf, 100uf and 4.7uf i need.

P.S. I am looking to avoid using U.S. Stock as it pulls a ?20 charge on top!

Thanks guys!!

balford · October 2013

You could always use radial components and bend one leg over the cap if you're not too worried about originality, these will be much cheaper?

B

Edge · October 2013

balford wrote: »

You could always use radial components and bend one leg over the cap if you're not too worried about originality, these will be much cheaper?

B

I could indeed, I saw a few threads on how to achieve that, was going to try Axial as first time out doing this :) but would probably face the same question.....

I followed the advice here and sourced from other threads, but as i said above.

Aluminium Electo leaded -
correct Uf - check!
close enough Voltage - Check!
temperature either 85 or 105-Check!
size to fit - Check!

gives me over 30 options --Eeeek!

Axial preferred and I still get a list of 3, one from U.S. so discount it, leaves me those two.

Does 50+ tolerance vs 20+ have a factor?

Was really more concerned that i buy the wrong part, as i can see no difference between the two above, yet one is nearly 4 x as much? It's not going to be terribly expensive either way - It's the part I am concerned about.

1024MAK · October 2013

These should be okay:

Edge wrote: »

http://ie.farnell.com/jsp/search/productdetail.jsp?sku=1165420
The above is 47c each

But keep in mind

Order Multiple: 5

If you get stuck, I have some spare from the list I posted earlier of Rapid parts. I have no idea how much it would cost to post them to you, but I would only charge cost price of postage & cost price of parts.

Most of the capacitors are used on the +5V supply, so 10V parts are also okay for some positions (I forget if I posted this info, if not I can - just ask). Modern electrolytic capacitors are normally smaller, so that should not be a problem.

Mark

1024MAK · October 2013

Edge wrote: »

gives me over 30 options --Eeeek!

Yes, sometimes too much choice is not helpful :-o

Edge wrote: »

Does 50+ tolerance vs 20+ have a factor?

Not really. All electrolytic capacitors have very wide tolerances.

Edge wrote: »

Was really more concerned that i buy the wrong part, as i can see no difference between the two above, yet one is nearly 4 x as much? It's not going to be terribly expensive either way - It's the part I am concerned about.

The more expensive one is a slightly better part. But this would make no difference to the Spectrum, so no point paying for it.

Mark

Edge · October 2013

Once again, thanks lads for the advice :) I'll work away on those capacitors.

I noticed they stock this:-

http://ie.farnell.com/diodes-inc/ztx651/transistor-npn-60v-2a-e-line/dp/9525572

.......the ZTX651 which i understand can be used as a substitute for the ZTX650 (Obsolete) (TR4)

for TR1,2, 3 & 6 - the ZTX313(Obsolete) which can be replaced with BC172, BC183, BC238, BC383 (From another thread) although i cannot find any of these listed?

neither can i find the TR5 - ZTX231(obsolete) which can be replaced with BC251, BC307, BC512, BC557?

This really stems from the fact that, as most these parts are less than a euro each, i don't mind throwing them on the shelf like i said earlier.

Any ideas??

balford · October 2013

For what it's worth, I've used ZTX653 and BC557B's as replacements for the 650/213 respectively on a grey +2 successfully.

No reason why this wouldn't work on a 48k I think, I can try them out later on.

B

1024MAK · October 2013

Replacement transistors

TR1 - ZTX313

Replacement #1
TR2 - ZTX313

Replacement #1
TR3 - ZTX313

Replacement #1
TR4 - ZTX650

Replacement ZTX651
TR5 - ZTX213/BC213 --- Replacement BC557C
TR6 - ZTX313

Replacement #1
TR7 - ZTX450

Replacement ZTX450
TR8 - BC184/BC549B --- Replacement #1
TR9 - BC184/BC549B --- Replacement #1

#1 - I use BC549B or BC549C, but many NPN types will work.

Note that in some positions the transistor goes in the opposite way round compared to the markings on the board.

Mark

1024MAK · October 2013

Edge wrote: »

neither can i find the TR5 - ZTX231(obsolete) which can be replaced with BC251, BC307, BC512, BC557?

I think ZTX231 is a typo that keeps being carried forward, as the transistor in position TR5 on my boards are ZTX213. This is the type shown on schematics as well.

I can only find references to a ZTX231 on Spectrum related documents, it does not appear in data books or data sheets (unlike a ZTX213 which does have published data)

Mark

1024MAK · October 2013

Data sheets
ZTX213
ZTX313
ZTX450
ZTX650 and ZTX651

BC549C
BC557C

The data sheets give the lead-outs diagrams.

Mark

Edge · October 2013

Triple post! Love it :D

Thanks, be sorting my parts order tonight, also decided to go and recap my amiga while I'm at it, but that's not for this forum!! But all this advice has me well set up now.

Ill be back with an update soon enough, as I am sure i wont be lucky enough for the recap to make it spring to life :p but its a good start!

Macc · October 2013

Just to be sure, the ztx213 and the BC557c are opposite in e,b,c?

balford · October 2013

Answer is in the datasheets that Mark linked to :)

1024MAK · October 2013

This help? :p

Mark

schombi · October 2013

Did I get this right that TR4, which normally is a ZTX650 on a grey +2, can be replaced with ZTX653?

Could someone please update thread http://www.worldofspectrum.org/forums/showthread.php?p=160656#post160656
and make it sticky?

1024MAK · October 2013

schombi wrote: »

Did I get this right that TR4, which normally is a ZTX650 on a grey +2, can be replaced with ZTX653?

Yes, a ZTX650 can be replaced by either a ZTX651 or a ZTX653.
The ZTX651 and ZTX653 are higher voltage versions.

Mark

DEATH · October 2013

Not sure why, but I seem to have lost the ability to edit that thread.

Any moderators about?

Macc · October 2013

Just to confirm what ive just looked at ZTX213 and BC213B are opposite pinouts yeah?

DEATH · October 2013

Pretty much any general purpose PNP transistor will work in that position - if you use a ZTX 750 then you don't have to worry about pin outs - the 750 and 213 both being in an E-LINE package. Although the '750 is way over-spec for what's needed, it will still work perfectly well and wll remove any doubt as to the pin-outs etc.

48p each - not gonna break the bank either.

http://www.bowood-electronics.co.uk/product_info.php/ztx751-p-982

The 751 is a higher voltage spec device - as the 651 is to the 650.

Zorn · October 2013

The subject of this thread is a very frequently asked about topic, so I have created my own guide to replacing the electrolytic capacitors in a Spectrum.

DEATH · October 2013

Zorn wrote: »

The subject of this thread is a very frequently asked about topic, so I have created my own guide to replacing the electrolytic capacitors in a Spectrum.

Yes, I've subscribed to your channel - you sir would make an excellent teacher.

We do need the substitution thread made stick and editable by me (since it's my first initial post), however I have lost the ability to edit the post, and the moderators seem to have deemed it unnecessary to be made a sticky. Maybe they haven't seen it, I shall PM Foggy and see what he reckons.

Edge · October 2013

Zorn you are the man, thanks for that another great vid! Reminds a little of the OU on BBC many moons ago :D

schombi · October 2013

Great, thanks! I already subscribed your channel. Very useful.

Edge · October 2013

Update time...

So I got a little package in the post today from farnells, and spent an hour or so installing the replacements. As you pointed out, on my board version 2, one of the capacitors is indeed the wrong way round from the board markings, I installed as was removed.

First pic of the handy work( well it is my first attempt!) of suggested radial installation fairly straightforward with s little patience

The others are of the unfortunate results having completed the composite mod :(. Time to do some testing I assume!! It starts with border and black screen, then repeatedly fills with the same junk. Any indicators? I did notice that the +12v to the lower chips is only 10.4 where ad the rest check out at 0, +5 and -5

Zorn · October 2013

10.4 V could be OK, but it's a bit further off than usual. I'd still suspect a problem with the lower RAM or its power supply.

balford · October 2013

The low +12v rail voltage is a worry alright, although the screen doesn't exhibit the typical pattern of a lower RAM failure any more.

I'd reckon the fault is most likely in the upper RAM area.

You could try following the service manual diagnosis steps here.

Alternatively I seem to recall you're based in Ireland, if you're anyway close to north Dublin I'd be glad to take a look at the board for you?

B

roko · October 2013

The +10.4V most probably is just the +9V 'power' peeping through. Use -5V to check a working voltage convertor.

First time capacitor replacement

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