Bas Cab Restoration

[746169746f]

Hi Everyone,

Further to jase38 kindly donating a Bas cab to me last year, I've finally started working on its restoration

I'm starting with the electronics and getting the tube up and running then I'll tackle the wood and getting this cab back to its former glory and perhaps add a few things to it

So far, I've turned the cab on and confirmed the tube suffers indeed from vertical collapse. I've bought a high voltage probe to discharge the tube and started working on locating the right component(s) to replace on the chassis.

I'm pretty sure I've located the vertical IC (hopefully) as follows, a Thomson TEA1020SP:


My experience with fixing CRT is limited and I'm proceeding with a lot of caution, any help to confirm my investigation would be awesome and much appreciated!

I've located a few people/stores selling this IC albeit with different value at the end (ie not 215) so any guidance on that would be also very welcomed!

 

[Bods]

Don't worry about the other numbers, as long as it's TEA1020SP thats the number, if it's that at fault

Do you know what make/model the Monitor is? quite old by the components

Just found they have the old TV Servicing Magazines online, some old Monitors used TV chassis without the Tuner sections like Philips, Panasonic

Television Servicing

 

[georgek]

Have you got any pics of your cab? I've got two bas cabs that need restoring so interested in the state yours is in!

 

[746169746f]

Don't worry about the other numbers, as long as it's TEA1020SP thats the number, if it's that at fault

Do you know what make/model the Monitor is? quite old by the components

Just found they have the old TV Servicing Magazines online, some old Monitors used TV chassis without the Tuner sections like Philips, Panasonic

Television Servicing

Thanks very much, yes it all looks quite old.

The tube itself is an ITT (Nokia?) FSX 30-11 from what I can tell, not sure about the chassis. I haven't found much info on ITT Tubes.

I saw a number of references to the very component I need (and now ordered) in the magazines that you shared. I then went to archive.org to look and query more of these and found a service manual for a TV that uses the TEA1020SP and found more details about its function:

Manual: SPECTRASK3TP3327 SM NORDMENDE DE : Free Download, Borrow, and Streaming : Internet Archive

Manual: SPECTRASK3TP3327 SM NORDMENDE DE

archive.org

Also a little bit of Chatgpt who reckons TEA stands for Transistorized Electronic Amplifier, also had a go with Bard and got some very creative results about the TEA1020SP

I will replace when I receive it (in about a week) and report back on how I'm progressing.

 

[746169746f]

Have you got any pics of your cab? I've got two bas cabs that need restoring so interested in the state yours is in!

Yes, you can find the pictures that were taken for the original post here: https://www.ukvac.com/forum/threads/bas-cab-gone.77002/

I've taken quite a few pieces off at the moment but happy to take any further pictures to help.

 

[gunblade]

brave switching that monitor on, hope you replaced all the electrolytic caps first and gave it a good blast off with air

that looks like vertical ic to me, check the vcc as well

 

[746169746f]

brave switching that monitor on, hope you replaced all the electrolytic caps first and gave it a good blast off with air

that looks like vertical ic to me, check the vcc as well

Thank you for the confirmation I'll check the VCC too I agree, I think brave and ignorant but to my defence I was standing pretty far from it when I switched it just in case. I'll do an inventory of the caps and order replacements, thanks for the advice. I should get the Vertical IC next week, had to order it from France since it's a Thomson (now ST Microelectronics) component, couldn't find any in the UK. I'll post an update with more images in case someone has or ends up with the same monitor/chassis.

 

[RolyRetro]

If you re looking for inspiration, check out my own BAS arcade restoration.

I love these cabs, very robust and scrub up well. Monitor repair by gun blade, and CPO from Olly at arcadeartshop.

 

[746169746f]

Thank you, I must admit I’ve spend quite a bit of time on your website, really awesome work. Hopefully I can restore mine to that standard

 

[746169746f]

Hi everyone, I spent the evening yesterday working on the cab I discharged the tube (4x time at a least, armed with plastic shoes and rubber gloves), although there seems to be a mechanism to do this automatically on the tube. I changed the vertical IC, dusted off the chassis and put it all back together. I was hoping for an image to appear but it was a bit of an anti-climax ... the problem persists still only one horizontal line is appearing on the screen.

I plugged an MVS board known to work and I didn't even get any sound. I get continuity from the Jamma connector for the sound all the way to the speakers, I tried with an old Jamma board to no avail. Pretty sure I have a few additional things to fix. Surprisingly the chassis has no traces of corrosion on the PCB once you remove the layers of dust and bugs. I did notice a bit of corrosion on the anode and the anode cup is starting to deteriorate slightly.

The monitor is an ITT A66-540X which apparently was quite common and I managed to find a bit of information on it.

My attention is now drawn towards the synchro and horizontal deflection control IC which is a TFK 243 TDA 2593. The TDA 2593 seems to be quite common, not entirely sure they are all the same but I will order one on eBay. Failing I'm not quite sure where to go outside of changing all the caps. The new vertical IC chip could be faulty but that's unlikely.

Any further thoughts? Would pictures of the chassis help?

 

[746169746f]

So after a long hiatus, I finally spent some time restoring my BAS cab and actually got it running for a bit! I dedicated an afternoon to testing the chassis to track down the origin of the vertical collapse (it wasn't the vertical IC but now I have a spare) and right at the end of the day the culprits revealed themselves: a couple of rusty pots. I de-soldered them, dunked them in pickle juice to strip the rust (surprisingly effective), and moved on.

Next steps:

• Put the cleaned pots back in
• Fixed the audio section
• Added a diode to my RGBPi as the coin mech were tested working
• Powered the cab up… and there it was, coming back to life again

I’ll admit, leaving it running was a very brave move. It held for a few hours even let me get some games in. The picture was full of distortion and artefacts at first, but after about an hour (while playing Hot Chase, which I strangely love) the image finally stabilised. My MVS worked perfectly on it but I didn't attempt using less common boards for now. The tube is immaculate, no burns, vibrant colours but the chassis clearly needs a lot of work.

Eventually, I had to shut it down again when the image started acting up and I caught a faint whiff of burning plastic coming from the board. So the next step is a full teardown and a hunt for replacement parts.