Update: the power adapter is fine. Supposed to be 12v, multimeter reads 12.3 which I understand is within acceptable variance.

So, really looking like I just need a totally new (to me) TBC because the chip is fried.

As per the photo you uploaded there is not just one but around 13 chips in this unit. See my (now second) marked up photo.

I dont mean to be unkind but the way you write here it seems like you cant tell a chip from a capacitor.

This field of endeavour is science/technology/engineering/mathematics (STEM field). Is that your field?
When we are not expert in a field, we normally pay others who are experts in that field to do the work for us.

I've worked in and for audiovisual archives myself. Still do. Again with Aramkolt and others I suggest you request your archive pay an expert in electronics service to check out the equipment. That is normal procedure and commonsense.

Definitely not an expert. Just trying to figure out where the problem is so I can decide what to do next: try to source a new TBC or find an actual expert who can do repairs. I was happy to try some basic things, but you're absolutely right that this is outside of my wheelhouse. (Although, in my defense I do know the difference between chips and capacitors, at least. I had the impression from replies here that there was one chip that had obviously malfunctioned.)

Since you still work with audiovisual archives, do you have recommendations for repair shops? I already have recommendations for:
https://www.precisionvideoservice.com/
https://backporch.tv/

It's not as simple as that. We take it to an expert technician to learn about what's going on with the gear. The service technician themselves may have to perform tests and even some repairs as part of a normally paid upfront "inspection and quote" agreement to hopefully determine what is/are the problems, and whether a repair is economical compared to the other options, and sometimes whether the repair is even possible. Sometimes after performing some initial work a tech may judge the particular problems are beyond their skillset and refer the customer to a better equipped or better situated tech, if available. Other times it's more straightforward.

Our advice here must of necessity be limited because we dont have the item on our bench for testing, and normally a customer would pay for expert inspection and quotation, and sometimes necessary repairs just to hopefully facilitate diagnosis of the faults.

Assuming you work in a large archive do your supervising staff already have at least one and preferably more service technicians on the books, skilled in the service of the vintage equipment needed for playback/digitisation of the various vintage tape formats you deal with?

VCRs, TBCs, etc, are specialized gear. And not just specialized, but sub-specialty for each. Knowing about cameras gives you zero qualifications to mess with TBCs.

So going to random repairmen, who have zero experience with Cypress TBCs, will rarely end well. Right now, this is likely correctable. After an inexperienced goober plays with it, it probably will not. Why? For the reasons stated above, a tech has to tear into it, to see what's possible. But if the tech is inexperienced with Cypress TBCs, he/she will tear it up.

FYI, that's why most units have disappeared (failed, trashed), and why irreparable "for parts/repair" units end up on eBay. Somebody thought they knew better than us, put on their "big boy pants" (armed with their Youtube/Google degree), and then essentially pooped in them. Play stupid games, win stupid prizes.

TBCs cost too much to FAFO. ;)

I want to help here, but I can't move as fast as others. (As I always say: I'm a person, with health issues, not Amazon Prime.) And I need to connect with somebody to make it happen.

BTW, the person that I want to work on this learned from my R&D TBCs. He got full access to multiple units (working, failed, and unreliable), and my various documentation over the years. And told to "have fun". He did; I did; we did. The troubleshoots were interesting, and he/we salvaged a few from the ashes. Others became fodder and paperweights.

@timtape, I think you vastly overestimate archive budgets these days. Having a tech on staff is pipe dream for probably 99% of such operations.

By "on the books" I mean outside technical companies/sole traders officially known to the organisation as competent and reliable operators and available to be employed when and as needed, and their details such as company name, company address, point of delivery etc officially recorded for regular inside staff, both current and future to contact and employ as required. I'm on such lists with a couple of archives.

Ah, yeah, I missed where you wrote "on the books". :smack:

The more formal way of saying "I got a guy". :laugh:

OT: I need one of those to fix our family's vintage 1970s stereo (the "piece of furniture" kind). I have everything needed to externally restore it, but the components output distortion, the 8-track eats tapes, and the record player has stuck speed (cannot change from 45 to 78, etc). Eventually, I'll at least fix the outside.