Search found 1313 matches
- Wed Apr 24, 2024 11:52 am
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
Re: PSU Primary side issue (non QL)
Using my crude methods the new thyristors test very similar to the removed part. So I'll fit a new (NOS) one and will then test voltages at various places on the secondary side. What I can also do - as various other boards are plugged into the main PSU board - is remove some/all of them and see if t...
- Sun Apr 21, 2024 8:27 pm
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
Re: PSU Primary side issue (non QL)
I ordered a couple. Cheap enough and easy to swap.
- Sat Apr 20, 2024 11:42 pm
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
Re: PSU Primary side issue (non QL)
If you have a multimeter with a DC input voltage rating of 500v or higher - you should be able to measure across the main capacitor - on DC voltage range - you should see some 350-400V. You could also check the stripe (cathode) side of the rectifiers on the secondary side - these should give some i...
- Sat Apr 20, 2024 5:50 pm
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
Re: PSU Primary side issue (non QL)
My 'scope isn't rated for that high. I wonder if that new big cap is crap.
- Sat Apr 20, 2024 5:06 pm
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
Re: PSU Primary side issue (non QL)
I get 320v across the big cap (C395) but from the cap negative to pin 5 of the transformer (the circled test point no.1) the multimeter throws a fit but did briefly show around 11v. Not 400v!
So that seems to confirm that the issue (assuming it's the only issue) is on the primary side?
So that seems to confirm that the issue (assuming it's the only issue) is on the primary side?
- Sat Apr 20, 2024 4:49 pm
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
Re: PSU Primary side issue (non QL)
Thanks ever so much Pr0f. There is indeed an illustration of what to expect at those circled points: GrundigPrimary2.jpg Before I dig out the oscilloscope, circled no.1 should be approx 400v and it's one of the winding ends (the 5 between 5 and 3). But I assume it should be 400v between circled poin...
- Sat Apr 20, 2024 3:12 pm
- Forum: The Off-Topic Section
- Topic: PSU Primary side issue (non QL)
- Replies: 12
- Views: 248
PSU Primary side issue (non QL)
I know there are some expert electrical gurus here so thought I'd post this issue... This schematic is the primary PSU side of a 1993 Grundig GV280S VCR. Mains comes in at the top, optocoupler bottom right and you can just about see the secondary windings along the bottom. GrundigPrimary.jpg I bough...
- Mon Apr 08, 2024 7:05 pm
- Forum: The Off-Topic Section
- Topic: The Victorian Age
- Replies: 5
- Views: 248
- Mon Apr 08, 2024 6:01 pm
- Forum: The Off-Topic Section
- Topic: The Victorian Age
- Replies: 5
- Views: 248
Re: The Victorian Age
One of mine was, but only just (1900). The others were 1915 and 2x 1926.
- Fri Mar 22, 2024 3:56 pm
- Forum: General QL Chat
- Topic: Quick Disassembly Question
- Replies: 6
- Views: 232
Re: Quick Disassembly Question
I think that's the insulation thing that is normally pressed/glued against the RF shield that covers the ULA on mdv1_ (the other drive doesn't have one).