TT Phihong PSM-5341 repair and recap

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TT Phihong PSM-5341 repair and recap

Post by Steve » Tue Jun 29, 2021 1:11 pm

Been working on this for a customer, said his TT would just randomly shut down with a 'wheeee' noise and then refuse to turn on. Sent it to me and under testing sure enough it would turn on for 5 seconds and then shut down. Wasn't sure exactly to the cause so I started with a full re-cap, which didn't fix the problem.

After inspecting the underside of the PCB I noticed the usual track cut from the factory wasn't 100% done properly, so I cut the trace fully and retested. But no it still showed the same behaviour.

I then suspected the opto-isolator because I've read that the trace cutting is somehow related to it, so it's possible it could have died due to the trace not being cut properly. So swapped it out for the proper Sharp pc-111 (because it had the 'bad' type) and voila, it now works perfectly :)

Before re-cap:

PXL_20210629_094134429.jpg (389.88 KiB) Viewed 574 times

After re-cap:

PXL_20210629_101111676.jpg (411.89 KiB) Viewed 574 times

The almost-cut trace:

PXL_20210629_101751254.jpg (362.03 KiB) Viewed 574 times

Swap opto-isolator:

PXL_20210629_105556074.jpg (338.25 KiB) Viewed 574 times

New opto:

PXL_20210629_105815859.jpg (338.34 KiB) Viewed 574 times


PXL_20210629_111122380.jpg (410.9 KiB) Viewed 574 times


PXL_20210629_111133593.jpg (409.69 KiB) Viewed 574 times


PXL_20210629_111147239.jpg (413.1 KiB) Viewed 574 times

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Re: TT Phihong PSM-5341 repair and recap

Post by thesofa » Wed Jun 30, 2021 3:56 pm

Thank you so much for an excellent job, first class fast service and good comms.
Cheers sir
TT030 with Storm with 256 Mb Ram, Thunder with a CF drive and Lightning, HxC floppy emulator and one of Codekiller's magical Mono/Colour switchers, also 3 STS one has TOS1.0 AND 2.06 switchable with an HD drive, the other two are untested as yet, just bought for spares!!

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Re: TT Phihong PSM-5341 repair and recap

Post by rubber_jonnie » Wed Jun 30, 2021 4:20 pm

Nice one, and you've just reminded me, I think need to order opto isolators for my Mac Classic.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...

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