Philips 6652 battery? - Page 1
Forum section: electronics / repair

author: DrijSkij
author_rank: Contributor
timestamp: April 11, 2025, 06:37:39 pm
content: Hi all. I have an old 6652. Lately it seems like the unit needs about 5 minutes to boot up. When I press the on button, the only thing that will blink initially is one of the trigger level LEDs. Then, as time goes on the other indicators will slowly join in one by one. It's actually a bit funny to watch. So, this leads me to suspect that there may be a type of small battery that has gotten very dead and now needs to be "recharged" when then power come on. It seems like it's pulling all else down with it until it gets recharged. Any ideas? Thank you.

author: minifloat
author_rank: Contributor
timestamp: April 11, 2025, 09:31:19 pm
content: Hi, do you mean PM6652?This site ...http://ftb.ko4bb.com/getsimple/index.php?id=manuals&dir=Philips/PM6652_6654_Frequency_Counter... has a service manual and schematics to download. Usually these old Philips service manuals include everything one would need for troubleshooting.br, mf

author: DrijSkij
author_rank: Contributor
timestamp: April 12, 2025, 01:41:11 pm
content: Hi. been there , done that. Nothing that I could see from the schemas or the user manual.

author: DrijSkij
author_rank: Contributor
timestamp: April 12, 2025, 01:42:57 pm
content: Why would you think it would be the CPU clock? I'd like to hear your rationale. Thanks

author: DrijSkij
author_rank: Contributor
timestamp: April 12, 2025, 05:19:19 pm
content: Quote from: edavid on April 12, 2025, 02:52:07 pmI'm not sure you understood what I initially wrote. I took a video that's about 4:30 minutes long to show what a slow and unusual process it takes to get fully booted. I tried loading the video that I took from my phone but this forum won't accept mp4s? Strange.

author: gmac34
author_rank: Regular Contributor
timestamp: April 13, 2025, 07:52:37 am
content: I would check the voltages first. Small blu Philips capacitors often dry up and they might be bringing down one of the lines

author: DrijSkij
author_rank: Contributor
timestamp: April 15, 2025, 05:57:03 pm
content: Quote from: gmac34 on April 13, 2025, 07:52:37 amThanks for the most sensible answer thus far.However, I can understand that a cap would bring down a rail - but not temporarily like the issue I am facing.

author: gmac34
author_rank: Regular Contributor
timestamp: April 15, 2025, 06:05:21 pm
content: Well, I would not put it past a bad capacitor to have very bad ESR when cold and change just enough when warmed up to lower the ripple in a rail to an acceptable level.I would still check the voltage's as a good troubleshooting step.Also, I should have mentioned that one I had an issue with one of those counters, it would not start because of corrosion on the rom sockets, and in that condition you would just see some action on the trigger lights. I imagine they are just part of an analogue circuits independent of what the digital part is doing. And thus they are not an indication that the cpu is “booting”After voltages I would check if there is activity between the ROM ics and the microcontroller. I expect you would see its stuck in a loop trying to start.

author: DrijSkij
author_rank: Contributor
timestamp: April 17, 2025, 09:59:35 am
content: Quote from: gmac34 on April 15, 2025, 06:05:21 pmThank you again. I'm hesitant to tear it apart at this moment. However, if it gets worse I'll know where to begin the search.