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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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18th May 2022, 9:50 am | #1 |
Tetrode
Join Date: Mar 2022
Location: London, UK.
Posts: 75
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Revox PR99 Keeps Blowing Fuse
Hi All,
My RevoxPR99 started giving me problems yesterday. It was suddenly jumping out of record mode. As the day wore on it started dropping out of record and also the counter display would go out. After turning on and off it could be put into record again and was fine for the rest of the day. Got the job done Came in the morning to have a look at it and see if I could figure out what the issue. But now it will immediately blow a fuse when turned on. The fuse that blows is the empty fuse holder in the photo. Any thoughts on what to test first would be greatly appreciated. Many thanks Ed |
18th May 2022, 12:26 pm | #2 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,670
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Re: Revox PR99 Keeps Blowing Fuse
Could be the rectifier or smoothing on that circuit breaking down.
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18th May 2022, 1:39 pm | #3 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
Posts: 273
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Re: Revox PR99 Keeps Blowing Fuse
That is the fuse for the 21v power supply to the electronics.
You have obviously got a short circuit on that line. If you have an Avo meter check the resistance on the 21v line and fault find from there. Suspect are the Fraco's and riva's caps. Ckeck the suppression cap across the mains input supply, it is behind the panel with the mains socket and fuse holder on it. If it has not been changed, it will blow eventually, and blow the mains fuse. John. |
18th May 2022, 5:23 pm | #4 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,224
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Re: Revox PR99 Keeps Blowing Fuse
I have had the bridge rectifiers fail on these recorders. You have to remove the power transformer to get to it.
I suggest you also replaced the two 2200uF capacitors on the power board. Whilst you are working on the machine, replace the Rifa capacitors, one on the capstan control board, the other across the mains (Located on the panel where the mains input socket and the fuse holder are located. |
18th May 2022, 6:25 pm | #5 |
Tetrode
Join Date: Mar 2022
Location: London, UK.
Posts: 75
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Re: Revox PR99 Keeps Blowing Fuse
Thanks Guys!! Fantastic advise.
Going to spend a day on it this week. I'll report back Thanks again |
19th May 2022, 1:12 pm | #6 |
Tetrode
Join Date: Mar 2022
Location: London, UK.
Posts: 75
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Re: Revox PR99 Keeps Blowing Fuse
Hi All,
I believe the problem is the rectifier connected to the fuse in question. The test results below are taken with the rectifier still soldered to the PCB. MM in diode mode. With + probe of MM on - of rectifier: - to AC pin 1 - 001 - to AC pin 2 - 663 With - probe of MM on + of rectifier: + to AC 1 pin 1 - 663 + to AC 2 pin 2 - 636 Same test on the other rectifier gives readings of around 650 throughout. Markings on the original Rectifier are KBPC1-01 204. I was going to replace them with these. what do you think: https://uk.rs-online.com/web/p/bridg...ifiers/7005478 For the two capacitors: https://uk.rs-online.com/web/p/alumi...citors/1084992 Any thoughts on a good replacement for the RIFA cap? (0.47 uf150v 60Hz) I tested the 3 caps behind the mains cable socket and they all appear ok. Thanks so much guys. Ed |
19th May 2022, 1:45 pm | #7 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: Revox PR99 Keeps Blowing Fuse
In 2000, I bought an ex broadcast PR99MK3 for £500 - a bargain, I thought.
It worked fine the first time powered up, but the second time the fuse blew - yes it was the bridge. I was able to replace it with the pcb in situ - I used a 200V version. I would use a 105 degree type for the capacitor though rather than the 85 degree shown. |
19th May 2022, 3:03 pm | #8 |
Tetrode
Join Date: Mar 2022
Location: London, UK.
Posts: 75
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Re: Revox PR99 Keeps Blowing Fuse
Dont think RS do a 200v version. Keen to use RS as i can get the parts by tomorrow. Have an account.
So was thinking of ordering these today: https://uk.rs-online.com/web/p/bridg...ifiers/7005478 and https://uk.rs-online.com/web/p/alumi...citors/7111510 Do you think they will suffice? Thanks guys |
21st May 2022, 8:11 am | #10 | |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,600
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Re: Revox PR99 Keeps Blowing Fuse
Quote:
David |
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27th May 2022, 3:30 pm | #11 |
Tetrode
Join Date: Mar 2022
Location: London, UK.
Posts: 75
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Re: Revox PR99 Keeps Blowing Fuse
!!!!PR99 WORKING!!!!
Thanks so much everyone. Hardest part was getting the PCB out so I could change the components. Ed |